Patent Publication Number: US-10766192-B2

Title: Laser 3D printer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to Italian Patent Application No. 102016000068807 filed on Jul. 1, 2016, the disclosure of which is incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a laser 3D printer. 
     In particular, the present invention relates to a laser 3D printer of the type comprising a tubular compartment having a substantially vertical longitudinal axis; a lifting platform engaged in a sliding manner in the tubular compartment; a feeding unit for feeding a powdered material onto the lifting platform; a laser printing head for sintering the powdered material laid on the lifting platform; and a collection chamber, which extends around at least part of the tubular compartment. 
     The lifting platform is progressively lowered to enable the feeding unit to feed each time a new layer of powdered material onto the lifting platform at the end of each operating cycle of the laser printing head. 
     At the end of processing, the lifting platform is raised into a position corresponding to an open top end of the tubular compartment to enable recovery of the article produced. 
     Raising of the lifting platform at the end of processing involves dispersion of the residual powdered material into the space surrounding the tubular compartment. 
     BACKGROUND OF THE INVENTION 
     Known laser 3D printers of the type described above present some drawbacks mainly resulting from the fact that recovery of the residual powdered material dispersed at the end of processing is performed by the operating staff using a suction device and hence entails the exposure of the staff to the powdered material itself. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide a laser 3D printer that will be free from the drawbacks described above and that will be simple and economically advantageous to produce. 
     According to the present invention a laser 3D printer is provided as specified in the annexed claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described with reference to the annexed drawings, which illustrate a non-limiting example of embodiment thereof and in which: 
         FIG. 1  is a schematic lateral view, with parts in cross-sectional view and parts removed for reasons of clarity, of a preferred embodiment of the laser 3D printer according to the present invention; 
         FIGS. 2 and 3  are two schematic lateral views, with parts removed for reasons of clarity, of a first detail of the laser 3D printer of  FIG. 1  illustrated in two different operative positions; 
         FIG. 4  is a schematic perspective view of a first detail of  FIGS. 2 and 3 ; 
         FIG. 5  is a schematic plan view, with parts removed for reasons of clarity, of a second detail of  FIGS. 2 and 3 ; 
         FIG. 6  is a schematic lateral view, with parts removed for reasons of clarity, of a second detail of the laser 3D printer of  FIG. 1  illustrated in two different operative positions; 
         FIG. 7  is a schematic lateral view, with parts in cross section and parts removed for reasons of clarity, of a detail of  FIG. 6 ; 
         FIG. 8  is a schematic perspective view of a third detail of  FIGS. 2 and 3 ; and 
         FIG. 9  is a schematic perspective view of a fourth detail of  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1, 2, and 3 , designated as a whole by 1 is a laser 3D printer for producing three-dimensional objects  2  by sintering of a powdered material  3  using a laser head  4 . 
     The printer  1  comprises a supporting frame  5 , which in turn comprises a bottom box-shaped body  6  and a top box-shaped body  7  connected together along a substantially horizontal plane P of separation. 
     The body  6  houses within it a tubular compartment  8 , which has a longitudinal axis  9  parallel to a substantially vertical direction  10  perpendicular to the plane P, extends downwards starting from the plane P, and has a cross section having a substantially square shape. 
     The compartment  8  is limited by a side wall  11  engaged in a sliding manner by a lifting platform  12 , which extends perpendicular to the direction  10  and is mobile along the compartment  8  in the direction  10  itself under the thrust of a driving device (known and not illustrated). 
     The platform  12  is connected to a known vibrating device (not illustrated) designed to impart on the platform  12  itself vibrations according to a given law. 
     The compartment  8  is inserted within a collection chamber  13 , which extends downwards starting from the plane P, moreover extends around the wall  11 , and is limited by a side wall  14 . 
     The walls  11 ,  14  define between them an annular channel  15 , which communicates with the compartment  8  via a plurality of openings  16 , which are made in an intermediate point of the wall  11  and are distributed about the axis  9 . 
     According to what is illustrated in  FIG. 5 , the channel  15  has a substantially U-shaped inlet section, and is closed by the plane P on a fourth side thereof. 
     The chamber  13  has an outlet  17  for the material  3  from the channel  15  and is limited by a bottom wall  18 , which is configured for feeding the material  3  towards the outlet  17  and in particular is inclined downwards. 
     The printer  1  further comprises a feeding unit  19  for feeding the material  3  onto the platform  12 . 
     The unit  19  comprises a top tank  20  mounted on the body  7 , and a dispensing and distribution unit  21  mounted above the plane P and connected to the tank  20  via a vibrating feeding duct  22 . 
     With reference to  FIGS. 2, 3, 8, and 9 , the unit  21  comprises a dispensing device  23 , in turn comprising a fixed inner pipe  24 , which has a longitudinal axis  25  parallel to the plane P and transverse to the direction  10 , is coupled in an angularly fixed way to the frame  5 , and communicates with the duct  22 . 
     The pipe  24  has a slit  26 , which is made through the pipe  24  parallel to the axis  25 , and faces the plane P. 
     The device  23  further comprises a rotating outer pipe  27 , which extends around the pipe  24  coaxially thereto about the axis  25  and is coupled in a rotating manner to the pipe  24  for rotating, with respect to the pipe  24  and under the thrust of a driving device  28 , about the axis  25  itself. 
     The pipe  27  has a slit  29 , which is made through the pipe  27  and winds in a helix about the axis  25  according to an angle of substantially 180°. 
     According to what is illustrated in  FIGS. 2, 3, and 4 , the unit  21  further comprises a distributor  30 , which has the shape of a hopper converging towards the plane P, extends in a direction  31  parallel to the axis  25 , and is mounted between the plane P and the dispensing device  23 . 
     The distributor  30  is limited underneath by a plane face  32 , and is provided with a spatula  33 , which extends in the direction  31 , and projects downwards from the face  32  itself. 
     The distributor  30  is mobile, with respect to the dispensing device  23  and above the compartment  8 , in a feeding direction  34  parallel to the plane P and orthogonal to the directions  10  and  31  with a reciprocating rectilinear motion comprising a forward stroke and a return stroke. 
     In this connection, it should be pointed out that, at the end of the return stroke, the distributor  30  sets itself underneath the dispensing device  23 . 
     The distributor  30  is displaced in the direction  34  by a driving device  35  comprising a belt conveyor  36 , in turn comprising a belt  37  wound in a loop about a pair of pulleys  38 , one of which is motor-driven in an intermittent way and which are mounted so as to turn about respective rotation axes  39  parallel to one another and to the direction  31 . 
     The device  35  further comprises an engagement plate  40 , which is fixed to the belt  37 , and carries connected thereto a rocker  41  projecting upwards from the distributor  30 . 
     The rocker  41  is hinged to the plate  40  so as to turn, with respect to the plate  40 , about a pivot axis  42  parallel to the direction  31  between a lowered, operating, position (illustrated with a solid line in  FIG. 6 ), in which the plane of vertical symmetry of the distributor  30  is perpendicular to the plane P, and a raised, resting, position (illustrated with a dashed line in  FIG. 6 ), in which the plane of vertical symmetry of the distributor  30  is inclined with respect to the plane P and the spatula  33  is raised with respect to the plane P itself. 
     With reference to  FIGS. 6 and 7 , the distributor  30  is locked in its operating position and in its resting position by a locking device  43  comprising a pair of slots  44 , which are provided in the plate  40  and are circumferentially aligned with respect to one another about the axis  42 . 
     The device  43  further comprises an engagement ball  45 , which is mounted in a top arm of the rocker  41  and is displaced into a locking position, in which the ball  45  engages one of the slots  44 , and normally kept therein, by a spring  46  set between the rocker  41  and the ball  45  itself. 
     At the end of the return stroke, the distributor  30  is displaced into its operating position by a first end-of-travel element  47  designed to come into contact with a bottom arm of the rocker  41 . 
     At the end of the forward stroke, the distributor is displaced into its resting position by a second end-of-travel element  48  designed to come into contact with the bottom arm of the rocker  41 . 
     Finally, the printer  1  comprises a device  49  for recycling the material  3  collected in the chamber  13  and fed to the outlet  17 . 
     The device  49  comprises a bottom tank  50  set underneath the outlet  17 ; a chute  51 , which extends between the outlet  17  and the tank  50 ; a filter  52  mounted at the inlet of the chute  51 ; and an auger  53  designed to transfer the material  3  from the tank  50  to the tank  20 . 
     Operation of the printer  1  will now be described starting from an instant in which:
     the platform  12  is set at a distance from the plane P that is approximately equal to the thickness of a layer of material  3 ; and   the distributor  30  is set in its operating position underneath the dispensing device  23 .   

     The rotating outer pipe  27  is set in rotation about the axis  25  by the driving device  28  so as to enable the slit  29  to align radially with the slit  26  and define an outlet opening (not illustrated) for the material  3  from the dispensing device  23 . 
     Since the slit  29  winds in a helix about the axis  25  according to an angle substantially equal to 180°, the aforesaid outlet opening (not illustrated) for exit of the material  3  from the device  23  progressively advances along the axis  25  so as to deposit a homogeneous layer of material  3  within the distributor  30 . 
     At the end of a rotation through 180° of the pipe  27  about the axis  25 , the slit  29  disengages the slit  26 , and the outlet opening (not illustrated) is closed during the next rotation through 180° of the pipe  27  itself. 
     Once the material  3  has been fed into the distributor  30 , the distributor  30  is displaced above the compartment  8  with its forward stroke in the direction  34  so as to distribute the material  3  over the platform  12 . 
     At the end of its forward stroke, the distributor  30  is first displaced into its resting position by the element  48 , and is then displaced above the compartment  8  in its return stroke, without interfering with the material  3 . 
     At the end of the return stroke, the distributor  30  is again displaced into its operating position by the element  47 . 
     The above operating cycle of the dispensing and distribution unit  21  is repeated and combined with lowering of the platform  12  so as to create an object  2 . 
     During production of the object  2 , the platform  12  is always set above the openings  16 . 
     Once the object  2  is obtained, the platform  12  is lowered below the openings  16  and set in vibration so as to enable the material  3  to exit from the compartment  8 , enter the chamber  13 , and proceed towards the outlet  17 . 
     The material  3  is fed from the outlet  17  through the filter  52 , along the chute  51 , and into the tank  50 , and is finally again fed into the tank  20  by the auger  53 . 
     The printer  1  consequently presents the advantage that the powdered material  3  is partially used to make the object  2  and partially recirculated in the tank  20  without being dispersed in the environment surrounding the compartment  8  and without requiring recovery operations of the residual material  3  by the operating staff.