Patent Description:
As a conventional apparatus for implementing additive manufacturing, a laser processing apparatus aiming to perform processing with a high processing quality is disclosed for example in <CIT> (PTD <NUM>).

The laser processing apparatus disclosed in PTD <NUM> includes: a laser source emitting a laser beam; a holding table holding a workpiece to be processed; an optical system generating a laser beam having a ring-band-shaped cross section from the laser beam emitted from the laser source, and applying the laser beam with a variable radius to the workpiece held on the holding table; and a controller configured to change the width of the output of the laser source or the ring-band-shaped laser beam, in a direction of suppressing a change of the peak intensity in the same orientation of the ring-band-shaped laser beam, when the radius of the ring-band-shaped laser beam is changed.

In addition, <CIT> (PTD <NUM>), <CIT> (PTD <NUM>), <CIT> (PTD <NUM>), <CIT> (PTD <NUM>), <CIT> (PTD <NUM>), <CIT> (PTD <NUM>), and <CIT> (PTD <NUM>) also disclose various apparatuses for implementing additive manufacturing.

Creation of a three-dimensional form on a workpiece by attaching materials on the workpiece is implemented by a method of additive manufacturing. The mass of the workpiece after additive manufacturing has been increased relative to the workpiece before additive manufacturing. Examples of such an additive manufacturing method include a directed energy deposition method and a powder bed fusion method. In a process of the directed energy deposition method, a material (a typical example is material powder) is fed from an additive-manufacturing head to a workpiece, and the workpiece is irradiated with a laser beam. In a process of the powder bed fusion method, a powder bed is selectively fused and hardened by heat in the vicinity of the surface to form a layer.

Advantages of the directed energy deposition method are as follows:.

On the contrary, disadvantages of the directed energy deposition method are as follows:.

Regarding the directed energy deposition method, a region near a melt pool, which is formed in a surface of a workpiece by irradiation with a laser beam, is caused to be in an inert gas environment by use of shielding gas, while a machining chamber is in a normal ambient opened to the atmosphere. This is another advantage of the directed energy deposition method, especially for a large manufacturing machine and, unlike the powder bed fusion method, it is unnecessary to fill a completely sealed machining chamber with an expensive gas. The manufacturing machine requires a chip conveyor for discharging chips to the outside of the machine, or the like, and it is difficult for a machining chamber of a large-sized machine to be completely sealed. It is therefore advantageous to develop a manufacturing machine capable of additive manufacturing and subtractive manufacturing based on the directed energy deposition method.

As seen from the above, the directed energy deposition method has many advantages. However, the material powder usage efficiency depends on the combination of process parameters. In the case where the material powder usage efficiency is low, the following problems arise.

However, regarding the directed energy deposition method, the combination of process parameters is complicated as described above. In addition, when the material powder is fed from outside the laser beam, it is difficult to prevent scattering of the material powder to the outside of the melt pool. It is therefore extremely difficult to achieve a material powder usage efficiency close to <NUM>%.

Accordingly, an object of the present invention is to solve the above-described problems and provide an additive-manufacturing head, a manufacturing machine, and a manufacturing method that can improve the material usage efficiency for the directed energy deposition method.

An additive-manufacturing head according to the present invention is an additive-manufacturing head for performing additive manufacturing as defined in claim <NUM>.

Regarding the additive-manufacturing head configured in this manner, the outlet of the material feeding unit is disposed inside the ring-shape laser beam, and therefore, the position from which the material is fed toward the workpiece can be disposed close to a region on a workpiece surface that is irradiated with the laser beam. Accordingly, the material usage efficiency can be improved.

Further, the additive-manufacturing head configured in this manner, the outlet of the material feeding unit can be disposed inside the ring-shape laser beam in the simple and easy manner.

Preferably, the additive-manufacturing head further includes a guide mirror provided on a central axis of the ring-shape laser beam emitted from the laser beam emitting unit toward the workpiece, the guide mirror being configured to guide the laser beam from the optical element toward the laser beam emitting unit. The material feeding unit penetrates a through hole formed in the guide mirror.

Regarding the additive-manufacturing head configured in this manner, the outlet of the material feeding unit can be disposed inside the ring-shape laser beam in the simple and easy manner.

Preferably, feed of the material from the outlet toward the workpiece and emission of the ring-shape laser beam from the laser beam emitting unit toward the workpiece are coaxial.

Regarding the additive-manufacturing head configured in this manner, the outlet of the material feeding unit can be disposed closer to a region on a workpiece surface that is irradiated with the laser beam.

Preferably, the optical element is configured to form the laser beam in a shape of a circular ring, rectangular ring, or triangular ring.

Regarding the additive-manufacturing head configured in this manner, additive manufacturing is performed by feeding a material to a workpiece and irradiating the workpiece with the laser beam in the shape of a circular ring, rectangular ring, or triangular ring.

A manufacturing machine according to the present invention is a manufacturing machine capable of subtractive manufacturing and additive manufacturing for a workpiece as defined in claim <NUM>.

Regarding the manufacturing machine configured in this manner, the material usage efficiency in additive manufacturing by the manufacturing machine can be improved.

As described above, according to the present invention, the additive-manufacturing head and a manufacturing machine that can improve the material usage efficiency for the directed energy deposition method can be provided.

An embodiment of the present invention will be described with reference to the drawings. In the drawings referenced below, the same or corresponding members are denoted by the same numerals.

<FIG> is a front view showing a manufacturing machine in an embodiment of the present invention. In <FIG>, a cover body which presents the appearance of the manufacturing machine is shown as if it is transparent, so that the inside of the manufacturing machine is visible. <FIG> is a perspective view showing an inside of a machining area when additive manufacturing is performed in the manufacturing machine in <FIG>.

Referring to <FIG> and <FIG>, manufacturing machine <NUM> is an AM/SM hybrid manufacturing machine capable of additive manufacturing (AM) for a workpiece and subtractive manufacturing (SM) for a workpiece. Manufacturing machine <NUM> has a turning function by means of a stationary tool and a milling function by means of a rotary tool, as functions of SM.

First, a description will be given of the overall structure of manufacturing machine <NUM>. Manufacturing machine <NUM> includes a bed <NUM>, a first headstock <NUM>, a second headstock <NUM>, a tool spindle <NUM>, and a lower tool rest <NUM>.

Bed <NUM> is a base member for supporting first headstock <NUM>, second headstock <NUM>, tool spindle <NUM>, and lower tool rest <NUM>, and mounted on an installation surface in a factory or the like. First headstock <NUM>, second headstock <NUM>, tool spindle <NUM>, and lower tool rest <NUM> are provided in a machining area <NUM> defined by a splashguard <NUM>.

First headstock <NUM> and second headstock <NUM> are provided to face each other in a z-axis direction which extends horizontally. First headstock <NUM> and second headstock <NUM> have a first spindle <NUM> and a second spindle <NUM>, respectively, for rotating a workpiece in a turning process which is performed by means of a stationary tool. First spindle <NUM> is provided rotatably about a central axis <NUM> which is in parallel with the z axis. Second spindle <NUM> is provided rotatably about a central axis <NUM> which is in parallel with the z axis. First spindle <NUM> and second spindle <NUM> are each provided with a chuck mechanism for detachably holding a workpiece.

Second headstock <NUM> is provided to be movable in the z-axis direction by means of any of various feed mechanisms, guide mechanisms, a servo motor, and the like.

Tool spindle (upper tool rest) <NUM> causes a rotary tool to rotate in a milling process which is performed by means of the rotary tool. Tool spindle <NUM> is provided rotatably about a central axis <NUM> which is in parallel with an x axis extending vertically. Tool spindle <NUM> is provided with a clamp mechanism for detachably holding the rotary tool.

Tool spindle <NUM> is supported above bed <NUM> through a column or the like (not shown). Tool spindle <NUM> is provided to be movable, by any of various feed mechanisms, guide mechanisms, a servo motor, and the like provided on the column or the like, in the x-axis direction, a y-axis direction which extends horizontally and orthogonally to the z-axis direction, and the z-axis direction. The position of machining by the rotary tool attached to tool spindle <NUM> moves three-dimensionally. Further, tool spindle <NUM> is provided to be swivelable about a central axis <NUM> which is in parallel with the y axis.

Although not shown in <FIG>, an automatic tool-change device for automatically changing a tool attached to tool spindle <NUM> and a tool magazine storing replacement tools to be attached tool spindle <NUM> are provided around first headstock <NUM>.

To lower tool rest <NUM>, a plurality of stationary tools for turning are attached. Lower tool rest <NUM> has a so-called turret shape, and a plurality of stationary tools are attached radially to lower tool rest <NUM>. Lower tool rest <NUM> is provided for swivel indexing.

More specifically, lower tool rest <NUM> includes a swivel unit <NUM>. Swivel unit <NUM> is provided to be swivelable about a central axis <NUM> which is in parallel with the z axis. At positions located at intervals in the direction of the circumference centered at central axis <NUM>, tool holders for holding stationary tools are attached. Swivel unit <NUM> swivels about central axis <NUM> to thereby move the stationary tools held by the tool holders, and a stationary tool to be used for turning is indexed.

Lower tool rest <NUM> is supported above bed <NUM> through a saddle or the like (not shown). Lower tool rest <NUM> is provided to be movable in the x-axis direction and the z-axis direction, by any of various feed mechanisms, guide mechanisms, a servo motor, and the like provided on the saddle or the like.

Manufacturing machine <NUM> further includes an additive-manufacturing head <NUM>. Additive-manufacturing head <NUM> performs additive manufacturing (directed energy deposition) by feeding a material to a workpiece and irradiating the workpiece with a laser beam. In the present embodiment, additive-manufacturing head <NUM> feeds material powder to a workpiece. As the material powder, stainless, Inconel (registered trademark), or titanium alloy, or the like, for example, may be used.

The form of the material fed to a workpiece by additive-manufacturing head <NUM> is according to the invention a powder but may be, as examples not covered by the present invention, wire, long slender strip, or the like.

Additive-manufacturing head <NUM> is provided to be attachable to and detachable from tool spindle <NUM>. When additive manufacturing is performed, additive-manufacturing head <NUM> is attached to tool spindle <NUM>. Tool spindle <NUM> moves in the x-axis direction, the y-axis direction, and the z-axis direction to thereby three-dimensionally displace the position of additive manufacturing by additive-manufacturing head <NUM>. When subtractive manufacturing is performed, additive-manufacturing head <NUM> is separated from tool spindle <NUM> and stored in a head stocker (not shown).

Tool spindle <NUM> is provided with a clamp mechanism. When additive-manufacturing head <NUM> is attached to tool spindle <NUM>, the clamp mechanism operates to couple additive-manufacturing head <NUM> to tool spindle <NUM>. An example of the clamp mechanism may be a mechanism obtaining a clamping state through a spring force and obtaining an unclamping state through a hydraulic pressure.

Manufacturing machine <NUM> further includes a powder feeder <NUM>, a laser oscillator <NUM>, and a cable <NUM>.

Powder feeder <NUM> introduces material powder to be used for additive manufacturing, toward additive-manufacturing head <NUM> in machining area <NUM>. Powder feeder <NUM> includes a powder hopper <NUM> as a tank portion, and a mixing unit <NUM>. Powder hopper <NUM> forms a closed space for storing material powder to be used for additive manufacturing. Mixing unit <NUM> mixes the material powder stored in powder hopper <NUM> with carrier gas for the material powder.

Laser oscillator <NUM> generates a laser beam to be used for additive manufacturing. Cable <NUM> is made up of an optical fiber for directing the laser beam from laser oscillator <NUM> toward additive-manufacturing head <NUM>, pipes for directing material powder from powder feeder <NUM> toward additive-manufacturing head <NUM>, and a tube member which encloses the pipes.

Next, a detailed description will be given of a structure of additive-manufacturing head <NUM>. <FIG> is a diagram showing an internal structure of the additive-manufacturing head in <FIG> and <FIG>.

Referring to <FIG>, additive-manufacturing head <NUM> includes, as optical systems for emitting an externally introduced laser beam toward a workpiece, a laser beam collimating unit <NUM>, a ring-shape laser beam forming unit <NUM>, a laser beam guiding unit <NUM>, and a laser beam emitting unit <NUM>.

Laser beam collimating unit <NUM>, ring-shape laser beam forming unit <NUM>, laser beam guiding unit <NUM>, and laser beam emitting unit <NUM> are arranged in this order from upstream to downstream of an optical path of the laser beam in additive-manufacturing head <NUM>.

A laser beam from cable <NUM> (see <FIG> and <FIG>) is introduced through an optical fiber <NUM> into laser beam collimating unit <NUM>. Laser beam collimating unit <NUM> includes a collimation lens <NUM>. Collimation lens <NUM> is provided on a central axis <NUM>. Laser beam collimating unit <NUM> produces, by means of collimation lens <NUM>, parallel rays from the laser beam which is input from optical fiber <NUM>, and sends the parallel rays toward ring-shape laser beam forming unit <NUM>.

Ring-shape laser beam forming unit <NUM> includes an axicon lens <NUM>, an axicon lens <NUM>, and a spherical lens <NUM>. Axicon lens <NUM>, spherical lens <NUM>, and axicon lens <NUM> are arranged in this order from upstream to downstream of the optical path of the laser beam in additive-manufacturing head <NUM>. Axicon lens <NUM>, spherical lens <NUM>, and axicon lens <NUM> are provided on central axis <NUM>.

Axicon lens <NUM> has one surface <NUM> in the shape of a conical surface and the other surface 43n in the shape of a planar surface. Axicon lens <NUM> has one surface <NUM> in the shape of a conical surface and the other surface 45n in the shape of a planar surface. Axicon lens <NUM> and axicon lens <NUM> are arranged so that one surface <NUM> of axicon lens <NUM> faces one surface <NUM> of axicon lens <NUM>.

Ring-shape laser beam forming unit <NUM> forms the laser beam which is input from laser beam collimating unit <NUM> into a ring shape through axicon lens <NUM>, spherical lens <NUM>, and axicon lens <NUM>. The laser beam which is output from ring-shape laser beam forming unit <NUM> is in the shape of a ring, namely the shape of a closed band around central axis <NUM> as seen in a cross section along a plane orthogonal to the direction in which the laser beam travels. In the present embodiment, ring-shape laser beam forming unit <NUM> forms the laser beam input from laser beam collimating unit <NUM> into a circular ring-shape. The ring-shape laser beam emitted from ring-shape laser beam forming unit <NUM> is centered on central axis <NUM> and travels in the axial direction of central axis <NUM>.

Laser beam guiding unit <NUM> includes a guide mirror <NUM> and a guide mirror <NUM>. Guide mirror <NUM> and guide mirror <NUM> are arranged in this order from upstream to downstream of the optical path of the laser beam in additive-manufacturing head <NUM>. Guide mirror <NUM> is provided on central axis <NUM>. Guide mirror <NUM> is provided to be inclined with respect to central axis <NUM>. Guide mirror <NUM> is provided on a central axis <NUM> which runs in parallel with central axis <NUM>. Guide mirror <NUM> is provided to be inclined with respect to central axis <NUM>.

Laser beam guiding unit <NUM> guides the ring-shape laser beam which is input from ring-shape laser beam forming unit <NUM> toward laser beam emitting unit <NUM>, through reflection by guide mirror <NUM> and guide mirror <NUM>. The ring-shape laser beam which is output from laser beam guiding unit <NUM> is centered on central axis <NUM> and travels in the axial direction of central axis <NUM>.

Laser beam emitting unit <NUM> includes a condenser lens <NUM>, a condenser lens <NUM>, and a protective lens <NUM>. Condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM> are arranged in this order from upstream to downstream of the optical path of the laser beam in additive-manufacturing head <NUM>. Condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM> are provided on central axis <NUM>.

Laser beam emitting unit <NUM> emits the ring-shape laser beam which is input from laser beam guiding unit <NUM> toward a workpiece. Laser beam emitting unit <NUM> concentrates the ring-shape laser beam emitted toward the workpiece, through condenser lens <NUM> and condenser lens <NUM>. The ring-shape laser beam emitted from laser beam emitting unit <NUM> is centered on central axis <NUM> and travels in the axial direction of central axis <NUM>. Protective lens <NUM> is provided for protecting the lens system installed in additive-manufacturing head <NUM> from the external ambient.

Additive-manufacturing head <NUM> includes a material powder feeding unit <NUM>, as a mechanism for feeding material powder to a workpiece.

Material powder feeding unit <NUM> has a pipe shape capable of delivering material powder. Material powder feeding unit <NUM> is provided along central axis <NUM>. Material powder is introduced from cable <NUM> (see <FIG> and <FIG>) into material powder feeding unit <NUM>. Material powder feeding unit <NUM> has an outlet <NUM>. Outlet <NUM> is an opening of material powder feeding unit <NUM> releasing material powder. Material powder feeding unit <NUM> feeds material powder from outlet <NUM> toward a workpiece.

Outlet <NUM> is disposed inside the ring-shape laser beam emitted from laser beam emitting unit <NUM>. Outlet <NUM> is provided on central axis <NUM>. Feed of the material from outlet <NUM> toward a workpiece and emission of the ring-shape laser beam from laser beam emitting unit <NUM> toward the workpiece are coaxial with central axis <NUM> and coaxial with each other.

Outlet <NUM> is disposed downstream of condenser lens <NUM> and condenser lens <NUM> on the optical path of the laser beam in additive-manufacturing head <NUM>. Outlet <NUM> is provided downstream of protective lens <NUM> on the optical path of the laser beam in additive-manufacturing head <NUM>.

A through hole <NUM> is formed in guide mirror <NUM>. Through hole <NUM> is formed to be located on central axis <NUM> and penetrate guide mirror <NUM>. Through hole <NUM> has an opening larger than a cross section of material powder feeding unit <NUM> along a plane orthogonal to central axis <NUM>. Material powder feeding unit <NUM> penetrates through hole <NUM>.

In condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM>, a through hole <NUM>, a through hole <NUM>, and a through hole <NUM> are formed, respectively. Through hole <NUM>, through hole <NUM>, and through hole <NUM> are formed to be provided on central axis <NUM> and penetrate condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM>, respectively. Through hole <NUM>, through hole <NUM>, and through hole <NUM> each have an opening larger than a cross section of material powder feeding unit <NUM> along a plane orthogonal to central axis <NUM>. Material powder feeding unit <NUM> penetrates through holes <NUM>, <NUM>, and <NUM>.

Additive-manufacturing head <NUM> includes a cover body <NUM>. Cover body <NUM> has the shape of a casing and forms a space which houses condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM>. An opening <NUM> is formed in cover body <NUM>. Opening <NUM> is provided on central axis <NUM>. Opening <NUM> is located to face a surface of a workpiece during additive manufacturing. Opening <NUM> allows the space housing condenser lens <NUM>, condenser lens <NUM>, and protective lens <NUM> to communicate with the external space. The ring-shape laser beam is emitted from laser beam emitting unit <NUM> to the external space through opening <NUM>.

In the axial direction of central axis <NUM>, outlet <NUM> is located in the external space, namely located outward with respect to opening <NUM>. In this case, outlet <NUM> is disposed closer to a workpiece.

Outlet <NUM> may be, as examples not covered by the present invention, located identically to opening <NUM> in the axial direction of central axis <NUM>, or provided in cover body <NUM>. As long as outlet <NUM> is located inside the ring-shape laser beam emitted from laser beam emitting unit <NUM>, the position of outlet <NUM> is not particularly limited, and may be displaced from central axis <NUM>.

Next, a description will be given of a manufacturing method as an example not covered by the present invention. <FIG> is a cross-sectional view showing a surface of a workpiece during additive manufacturing based on a manufacturing method in the present example. <FIG> is a plan view of the surface of the workpiece in <FIG>. <FIG> is a diagram showing a positional relation between a workpiece and a laser beam emitted toward the workpiece.

Referring to <FIG>, the manufacturing method in the present example is a manufacturing method for performing additive manufacturing by feeding material powder to a workpiece <NUM> and irradiating workpiece <NUM> with a laser beam, and includes the steps of: forming a laser-beam-irradiated region <NUM> on a surface of the workpiece by emitting a laser beam <NUM> in a ring shape toward workpiece <NUM>; and feeding the material powder from inside ring-shape laser beam <NUM> which is emitted toward workpiece <NUM>, toward a region on the surface of the workpiece, the region including a range located inside an outer circumference 312p of laser-beam-irradiated region <NUM>.

In the case where manufacturing machine <NUM> (additive-manufacturing head <NUM>) in <FIG> is used to perform additive manufacturing, ring-shape laser beam <NUM> is emitted from laser beam emitting unit <NUM> toward workpiece <NUM> to thereby form laser-beam-irradiated region <NUM> on a surface of the workpiece. The material powder is released from outlet <NUM> of material powder feeding unit <NUM> to thereby feed, from inside ring-shape laser beam <NUM> which is emitted toward workpiece <NUM>, the material powder to a region on the workpiece surface, the region including the range located inside outer circumference 312p of laser-beam-irradiated region <NUM>.

Movement of tool spindle <NUM> to which additive-manufacturing head <NUM> is attached and/or rotation of first spindle <NUM> of first headstock <NUM> which holds workpiece <NUM> cause additive-manufacturing head <NUM> and workpiece <NUM> to move relative to each other with additive-manufacturing head <NUM> facing workpiece <NUM>. At this time, the step of emitting ring-shape laser beam <NUM> toward workpiece <NUM> and the step of feeding the material powder toward the workpiece surface are simultaneously performed to thereby melt and attach the material powder to the workpiece surface.

A curved line <NUM> in <FIG> represents a normalized laser beam density distribution on the workpiece surface.

As shown in <FIG>, laser beam <NUM> emitted toward workpiece <NUM> includes a convergence section <NUM> and a divergence section <NUM> in the direction in which the laser beam travels. In the convergence section, the laser beam converges toward a focal position <NUM>. In the divergence section, the laser beam diverges from focal position <NUM>.

In the present example, as shown in <FIG>, laser beam <NUM> in convergence section <NUM> forms laser-beam-irradiated region <NUM> on the workpiece surface. In this case, laser-beam-irradiated region <NUM> has the shape of a closed band around central axis <NUM>. Laser-beam-irradiated region <NUM> has the shape of a circular closed band around central axis <NUM> that corresponds to the shape of the laser beam (circular ring-shape) emitted from laser beam emitting unit <NUM> toward workpiece <NUM>. Outer circumference 312p of laser-beam-irradiated region <NUM> has the shape of a circle centered on central axis <NUM>.

Feed of the material powder toward workpiece <NUM> and emission of the ring-shape laser beam toward workpiece <NUM> are coaxial with central axis <NUM> and coaxial with each other. In the step of feeding the material powder toward the workpiece surface, the material powder is fed toward a region which is centered on central axis <NUM> on the workpiece surface and which is located inside laser-beam-irradiated region <NUM>.

Regarding manufacturing machine <NUM> and the manufacturing head <NUM> in the embodiment of the present invention as described above, the position (outlet <NUM>) from which the material powder is released toward a workpiece can be made closer to the region on the workpiece surface irradiated with the laser beam. Accordingly, the material powder is less likely to scatter and the efficiency of usage of the material powder can be improved.

In the present embodiment, laser beam <NUM> in convergence section <NUM> forms laser-beam-irradiated region <NUM> on the workpiece surface. Alternatively, laser beam <NUM> at focal position <NUM> may form the laser-beam-irradiated region. At this time, the laser-beam-irradiated region has a circular shape. In the case where laser beam <NUM> in convergence section <NUM> or at focal position <NUM> forms the laser-beam-irradiated region, the position (outlet <NUM>) from which the material powder is released toward the workpiece can be made closer to the region on the workpiece surface irradiated with the laser beam.

Still alternatively, laser beam <NUM> in divergence section <NUM> may form the laser-beam-irradiated region. At this time, the laser-beam-irradiated region has the shape of a circular closed band around central axis <NUM>. In this case, the material powder is heated (preheated) by the laser beam at a position preceding and at a position following focal position <NUM>. Thus, the material powder is more easily melt and attached to the workpiece surface.

<FIG> and <FIG> are each a plan view of a workpiece surface illustrating a modification of the laser-beam-irradiated region in <FIG>. Referring to <FIG>, a laser-beam-irradiated region <NUM> in the present modification has the shape of a rectangular closed band around central axis <NUM>. In this case, ring-shape laser beam forming unit <NUM> of additive-manufacturing head <NUM> forms the laser beam in the shape of a rectangular ring.

Referring to <FIG>, a laser-beam-irradiated region <NUM> in the present modification has the shape of a triangular closed band around central axis <NUM>. In this case, ring-shape laser beam forming unit <NUM> of additive-manufacturing head <NUM> forms the laser beam in the shape of a triangular ring.

As illustrated in connection with these modifications, the shape of the laser beam emitted toward a workpiece is not particularly limited, as long as the shape of the laser beam is a ring shape. Any of various prisms can be used in ring-shape laser beam forming unit <NUM> to form the laser beam in any of various ring shapes.

<FIG> is a perspective view illustrating the material powder feeding pipe in <FIG>. Referring to <FIG>, according to the present invention, material powder feeding unit <NUM> includes a plurality of tube members <NUM>, <NUM>, <NUM>, and an outer tube <NUM>. Tube member <NUM>, tube member <NUM>, and tube member <NUM> are enclosed in outer tube <NUM>. Into tube member <NUM>, tube member <NUM>, and tube member <NUM>, materials in the powder form that are different from one another are introduced, respectively. This characteristic enables a mixture of multiple different materials in the powder form to be fed to a workpiece.

The number of tube members of material powder feeding unit <NUM> is not limited to three. The number of tube members may be two, or four or more.

It should be construed that embodiments disclosed herein are given by way of illustration in all respects, not by way of limitation. It is intended that the scope of the present invention is defined by claims, not by the description above, and encompasses all modifications within the scope to the claims.

The present invention is mainly applied to additive manufacturing based on the directed energy deposition method.

Claim 1:
An additive-manufacturing head (<NUM>) for performing additive manufacturing by feeding a material powder to a workpiece (<NUM>) and irradiating the workpiece (<NUM>) with a laser beam, the additive-manufacturing head (<NUM>) comprising:
an optical element (<NUM>) configured to form a laser beam in a ring shape;
a laser beam emitting unit (<NUM>) configured to emit the ring-shaped laser beam toward the workpiece (<NUM>); and
a material feeding unit (<NUM>) having an outlet (<NUM>) which is disposed inside the ring-shaped laser beam emitted from the laser beam emitting unit (<NUM>) and from which the material powder is released, and configured to feed the material powder from the outlet (<NUM>) toward the workpiece (<NUM>),
the material feeding unit (<NUM>) having a pipe shape capable of delivering the material powder, the laser beam emitting unit (<NUM>) including condenser lenses (<NUM>, <NUM>) and a protective lens (<NUM>) configured to concentrate the ring-shaped laser beam emitted toward the workpiece (<NUM>), and
the material feeding unit (<NUM>) penetrating a through hole formed in the condenser lenses (<NUM>, <NUM>), wherein
the additive-manufacturing head (<NUM>) being characterized in that the material feeding unit (<NUM>) includes a plurality of tube members (<NUM>, <NUM>, <NUM>) configured to feed respective different types of material powder, wherein the plurality of tube members (<NUM>, <NUM>, <NUM>) is enclosed in an outer tube (<NUM>), wherein
a cover body (<NUM>) forming a space which houses the laser beam emitting unit (<NUM>), wherein an opening (<NUM>) is formed in the cover body (<NUM>) which is located to face a surface of the workpiece (<NUM>) during the additive manufacturing, wherein
the material feeding unit (<NUM>) protrudes from the space in the cover body (<NUM>) to an external space through the opening (<NUM>), and
the outlet (<NUM>) is located in the external space.