Abstract:
The present disclosure provides a blank forming device which includes: first and second blanks to be loaded at one side in a width direction and unloaded at the other side in the width direction; an upper electrode and a lower electrode to contact upper portions and lower portions of one side of the loaded first and second blanks; an upper moving electrode and a lower moving electrode to contact upper portions and lower portions of the other side of the first and second blanks and movably disposed in a length direction of the first and second blanks; and a sagging preventing part being disposed at the lower portions of the first and second blanks between the upper electrode and the upper moving electrode and between the lower electrode and the lower moving electrode to let the first and second blanks support sagged portions upward.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2015-0041784, filed on Mar. 25, 2015, which is hereby incorporated by reference in its entirety. 
       FIELD 
       [0002]    The present disclosure relates to a blank forming device using an electric direct heating method for directly applying electricity to a blank for making a vehicle body to heat the blank and forming the blank using a mold. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    Keeping pace with improving fuel consumption and weight reduction of a vehicle, increased strengthening of vehicle parts has been continuously undertaken. 
         [0005]    Further, due to structural characteristics of each part of the vehicle, some parts may require high strength and other parts may require high impact toughness. 
         [0006]    Typically, vehicle parts having heterogeneous strength have been manufactured by a method of manufacturing parts requiring high strength using a quenched steel sheet and parts requiring relatively lower strength using a general steel sheet and then bonding between these parts by welding. 
         [0007]    Meanwhile, a method of heating a blank (steel sheet) using a heating furnace requires a space for the heating furnace. However, it is not easy to heat a portion of the blank using the heating furnace and maintenance costs for operating the heating furnace are high. As the related art, there is Korean Patent Publication No. 10-2011-0075732. 
         [0008]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure 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 
       [0009]    The present disclosure provides a blank forming device using an electric direct heating method capable of saving a space required for a heating furnace, easily heating a portion of the blank, saving maintenance costs, and improving productivity. 
         [0010]    An exemplary form of the present disclosure provides a blank forming device using an electric direct heating method, including: first and second blanks configured to be loaded at one side in a width direction and unloaded at the other side in the width direction; an upper electrode and a lower electrode configured to contact upper portions and lower portions of one side of the loaded first and second blanks; an upper moving electrode and a lower moving electrode configured to contact upper portions and lower portions of the other side of the first and second blanks and movably disposed in a length direction of the first and second blanks; and a sagging preventing part configured to be disposed at the lower portions of the first and second blanks between the upper electrode and the upper moving electrode and between the lower electrode and the lower moving electrode to let the first and second blanks support sagged portions upward. 
         [0011]    The blank forming device may further include: an upper cover configured to be fixedly disposed over the upper electrode and the upper moving electrode; a chiller configured to be disposed over the upper cover to supply a coolant to a circumference of the electrodes; a transformer configured to be disposed over the upper cover to supply a voltage to the electrodes; and a bus bar configured to be disposed on the upper cover to connect between the transformer and each of the electrodes. 
         [0012]    The blank forming device may further include a moving part configured to move the upper moving electrode and the lower moving electrode in the length direction of the first and second blanks. 
         [0013]    The blank forming device may further include a pressing part configured to press the upper electrode or the lower electrode to the first and second blanks and press the upper moving electrode or the lower moving electrode to the first and second blanks. 
         [0014]    The moving part may include: a motor configured to provide a torque; a lead screw configured to rotate by a rotation of the motor; a reference frame configured to be disposed to move by a rotation of the lead screw; a moving frame configured to be disposed at one side of the reference frame and that has the lower moving electrode disposed thereabove; and a tension control cylinder configured to control a position of the moving frame based on the reference frame to control a tension applied to the first and second blanks. 
         [0015]    The blank forming device may further include a brake configured to stop the rotation of the lead screw rotating by the motor. 
         [0016]    The blank forming device may further include: a moving rail configured to be disposed in a direction in which the upper moving electrode or the lower moving electrode moves to supply power to the upper moving electrode or the lower moving electrode and guide motions thereof; and a shunt configured to be directly connected to the upper moving electrode or the lower moving electrode in the moving rail to apply a current. 
         [0017]    The sagging preventing part may include: a sagging preventing cylinder configured to provide a force for supporting the first and second blanks upward; a plate configured to be disposed to move upward by the sagging preventing cylinder; and support protrusions configured to be disposed on the plate to contact lower surfaces of the first and second blanks. 
         [0018]    The plate may be disposed on a moving rail to move in a direction in which the first and second blanks move, and the sagging preventing cylinder may have a linear bearing disposed thereunder to move in the length direction of the first and second blanks. 
         [0019]    The support protrusions may be arranged at a predetermined interval, and may be made from a material having lower hardness than that of the first and second blanks to prevent the first and second blanks from being damaged. 
         [0020]    The first and second blanks may be loaded at one side of the width direction thereof and unloaded at the other side in the width direction thereof. 
         [0021]    Another form of the present disclosure provides a blank forming method using an electric direct heating method, including: loading the blank through an inlet of a blank forming device; pressing an electrode on upper and lower surfaces of one side and the other side of the blank and applying a current through the blank; stopping the application of current and releasing the pressing of the electrode; releasing the pressing of the electrode and supporting a lower surface of a central portion of the blank to prevent the lower surface of the blank from sagging; and unloading the blank through an outlet of the blank forming device. 
         [0022]    In the applying of a current through the blank, the electrode may move in a length direction of the blank to control a tension of the blank in a state in which the electrode presses the blank. 
         [0023]    In the loading of the blank, at least two blanks may be input. 
         [0024]    The blank forming method may further include: performing a braking operation of making the electrode move in the length direction of the blank and fixing a motion of the electrode. 
         [0025]    According to an exemplary form of the present disclosure, it is possible to save the space required for the heating furnace, easily heat a portion of the blank, save the maintenance costs, and improve the productivity. 
         [0026]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0027]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0028]      FIG. 1  is a perspective view of a blank forming device using an electric direct heating method according to an exemplary form of the present disclosure; 
           [0029]      FIG. 2  is a partial perspective view of a moving part and a tension control part in the blank forming device using an electric direct heating method according to the exemplary form of the present disclosure; 
           [0030]      FIG. 3  is a partial perspective view of a sagging preventing part in the blank forming device using an electric direct heating method according to the exemplary form of the present disclosure; and 
           [0031]      FIG. 4  is a flowchart of a forming order of the blank forming device according to the exemplary form of the present disclosure. 
       
    
    
       [0032]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION 
       [0033]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0034]      FIG. 1  is a perspective view of a blank forming device using an electric direct heating method according to an exemplary form of the present disclosure. 
         [0035]    Referring to  FIG. 1 , the blank forming device includes a transformer  120 , a bus bar  130 , an upper cover  170 , a fixed electrode pressing part  162 , an upper electrode  144 , a lower electrode  142 , a fixed frame  154 , a sagging preventing part  158 , a first blank  150 , a second blank  152 , a frame moving rail  180 , a moving frame  156 , a lower moving electrode  146 , an upper moving electrode  148 , a moving electrode pressing part  164 , an inverter  110 , a chiller  100 , and a controller  190 . 
         [0036]    The lower electrode  142  is disposed at a predetermined interval from the lower moving electrode  146  in a length direction, and the upper electrode  144  and the upper moving electrode  148  are positioned over the lower electrode  142  and the lower moving electrode  146 , corresponding to the lower electrode  142  and the lower moving electrode  146 . 
         [0037]    The fixed electrode pressing part  162  is disposed to press the upper electrode  144  downward and the moving electrode pressing part  164  is disposed to press the upper moving electrode  148  downward. 
         [0038]    The moving frame  156  is disposed to reciprocate in a length direction along with the lower moving electrode  146 , the upper moving electrode  148 , and the moving electrode pressing part  164 , and the lower electrode  142  is disposed over the fixed frame  154 . 
         [0039]    The bus bar  130 , the transformer  120 , the inverter  110 , and the chiller  100  are each disposed over the upper cover  170 , and the chiller  100  includes a coolant which cools the circumference of the upper electrode  144 , the lower electrode  142 , the upper moving electrode  148 , and the lower moving electrode  146 , and circulates the coolant to a circumference of the electrodes. 
         [0040]    Further, power supplied to the inverter  110  is supplied to the electrodes through the transformer  120  and the bus bar  130 . 
         [0041]    According to the exemplary form of the present disclosure, the sagging preventing part  158  and the moving frame  156  are adjusted to a predetermined position along the frame moving rail  180  before the first and second blanks  150  and  152  are loaded, and the first and second blanks  150  and  152  are loaded at one side in a width direction in parallel with each other. 
         [0042]    The first and second blanks  150  and  152  are disposed over the lower electrode  142  and the lower moving electrode  146 , and the upper electrode  144  and the upper moving electrode  148  each descend by the fixed electrode pressing part  162  and the moving electrode pressing part  164  and are pressed to upper surfaces of both ends of the first and second blanks  150  and  152 . 
         [0043]    When the first and second blanks  150  and  152  are heated with a current, the moving frame  156  moves to absorb the thermal expansion of the first and second blanks  150  and  152 , thereby applying a constant tension to the first and second blanks  150  and  152 . Further, after the first and second blanks  150  and  152  are heated, the sagging preventing part  158  prevents middle portions of the first and second blanks  150  and  152  from sagging downward. 
         [0044]    The controller  190  controls a driver and a power supply unit for each component, the controller  190  may be implemented as at least one microprocessor executed by a predetermined program, and the predetermined program may include a series of commands for executing a method according to an exemplary form of the present disclosure to be described below. 
         [0045]      FIG. 2  is a partial perspective view of a moving part and a tension control part in the blank forming device using an electric direct heating method according to the exemplary form of the present disclosure. 
         [0046]    Referring to  FIG. 2 , the moving electrode pressing part  164  is disposed at an upper portion, an upper electrode holder  264  is disposed thereunder, and the upper moving electrode  148  is fixed to the upper electrode holder  264 . 
         [0047]    The lower moving electrode  146  is disposed at a position corresponding to the upper moving electrode  148 , a lower electrode holder  262  is disposed thereunder, and the lower moving electrode  146  is fixed to the lower electrode holder  262 . 
         [0048]    The moving frame  156  is disposed under the lower electrode holder  262 , and the moving frame  156  is disposed to move along the frame moving rail  180  through a linear bearing thereunder. In this configuration, the moving electrode pressing part  164  is also disposed to move along a rail along with the moving frame  156 . 
         [0049]    A reference frame  230  is disposed under one side of the moving frame  156 , and a tension control cylinder  210  is disposed over the reference frame  230  through a bracket  240 . The tension control cylinder  210  may push or pull the moving frame  156  based on the reference frame  230  to control a tension applied to the first and second blanks  150  and  152 . 
         [0050]    According to the exemplary form of the present disclosure, the reference frame  230  is disposed to reciprocate in the length direction by the rotation of a lead screw  220 , and the lead screw  220  has a structure rotating by a frame moving part  225 . 
         [0051]    The frame moving part  225  includes a motor and a deceleration mechanism, and may include a brake for fixing a rotating position of the lead screw  220 . Here, the brake may directly fix a motion of the reference frame  230 . 
         [0052]    An electrode moving rail  200  is disposed at one side of the moving frame  156  in a length direction, a current flows through the electrode moving rail  200 , and the current flowing the electrode moving rail  200  is applied to the lower electrode holder  262  and the lower moving electrode  146  through a shunt  250 . 
         [0053]      FIG. 3  is a partial perspective view of a sagging preventing part in the blank forming device using an electric direct heating method according to the exemplary form of the present disclosure. 
         [0054]    Referring to  FIG. 3 , the sagging preventing part  158  is disposed to move in a length direction on the frame moving rail  180  through a linear bearing  300 , and a sagging preventing cylinder  310  is vertically disposed on the linear bearing  300 . 
         [0055]    A plate moving rail  320  and a plate  330  are disposed on the sagging preventing cylinder  310 , and blank support protrusions  340  are arranged on the plate  330  in one direction. 
         [0056]    The plate  330  may reciprocate in a width direction of the first and second blanks  150  and  152  along the plate moving rail  320 , and the plate moving rail  320  and the plate  330  may vertically move by the sagging preventing cylinder  310 . 
         [0057]    The blank support protrusions  340  may be made from a rubber material or a plastic material to prevent the first and second blanks  150  and  152  from being scratched, and may be made from a material having lower hardness than that of the first and second blanks  150  and  152  among metal materials. 
         [0058]    According to the exemplary form of the present disclosure, a cylinder is operated by air pressure, oil pressure, or an electric motor. 
         [0059]      FIG. 4  is a flowchart of a forming order of the blank forming device according to the exemplary form of the present disclosure. 
         [0060]    Referring to  FIG. 4 , in S 400 , a supply of power is prepared and an operation of all drivers is prepared. Here, positions of the upper moving electrode  148  and the lower moving electrode  146  return to set positions and the upper electrode  144  and the upper moving electrode  148  return to set height positions. Further, the plate  330  of the sagging preventing part  158  returns to a predetermined height position. 
         [0061]    In S 410 , the first and second blanks  150  and  152  are loaded together, and in S 420 , the upper electrode  144  and the upper moving electrode  148  descend by the moving electrode pressing part  164  to adhere to the first and second blanks  150  and  152 . In this case, the plate  330  descends. 
         [0062]    In S 430 , power is applied to the electrodes by the inverter  110  and the transformer  120 , and a tension applied to the first and second blanks  150  and  152  is controlled by the tension control cylinder  210 . 
         [0063]    If it is determined that heating is completed, in S 440 , power supplied to the electrode is cut off and the brake for fixing the motion of the moving frame  156  is operated. 
         [0064]    In S 450 , the upper electrode  144  and the upper moving electrode  148  ascend by the moving electrode pressing part  164  and the plate  330  ascends to prevent the first and second blanks  150  and  152  from sagging. 
         [0065]    Further, in S 460 , the first and second blanks  150  and  152  are unloaded, and in S 470 , the brake for fixing the moving frame  156  is released and the moving frame  156  returns to a predetermined position. 
         [0066]    While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 &lt;Description of symbols&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 100: Chiller 
                 110: Inverter 
               
               
                 120: Transformer 
                 130: Bus bar 
               
               
                 142: Lower electrode 
                 144: Upper electrode 
               
               
                 146: Lower moving electrode 
                 148: Upper moving electrode 
               
               
                 150: First blank 
                 152: Second blank 
               
               
                 154: Fixed frame 
                 156: Moving frame 
               
               
                 158: Sagging preventing part 
                 162: Fixed electrode pressing part 
               
               
                 164: Moving electrode pressing part 
                 170: Upper cover 
               
               
                 180: Frame moving rail 
                 190: Controller 
               
               
                 200: Electrode moving rail 
                 210: Tension control cylinder 
               
               
                 220: Lead screw 
                 225: Frame moving part 
               
               
                 230: Reference frame 
                 240: Bracket 
               
               
                 250: Shunt 
                 262: Lower electrode holder 
               
               
                 264: Upper electrode holder 
                 300: Linear bearing 
               
               
                 310: Sagging preventing cylinder 
                 320: Plate moving rail 
               
               
                 330: Plate 
                 340: Blank support protrusion