Abstract:
Rapid prototyping modeling typically operates by utilizing an ink jet to lay down a thin surface of material as a liquid on a part platform. The material solidifies into a three dimensional object. Computer programs determine the shape of the object, the arrangement of objects and the sequence of objects being built to protect parts of the planarizer roller and planarizer blade of a rapid prototyping machine from erosion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     It is known that rapid prototype modeling equipment utilize a planarizer to smooth the surface of the object being made by the prototyping method. 
     2. Description of the Art of Practices 
     It is known that materials may be melted and re-solidified in order to form solid objects such as in the field of rapid-prototype modeling. The present invention deals with rapid prototype modeling, in particular, with an efficient manner for melting the materials utilized to form the model and to evenly distribute the materials. 
     Rapid prototyping modeling typically operates by utilizing an ink jet to lay down a thin layer of material as a liquid on a part platform. Computer programs determine the shape of the object to be formed and such cross-sectional data in the program ultimately defines the shape of the object. 
     In order to ensure that thin layers are formed and that excess material does not build up, a planarizer is utilized to level the surface of the object being built. An element of the planarizer is a roller which effectively evens out the surface of the object to a single layer upon each pass of the ink jet heads utilized to form the object. 
     Patent Cooperation Treaty Application WO 97/11835 published on Apr. 3, 1997, by Earl, et al. discloses equipment utilizing a planarizer. The disclosure of Patent Cooperation Treaty Application WO 97/11835 is herein incorporated by reference. 
     SUMMARY OF THE INVENTION 
     The present invention describes a hot melt machine for building a part from a material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said part platform and said blade removes material from said roller, the improvement therein comprising building a desired part and a phantom part on said part platform such that said roller takes up excess material from the desired part and the phantom part substantially along the length of said roller, wherein an operator determines where the phantom part should be located on said part platform to effect substantial wefting along the length of said roller. 
     The present invention also describes a hot melt machine for building a part from a material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said part platform and said blade removes material from said roller, the improvement therein comprising building a first desired part and at least one second desired part on said part platform such that said roller takes up excess material from the first desired part and the second desired part substantially along the length of said roller, wherein an operator determines the positioning of the first desired part and the positioning of at least one second desired part on said part platform to effect substantial wetting along the length of said roller when the first desired part and the at least one second desired part are built simultaneously. 
     Yet another embodiment of the present invention describes a hot melt machine for building a part from a material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said part platform and said blade removes material from said roller, the improvement therein comprising building a first desired part and at least one second desired part on said part platform such that said roller takes up excess material from the first desired part and the second desired part substantially along the length of said roller, wherein an operator determines the positioning of the first desired part and the positioning of at least one second desired part on said part platform to effect substantial wetting along the length of said roller when the first desired part and the at least one second desired part are built sequentially. 
     Yet still another embodiment of the present invention is a method for building a part on a hot melt machine from a hot melt material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said platform and said blade removes material from said roller, the improvement therein comprising building a desired part and a phantom part on said part platform such that said roller takes up excess material from the desired part and the phantom part substantially along the length of said roller, wherein an operator determines where the phantom part should be located on said part platform to effect substantial wetting along the length of said roller. 
     A further feature of the present invention is a method for building a part on a hot melt machine from a hot melt material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said part platform and said blade removes material from said roller, the improvement therein comprising building a first desired part and at least one second desired part on said part platform such that said roller takes up excess material from the first desired part and the second desired part substantially along the length of said roller, wherein an operator determines the positioning of the first desired part and the positioning of at least one second desired part on said part platform to effect substantial wetting along the length of said roller when the first desired part and the at least one second desired part are built simultaneously. 
     Another aspect of the present invention is a method for building a part on a hot melt machine from a hot melt material wherein the hot melt machine comprises, a part platform, a blade having a length and a width, and a roller having a length and a width, for when in use said roller removes excess material from the part being built on said part platform and said blade removes material from said roller, the improvement therein comprising building a first desired part and at least one second desired part on said part platform such that said roller takes up excess material from the first desired part and the second desired part substantially along the length of said roller, wherein an operator determines the positioning of the first desired part and the positioning of at least one second desired part on said part platform to effect substantial wetting along the length of said roller when the first desired part and the at least one second desired part are built sequentially. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from the following specification with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic showing the components of a blade assembly and planarizer in use; 
     FIG. 2 is a second view of the elements of a blade assembly and planarizer in use; and, 
     FIG. 3 is an alternative view of the arrangement of the parts being built in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A hot-melt machine  10  for building a part from a hot melt material is shown in FIG.  1 . The hot-melt machine  10  comprises a part platform  12 , a part platform build surface  14 , a blade  16  having a length and a width, and a roller  20  having a length and a diameter. The roller  20  has an endless roller surface  22 . 
     As shown in FIG. 1, a part  100  which is a desired part may be manufactured on the hot-melt machine  10 . Also shown in FIG. 1 is a phantom part  200 . 
     As best seen in FIG. 2, the hot-melt machine  10  has a part platform  12  and a part platform build surface  14  on which a plurality of parts my be built. Also shown in FIG. 2 is a plurality of parts including a three-dimensional triangular shape part  104 , a rectangular solid part  102  and a solid second rectangular part  106 . A series of cylindrical parts are also present in FIG.  2 . and are labeled  108 ,  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124 ,  126 ,  128 , and  130 . 
     As best shown in FIG. 3, is the hot-melt machine  10  with a blade  16 , a roller  20 , and an endless roller surface  22  has a part platform  12  having a part platform surface  14  on which parts may be built. The parts shown in FIG. 2 are now shown in FIG.  3 . The arrangement of the parts in FIG. 3 is different than that in FIG.  2 . Although it is apparent that about the same amount of surface area and material volume are utilized in forming the parts of FIG.  2  and FIG. 3 there are substantial differences in the build process. In FIG. 2, the wefting of the endless roller surface  22  throughout the length of the roller  12  means that there is less friction between the endless roller surface  22  and the blade  16 . The friction between the endless roller surface  22  and the blade  16  results in increased energy cost to overcome the friction. The friction also results in erosion of the endless roller surface  22  and the blade  16 . The approximate time to build all the parts in FIG.  2  and FIG. 3 is not identical due to down time and friction which is not addressed. 
     In the practice of the present invention, an operator, conveniently a computer program, determines the order and spacing of the parts to be built. The present invention is directed to maintaining minimal wear on the blade  16  and the endless roller surface  22 . The blade surface  16  makes prolonged contact with the endless roller surface  22 . Where there is little or no lubricant present the endless roller surface  22  becomes eroded as does the corresponding surface of the blade  16 . 
     Conversely, the wetting of the endless roller surface  22  begins and the wetting of corresponding surface of the blade  16  provides lubricity to those parts. The hot-melt material used to build the parts will effectively wet the blade  16  from the endless roller surface  22  and accordingly wear of the surfaces of the blade  16  and the endless roller surface  22  of the roller  20  will be minimized. 
     While the ink jet heads are not shown in FIG. 1, it is presumed there is a familiarity with the preparation of rapid prototype modeling through the use of ink jets. In its simplest nature, the hot-melt machine  10  presents a situation where the part platform  12  may move in the direction of the x-axis. The surface of the planarizer moves in the direction of the y-axis. The planarizer also moves in the direction of z-axis as shown. Thus, a part  100  is conveniently built by passing the ink jet head over the part platform surface  14  of the part platform  12  and activating the ink jets in the configuration of the part  100 . 
     If the part  100  is relatively small relative to the lengthwise endless roller surface  22  of the roller  20 , then only the corresponding portion of the endless roller surface  22  will be wetted by the hot melt which is being removed from the surface of the part  100 . Accordingly, the endless roller surface  22  will only wet a portion of the blade  16 . Thus all the surfaces which are not wetted on the endless roller surface  22  and the blade  16  will erode at a more rapid rate than a wetted portion of the endless roller surface  22  and the blade  16 . 
     The proposed solution to the non-wetting of the endless roller surface  22  of the roller  20  and the blade  16  is to build a phantom part  200 . As best shown in FIG. 1, the phantom part  200  is an elongated section of a relatively thin material formed from the hot-melt. The phantom part  200  generally corresponds to a lengthwise section of the endless roller surface  22 . Thus as the part  100  is being built, the part  200  is also being built (preferably using a minimum amount of material). As the endless roller surface  22  passes over the part  100  on each pass of the roller  20 , the traversal in the direction  60  also permits the endless roller surface  22  to move over the phantom part  200 . 
     The phantom part being of the same height in the direction of the z-axis as the desired part  100  causes wetting of the entire endless roller surface  22  of the roller  20 . As the endless roller surface  22  of the roller  20  is completely wetted, the blade  16 , which scrapes excess material from the endless roller surface  22 , is also completely wetted. 
     Thus, as best shown in FIG. 1, the endless roller surface  22  of the roller  20  and the blade surface  16  will wear approximately evenly. The building of the phantom part  200  may be designated from a catalog of materials by a human operator of the hot-melt equipment  10 . Alternatively, it is a computer program which determines the object  100  is far too small to effectively wet the endless roller surface  22  of the roller  20 . It is also possible for a human operator of the equipment to override the building of the phantom part  200  should such be desired. 
     As best shown in FIG. 2, a substantial number of parts are built on the part platform  12  rising from the part platform surface  14 . The arrangement of the parts  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  116 ,  118 ,  120 ,  122 ,  124 ,  126 ,  128 , and  130  is accomplished by means of a computer program. The program determines that a number of parts may be built substantially simultaneously. The parts  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  116 ,  118 ,  120 ,  122 ,  124 ,  126 ,  128 , and  130 , as may be observed, cover approximately 90 percent of the lengthwise area of endless roller surface  22  of the roller  20 . Accordingly, when the parts rise from the part platform surface  14 , they are all approximately the same height and will cover more than 90 percent of the endless roller surface  22  of the roller  20 . Therefore, the blade  16  is substantially wetted by the endless roller surface  22  of the roller  20 . Thus the wear on the blade  16  and the endless roller surface  22  of the roller  20  is minimized by the transfer of material from the parts being built. 
     FIG. 3 shows the same parts  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  116 ,  118 ,  120 ,  122 ,  124 ,  126 ,  128 , and  130 , being built as in FIG.  2 . However, the surface area of the part platform  12  is about 50 percent of what is utilized in FIG.  2 . Thus the endless roller surface  22  of the roller  20  is only wetted to about 50 percent of the extent that it is as shown in FIG.  2 . Therefore, the blade  16  is only wetted in the same approximate surface area that is wetted on endless roller surface  22  of roller  20 . Therefore, while half of the roller surface and half of the blade are wetted sufficiently to prevent erosion, the remaining half of the endless roller surface  22  of roller  20  and the half of the blade  16  are not wetted and both are subject to substantial erosion. 
     In an alternative embodiment, and referring to FIG. 2, it is possible to build parts  102 ,  104 ,  106 ,  108 , and  110 , in one operation of the hot-melt machine  10 . After removing the parts  102 ,  104 ,  106 ,  108 , and  110 , the parts  112 ,  116 ,  118 ,  120 ,  122 ,  124 ,  126 ,  128 , and  130 , are manufactured in a separate operation. While the second embodiment is not as desirable because the endless roller surface  22  of the roller  20  and the blade  16  are not wetted in a single operation; their erosion is minimized. That is, as the parts are being built on different portions of the part platform  12 , the wetting takes place sequentially along the endless roller surface  22  of roller  20  and the corresponding area of the blade  16 . While the erosion is greater than as shown in the original version of FIG. 2, at least the roller surface erosion is minimized by setting the program to build at different portions of the platform part platform surface  14  over time. 
     Having described the invention in sufficient detail to allow one of ordinary skill in the art to practice the invention without limitation the following is now claimed.