Additive manufacturing apparatus with a chamber and a removably-mountable optical module; method of preparing a laser processing apparatus with such removably-mountable optical module

Abstract

An additive manufacturing apparatus comprises a processing chamber (100) defining a window (110) for receiving a laser beam and an optical module (10) The optical module is removably-mountable to the processing chamber for delivering the laser beam through the window. The optical module contains optical components for focusing and steering the laser beam and a controlled atmosphere can be maintained within the module.

Claims

1. An additive manufacturing apparatus comprising: a processing chamber containing a planar build surface; a plurality of lasers for generating laser beams having different properties; an optical system for independently steering each one of a plurality of laser beams to direct a spot of the laser beam to the planar build surface and having an optical module with a plurality of optical trains, each optical train delivering one of said plurality of laser beams to the planar build surface.

2. An additive manufacturing apparatus according to claim 1, wherein the different property is wavelength of the laser beam.

3. An additive manufacturing apparatus according to claim 1, wherein the different property is power of the laser beam.

4. An additive manufacturing apparatus according to claim 1, wherein the optical system comprises different set ups of optical components for steering each laser beam.

5. An additive manufacturing apparatus according to claim 4, wherein the different optical set ups comprise optical components of different optical materials or different optical coating materials suitable for the properties of the laser beam.

6. An additive manufacturing apparatus comprising a processing chamber, a plurality of lasers for generating a plurality of laser beams and an optical module comprising a housing containing a plurality of optical trains for delivering the plurality of laser beams into the processing chamber simultaneously.

7. An additive manufacturing apparatus according to claim 6, wherein each optical train of the plurality of optical trains has an identical set-up of optical components to allow for the delivery of multiple identical laser beams to the processing chamber.

8. An additive manufacturing apparatus comprising a processing chamber and an optical module for delivering a laser beam into the processing chamber, the optical module comprising a housing, the housing containing optical components for focussing and steering the laser beam, wherein walls of the housing define cooling channels for carrying cooling fluid for cooling the module.

Description

(1) Preferred aspects of the invention will now be described in detail with reference to the drawings in which

(2) FIG. 1 illustrates a schematic cutaway of an optical module showing some of the optical components contained therein.

(3) FIG. 2 is a schematic illustration of the optical module illustrated in FIG. 1 mounted as part of a laser processing apparatus to direct a laser beam into the processing chamber of the laser processing apparatus.

(4) FIG. 3 illustrates a cutaway view of an optical module mounted as part of a SLM apparatus to direct a laser beam into the build chamber of the SLM apparatus.

(5) FIG. 4 illustrates a cutaway view of an optical module mounted as part of a SLM apparatus to direct a laser beam into the build chamber of the SLM apparatus.

(6) FIG. 5 illustrates a perspective view of an optical module as illustrated in FIG. 4 or 5 mounted onto and forming part of a SLM apparatus.

(7) FIG. 6 illustrates a laser module embodying the invention mounted to direct a laser beam into the processing chamber of a laser processing apparatus with a separator component arranged between the optical module and the processing chamber.

(8) FIG. 1 shows an optical module 10 for delivering a laser beam to a manufacturing apparatus. The module comprises a hermetically sealable housing 20 including a rigid base plate 25. The housing, including the rigid base plate 25, provides a rigid chassis that substantially reduces or eliminates distortions during use. Even minor distortions to the chassis could compromise the sensitive alignment of components within the module.

(9) An interface 30 through the housing couples to a fibre optic cable to deliver a laser beam to the module from a laser source.

(10) The laser source could be any suitable laser source for example a yttrium aluminium garnet (YAG) laser source or a diode laser or a disk laser. Lasers having longer wavelengths such as, for example, a C0.sub.2 laser may also be used with suitable modification to the interface supplying the laser into the housing (longer wavelength lasers are not usually supplied via a fibre optic cable).

(11) The laser source will be primarily selected according to the wavelength of the laser and the power produced by the laser source. A preferable laser source is a ytterbium fibre laser, typically having a power up to 400 watts for example 50 watts or 100 watts or 200 watts. Preferably the laser source will supply a collimated output beam via optical fibre cable to the optical fibre interface 30 of the optical module 10.

(12) The purpose of the optical module is to take the beam produced by the laser source, configure the beam to the required characteristics, and deliver it to a work-piece. In a preferred example (as schematically illustrated in FIG. 1) the delivery path or optical path of the laser beam includes a beam expander 40, a varioscan module 50, a galvanometer scanning head 60 and a flat field objective (f-theta lens) 70.

(13) As is also schematically illustrated in FIG. 1 a second delivery path or optical path of the laser beam includes a second beam expander 40′, a second varioscan module 50′, to direct laser beams into processing chamber 120. Such second delivery path would also have its own scanning head and f-theta lens housed with the first delivery path.

(14) Varioscan is a trade name for an optical component that combines a beam expander and a telescope. The varioscan module operates in conjunction with the galvanometer scanning head to provide continual adjustment to image size, working distance and spot size of the laser beam, as required. For a preferred optical module accepting a laser output power of 200 watts the varioscan module allows spot size variation of between 50 micrometers and 500 micrometers to a processing area of 250 mm.sup.2.

(15) The varioscan module and the beam expander are mounted on a linear rail 90 within the housing. The rail is preferably made from a material such as Invar to reduce the effect of thermal distortion of the rail on the alignment of the optical components.

(16) FIG. 2 illustrates the optical module of FIG. 1 10 mounted to and forming part of a laser manufacturing apparatus 100, such that a laser beam delivered by the optical module can be delivered through a window 110 of a processing chamber of the apparatus 120. The laser beam is delivered to a work surface of the apparatus 130.

(17) The window of the processing chamber is sealed by a 15 mm thick quartz plate 115 that is transparent to laser light of the selected laser beam. The quartz plate 115 is coated on both sides for optimum optical performance.

(18) The processing chamber is constructed such that it can operate at low pressure, for example a pressure of 1×10.sup.−4 tool or less.

(19) In addition to the interface 30 for allowing access to a laser beam from a laser source, the housing 20 of the module includes couplings and ports for water cooling channels 95, communication cables and power supply cables (not shown). Communications ports on the outer surface of the housing allow connection to and communication between a computer or control module and optical components including the galvanometer scanner and the varioscan unit.

(20) FIG. 3 illustrates a selective laser melting (SLM) apparatus 3100 according to an aspect of the invention comprising an optical module 310 and a build chamber 3120. A laser beam from a fibre laser source is delivered to the module by a flexible ruggedised fibre optic cable 311 and into the optical module via optic fibre interface 330. The laser beam passes through a number of optical components 332 mounted on an invar linear rail 390 within the optical module. A galvanometer scanning mirror 360 delivers the laser beam through an f-theta lens 370 and a quartz window 3115 into the processing chamber 3120 or build chamber of the SLM apparatus 3100.

(21) The laser beam can be scanned by the laser scanning mirrors 360 across the surface of an image field or build surface 3130. The build surface may be of any practical dimensions, for example 100 mm by 100 mm, or 265 mm×265 mm or 300 mm by 300 mm, or 500 mm by 500 mm.

(22) FIG. 4 illustrates a cut-away portion of the SLM apparatus of FIG. 3. This illustration clearly shows the build surface 3130, the quartz covering to the window into the build chamber 3115, the galvanometer scanning head 360, a varioscan unit 350 and a beam expander 340. It can be seen that the quartz window 3115 is sealed to an upper portion of the processing chamber 3120 by a sealing means incorporating O-rings 3116.

(23) FIG. 5 illustrates a perspective view of the SLM apparatus of FIGS. 3 and 4. The optical module 310 is mounted to an upper portion of the build chamber 3120 via a mounting block 500 on an upper portion of the build chamber.

(24) FIG. 6 is a schematic illustration of a laser manufacturing apparatus 100 according to an aspect of the invention. The apparatus of FIG. 6 is similar to the apparatus of FIG. 2 and, for convenience, the same reference numerals are used for components that are common to both embodiments. Thus, the apparatus of FIG. 6 comprises an optical module 10 substantially as illustrated in FIG. 2 and described in the text accompanying FIG. 2. The difference between the apparatus illustrated in FIG. 6 and that illustrated in FIG. 2 is that the optical module 10 is coupled to a processing chamber 120 of the apparatus 100 by means of a coupling member 600.

(25) Coupling member 600 may simply be a spacing block that allows the optical module to be spaced a pre-determined unit distance above a build or processing surface 130 to provide optimum focus and scanning parameters.

(26) The coupling member 600 may also allow vertical movement of the optical module with respect to the processing chamber so that the working height of the module can be varied. The coupling member 600 may also be adjustable so as to allow some pitch and/or roll of the optical module to position the laser beam optimally for carrying out a manufacturing process.

(27) A preferred module according to any aspect of the invention also contains thermometers or thermosensors to measure the temperature at different locations within the module and an atmospheric sensor to monitor atmospheric conditions within the module. The housing includes external communication ports allowing communication between the sensors and a computer or control module.

(28) In the specific embodiments described above, the communications between various optical components and sensors within the optical module are achieved in this embodiment by means of umbilical connection, i.e. a physical cable connection between a computer and the module. It is clear, however, that wireless technology allows control of various components, or the

(29) reporting of data from a sensor, to be achieved by wireless means using one of a number of wireless communication protocols.

(30) When the optical module according to an aspect of the invention is set up for use with a laser source, optical components are selected to be compatible with the specific wavelength, or range of wavelengths, produced by the laser source and the power of the laser. These components are then, in a preferred module, mounted to a fixed rail and carefully space oriented and aligned. The components are tested and the optical module is sealed. In a preferred method of setting up the optical module, the set up process is performed in a clean room having a dehumidified dust-free atmosphere. Thus, when the module is sealed, the atmosphere inside the module is a dehumidified dust-free air atmosphere. Because the sealing of the module produces a hermetic seal, this atmosphere is maintained within the module.

(31) The module is then delivered to a manufacturing site having a manufacturing apparatus, and the module housing or chassis simply needs to be mounted to a laser manufacturing apparatus. As the optical components of the module have been aligned and tested, the module only needs to be mounted to the apparatus and the various power and communications connections to be attached. Effectively the module should be “plug and play”, and not require the services of a skilled technician to mount to a laser processing apparatus.

(32) In a preferred system, the optical module is controlled by software on a computer. Sensors within the module monitor various parameters, such as temperature and beam profile and quality, and this data is transmitted to the computer. Data relating to the module's performance is then transmitted via the Internet to a central server where details of the module's performance are compared with minimum performance values. If the module performance falls below a pre-determined level, a new module can be ordered and shipped, or the module can be recalled for servicing.