Abstract:
A system for developing a composition for powder molding which, after a viscosity of the composition for powder molding and a degreasing process, extracts optimal compositional information of the composition in terms of the ratios of the residual binder materials is disclosed. Such a system includes a searching logic unit configured, after generating a plurality of candidate compositional information, to extract the optimal compositional information therefrom and a synthesis/analysis module configured to synthesize and analyze compositions corresponding to the plurality of candidate compositional information and provide to the searching logic unit measurement information on the viscosities of the compositions corresponding to each of the plurality of candidate compositional information and ratios of residual binder materials after a degreasing process. Also, the searching logic unit extracts the optimal compositional information based on the candidate compositional information and the measurement information thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0027798, filed on Feb. 27, 2015, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a system and a method of developing a composition for powder molding capable of extracting compositional information on the composition applied to powder molding such as powder injection molding or powder extrusion molding of metal materials or ceramic materials. 
         [0004]    2. Discussion of Related Art 
         [0005]    In recent years, a lot of research on powder molding technology such as powder injection molding and powder extrusion molding of various metal materials or ceramic materials has been conducted for mass-producing with low production costs highly functional precision parts with complicated shapes because the precision parts are difficult to manufacture using a conventional molding technology such as a cutting process, precision casting, die casting, powder metallurgy, and the like, or has a price problem. 
         [0006]    Generally, powder molding of metal materials or ceramic materials is performed in the order of a process of mixing a binder material with a metal or ceramic powder, a process of subjecting the mixture to injection molding or extrusion molding, a degreasing process of removing the binder material, and a sintering process of strengthening a bond between powders. For the powder molding method for such a metal or ceramic material, development of a powder-binder system for precision parts capable of easy removal of a binder material and exhibiting excellent fluidity for complex manufacturing on a larger scale and miniaturization of powder into finer particles is needed. 
         [0007]    However, developments of most materials and processes conducted in the past have been made by very inefficient methods based on trial and error. As a result, these methods have exposed many problems. The most basic problem of the methods based on the conventional trial and error method is that it is practically impossible to search for the proper compositions since basically the range of the compositions to be searched is too wide for developing a binder essential for powder molding. For example, when a new composition for binders is developed by mixing 2 to 5 generally used main materials (lost wax, carnauba wax, polyethylene, polypropylene, polystyrene, etc.) with 2 to 3 auxiliary materials (surfactant, mixed inducing agent, reaction accelerator, etc.), approximately  10   4  to  10   8  experimental compositions need to be tested even when the corresponding additives are varied and within a range of 10% and tested, making it practically impossible to test the compositions using the conventional trial and error method. Also, the conventional methods having focused on the research of the compositions themselves, thus neglecting the optimization of subsequent processes such as degreasing, have resulted in the problem where the binder material cannot completely be removed when complex molded products of micro-powder are manufactured on a larger scale or small parts are manufactured using a nano-powder. 
         [0008]    Therefore, to develop a composition for powder molding a metal or ceramic material that ensures a technical foundation for manufacturing complex products, there is an urgent need for a system for developing a novel binder material capable of overcoming the limitations of a strategy for developing a binder material depending on a trial and error method with no principles or impractical theoretical calculations and compensating for the drawbacks of these two approaches. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to a system and method of developing a composition for powder molding capable of effectively developing a composition powder molding in a short period of time by extracting compositional information on candidate compositions using a genetic algorithm and combining actually synthesized and analyzed information with the extracted compositional information. 
         [0010]    According to an aspect of the present invention, there is provided a system for developing a composition for powder molding capable of extracting compositional information on the composition in terms of a viscosity of the composition for powder molding and ratios of residual binder materials after a degreasing process. Such a system for developing a composition for powder molding may include a searching logic unit configured to generate a plurality of candidate compositional information and extract the optimal compositional information from the plurality of candidate compositional information, and a synthesis/analysis module configured to synthesize and analyze compositions corresponding to the plurality of candidate compositional information and provide measurement information on viscosities of the compositions corresponding to each of the plurality of candidate compositional information, and ratios of residual binder materials after a degreasing process to the searching logic unit. Here, the searching logic unit may extract the optimal compositional information based on the candidate compositional information and the measurement information on the candidate compositional information. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: 
           [0012]      FIG. 1  is a diagram for describing a system for developing a composition for powder molding according to one exemplary embodiment of the present invention; 
           [0013]      FIGS. 2 to 4  are each diagrams showing algorithms for describing functions of first to third search units shown in  FIG. 1 ; and 
           [0014]      FIG. 5  is a diagram for describing evaluation rankings of candidate compositional information. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0015]    Exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. While the present invention is shown and described in connection with exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the invention. 
         [0016]    Unless specifically stated otherwise, all the technical and scientific terms used in this specification have the same meanings as generally understood by a person skilled in the related art to which the present invention belongs. In general, the nomenclatures used in this specification and the experimental methods described below are widely known and generally used in the related art. 
         [0017]    A system for developing a composition for powder molding according to one exemplary embodiment of the present invention may be used to extract optimal compositions from predetermined binder materials in a powder molding method such as powder injection molding or powder extrusion molding of metal materials or ceramic materials. 
         [0018]    Generally, a mixture obtained by mixing a main binder including at least one material selected from thermoplastic polymer materials such as polyethylene, polypropylene, polystyrene, ethylene vinyl acetate, and the like, a secondary binder selected from wax materials such as polyethylene wax, paraffin wax, carnauba wax, and the like, and one or more process formulations selected from a surfactant, a mixing inducing agent, a reaction accelerator, and the like may be used as a binder material for powder molding of a metal powder or a ceramic powder. 
         [0019]    According to one exemplary embodiment of the present invention, the system for developing a composition for powder molding may, after specifying component materials included in powder and binder materials, extract optimal compositions of the respective components for powder molding in terms of viscosity of the composition for powder molding, ratios of residual binder materials after a degreasing process, etc. The viscosity of the composition is a factor having the greatest influence on molding characteristics, and the ratio of the residual binder material after the degreasing process is a factor having the greatest influence on mechanical properties of sintered moldings 
         [0020]    Hereinafter, the system for developing a composition for powder molding according to one exemplary embodiment of the present invention will be described with reference to  FIGS. 1 to 5 . 
         [0021]      FIG. 1  is a diagram for describing a system for developing a composition for powder molding according to one exemplary embodiment of the present invention, and  FIGS. 2 to 4  are each diagrams showing algorithms for describing functions of first to third search units shown in  FIG. 1 . 
         [0022]    Referring to  FIGS. 1 to 4 , the system  100  for developing a composition for powder molding according to one exemplary embodiment of the present invention may include a searching logic unit  110  and a synthesis/analysis module  120 . 
         [0023]    The searching logic unit  110  may include a control unit  111 , first to third search units  112 A,  112 B and  112 C, a storage unit  113 , and an output unit  114 . 
         [0024]    The first search unit  112 A may be driven by a first control signal C 1  from the control unit  111  and generate ‘N’ first parent solutions according to a first algorithm as shown in  FIG. 2  and store in the storage unit  113 . Each of the ‘N’ first parent solutions may include specific compositional information on the compositions for powder molding composed of predetermined component materials, and the first search unit  112 A may randomly generate the ‘N’ first parent solutions. 
         [0025]    When the ‘N’ first parent solutions are generated by the first search unit  112 A may, after the synthesis/analysis module  120  synthesizes compositions corresponding to each of the ‘N’ first parent solutions according to an analysis command signal SA of the control unit  111 , analyze characteristics of each thereof such as viscosities and ratios of residual binder materials after a degreasing process and provide the analysis results to the first search unit  112 A. That is, the synthesis/analysis module  120  may provide to the first search unit  112 A measured target values R 1  including the measurement information on the viscosities of the compositions corresponding to each of the ‘N’ first parent solutions and the ratios of the residual binder materials after the degreasing process. Also, the first search unit  112 A may store in the storage unit  113  the measured target values with the ‘N’ first parent solutions, that is, a combination SR 1  of the first parent solutions and the measured target values thereof. 
         [0026]    When the combination SR 1  of the ‘N’ first parent solutions and the measured target values corresponding to each thereof are stored in the storage unit  113 , the second search unit  112 B may generate first offspring solutions according to an algorithm  2  as shown in  FIG. 3 . Each of the first offspring solutions may also include specific compositional information on the compositions for powder molding composed by the predetermined component materials. According to one exemplary embodiment, the second search unit  112 B may, after first drawing the combination SR 1  of the ‘N’ first parent solutions and the measured target values corresponding to each thereof from the storage unit  113  according to a second control signal C 2  from the control unit  111 , assign evaluation rankings to each of the first parent solutions. Specifically, the second search unit  112 B may assign the evaluation rankings to the ‘N’ first parent solutions using the measured target values. 
         [0027]    According to one exemplary embodiment, the second search unit  112 B may, after aligning the ‘N’ first parent solutions in a plane defined by parameters corresponding to the target values, compare each of the first parent solutions against each other to determine a dominance relation, thereby assign the front ranking to each of the first parent solutions. For example, when 10 first parent solutions are aligned in a plane defined by a parameter f 1  corresponding to the ‘viscosity of the composition’ and a parameter f 2  corresponding to the ‘ratios of the residual binder materials after a degreasing process’ as shown in  FIG. 5 , a first front ranking (Front 1) may be assigned to the non-dominant first parent solutions ‘ 1 ’, ‘ 2 ’ and ‘ 3 ’ of the innermost positions. Thereafter, depending on the strength of the dominance, a second front ranking (Front 2) may be assigned to the first parent solutions ‘ 4 ’, ‘ 5 ’, ‘ 6 ’ and ‘ 7 ,’ a third front ranking (Front 3) may be assigned to the first parent solutions ‘ 8 ’ and ‘ 9 ,’ and a fourth front ranking (Front 4) may be assigned to the first parent solution ‘ 10 ,’. Subsequently, in the plane defined by the parameters corresponding to the target values, the second search unit  112 B may, after calculating inter-distance between each of the first parent solutions according to each of front rankings, assign the inter-distance to each of the first parent solutions according to the inter-distance rankings. According to one exemplary embodiment, an inter-distance for the ‘i th ’ first parent solution may be defined as an average of distances between the ‘i th ’ first parent solution and the ‘i− 1   st ’ and ‘i+ 1   st ’ first parent solutions adjacent to the ‘i th ’ first parent solution in the plane. As described above, when the front rankings and the inter-distance rankings are assigned to the ‘N’ first parent solutions, evaluation rankings for the ‘N’ first parent solutions may be primarily determined by the front rankings and may be determined by the inter-distance rankings in the case of duplicate front rankings. 
         [0028]    After the evaluation rankings are assigned to each of the ‘N’ first parent solutions, the second search unit  112 B may generate ‘N’ first offspring solutions by performing a ‘crossover’ operation and a ‘mutation’ operation on the first parent solutions selected from the ‘N’ first parent solutions in a tournament manner using the evaluation rankings. Crossover operations and mutation operations applied to known genetic algorithms may be used as the ‘crossover operation’ and the ‘mutation operation’ without limitation, and thus a detailed description thereof will be omitted. 
         [0029]    When the ‘N’ first offspring solutions are generated by the second search unit  112 B, the synthesis/analysis module  120  may, after synthesizing compositions corresponding to each of the ‘N’ first offspring solutions according to the analysis command signal SA from the control unit  111 , analyze and then provide measured target values of each thereof to the second search unit  112 B. Thereafter, the second search unit  112 B may store a combination SR 2  of the ‘N’ first offspring solutions and the measured target values in the storage unit  113 . 
         [0030]    When the combination SR 2  of the ‘N’ first offspring solutions and the corresponding measured target values thereof is stored in the storage unit  113 , the third search unit  112 C may select the second parent solution according to an algorithm  3  shown in  FIG. 4  and determine whether convergence thereof within target range is achieved. According to one exemplary embodiment, the third search unit  112 C may, after drawing the combination SR 1  of the ‘N’ first parent solutions and the measured target values corresponding to each thereof and the combination SR 2  of the ‘N’ first offspring solutions and the measured target values corresponding to each thereof from the storage unit  113  depending on a third control signal C 3  from the control unit  111 , assign to the ‘N’ first parent solutions and the ‘N’ first offspring solutions new evaluation rankings among thereof. In this case, the evaluation rankings is assigned in substantially the same manner as described above, and thus a detailed description thereof will be omitted. 
         [0031]    After the evaluation rankings are assigned to each of the ‘N’ first parent solutions and the ‘N’ first offspring solutions, the third search unit  112 C may select the ‘N’ second parent solutions from the ‘N’ first parent solutions and the ‘N’ first offspring solutions based on the evaluation rankings and may store a combination SR 3  of the second parent solutions and measured target values thereof in the storage unit  113 . 
         [0032]    Meanwhile, when the measured target values for the second parent solutions converge within a preset target range, the control unit  111  may output to the output unit  114  the second parent solutions as the optimal compositions for powder molding, and terminate the operation of the system  100 . 
         [0033]    On the other hand, when the measured target values for the second parent solutions do not converge within the target range, the second search unit  112 B may, depending on a control signal C 2  from the control unit  111 , generate ‘N’ second offspring solutions based on the ‘N’ second parent solutions, which is then stored with the measured target values for the second offspring solutions provided from the synthesis/analysis module  120 . Thereafter, the third search unit  112 C may select ‘N’ third parent solutions from the storage unit  113  in the same manner as described above for the ‘N’ second parent solutions and the ‘N’ second offspring solutions, which is then stored with the measured target values in the storage unit  113 . 
         [0034]    Also, when the measured target values for the third parent solutions converge within the target range, the control unit  111  may output the third parent solutions as the optimal compositions for powder molding. However, when the measured target values for the third parent solutions do not converge within the target range, the above-described operations may be repeatedly performed. 
         [0035]    According to the exemplary embodiments of the present invention, since the optimal compositions for powder molding may be extracted by combining the target value measured by experiments with the compositional information generated by calculations using a computer, a wide range of compositions which have not been searched in conventional studies may be optimized within a short period of time with minimum effort. 
         [0036]    According to the exemplary embodiments of the present invention, the optimal compositional information on the compositions for powder molding can be effectively extracted within a short period of time by evolving the initially generated compositional information using the genetic algorithm and using the information actually measured by the synthesis/analysis module. 
         [0037]    It will be apparent to those skilled in the art that various modifications can be made to the above-described exemplary embodiments of the present invention without departing from the scope of the invention. Thus, it is intended that the present invention covers all such modifications provided they come within the scope of the appended claims and their equivalents.