Abstract:
A mold for hot stamping is disclosed. The mold may include: a base plate configured to receive and exhaust coolant; at least one appearance block mounted at a surface of the base plate and positioned along a shape of a product, the appearance block having a mounting space therein; and an insert block inserted in the mounting space so as to be fixed to the appearance block and mounted at a surface of the base plate. The insert block is provided with a plurality of passages in an exterior surface thereof for circulating coolant, wherein the plurality of passages are in fluidly communication with the base plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0115152 filed in the Korean Intellectual Property Office on Nov. 7, 2011, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a mold for hot stamping. More particularly, the present invention relates to a mold through which a coolant can be smoothly flowed to improve cooling speed and cooling performance, such that a super high strength product is manufactured at a high temperature. 
         [0004]    (b) Background Art 
         [0005]    Generally, molds are divided into three types: an injection mold for manufacturing plastic products, a press mold for manufacturing products by using steel plates, and a die casting mold for manufacturing products by melting metals and injecting the molten metal into the die casting mold. Typically, such molds include a movable mold and a fixed mold which make the manufacturing process run more smoothly. 
         [0006]    Recently there has been an increase in the use of molds for manufacturing products used in vehicles (i.e. various vehicle components). Accordingly, there is a need to properly design these molds in order to produce high quality products which posses desired properties and specifications. 
         [0007]    Improving collision performance and securing safety are two main concerns of vehicle industries. In order to provide a lightweight vehicle with a strong vehicle body, motor companies typically use materials such as TRIP steel, DP steel, aluminum alloy steel, and magnesium alloy steel to produce various vehicle parts, or investigate new technologies such as tailed welding blank (TWB), hydroforming and hot stamping. 
         [0008]    As used herein, a hot stamping process is a process for forming a structure (such as a vehicle panel) at a high temperature so as to reduce the weight thereof while maintaining the strength, and is particularly used with reference to manufacturing a vehicle body. In general, after a material is heated to the high temperature, the material is pressed in a mold and the mold itself is cooled so as to manufacture high strength products. 
         [0009]    The hot stamping process includes heating a blank to a temperature higher than the Ac3 transformation point (i.e. the temperature at which transformation of ferrite into austenite is completed) so as to austenitize the blank completely, and forming and quickly cooling the blank in the mold so as to transform the blank into high strength martensite. 
         [0010]    The components of the vehicle body manufactured by the hot stamping have high tensile strength, particularly tensile strengths higher than or equal to 1500 MPa. Therefore, collision performance of the vehicle may be improved and high safety of occupants may be provided. 
         [0011]    In a conventional hot stamping process and device, coolant is supplied into the mold through coolant holes directly formed in the mold. However, it is very difficult to form the coolant holes in the mold, particularly when manufacturing products of complex shapes, and much time is necessary for forming the coolant holes. 
         [0012]    Further, if a large number of coolant holes are formed in the mold so as to cool the mold more quickly, strength of the mold may be deteriorated using the conventional hot stamping process and device. This decrease in strength can result in cracks or damage to the mold, particularly due to contraction or deformation of the mold during quick temperature changes. As a result, the coolant flowing through the mold may leak. 
         [0013]    Since design, manufacture, and verification of coolant flow lines in the mold is achieved based on an actual model, initial investment and time for developing the products may increase. Therefore, it is preferable to develop the optimal cooling method for the mold at a design step of new products. 
         [0014]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention has been made in an effort to provide a mold for hot stamping that is capable of quickly cooling a structure, particularly a panel, when manufacturing the structure by a hot stamping process. 
         [0016]    In addition, the present invention has been made in an effort to provide a mold for hot stamping that has improved durability, particularly by preventing, in advance, the potential for the occurrence of deformations and cracks in the mold which can result from temperature fluctuations (e.g. when cooling a product). The present invention has further been made in an effort to provide a mold and method that produces a flawless product and improves productivity by achieving uniform cooling. 
         [0017]    According to one aspect, the present invention provides a mold for hot stamping that may include: a base plate configured to receive and exhaust coolant; at least one appearance block mounted at a surface of the base plate in a shape of a product to be formed, and having a mounting space formed therein; and an insert block disposed in the mounting space so as to be fixed to the appearance block and mounted at a surface of the base plate. According to various embodiments, the insert block is provided with a plurality of passages for circulating coolant. The plurality of passages can be formed at an exterior circumference thereof close to the appearance block where the insert block is fixed to the appearance block. The plurality of passages can be in fluid communication with the base plate. 
         [0018]    According to various embodiments, the shape of the appearance block may be substantially the same as that of the product. Further, and the mounting space may have a shape similar to the shape of the appearance block. 
         [0019]    According to various embodiments, the insert block may include: a body portion having a shape that is the similar to or the same as the shape of the mounting space, and it may be fixed to the appearance block when it is disposed in the mounting space; a pair of storing recesses (although it is understood that any number of storing recesses could also be provided at various desired locations) formed respectively at opposite sides of a lower portion of the body portion along a length direction of the body portion, and configured so as to store the coolant therein; and a plurality of coolant flowing grooves adapted to provide a connection between the pair of storing recesses, formed at an exterior circumference of the body portion along a width direction thereof, and defining the plurality of passages. 
         [0020]    According to various embodiments, edges of the body portion may be formed to be rounded. 
         [0021]    According to various embodiments, the plurality of coolant flowing grooves may be disposed spaced apart from each other along the length direction of the body portion. 
         [0022]    According to various embodiments, the body portion may have a coolant inflow hole and a coolant exhaust hole formed therein and fluidly connected to the base plate. 
         [0023]    According to various embodiments, a pair of storing recesses may be connected to the coolant inflow hole and the coolant exhaust hole respectively. 
         [0024]    According to various embodiments, the base plate may have a pair of first coolant chambers formed at both sides of the other surface (the appearance block(s) mounted at one surface of the base plate, and the coolant chambers formed at a different “other surface”, e.g. see  FIG. 5 ) along a length direction thereof, and the coolant may be stored in each of the first coolant chamber. 
         [0025]    According to various embodiments, the base plate may further have a pair of second coolant chambers formed at both side portions of the surface (i.e. a common surface as the appearance block) thereof, and each of the second coolant chambers may store coolant therein and may be fluidly connected to a corresponding first coolant chamber. 
         [0026]    According to various embodiments, the base plate may further have a seal cover mounted at the other surface (i.e. the same surface as the first and second coolant chambers) corresponding to each of the first coolant chambers. 
         [0027]    According to various embodiments, the insert block may be fixed to the appearance block by welding when it is inserted in the mounting space of the appearance block. 
         [0028]    It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a perspective view of a mold for hot stamping according to an exemplary embodiment of the present invention. 
           [0030]      FIG. 2  is an enlarged perspective view of “A” portion in  FIG. 1 . 
           [0031]      FIG. 3  is an exploded perspective view of a mold for hot stamping according to an exemplary embodiment of the present invention. 
           [0032]      FIG. 4  is a perspective view showing flow direction of coolant supplied to a mold for hot stamping according to an exemplary embodiment of the present invention. 
           [0033]      FIG. 5  is a cross-sectional view taken along the line B-B in  FIG. 4 . 
           [0000]    
         
           
                 
               
                 
                 
                 
               
             
                 
                     
                 
                 
                   &lt;Description of symbols&gt; 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                     
                   10: base plate 
                   11: nipple 
                 
                 
                     
                   13: first coolant chamber 
                   15: second coolant chamber 
                 
                 
                     
                   20: appearance block 
                   21: mounting space 
                 
                 
                     
                   30: insert block 
                   31: body portion 
                 
                 
                     
                   33: storing recess 
                   35: coolant flowing groove 
                 
                 
                     
                   37: coolant inflow hole 
                   39: coolant exhaust hole 
                 
                 
                     
                     
                 
               
            
           
         
       
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
         [0035]    Exemplary embodiments described in this specification and drawings are just exemplary embodiments of the present invention. It is to be understood that there can be various modifications and equivalents included in the spirit of the present invention at the filing of this application. 
         [0036]      FIG. 1  is a perspective view of a mold for hot stamping according to an exemplary embodiment of the present invention;  FIG. 2  is an enlarged perspective view of “A” portion in  FIG. 1 ;  FIG. 3  is an exploded perspective view of a mold for hot stamping according to an exemplary embodiment of the present invention;  FIG. 4  is a perspective view showing flow direction of coolant supplied to a mold for hot stamping according to an exemplary embodiment of the present invention; and  FIG. 5  is a cross-sectional view taken along the line B-B in  FIG. 4 . 
         [0037]    Referring to drawings, a mold  1  for hot stamping according to an exemplary embodiment of the present invention is adapted to quickly cool a product, such as a panel, when manufacturing the product by the hot stamping. In particular, the mold is designed such that hydraulic lines for flowing coolant are formed in the mold. As such, the coolant may flow smoothly and cooling performance may be improved. 
         [0038]    In addition, deformation and cracks occurring in the mold when the mold is cooled is prevented in advance. In particular, because the present invention does not directly form coolant flow lines in the mold but, rather, forms these coolant flow lines in the exterior surface of an insert block which is subsequently disposed in the appearance block, the durability of the mold may be improved and such deformation and cracking can be prevented. In addition, according to the present invention, product defects may be reduced or even eliminated and productivity may be improved by achieving uniform cooling of the mold. 
         [0039]    For this purpose, the mold  1  for hot stamping according to an exemplary embodiment of the present invention, as shown in  FIG. 1  to  FIG. 3 , includes a base plate  10 . The base plate  10  includes at least one appearance block  20  and an insert block  30 . 
         [0040]    A nipple  11  is mounted at a side of the base plate  10 . The nipple  11  is adapted to supply the coolant to the base plate  10  and/or exhaust the coolant from the base plate  10 . 
         [0041]    Coolant lines (not shown) connected to the nipple  11  are formed in the base plate  10 . Therefore, the coolant flowing into the base plate  10  through the nipple  11  circulates along the coolant lines, and thereafter t is exhausted through the nipple  11 . 
         [0042]    In this exemplary embodiment, a plurality of appearance blocks  20  is provided. As shown in  FIG. 1 , five appearance blocks  20  are provided. However, it is understood that any number of appearance blocks  20  can be provided. The plurality of appearance blocks  20  together (or alternatively a single appearance block) form the same shape as that of the product so as to form the shape of the product during hot stamping. Each appearance block  20  is mounted at a surface of the base plate  10  and has a mounting space  21  formed therein. In other words, the each appearance block  20  is hollow, thus providing a mounting space  21  therein. 
         [0043]    The appearance blocks  20  are mounted along the base plate  10 , such as along the length as shown in  FIG. 1 , according to the shape of the product. 
         [0044]    Herein, the shape of the appearance block  20  is the same as that of the product, and a shape of the mounting space  21  is similar to that of the appearance block  20 . Because the mounting space  21  is within the appearance block, the size of the mounting space  21  is slightly smaller than that of the appearance block  20 . As such, the coolant can flow along the shape of the product (e.g. panel) close to the product. According to various embodiments the product forms at a location outside of the appearance block. Therefore, cooling performance may be improved. 
         [0045]    According to various embodiments, the insert block  30  is adapted to supply the coolant in the mounting space  21  of the appearance block  20 . As shown, the insert block  30  is disposed in the mounting space  21  and is coupled to the appearance block  20 . 
         [0046]    As shown in  FIG. 5 , the insert block  30  is mounted between the base plate  10  and the appearance block  20 . 
         [0047]    The insert block  30  can be fixedly mounted to the appearance block  20  through any suitable means, such as welding, when the insert block is inserted in the mounting space  21  of the appearance block  20 . 
         [0048]    The insert block  30 , as shown in  FIG. 3  to  FIG. 5 , includes a body portion  31 , a storing recess  33 , and a coolant flowing groove  35 . 
         [0049]    As shown in  FIGS. 2 ,  3  and  5 , the shape of the body portion  31  is the same as that of the mounting space  21 . Therefore, the body portion  31  can be fixedly mounted at the appearance block  20  through welding or other suitable means when it is inserted in the mounting space  21 . 
         [0050]    in particular, the body portion  31  can be inserted in the mounting space  21  such that an exterior circumference of the body portion  31  is disposed within the mounting space  21 , and contacts an interior surface of the appearance block  20 . 
         [0051]    As shown in the figures, according to preferred embodiments outer edges of the body portion  31  are rounded to prevent damage and breakage that can occur when the body portion  31  is inserted in the mounting space  21  and the edge portions of the body portion  31  contact the interior surface of the appearance block  20 . The rounded edge portions, further, allow for more smooth insertion of the body portion  31  in the mounting space  21 . 
         [0052]    As shown in  FIG. 5 , a pair of storing recesses  33  are formed respectively at a opposite sides of a lower portion of the body portion  31  close to the base plate  10 . These storing recesses  33  may, as shown in  FIG. 2 , run along the length direction of the body portion  31 . The coolant supplied from the base plate  10  is adapted to be stored in the storing recess  33 . In particular, the storing recess  33  may be adapted, as shown, to store the coolant supplied to or exhausted from the base plate  10  between the interior of the appearance block and the exterior of the body portion  31 . 
         [0053]    As shown in  FIG. 5 , the pair of storing recesses  33  are connected to a coolant inflow hole  37  and a coolant exhaust hole  39  formed in the body portion  31 , respectively. 
         [0054]    In other words, the one of the storing recesses  33  is connected to the coolant inflow hole  37  so as to store the coolant received through the coolant inflow hole  37 , while the other of the storing recesses  33  is connected to the coolant exhaust hole  39  so as to store the coolant that has circulated through the coolant flowing groove  35 . 
         [0055]    Meanwhile, first coolant chambers  13  for storing the coolant can be further formed respectively at both sides of the other surface of the base plate  10  (i.e. wherein a “top surface” is a surface on which the appearance block  20  is provided, and the “other surface” is a lower “interior” surface as shown in  FIG. 5  on which the coolant chambers  13  are mounted). The coolant chambers  13  may run along the length direction of the base plate  10 , as shown in  FIG. 5 . Second coolant chambers  15  can further be provided in connection with the first coolant chambers  13  for storing coolant. The second coolant chambers  15  can be formed at a surface of the base plate  10 , such as an upper interior surfaced as shown in  FIG. 5 . As shown in  FIG. 5 , the second coolant chambers  15  can be disposed at two locations along the length of the base plate  10 , such that they are aligned with the coolant inflow hole  37  and coolant exhaust hole  39 . Each of the second coolant chambers  15  is further in connection with each of the storing recesses  33 . 
         [0056]    As shown in  FIG. 5 , the first coolant chambers  13  and the second coolant chambers  15  are formed at positions where the coolant flows or is exhausted, and are configured so as to store the inflow or exhaust coolant. 
         [0057]    As further shown in  FIG. 5 , seal covers  17  corresponding to the first coolant chambers  13  can further be mounted at the other surface of the base plate  10 . The seal covers  17  are adapted to prevent leakage of the coolant stored in the first coolant chamber  13  to the exterior of the base plate  10 . 
         [0058]    According to the described embodiment, the coolant flowing into the nipple  11  is primarily stored in the one of the pair of the first coolant chambers  13 , and the coolant stored in the first coolant chamber  13  is secondarily stored in the corresponding second coolant chamber  15  which is in connection with the first coolant chamber  13 . After the coolant has flowed through the coolant line, it passes through the coolant exhaust hole  39 . Before it is exhausted through the nipple  11 , it is primarily stored in the other of the first coolant chambers  13 , and is secondarily stored in the second corresponding coolant chamber  15  which is in connection with the other of the first coolant chambers  13 . The coolant stored in the second coolant chamber  15  connected to the other of the first coolant chamber  13  is subsequently exhausted from the base plate  10  through the nipple  11 . 
         [0059]    As shown, one of the pair of the second coolant chambers  15  is in connection with the coolant inflow hole  37  of the body portion  31  so as to supply the coolant to the storing recess  33  connected to the coolant inflow hole  37 . The other of the pair of the second coolant chambers  15  is in connection with the coolant exhaust hole  39  of the body portion  31  so as to store the coolant exhausted from the storing recess  33  connected to the coolant exhaust hole  39 . 
         [0060]    In an exemplary embodiment of the present invention, at least one coolant flowing groove  35  is formed in the body portion and connects the pair of storing recesses  33  disposed on opposing sides of the body portion. 
         [0061]    As shown in the  FIG. 3  embodiment, each coolant flowing groove  35  is extends along a width direction of the body portion  31 , and in particular, extends along an outer surface of the body portion  31  along the width thereof. In addition, a plurality of coolant flowing grooves  35  can be disposed spaced apart from each other in the length direction of body portion  31 . In one or more exemplary embodiments, the plurality of coolant flowing grooves  35  are disposed spaced apart from each other at an even distance. As further shown in  FIG. 3 , according to a variety of embodiments, the plurality of coolant flowing grooves  35  run parallel to each other along the width of the body portion  31 . 
         [0062]    The coolant flowing grooves  35  form hydraulic lines through which the coolant can flows between the interior surface of the appearance block  20  and the body portion  31  (i.e. within the mounting space  21 ). In other words, the coolant flowing grooves  35  may be defined as a space between the appearance block  20  inner surface and the outer “recessed” surface of the body portion  31 , wherein the outer surface of the body portion  31  at the position of the coolant flowing grooves  35  is recessed as shown in  FIG. 3 ). Therefore, the coolant flows smoothly along the width direction of the body portion  31  through the coolant flowing grooves  35  formed between the exterior recessed surface of the body portion  31  and the interior surface of the appearance block  20 . 
         [0063]    According to embodiments of the present invention, since the coolant supplied through or exhausted through the nipple  11  of the base plate  10  can be stored in the first and second coolant chambers  13  and  15  and the storing recesses  33 , the coolant can flow through the coolant flowing grooves  35  continuously. 
         [0064]    It is noted that while the coolant flowing grooves  35  are depicted in the figures and described herein as being formed along the exterior circumference of the body portion  31  spaced apart with an even distance therebetween, the present invention is not limited to this configuration and spacing. For example, as one of skill in the art would appreciate, the number of and distances between the coolant flowing grooves  35  can be changed taking into account of the shape and the size of the product and desired flow of the coolant. 
         [0065]    An assembly process and function of the mold for hot stamping according to an exemplary embodiment of the present invention will now be described in detail with reference to  FIG. 4  and  FIG. 5 . 
         [0066]    The exterior circumference of the appearance block  20  is formed so as to have a shape that is the same as that of the product (e.g. panel), and the mounting space  21  is formed at the interior circumference of the appearance block  20 . In particular, the appearance block  20  is formed hollow such that the interior surface of the appearance block  20  corresponds to the outer shape of the appearance block  20 . In addition, the insert block  30  is formed to have a shape also corresponding to that of the appearance block  20 , with storing recesses  33  and a plurality of coolant flowing grooves  35  formed at the exterior circumference of the body portion  31 . The insert block  30  thus formed is inserted in the mounting space  21  of the appearance block  20  and is fixed to appearance block  20  through suitable fixation means, such as welding. 
         [0067]    According to the exemplary embodiment, the insert block  30  is mounted on the appearance block  20  such that the exterior circumference of the body portion  31  is in disposed within the mounting space  21 , particularly wherein the exterior surface of the body portion  31  is in contact with the interior surface of the appearance block  20 . 
         [0068]    After assembling of the appearance block  20  and the insert block  30 , the coolant inflow hole  37  and the coolant exhaust hole  39  of the insert block  30  are provided at positions corresponding to the pair of the second coolant chambers  15  formed in the base plate  10 , and the plurality of appearance blocks  20  are mounted to the base plate  10  so as to complete assembling of the mold  1 . 
         [0069]    As shown in  FIG. 4 , if the coolant is supplied to the base plate  10  through the nipple  11 , the coolant flows along the length direction of the base plate  10  and flows into each appearance block  20 . 
         [0070]    In this case, as shown in  FIG. 5 , the coolant is primarily stored in the one of the first coolant chambers  13  and is supplied to the second coolant chamber  15  connected thereto. 
         [0071]    The coolant stored in the second coolant chamber  15  is then supplied to the coolant inflow hole  37  of the insert block  30 , and is stored in the one of the storing recesses  33 . 
         [0072]    The coolant stored in the one of the storing recesses  33  flows along the interior circumference of the mounting space  21  through the coolant flowing grooves  35  formed in the body portion  31  of the insert block  30 . 
         [0073]    After the coolant flows through the coolant flowing grooves  35 , it passes to the other of the storing recesses  33  where it is stored and is then exhausted to the second coolant chamber  15  connected to the coolant exhaust hole  39 . After that, the coolant is stored in the other of the first coolant chambers  13 , and is subsequently exhausted to the exterior of the base plate  10  through the nipple  11 . 
         [0074]    According to an exemplary embodiment of the present invention, coolant flow lines for flowing the coolant are not directly formed at the mold  1  but, rather, are formed in the exterior surface of the insert block  30  which is then disposed and assembled in the appearance block  20 . Therefore, degree of freedom in mold design may be improved and cooling performance of the mold, which is a major factor of hot stamping, may be enhanced. 
         [0075]    In addition, deformation and cracking of the mold when the mold is cooled is prevented in advance. Therefore, durability may be improved. In addition, a product may be manufactured without defects, and productivity may be improved by achieving uniform cooling of the panel. 
         [0076]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.