DE102013021961A1 - Stereolithography system - Google Patents

Abstract

The invention relates to a stereolithography system having more than one independent beam source for producing three-dimensional components, the stereolithography system comprising a receiving block (1) for receiving y-and x-axes movable linear drives (4, 5) as a crossed arrangement and for recording a construction vessel (2) with integrated, height-adjustable construction platform (3). The crossed arrangement of the linear drives (4, 5) for the y-axes and for the x-axes are vertically arranged vertically above the building vessel (2), wherein independently movable, each a radiation source (7) carrying carriage ( 6) are arranged in x-axes independent movable linear drives (5) and in the x-axes independently moved linear drives (5) on independently movable linear drives (4) are arranged in y-axes.

Description

The invention relates to a stereolithography system with more than one independent beam source for the production of three-dimensional components.

The DE 10 2011 012 412 A1 describes an apparatus and a method for the layered production of 3D structures with a printhead assembly, which is positioned relative to a working plane controlled and connected to at least two reservoir containers, in which liquid to pasty photocrosslinkable material, each with different photosensitivity is stored, each about the printhead assembly in the region of the working plane is spatially selectively deployable, as well as with a radiation source arrangement which emits electromagnetic radiation as a function of the photosensitivity of the site selectively applied to the working plane photocrosslinkable material surface. The invention is characterized in that the radiation source arrangement comprises at least one laser light source whose laser beam can be focused using optical beam deflection and focusing in a range of photocrosslinkable material layer can be spread over the working plane by means of the printhead assembly and two-photon or Mehrphotonenprozesse within the photocrosslinkable material layer in the focus area , which leads to the site-selective solidification of the photocrosslinkable material initiated.

In the DE 10 235 427 A1 discloses an apparatus and method for layered, generative production of three-dimensional objects. Several objects are produced parallel to different process chambers by means of successive application of layers of a building material and subsequent solidification of a layer or bonding of the layer to the previously applied layer by means of radiation. The radiation is supplied from a radiation source arranged outside the process chambers to one part of the process chambers, while a layer is applied in the other part of the process chambers.

In the DE 10 2012 011 418 A1 is a stereolithography system consisting of a receiving block for receiving the movable in y- and x-axis linear actuators as a crossed arrangement and for receiving a construction vessel with integrated, movable in the z-axis construction platform, the crossed arrangement of the linear drives for the y-axis and for the x-axis in the vertical direction are arranged vertically above the building vessel. A laser source is directed with the beam exit vertically downwards in the direction of the resin-filled building vessel, attached via a fastener on the linear actuator for the x-axis and directly on the laser source can be mounted on a holder integrated focusing optics.

The DE 10 2009 009 503 B3 relates to an apparatus and a method for producing a workpiece according to a rapid prototyping method with a laser for generating a laser beam for the curing of a material and a workpiece carrier, which can be directly irradiated by the laser from a predetermined solid angle range. In addition, the device has an optical device, in particular a mirror, with which the laser beam is deflected, so that the workpiece carrier with the laser is also indirectly irradiated.

In the DE 10 2004 057 527 B4 For example, a method for producing an electrode body for electrochemical machining (ECM) for workpieces is described, wherein the stamp is produced by the stereolithography method. In the rapid prototyping process (RP), the electrode body is built up layer by layer in a liquid plastic bath. For this purpose, the desired cross section of a layer of the electrode body is generated by means of a laser, which is movable both in the horizontal plane and adjustable in height. For this purpose, the laser is moved according to the desired contour in the horizontal plane and exposed by appropriate exposure, a portion of the plastic layer of the liquid plastic and cured.

The invention according to US 2003 001313 A discloses a method and apparatus for making ceramic shaped bodies by sintering selected locations of a ceramic material with a laser beam to form the shaped body. To produce the shaped body, the liquid suspension or plastic mass is applied in layers and the respective layer of the material is sintered with the laser beam at selected locations.

In this case, the laser beam is preferably controlled by means of the layered design data. The device for producing ceramic shaped bodies has a support surface, an application unit for applying layers of a ceramic material, a drying unit for the applied layers and a laser unit for generating a laser beam with means for the controlled alignment of the laser beam to selected locations of a respective layer of the ceramic material to sinter the irradiated material and to form the shaped body. The means for the controlled alignment of the laser beam are preferably designed as laser scanners, wherein the control of the laser scanner is carried out by means of digital design data for the molded part. Thus, a production of a prototype can be done directly from the design data. The laser unit is powered by a Robot arm moves over the surface of the applied layer and imaged the corresponding layer of the shaped body to be produced on the applied layer.

The US 2002 185 782 (A1) describes a method for producing a three-dimensional object by stereolithography. Solid reinforcing materials are mixed with the liquid medium such that at least a portion of the solid reinforcing agent is disposed in the layer of liquid medium between the upper surface of the last formed layer and the upper surface of the liquid medium. An acoustic field is then generated in the liquid medium such that the acoustic field is present in at least a portion of the layer of liquid medium between the top surface of the last formed layer and the top surface of the liquid medium, thereby curing the liquid medium.

In the US 2004 094 728 A a device for sintering and optionally ablation and / or labeling and for subsequent reworking of the finished workpiece by means of electromagnetic radiation is described. The device consists of a machine housing, in which a space is housed. In the upper area of the installation space, a scanner is arranged, in which the beam of a sintered laser is coupled. In the lower region of the construction space, a height-adjustable workpiece platform and a material supply device are provided, with which powdery or also pasty or liquid sintered material can be transported from a storage container into the process area via the workpiece platform. The scanner is movable in the upper region of the installation space, can be moved in one axis, arranged on a scanner carrier bridge which can be moved over the workpiece platform, the scanner support bridge being arranged on two supports arranged parallel to one another in a width corresponding to the width of the construction vessel the second axis is movable.

Motorized drive elements of the scanner carrier are connected to a control computer, which is responsible for the entire process sequence. During the construction process, this control computer controls both the movement of the scanner over the workpiece platform and the movement of the scanner mirror in the housing of the scanner. In addition to a possible displacement of the scanner along the x-axis and the y-axis also a displacement of the scanner along the z-axis is possible, whereby the scanner is height-movable over the workpiece platform or in adjacent areas. For this purpose, the two mutually parallel carriers run in turn as a bridge to two vertically arranged carrier in the form of linear axes on the right and left wall of the building vessel. The irradiation of the beam of the sintered laser into the area of the scanner carrier takes place parallel to the axes of the suspension of the scanner carrier and via deflection mirrors to the optical input of the scanner.

In addition to the high cost due to the arrangement of the three linear axes in the two-axis mobility or the seven linear axes in the three-axis mobility and the use of four mirrors problems arise in the synchronization of the motors of the linear axes, up to the total failure of stereolithography System.

The invention according to DE 100 53 741 C1 relates to a device for sintering, ablating and / or inscribing by means of electromagnetic bundled radiation, in particular laser sintering machine and / or laser surface processing machine with an accommodated in a machine housing space, in or above which a light guide, in particular by means of a cross slide assembly in all directions movable Scanner, in which the beam is coupled to a sintered energy source, a height-adjustable workpiece platform and a material supply device are arranged with a for supplying sintered material from a reservoir in the process area above the workpiece platform coater, wherein the workpiece platform as removable element removed from the space is and wherein the height-movable workpiece platform, the reservoir and the coater formed as a contiguous removable from the space process platform exchange unit and Dur the same or different machining processes, further process platform changing units of identical or different configurations can be introduced into the installation space.

The cross slide for the movable in all directions scanner is designed as a movable in the y-direction carrier bridge on which a linear actuator for the z-axis is arranged with a laser scanner. This support bridge runs on two parallel to each other, arranged in a width of the construction vessel corresponding distance from each other, movable in x-axis carriers. The laser beam is guided through a large number of mirrors along the carrier and the carrier bridge and the linear drive for the z-axis to the laser scanner. The parallel arranged carrier and the carrier bridge are designed as linear drives.

As in the invention according to US 2004 094 728 A arise in addition to the high effort by the arrangement of the four linear drives and the use of five mirrors problems the synchronization of the motors of the linear drives, which can lead to the total failure of the stereolithography system. Furthermore, this solution requires the use of powerful lasers with high energy and cost to compensate for the loss of energy through the mirrors

In the US 2002 171 178 (A1) The method employs a stereolithography apparatus wherein, by means of a three-dimensional CAD model, chains of one or more photopolymers and a photoinitiator form a layered, polymeric, layered polymer form prosthetic implant. As a photocurable, bioerodible polymer, the solution of poly (propylene) fumarate (PPF) and a solvent for adjusting the viscosity of the solution will be described.

During the manufacturing process, the solution is placed in a container in the stereolithography apparatus (a commercially available SLA 250 stereolithography unit). The container includes a z-axis movable structural panel for supporting each of the covalently bonded layers of the polymeric prosthetic implant exposed to the UV light energy in successive layers of the solution. The UV light energy is generated by means of a commercially available UV laser, wherein the beam of the laser is arranged on the vector-based scanner mirror in the x- and y-axis movable above the container ( www.klartext-pr.de/..../artikel/The culture of prototyping.pdf ).

In the US 45.753.30 B1 A system with external laser source, optical beam conditioning (expander, shutter, etc.), laser scanner for beam deflection and F-theta lens for offset compensation of the laser focus is described. The laser beam is guided over two rotating mirrors to reach the entire construction field. If you need a high resolution very exact motors are needed. In addition, the focus must be constantly corrected by the F-theta lens, so that the working distance varies depending on the laser beam / surface angle. An additional disadvantage is that the laser beam penetrates very obliquely into the polymer in the edge region. The scanner, the F-theta lens and the sufficiently powerful beam source are very expensive to buy. Due to the constantly changing angle substrate / laser beam, no teleoptics or replaceable optics can be positioned above the bath.

The in the US 55 95 703 A Apparatus for fabricating an object by stereolithography comprises, in the main, a container filled with a liquid photopolymerizable prepolymer, a plateau attached therein which can be moved up and down in the liquid prepolymer by a mechanism, not shown, and a laser beam source can be moved over the surface of the liquid prepolymer according to a specific pattern by a mechanism, also not shown.

A 2D opto-mechanical laser scanner is a solution in which the laser beam is not controlled by a scanner with rotating mirrors, but by means of several parallel displaceable deflecting mirrors (US Pat. Gandhi, PS et. al. Micromech. Microeng., No 20, pp 1-11, 2010 ). Due to the guidance over right angles, the laser focus can always be positioned vertically above the construction field. The decisive disadvantages are the number of deflection mirrors required. Since the deflecting mirrors are guided dynamically, a high degree of precision is required in each mirror drive and also in the flatness of the mirror. Furthermore, a loss of the laser power of approx. 10% is to be expected on every reflecting surface. Therefore, a powerful beam source is needed here as well. Both factors, precision at several points and laser power, drive up the costs of the system technology.

A further development with regard to the production of several identical components parallel to one another is provided by the design with several parallel-guided glass fibers on an X-Y plotter. The laser is controlled via shutters and beam guiding optics. A glass fiber bundle then multiplies the beam source and via an x-y plotter system, the contour is processed line by line or via vectors.

The multiplication achieves the construction of several identical components in parallel with normal incidence of the laser radiation. The use of glass fibers to multiply the beam source allows the parallel production of components ( K. Ikuta et. al. "New Micro Stereo Lithography for Floating 3 D Micro Structure", IEEE, pp. 290-295, 1998 ). The processing speed compared to a scanner optics will hardly increase. The components cause the splitting of the laser beam from the beam source (the collimator) as well as the exact uniform distribution of the laser power on the individual fiber strands. If not every fiber delivers identical parameters, the quality / dimensional accuracy of the components suffers. In addition, the use of fibers with UV lasers often leads to an aging process of the fiber. To distribute enough light into all fibers, enough power must be available.

Due to the large number of expensive individual components such as laser, collimator, fibers and Drive axes for the fibers, the equipment is very expensive.

The Colamm procedure ( Maruo, S. et. al. Sensors and Actuators, vol A 100, pp. 70-76, 2002 ) bypasses the problems of re-coating with a wiper. For this purpose, the resin is exposed through a window at the bottom of the vessel. The component is "glued" to the construction platform and then lifted in layers. It is important here that the cured resin does not adhere to the glass pane. The supply of the laser beam via scanner or glass fiber and there are also in this method, the disadvantages described above.

Other technical solutions for stereolithography offer so-called mask methods. These variants are referred to as surface processing. Here, no laser, but a UV lamp is used. A switchable LCD mask or prefabricated masks can then be used to create the contours for the respective layer in one operation ( K. Ikuta, et. al. "New micro stereo lithography for flexible 3D micro structure," IEEE. pp. 290-295, 1998 )

This technique can be applied from above (as well as from above) as well as from the Colamm-method ( M. Schuster et al., "Gelatin-Based Photopolymers for Bone Replacement Materials," Journal of Polymer Science: Part A: Polymer Chemistry, vol 47, pp. 7078-7089, 2009 )

Digital Light Processing (DLP) is another modification of stereolithography. The polymerization of the resin takes place here by visible, non-coherent light. The required pattern is imaged directly onto the resin either through micromirrors or through a dynamic LCD mask, so that the entire layer is simultaneously cured. The disadvantage of this method is that the size of the construction field or the number of pixels (pixels) are fixed. The higher the resolution of the structures to be built, the smaller are these structures. Common systems reach within the xy-plane resolutions of up to 5 μm with a layer thickness of 10 μm ( Ch. Maier, "Production of Biomimetic Materials with Rapid Prototyping Process," University of Vienna, diploma thesis 2005 )

The solutions of the prior art enable efficient production of small components. If the space and thus the construction field are larger, no matter whether larger components or only several components to be manufactured in one operation, the production time increases. Reason are very long travels of the axles. The longer the horizontal axes become, the more time is needed for the route. Basically, although the construction field can scale arbitrarily in size with the previous invention, the production speed per web remains constant. This increases the production time per shift for larger construction sites.

An enlargement of the areas that are to be exposed above the construction field is achieved by arranging several laser scanner systems in a fixed grid. Seen in this way, the installation space is divided into individual construction fields. As a result, the costs for the exposure increase very much, since several lasers, several optical systems and several laser scanner systems have to be used.

Furthermore, an attempt is made to increase the production speed of stereolithography by the simultaneous production of several components in operation. The disadvantage is that only identical components of the same size and shape can be produced. There is no possibility to manufacture different components in a single operation or any size components very quickly.

The object of the invention is to develop a stereolithography system with more than one independent beam source and associated therewith, to achieve an increase in the production speed, wherein in a single operation in shape, size and shape different components can be manufactured.

The object of the invention is achieved by a stereolithography system consisting of a recording block ( 1 ) for the reception of y-axis and x-axis linear drives ( 4 . 5 ) as a crossed arrangement and for receiving a construction vessel ( 2 ) with integrated, height-adjustable construction platform ( 3 ), wherein the crossed arrangement of the linear drives for the y-axes ( 4 ) and for the x-axes ( 5 ) in the vertical direction vertically above the construction vessel ( 3 ) are arranged. The independently movable, each a radiation source ( 7 ) carrying carriages ( 6 ) are independent of each other in x-axis movable linear drives ( 5 ) and in the x-axes independently moved linear drives ( 5 ) are on independently movable linear actuators ( 4 ) arranged in y-axes.

For optimum guidance of the radiation sources ( 7 ) over the construction field ( 9 ), in a further embodiment of the invention, the ratio of the linear drives which can be moved in the y-axis ( 4 ) to the x-axis movable linear drive ( 5 ) 1: 1 or 1: 2 or 2: 1, wherein at the ratio 1: 1 at least two carriages ( 6 ) for each one radiation source ( 7 ) on the x-axis movable linear drive ( 5 ) are arranged.

In a further embodiment of the invention, a stereolithography system is shown, the two, independently movable, a radiation source ( 7 ) carrying sleds ( 6 ) on at least one, movable in the x-axis and at least one movable in y-axis linear drive ( 4 ), linear drive ( 5 ) are attached.

In a further possibility according to this invention, a stereolithography system is described, each one, a radiation source ( 7 ) carrying carriage ( 6 ) at two, independently movable in the x-axis and at least one movable in Y-axis linear actuators ( 4 ), linear motors ( 5 ) are attached.

The linear drives ( 4 . 5 ) may be linear motors according to this invention.

The radiation sources ( 7 ) are formed according to this invention as laser sources.

The core of the invention is a new concept for suspending two or more radiation sources ( 7 ) for the independent exposure of a photopolymer bath. and the ability to operate several independently controlled carriages on a linear drive.

Thus, within a production line, a construction space can be polymerized by more than one laser. Thus doubled, tripled, etc. depending on the number of lasers, the production speed at the same axis length.

By designing the control electronics, a single component with several lasers can be manufactured simultaneously. For this, the working areas of the laser only have to overlap.

The stereolithography system according to the invention is distinguished by a significant increase in the productivity of conventional systems (multiple beam sources operating at the same time) and the possibility of producing very large components at a reasonable expense. This achieves a cost advantage over previous stereolithography systems.

The invention will now be explained in more detail by way of several examples, wherein the 1 the schematic structure of the stereolithography system with a linear drive ( 4 ) for the y-axis and a linear drive ( 5 ) for the x-axis with two a radiation source ( 7 ) carrying carriages ( 6 ), the 2 the division of work areas for two lasers ( 7 ) on the x-axis, the 3 a schematic representation of the stereolithography system with a linear drive ( 4 ) for the Y-axis and two linear drives ( 5 ) for the x-axis, the 4 a schematic representation of a stereolithography system for six independent laser ( 7 ) and the 5 the division of work areas for eight independent lasers ( 7 ) on six linear drives ( 4 ) for the x-axis and three linear drive for the y-axis. Mean

LIST OF REFERENCE NUMBERS

1

receiving block

2

space

3

building platform

4

Linear motor for driving on the y-axis

5

Linear motor for the x-axis

6

carriage

7

beam source

9

Baufeld

10

carrier

Example 1:

At the recording block ( 1 ) is a carrier ( 10 ) arranged on which a linear motor ( 4 ) is mounted as a drive on the y-axis. On this linear motor ( 4 ) as a drive on the y-axis is a linear motor ( 5 ) for the drive on the x-axis, both linear motors ( 4 . 5 ) are regulated independently of each other. The linear motor ( 5 ) for the drive on the x-axis is controlled by the linear motor ( 4 ) for the y-axis over the construction field ( 3 ) guided.

On the linear motor ( 5 ) for driving on the x-axis are two slides ( 6 ), which are independently adjustable in their travel paths.

To the sledge ( 6 ) are vertically above the construction field ( 9 ) one diode laser each ( 7 ) arranged by means of independently controllable linear motors ( 4 . 5 ) for the drives x and y axes as well as the carriage ( 6 ) over the entire construction field ( 9 ) can be performed. A light-curing plastic (photopolymer), for example epoxy resin, is cured by a laser in thin layers (standard layer thickness in the range 0.05-0.25 mm, in micro-stereolithography also up to 1 micron layers). The procedure is done in a bath filled with the base monomers of the photosensitive resin. After each step, the workpiece is lowered a few millimeters into the liquid and returned to a position which is lower than the previous one by the amount of a layer thickness. The liquid plastic over the part is then evenly distributed by a wiper. Then drive the two diode lasers ( 7 ) by means of linear motors ( 4 . 5 ) for the drives on the x and y axes on the new layer over the surfaces that are to be cured. After curing, the next step takes place, so that gradually a three-dimensional model is created.

In the stereolithography process, support structures are typically also included in the manufacturing process because the laser-hardened resin is still relatively soft and certain features (eg, overhangs) are also secure during the build process. After the construction process, the build platform ( 3 ) with the part (s) of the construction space ( 2 ) moved out. After the non-cured resin drips, the model is removed from the build platform, stripped of support structures, washed with solvents, and fully cured in a cabinet under UV light.

Example 2:

In this example, the device according to the invention is shown with eight independently controllable laser units. In this case, two linear motors ( 4 ) for the Y-axes four linear motors ( 5 ) for the X-axes with two carriages each ( 6 ) for receiving a diode laser ( 7 ) attached.

The construction field ( 9 ) is in quadrants (s. 5 ), each laser being associated with a quadrant and each laser exposing its quadrant by software control. The geometric overlap of the quadrants ensures a clean transition within a component. The schematic representation in the 3 shows such a plant.

The production of components in the respective quadrants is then proceed according to the principle in Example 1.

This stereolithography system is particularly suitable for installation dimensions larger than one meter in width.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011012412 A1 [0002]
• DE 10235427 A1 [0003]
• DE 102012011418 A1 [0004]
• DE 102009009503 B3 [0005]
• DE 102004057527 B4 [0006]
• US 2003001313 A [0007]
• US 2002185782 A1 [0009]
• US 2004094728 A [0010, 0015]
• DE 10053741 C1 [0013]
• US 2002171178 A1 [0016]
• US 4575330 B1 [0018]
• US 5595703 A [0019]

Cited non-patent literature

• www.klartext-pr.de/..../artikel/The culture of prototyping.pdf [0017]
• Gandhi, PS et. al. Micromech. Microeng., No 20, pp 1-11, 2010 [0020]
• K. Ikuta et. al. "New Micro Stereo Lithography for Floating 3 D Micro Structure", IEEE, pp. 290-295, 1998 [0022]
• Maruo, S. et. al. Sensors and Actuators, vol A 100, pp. 70-76, 2002 [0024]
• K. Ikuta, et. al. "New micro stereo lithography for flexible 3D micro structure," IEEE. pp. 290-295, 1998 [0025]
• M. Schuster et al., "Gelatin-Based Photopolymers for Bone Replacement Materials," Journal of Polymer Science: Part A: Polymer Chemistry, vol 47, pp. 7078-7089, 2009 [0026]
• Ch. Maier, "Production of Biomimetic Materials with Rapid Prototyping Process," University of Vienna, Diploma Thesis 2005 [0027]

Claims (6)

Stereolithography system consisting of a recording block ( 1 ) for the reception of y-axis and x-axis linear drives ( 4 . 5 ) as a crossed arrangement and for receiving a construction vessel ( 2 ) with integrated, height-adjustable construction platform ( 3 ) wherein the crossed arrangement of the linear drives ( 4 . 5 ) for the y-axes and for the x-axes in the vertical direction vertically above the construction vessel ( 2 ) are arranged, characterized in that independently movable, each a radiation source ( 7 ) carrying carriages ( 6 ) on the x-axes independently movable linear drives ( 5 ) and linear drives ( 5 ) to linear drives ( 4 ) are arranged along the y-axes, wherein the linear drives ( 5 ) independently of each other on the linear drives ( 4 ) are arranged movable along the y-axis. Stereolithographie system according to claim 1, characterized in that the ratio of the movable in the y-axis linear actuators ( 4 ) to the x-axis movable linear drive ( 5 ) is at least 1: 1 or 1: 2 or 2: 1, whereby at the ratio 1: 1 at least two carriages ( 6 ) for each one radiation source ( 7 ) on the x-axis movable linear drive ( 5 ) are arranged. Stereolithography system according to claim 1, characterized in that two, independently movable, a radiation source ( 7 ) carrying carriages ( 6 ) on at least one, in x-axis movable linear drive ( 5 ) are arranged, said, in the x-axis movable linear drive ( 5 ) on at least one linear drive which can be moved in the y-axis ( 4 ) is attached. Stereolithography system according to claim 1, characterized in that each one, a radiation source ( 7 ) carrying carriage ( 6 ) at two, independently movable in the x-axis and at least one movable in Y-axis linear actuators ( 5 ), linear motors ( 4 ) are attached. Stereolithography system according to claim 1 to 3, characterized in that the linear drives ( 4 . 5 ) are designed as linear motors. Stereolithography system according to claim 1 to 3, characterized in that the radiation sources ( 7 ) are formed as laser beam sources.

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