Patent Publication Number: US-2019193162-A1

Title: Method for manufacturing metal products having irregular shapes

Description:
FIELD 
     The subject matter herein generally relates to metal injection molding (MIM) field, especially to a metal injection molding method for manufacturing metal products having irregular shapes. 
     BACKGROUND 
     Metal powder injection molding is an industrial technology to prepare metal products. However, some products have special structures, such as an inverted buckle structure, such product is not conducive to demolding in the injection molding process. Large products may have special structures also difficult to mold. The above-mentioned disadvantages need to be overcome. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is a flowchart of a manufacturing method for metal products having irregular shapes. 
         FIG. 2A  is a cross-section view of workpieces and a substrate in one exemplary embodiment. 
         FIG. 2B  is a cross-section view showing soldering flux applied on jointing surfaces between the workpieces and the substrate and jointing surfaces between adjacent of the workpieces, and assembling the workpieces and the substrate together to form a preform as in  FIG. 2A . 
         FIG. 2C  is a cross-section view showing the preform soldered to obtain a metal product having irregular shapes. 
         FIG. 3A  is a cross-section view showing workpieces and a substrate in one exemplary embodiment. 
         FIG. 3B  is a cross-section view showing soldering flux applied on jointing surfaces between the workpieces and the substrate, the workpieces and the substrate being put together to form preform as in  FIG. 3A . 
         FIG. 3C  is a cross-section view of preform soldered to obtain a metal product having irregular shapes. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale, and the proportions of certain parts may be exaggerated to illustrate details and features of the present disclosure better. The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one.” 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. The references “a plurality of” and “a number of” mean “at least two.” 
       FIG. 1  illustrates a method for manufacturing metal product having irregular shapes according to one embodiment. The method is provided by way of example as there are a variety of ways to carry out the method. The method  300  can be used to manufacture hardware components, industrial machinery components and so on. 
     At block  301 , as shown in  FIG. 1 , a powder and a binding agent are provided, and the powder and binding agent are feed-mixed. The powder may be selected from metal powder, ceramic powder, or pre-alloyed powder. The diameter of the powder may be in a range between 0.01-50 um, and preferably in a range between 0.1-30 um. 
     The binding agent may be a wax based binder or a plastic binder. 
     At block  302 , the feed-mix is heated to be in a plastic state, and the feed-mix is injected in different mold cavities of injection molds to form a plurality of blanks. Structure of the blanks may be same with each other or may be different. Each blank undergoes a degreasing process and a sintering process successively to from a workpiece. The plurality of blanks may be formed by powder of same composition or formed by powder of different components. That is, if the plurality of blanks comprises two blanks, and the two blanks named as a first blank and a second blank. The first blank may be has a same component and a same component contents to the second blank. The first blank may be has a same component and a different component contents to the second blank. The first blank may be has a different component to the second blank. 
     At block  303 , the blanks are degreased to remove the binding agent, and the plurality of degreased blanks are sintered to form workpieces, respectively. Each workpiece is one part of the final metal product having irregular shapes. In the embodiment, the plurality of workpieces are having same component and same component contents. In other embodiment, the plurality of workpieces may have same component with same component composition contents, or have same component with different component contents, or have different components. 
     At block  304 , a substrate is provided. The substrate is also one part of the final metal product having irregular shapes and configured to support the plurality of the workpieces. The workpieces are disposed on the substrate according to a required appearance of the metal product having irregular shapes to form a preform. Component of the substrate is different from a component of the workpiece. A material of the substrate is metal formed by a forging method or ceramic. A process method to form the substrate is different from a process method to form the workpiece. The substrate  20  has a better compactness than the workpieces. The substrate is may be formed by a forging method. 
     At block  305 , the preform is bonded to ensure that each workpiece joints firmly with the substrate, and the final metal product having irregular shapes is obtained. By a heating process, powder particles in the workpiece and powder in the substrate contact each other, and thereby, the workpieces and the substrate are strongly bonded. 
     The bonding method is select from high temperature heat welding, laser welding, or resistance welding. If using high temperature heat welding method, it is necessary to apply flux on jointing surfaces between the workpieces and the substrate and jointing surfaces between adjacent workpieces. 
     Example 1 
       FIG. 2A ˜ 2 C show the formation of a large metal product  100  having irregular shape. The large metal product  100  is formed from a plurality of small workpieces  10  and a substrate  20 . The plurality of workpieces  10  are each formed by MIM method, and each workpiece  10  has same component, as described in block  301  to block  303 .  FIG. 2A  shows workpieces  10  and substrate  20 . In the illustrated embodiment, there are four workpieces  10 , and each workpiece  10  is different from others. Component of the substrate  20  is different from component of the workpieces  10 , and in the illustrated embodiment, the substrate  20  is substantially made of ceramic. The substrate  20  has a better compactness than the workpieces  10 , and the final large metal product  100  can be used for craftwork. 
     Each of the workpiece  10  includes a jointing surface  12  and a jointing surface  14 . The substrate  20  includes a jointing surface  22 . When the workpieces  10  are placed on the substrate  20 , the workpieces  10  are arranged side by side, and the jointing surface  12  bonds with the jointing surface  22  of the substrate  20 . The second jointing surface  14  of one workpiece  10  bonds with the jointing surface  14  of an adjacent workpiece  10 . 
     In  FIG. 2B , soldering flux  50  is applied to jointing surfaces  12  and jointing surfaces  22 . The workpieces  10  and the substrate  20  together form a preform  35 , as in  FIG. 2A . 
       FIG. 2C  shows bonding of the preform  35  to obtain the final complex metal product  100 . The workpieces  10  and the substrate  20  are strongly bonded. Consequently, the large metal product  100  is directly formed by bonding small workpieces  10  to the substrate  20 , rough machining is avoided, and deformation during a sintering process is avoided. 
     Example 2 
       FIG. 3A ˜ 3 C show the forming of a metal product  200  of irregular shape, such as an inverted buckle structure. The complex metal product  200  is also formed from workpieces  30  and substrate  40 . Structure of the metal product  200  is different from a structure the metal product  100  shown in  FIG. 2C . The workpieces  30  are also formed by MIM method, as in block  301  to block  303 . In this illustrated embodiment, the workpieces  30  both have the same structure. 
     As shown in  FIG. 3A , each workpiece  30  has substantially a “ ” shape, and includes a top plate  32  and a side wall  34  protruding from edges of the top plate  32 . The several workpieces  30  together form the inverted buckle structure. The substrate  40  includes a pedestal  42  and a supporting pillar  44  protruding from the pedestal  42 , and the pedestal  42  comprises a stepping portion  441 . 
     The supporting pillar  44  is symmetrical about the pedestal  42 , the supporting pillar  44  can be cylindrical or prismatic in shape. The first jointing surface  120  includes an outside surface  340  of the side wall  34  and a bottom surface  342  perpendicularly connected with the outside surface  340 . The outer side surface  340  may be an arc or a plane. The third jointing surface  220  includes a side surface  440  of the supporting pillar  44  and a top surface  442  surrounding the supporting pillar  44 . The upper surface  442  is perpendicular to the side surface  440 . The side surface  440  can be cylindrical or flat. 
       FIG. 3B  shows soldering flux  50  applied on the first jointing surfaces  120  of the workpieces  30  and the third joint surface  220  of the substrate  40 . The workpieces  30  and the substrates  40  are assembled together to form a preform  45 , as in  FIG. 3A . 
       FIG. 3C  shows the preform  45  bonded to obtain a metal product  200 . The metal product  200  with an inverted buckle structure is thereby obtained. 
     The embodiments shown and described above are only examples. Therefore, many commonly-known features and details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will, therefore, be appreciated that the embodiments described above may be modified within the scope of the claims.