权利要求：
CLAIMS
1. Apparatus for the deposition of successive layers of a powder material onto a print bed to enable the production of components by additive manufacturing, such as laser- based additive manufacturing from CAD files, in which each layer is subjected in turn to selective heating, such as to above the melting temperature for the metal powder material, by focussed electromagnetic radiation providing selective melting; wherein apparatus includes a housing defining a processing chamber in which a non-reactive or inert atmosphere is able to be maintained and. within the processing chamber, a system for the deposition of successive layers of powder material onto a print bed of the apparatus, wherein the system has an elongate, powder material spreader member that has its longitudinal extent disposed in a first direction over, and in close juxtaposition to, an upper surface of the print bed; at least one mounting member by which the spreader member is supported, at an end of the spreader member, for reversible movement of the spreader member in a second direction normal to the first direction across and between opposite sides of the upper surface of the print bed; and a powder material supply device located above one side of the print bed and operable to discharge under gravity or gas pressure, via an outlet member, successive charges of the powder material such that the spreader member is able to spread a charge of the powder material over the upper surface in being moved from the one of the opposite sides to the other of the opposite sides.
2. The apparatus of claim 1 , wherein the spreader member is in the form of an elongate vessel, such as an open-topped trough of U- or V-shape in transverse cross-sections, such that the vessel is movable to the one side of the opposite sides of the upper surface of the print bed so as to be locatable under the outlet member of the powder material supply device for receiving a charge of the powder discharged from the supply device, with the vessel provided with a slit forming a narrow elongate opening through which the powder material of the charge is able to flow onto the upper surface of the print bed and form a layer of the powder material as the spreader member is moved from the one, to the other, of the opposite sides of the print bed.
3. The apparatus of claim 2, wherein the spreader member has a capacity for holding a charge sufficient for forming a single layer of the powder material as the spreader
member is moved from the one, to the other, of the opposite sides such that the spreader member is required to return to the one side in order to receive a respective further charge of powder material, or a respective powder delivery supply device is provided above each side of the print bed to enable successive charges to be received from alternative supply devices.
4. The apparatus of claim 2, wherein the spreader member has a capacity enabling it to hold a charge of powder material sufficient to form two successive layers, comprising a first layer formed as the spreader member is moved from the one, to the other, of the opposite sides, and a second layer formed as the spreader member returns to the one side.
5. The apparatus of any one of claims 1 to 4, wherein there is only one mounting member by which the elongate spreader member is mounted for reversible movement between opposite sides of the print surface, with the other end of the spreader member resting on a support surface extending between those opposite sides so the spreader member is able to slide over the support surface as the one mounting member moves the spreader member.
6. The apparatus of any one of claims 1 to 4, wherein there is a respective mounting member supporting the spreader member at each end of the spreader member with the mounting members operable in unison to move the spreader member between the opposite sides of the upper surface of the print bed.
7. The apparatus of claim 5 or claim6, wherein the or each mounting member comprises a carriage device that is moveable along a track, or a respective track, extending between the opposite sides of the print surface, under the action of a drive device, or a respective drive device.
8. The apparatus of claim 7, wherein the drive device, or each drive device, is located within the processing chamber.
9. The apparatus of claim 7, wherein the drive device, or each drive device, is located externally of the housing and is operable through a wall, or a respective wall, of the housing.
10. The apparatus of claim 9, wherein the, or each, drive device is magnetically coupled to the carriage, or a respective carriage, through by the wall, or the respective wall, of a ferromagnetic material, with the or each drive device including a magnet and a linear drive for reversibly moving the magnet along a path along the wall, or the respective wall, of the housing, with the carriage, or the respective carriage, being of a ferromagnetic material or comprising a magnet that is magnetically coupled to the, or a respective, magnet of the drive device through the wall, or the respective wall, of the housing.
1 1.The apparatus of claim 10, wherein the arrangement is such that the magnet of the drive device, or the respective magnet of each drive device, is movable to thereby move the carriage with which it is magnetically coupled, and to thereby advance the spreader member across the print surface, as required for spreading a layer of powder material across the print surface. i 2.The apparatus of any one of claims 1 to 1 1 , wherein the powder material supply device is in the form of a hopper that, at or towards a top level, has an inlet, with the outlet member at or adjacent to a lower level, with the supply device fully contained within the housing, with a supply conduit or other suitable feed device providing communication between the inlet of the hopper and a supply source for powder material that is located outside the housing, to enable a flow of make-up powder material from the source to the hopper, as required, or with the supply device having an upper end portion that projects through an upper part of the housing such that the inlet is outside the housing for similarly receiving make-up powder material from the supply source; the hopper in each case being in the form of a container separable from the housing, or defined in part by a wall of the housing on which is mounted a fitting that, with the wall, forms a container comprising the hopper.
13.The apparatus of claim 12, wherein the outlet member is of elongate form and of a length that is the same, or substantially the same, as an elongate open top of a
vessel comprising the powder material spreader member, the outlet member having an elongate valve member that is rotatable on a longitudinal axis between a first position in which it enables powder material to flow from the hopper into the vessel and a second position in which it prevents such flow.
14.The apparatus of claim 13, wherein valve member comprises an elongate rod of circular cross-section through which a plurality of longitudinally spaced transverse holes extend through the rod, such as in a common longitudinal plane, with the holes enabling the flow of powder material from the hopper when the rod is rotated to the first position.
15.The apparatus of claim 1 , wherein the housing has an upstanding peripheral wall defined by a first and a second, mutually perpendicular pairs of opposed walls, such as with the walls of each pair substantially parallel, a base on which the peripheral was stands, and a top cover, the walls of the first pair comprising sidewalls, with the walls of the second pair comprising a front wall and a rear wall; the powder material supply device comprises a hopper located within the container, adjacent to and along one sidewall, or a respective hopper located adjacent to and along each sidewall; the powder material spreader member is supported above but close to the print surface, with the extending between the front and rear walls and so that the spreader member is movable laterally in a direction extending between the sidewalls; the spreader member is supported at each of its ends by a respective mounting member and is laterally movable by a respective drive system acting on each mounting member; the respective drive system for each mounting member including a linear drive, such as a stepper motor, located externally of the housing and operable to engage indirectly with a respective mounting member and operable to move a magnet device that provides a magnetic coupling with a respective mounting member, by the coupling acting through a respective one of the front and rear walls such that as the drive system acts to move the magnet device, the magnetic coupling causes the mounting member to move in unison with the magnet device thereby to move the spreader member laterally across the print surface.
16.The apparatus of claim 15, wherein each mounting member is movable along a respective rail secured within the housing, adjacent to the respective one of the front
and rear walls, with the drive system secured below the base defining the print surface, with a magnet of the magnet device supported on and movable along an upper surface of the base, such as on a rail fixed on the base outside the respective one of the front and rear walls; and wherein the drive system consists of a stepper motor mounted below the base, with the motor having an output shaft connected end- to-end to a threaded shaft mounted under the base and fixed against movement in the direction of its axis; the magnet device having a depending arm that extends below the base from the magnet with the arm having a threaded bore through which the shaft extends in threaded engagement; whereby with actuation of the stepper motor, the shaft is rotated on its axis, thereby causing the magnet and arm of the magnet device to progress along the shaft, in a direction determined by the direction of rotation of the threaded shaft.