Patent Publication Number: US-2023150017-A1

Title: Method of manufacturing hollow product using draft angle

Description:
TECHNICAL FIELD 
     The present disclosure relates to a method of manufacturing a hollow product. More particularly, the present disclosure relates to a method of manufacturing a hollow product using a draft angle. 
     BACKGROUND ART 
       FIG.  1    illustrates a related art hollow product  10 . The hollow product  10  may be made of a cast product including a hollow tube  15 . The hollow product  10  may be formed in a circular pipe shape. The hollow tube  15  may be formed to extend from a first side  16  disposed at an upper part of the hollow product  10  to the inside of the hollow product  10 . The hollow tube  15  inside the hollow product  10  may be formed to extend along the inside of an outer wall of the hollow product  10 . The hollow tube  15  inside the hollow product  10  may have a coil spring shape. The hollow tube  15  inside the hollow product  10  may be formed to extend to a second side  17  disposed at a lower part of the hollow product  10 . A longitudinal direction of the hollow tube  15  may be a direction in which the hollow tube  15  extends from the first side  16  to the second side  17 . The hollow tube  15  may be formed in the form of a circular pipe. 
       FIG.  2    is a cross-sectional view illustrating the related art hollow product  10  and a core  20 . In order to make the hollow product  10  of the circular pipe shape, the core  20  may be disposed at the center of a mold (not shown). The core  20  may have a form in which a center line CL extending in an up-down direction is used as a rotation axis. The core  20  may include a first upper surface  21  perpendicular to the center line CL, an outer surface  23  that is parallel to the center line CL and extends downward from a perimeter of the first upper surface  21 , and a second upper surface  22  that is perpendicular to the center line CL and extends from a lower end of the outer surface  23  in a direction away from the center line CL. A longitudinal direction of the outer surface  23  may be the up-down direction. 
     Thereafter, the hollow tube  15  may be installed at a position spaced apart from the outer surface  23  of the core  20 . An inner surface of the mold may be disposed at a position spaced apart from an outer surface of the hollow tube  15 . The hollow product  10  may be molded by pouring a molten metal into the mold. The hollow product  10  may include an inner surface  13  formed to extend from the lower end of the outer surface  23  of the core  20  along the longitudinal direction of the outer surface  23  of the core  20 , an upper surface  11  formed to extend from an upper end of the inner surface  13  in the direction away from the center line CL, a lower surface  12  formed to extend from a lower end of the inner surface  13  in the direction away from the center line CL, and outer surface  14  connecting an outer perimeter of the upper surface  11  and an outer perimeter of the lower surface  12 . 
     In order to obtain the finished hollow product  10 , it is necessary to remove the core  20  disposed inside the hollow product  10 . However, since the hollow product  10  and the core  20  of  FIG.  2    are configured such that the center line CL and the outer surface  23  of the core  20  are parallel to each other and the inner surface  13  of the hollow product  10  is in direct contact with the outer surface  23  of the core  20 , a sufficient draft angle for taking the core  20  out of the hollow product  10  is not formed. In this case, there is a problem in that it is difficult to remove the core  20  from the hollow product  10 .
     [Patent Document 1] Korean Patent No. 10-1761677   

     DISCLOSURE 
     Technical Problem 
     An object of the present disclosure is to address the above-described and other problems. 
     Another object of the present disclosure is to provide a core having a draft angle. 
     Another object of the present disclosure is to provide a method of manufacturing a hollow product using a core having a draft angle. 
     Another object of the present disclosure is to provide a carrier having a draft angle. 
     Another object of the present disclosure is to provide a method of manufacturing a hollow product using a carrier having a draft angle. 
     Another object of the present disclosure is to provide a clip having a draft angle. 
     Another object of the present disclosure is to provide a method of manufacturing a hollow product using a clip having a draft angle. 
     Technical Solution 
     In order to achieve the above-described and other objects, in one aspect of the present disclosure, there is provided a method of manufacturing a hollow product using a core having a draft angle, wherein the core is formed to protrude in one direction and has an outer surface at a perimeter of a protruding portion of the core, the outer surface of the core forms a slope with respect to the one direction, and a cross-sectional area of the core decreases as the core goes toward a protruding direction, the method comprising disposing a mold to be spaced apart from the outer surface of the core, disposing a hollow tube between the core and the mold, injecting a molten metal into a space between the core and the mold, and removing the core when the molten metal is solidified and the hollow product is molded. 
     Advantageous Effects 
     Effects of a method of manufacturing a hollow product using a draft angle according to the present disclosure are described as follows. 
     According to at least one embodiment of the present disclosure, the present disclosure can provide a core that is easily separated from a hollow product due to a draft angle of the core. 
     According to at least one embodiment of the present disclosure, the present disclosure can provide a carrier that is easily separated from a core due to a draft angle of the carrier. 
     According to at least one embodiment of the present disclosure, the present disclosure can provide a clip that is easily separated from a hollow product due to a draft angle of the clip. 
     Additional scope of applicability of the present disclosure will become apparent from the detailed description given blow. However, it should be understood that the detailed description and specific examples such as embodiments of the present disclosure are given merely by way of example, since various changes and modifications within the spirit and scope of the present disclosure will become apparent to those skilled in the art from the detailed description. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    illustrates a related art hollow product  10 . 
         FIG.  2    is a cross-sectional view illustrating a related art hollow product  10  and a core  20 . 
         FIG.  3    is an exploded cross-sectional view illustrating a core  120  and a carrier  130  according to an embodiment of the present disclosure. 
         FIG.  4    is a cross-sectional view illustrating the core  120  and the carrier  130  of  FIG.  3    and a hollow product  110  molded using them. 
         FIG.  5    is a cross-sectional view illustrating a core  220  and a hollow product  210  molded using the same according to another embodiment of the present disclosure. 
         FIG.  6    is an exploded cross-sectional view illustrating a core  320 , a clip  340 , and a hollow tube  315  installed in the clip  340  according to another embodiment of the present disclosure. 
         FIG.  7    is a plan view illustrating the core  320 , the clip  340 , and the hollow tube  315  of  FIG.  6   . 
         FIG.  8    is a cross-sectional view illustrating the core  320 , the clip  340 , and the hollow tube  315  of  FIG.  6    and a hollow product  310  molded using core  220 . 
         FIG.  9    is a plan view illustrating the core  320 , the clip  340 , the hollow tube  315 , and the hollow product  310  of  FIG.  8   . 
     
    
    
     MODE FOR INVENTION 
     Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In general, a suffix such as “module” and “unit” may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the present disclosure, and the suffix itself is not intended to give any special meaning or function. It will be noted that a detailed description of known arts will be omitted if it is determined that the detailed description of the known arts can obscure the embodiments of the disclosure. The accompanying drawings are used to help easily understand various technical features and it should be understood that embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. 
     The terms including an ordinal number such as first, second, etc. may be used to describe various components, but the components are not limited by such terms. The terms are used only for the purpose of distinguishing one component from other components. 
     When any component is described as “being connected” or “being coupled” to other component, this should be understood to mean that another component may exist between them, although any component may be directly connected or coupled to the other component. In contrast, when any component is described as “being directly connected” or “being directly coupled” to other component, this should be understood to mean that no component exists between them. 
     A singular expression can include a plural expression as long as it does not have an apparently different meaning in context. 
     In the present disclosure, terms “include” and “have” should be understood to be intended to designate that illustrated features, numbers, steps, operations, components, parts or combinations thereof are present and not to preclude the existence of one or more different features, numbers, steps, operations, components, parts or combinations thereof, or the possibility of the addition thereof. 
     In the drawings, sizes of the components may be exaggerated or reduced for convenience of explanation. For example, the size and the thickness of each component illustrated in the drawings are arbitrarily illustrated for convenience of explanation, and thus the present disclosure is not limited thereto unless specified as such. 
     If any embodiment is implementable differently, a specific order of processes may be performed differently from the order described. For example, two consecutively described processes may be performed substantially at the same time, or performed in the order opposite to the described order. 
       FIG.  3    is an exploded cross-sectional view illustrating a core  120  and a carrier  130  according to an embodiment of the present disclosure. 
     The core  120  may have a form in which a center line CL extending in an up-down direction is used as a rotation axis. The core  120  may have a shape in which a portion is formed to protrude upward. The core  120  may include an outer surface  123  formed around the protruding portion, a first upper surface  121  formed at an upper end of the outer surface  123 , and a second upper surface  122  formed at a lower end of the outer surface  123 . 
     The core  120  may include the first upper surface  121  perpendicular to the center line CL. The core  120  may include the outer surface  123  extending downward from a perimeter of the first upper surface  121 . The outer surface  123  may be formed to move away from the center line CL as it goes toward the lower side. The core  120  may include the second upper surface  122  that is perpendicular to the center line CL and extends from the lower end of the outer surface  123  in a direction away from the center line CL. 
     As illustrated in  FIG.  3   , the outer surface  123  of the core  120  may have a slope with respect to the center line CL. An angle forming the slope may be referred to as a first angle θ 1 . The first angle θ 1  may be formed such that a cross-sectional area of the core  120  decreases as the core  120  goes toward the upper side. The first angle θ 1  may be referred to as a draft angle. 
     The carrier  130  may have a form in which the center line CL extending in the up-down direction is used as a rotation axis. The carrier  130  may include an upper surface  131  that is perpendicular to the center line CL and extends from a position spaced apart from the center line CL in the direction away from the center line CL. The carrier  130  may include an outer surface  134  that is parallel to the center line CL and extends downward from an outer perimeter of the upper surface  131 . A longitudinal direction of the outer surface  134  may be the up-down direction. The carrier  130  may include a lower surface  132  that extends from a lower end of the outer surface  134  in a direction approaching to the center line CL. The carrier  130  may include an inner surface  133  that connects an inner perimeter of the upper surface  131  and an inner perimeter of the lower surface  132 . That is, a core insertion hole  135  may be formed inside the carrier  130 . A diameter of a lower end of the core insertion hole  135  may be equal to a diameter of a lower end of the outer surface  123  of the core  120 . 
     As illustrated in  FIG.  3   , an angle between the inner surface  133  and the outer surface  134  of the carrier  130  may be referred to as a second angle θ 2 . The second angle θ 2  may be equal to the first angle θ 1 . The second angle θ 2  may be referred to as a draft angle. That is, when the carrier  130  is fitted to the core  120 , the inner surface  133  of the carrier  130  and the outer surface  123  of the core  120  may be in close contact with each other. Hence, a molten metal can be prevented from penetrating between the core  120  and the carrier  130 . 
     The carrier  130  may be manufactured by forming a hollow in a cylindrical extruded material and machining the inner surface  133  of the hollow. The carrier  130  may be manufactured by rolling a flat plate material having the inner surface  133  and the outer surface  134  into a circular shape. A slope of the inner surface  133  of the carrier  130  may be formed to be same as a slope of the outer surface  123  of the core  120 , and a slope of the outer surface  134  of the carrier  130  may be formed to be parallel to the center line CL. 
     A material of the carrier  130  may be a metal or a non-ferrous metal. 
       FIG.  4    is a cross-sectional view illustrating the core  120  and the carrier  130 , and a hollow product  110  molded using them. A mold may be disposed to be spaced apart from the outer surface  134  of the carrier  130 . A hollow tube  115  may be disposed between the outer surface  134  of the carrier  130  and the mold. The molten metal may be injected into a remaining space between the outer surface  134  of the carrier  130  and the mold. When the molten metal is solidified, the hollow product  110  including the hollow tube  115  may be molded. 
     The hollow product  110  may include an inner surface  113  that extends from a lower end of the outer surface  134  of the carrier  130  along the longitudinal direction of the outer surface  134  of the carrier  130 . The hollow product  110  may include an upper surface  111  that extends from an upper end of the inner surface  113  in the direction away from the center line CL. The hollow product  110  may include a lower surface  112  that extends from a lower end of the inner surface  113  in the direction away from the center line CL. The hollow product  110  may include an outer surface  114  that connects an outer perimeter of the upper surface  111  and an outer perimeter of the lower surface  112 . 
     Referring to  FIGS.  3  and  4   , since the draft angles θ 1  and θ 2  are formed in the outer surface  123  of the core  120  and the inner surface  133  of the carrier  130 , the core  120  can be easily taken out of the carrier  130 . Hence, the hollow product  110  including the carrier  130  can be formed. 
     Unlike the above description, the carrier  130  can be easily removed from the hollow product  110 . When the core  120  is removed, the carrier  130  may be elastically deformed since the core insertion hole  135  of the carrier  130  becomes empty. Hence, the carrier  130  can be easily taken out of the hollow product  110 . 
       FIG.  5    is a cross-sectional view illustrating a core  220  and a hollow product  210  molded using the same according to another embodiment of the present disclosure. 
     The core  220  may have a form in which a center line CL extending in an up-down direction is used as a rotation axis. The core  220  may have a shape in which a portion is formed to protrude upward. The core  220  may include an outer surface  223  formed around the protruding portion, a first upper surface  221  formed at an upper end of the outer surface  223 , and a second upper surface  222  formed at a lower end of the outer surface  223 . 
     The core  220  may include the first upper surface  221  perpendicular to the center line CL. The core  220  may include the outer surface  223  extending downward from a perimeter of the first upper surface  221 . The outer surface  223  may be formed to move away from the center line CL as it goes toward the lower side. The core  220  may include the second upper surface  222  that is perpendicular to the center line CL and extends from the lower end of the outer surface  223  in a direction away from the center line CL. 
     As illustrated in  FIG.  5   , the outer surface  223  of the core  220  may have a slope with respect to the center line CL. An angle forming the slope may be referred to as a third angle θ 3 . The third angle θ 3  may be formed such that a cross-sectional area of the core  220  decreases as the core  220  goes toward the upper side. The third angle θ 3  may be referred to as a draft angle. A longitudinal direction of the outer surface  223  may be a direction that is inclined with respect to the center line CL by the third angle θ 3  in the up-down direction. 
     A mold may be disposed to be spaced apart from the outer surface  223  of the core  220 . A hollow tube  215  may be disposed between the outer surface  223  of the core  220  and the mold. A molten metal may be injected into a remaining space between the outer surface  223  of the core  220  and the mold. When the molten metal is solidified, the hollow product  210  including the hollow tube  215  may be molded. 
     The hollow product  210  may include an inner surface  213  that extends from a lower end of the outer surface  223  of the core  220  along the longitudinal direction of the outer surface  223  of the core  220 . That is, an angle between the inner surface  213  and the center line CL may be the same as the third angle θ 3 . The hollow product  210  may include an upper surface  211  that extends from an upper end of the inner surface  213  in the direction away from the center line CL. The hollow product  210  may include a lower surface  212  that extends from a lower end of the inner surface  213  in the direction away from the center line CL. The hollow product  210  may include an outer surface  214  that connects an outer perimeter of the upper surface  211  and an outer perimeter of the lower surface  212 . 
     Since the same draft angle θ 3  is formed in the outer surface  223  of the core  220  and the inner surface  213  of the hollow product  210 , the core  120  can be easily taken out of the hollow product  210 . 
       FIG.  6    is an exploded cross-sectional view illustrating a core  320 , a clip  340 , and a hollow tube  315  installed in the clip  340  according to another embodiment of the present disclosure.  FIG.  7    is a plan view illustrating the core  320 , the clip  340 , and the hollow tube  315 . 
     The core  320  may have a form in which a center line CL extending in an up-down direction is used as a rotation axis. The core  320  may have a shape in which a portion is formed to protrude upward. The core  320  may include an outer surface  323  formed around the protruding portion, a first upper surface  321  formed at an upper end of the outer surface  323 , and a second upper surface  322  formed at a lower end of the outer surface  323 . 
     The core  320  may include the first upper surface  321  perpendicular to the center line CL. The core  320  may include the outer surface  323  extending downward from a perimeter of the first upper surface  321 . The outer surface  323  may be formed to move away from the center line CL as it goes toward the lower side. The core  320  may include the second upper surface  322  that is perpendicular to the center line CL and extends from the lower end of the outer surface  323  in a direction away from the center line CL. 
     As illustrated in  FIG.  6   , the outer surface  323  of the core  320  may have a slope with respect to the center line CL. An angle forming the slope may be referred to as a fourth angle θ 4 . The fourth angle θ 4  may be formed such that a cross-sectional area of the core  320  decreases as the core  320  goes toward the upper side. The fourth angle θ 4  may be referred to as a draft angle. 
     The clip  340  may have a form in which the center line CL extending in the up-down direction is used as a rotation axis. As illustrated in  FIG.  7   , the clip  340  may be formed only in a partial area using the center line CL as the rotation axis. The clip  340  may be formed on the left side and the right side of the core  320 . 
     The clip  340  may include an upper surface  341  that is perpendicular to the center line CL and extends from a position spaced apart from the center line CL in the direction away from the center line CL. The clip  340  may include an outer surface  344  that is parallel to the center line CL and extends downward from an outer perimeter of the upper surface  341 . A longitudinal direction of the outer surface  344  may be the up-down direction. The clip  340  may include a lower surface  342  that extends from a lower end of the outer surface  344  in a direction approaching to the center line CL. The clip  340  may include an inner surface  343  that connects an inner perimeter of the upper surface  341  and an inner perimeter of the lower surface  342 . The hollow tube  315  may be fixed to the outer surface  344  of the clip  340 . 
     As illustrated in  FIG.  6   , an angle between the inner surface  343  and the outer surface  344  of the clip  340  may be referred to as a fifth angle θ 5 . The fifth angle θ 5  may be equal to the fourth angle θ 4 . The fifth angle θ 5  may be referred to as a draft angle. That is, when the clip  340  is installed in the core  320 , the inner surface  343  of the clip  340  and the outer surface  323  of the core  320  may be in close contact with each other. Hence, a molten metal can be prevented from penetrating between the core  320  and the clip  340 . 
       FIG.  8    is a cross-sectional view illustrating the core  320 , the clip  340 , and the hollow tube  315 , and a hollow product  310  molded using them.  FIG.  9    is a plan view illustrating the core  320 , the clip  340 , the hollow tube  315 , and the hollow product  310 . 
     The hollow tube  315  may be fixed to the outer surface  344  of the clip  340 . The mold may be disposed to be spaced apart from an outer surface of the hollow tube  315 , the outer surface  344  of the clip  340 , and the outer surface  323  of the core  320 . The molten metal may be injected into a remaining space between the outer surface  323  of the core  320  and the mold. When the molten metal is solidified, the hollow product  210  including the clip  340  and the hollow tube  315  may be molded. 
     A height of the hollow product  310  may be the same as a height of the clip  340 . The height of the hollow product  310  may be greater than the height of the clip  340 . The hollow product  310  may be formed so that the fixed hollow tube  315  of the clip  340  is covered. The hollow product  310  formed in a portion not having the clip  340  may have the same shape as the hollow product  210  described above. 
     A material of the clip  340  may be a metal or a non-ferrous metal. The material of the clip  340  may be the same as a material of the molten metal. That is, the material of the clip  340  may be the same as a material of the hollow product  310 .  FIG.  9    illustrates distinguishably a boundary between the hollow product  310  and the clip  340  for convenience of explanation. However, after going through a high-pressure casting process using the molten metal, an external surface of the clip  340  may be melted in the molten metal, and the boundary between the clip  340  and the hollow product  310  may disappear. 
     Referring to  FIGS.  8  and  9   , since the outer surface  323  of the core  320  and the inner surface  343  of the clip  340  have the draft angles θ 4  and θ 5 , respectively, the core  320  can be easily taken out of the clip  340 . Since the outer surface  323  of the core  320  and an inner surface (not shown) of the hollow product  310  each have the draft angle θ 4 , the core  320  can be easily taken out of the hollow product  310 . 
     Some embodiments or other embodiments of the present disclosure described above are not mutually exclusive or distinct from each other. Configurations or functions of some embodiments or other embodiments of the present disclosure described above can be used together or combined with each other. 
     It is apparent to those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the spirit and essential features of the present disclosure. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the present disclosure should be determined by rational interpretation of the appended claims, and all modifications within an equivalent scope of the present disclosure are included in the scope of the present disclosure.