Variable die, press device and press method

Abstract

A variable mold according to an embodiment of the present invention includes a first lower mold part and a first upper mold part arranged above the first lower mold part, the first lower mold part including a first lower mold center part and a first lower mold side part, the first lower mold center part including a first sensor part for measuring distance, the first lower mold side part including an inner member having an inclined surface formed therein, and a driving part for moving the inner member toward the first lower mold center part, the first sensor part measuring a forming distance which is the distance from the first sensor part to a material, and the driving part being driven based on the forming distance to adjust a correction distance which is the moving distance of the inner member.

Description

[Technical field]

[0001] The present invention relates to a variable die, a press device, and a press method. [Background technology]

[0002] In the automotive industry, the use of bending techniques is increasing due to the trend toward higher strength materials. Springback, which inevitably occurs during bending of materials, is a phenomenon caused by a combination of factors such as the elastic modulus of the material and stress distribution in the thickness direction, and it is not easy to accurately predict and correct this.

[0003] In the bending industry, attempts have been made to predict springback and improve the accuracy of product forming, for example by adding forming dies to the production process to compensate for springback based on the physical properties of the specific material.

[0004] However, this method has the problem that it is inefficient because a separate molding die must be prepared according to the physical properties of the material, and the problem is that even if this method is used, the desired effect of springback compensation cannot be achieved.

[0005] In other words, even if the physical properties of the sample used to prepare the above-mentioned molding die are the same as those of the material actually processed, if the processing environment changes, there is a problem that the desired springback correction effect may not be achieved.

[0006] As an example, for materials such as high-strength coiled steel sheets, the internal stress before forming may differ from that of the sample due to differences in the winding position or winding tension, etc., and as a result, even if the physical properties are the same, the target springback correction effect may not be achieved. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2010-0002958 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a variable die, a press device, and a press method that are capable of changing forming conditions to correct forming errors due to springback of the material.

[0009] In another aspect, the present invention aims to provide a variable die, a press device, and a press method that can change forming conditions in real time to compensate for springback of a material. [Means for solving the problem]

[0010] A variable mold according to an embodiment of the present invention includes a first lower mold part and a first upper mold part disposed above the first lower mold part, the first lower mold part includes a first lower mold center part on which a material is placed and which is provided with a first sensor part, and a first lower mold side part disposed on a side of the first lower mold center part, the first lower mold side part includes an inner member having an inclined surface which approaches the first lower mold center part from an upper part to a lower part, and a driving part which moves the inner member in a first direction which is a direction of the first lower mold center part, The mold section includes a first upper mold center section disposed above the first lower mold center section and moving downward toward the first lower mold center section, and a first upper mold side section disposed on a side of the first upper mold center section, moving downward, and being guided by the inclined surface during the downward movement, rotating and moving to the side of the first lower mold center section, wherein the first sensor section measures a molding distance which is the distance from the first sensor section to the material, and the driving section is driven based on the molding distance to adjust a correction distance which is the moving distance of the inner member.

[0011] In addition, a press apparatus according to an embodiment of the present invention may include a press body, a spare die installed in the press body for primary forming a material, and the variable die installed in the press body for secondary forming the material while compensating for forming errors due to springback.

[0012] The pressing method according to an embodiment of the present invention may include a first press stage of molding a first material with a variable die under molding conditions determined by a first set distance, a molding distance measurement stage of measuring a first molding distance which is a distance between the first material and a first sensor portion of the variable die, a set distance correction stage of determining a second set distance which is a next set distance based on a difference between the first set distance and the first molding distance, and a second press stage of molding a second material which is drawn in after the first material with the variable die under molding conditions determined by the second set distance. Effect of the Invention

[0013] The variable die, press apparatus, and press method of the present invention have the advantage that they are capable of changing the forming conditions to correct forming errors caused by springback of the material.

[0014] In another aspect, the variable die, press apparatus and press method of the present invention have the advantage that forming conditions can be changed in real time to compensate for springback of the material.

[0015] However, the various and beneficial advantages and effects of the present invention are not limited to the above, and can be more easily understood in the course of describing specific embodiments of the present invention. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing a press device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a preliminary mold according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a front view showing a variable mold according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing a first lower mold part according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a plan view showing a first lower mold side part according to the embodiment of the present invention. [Figure 6] FIG. 2 is a front view showing a cross section of a first lower mold center part according to an embodiment of the present invention. [Figure 7] FIG. 2 is a front view showing a cross section of a first lower mold center part according to an embodiment of the present invention. [Figure 8] 4 is a flowchart showing a pressing method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art. The shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

[0018] 1 is a perspective view of a press apparatus according to an embodiment of the present invention. Referring to the drawing, the press apparatus may include a press body 200, a preliminary mold 300, and a variable mold 100.

[0019] Here, the press body 200 serves as a body in which the preliminary mold 300 and the adjustable mold 100 are installed. In addition, a position adjustment block 500 may be installed in the press body 200.

[0020] The position adjusting block 500 may have a second protruding tab 500a formed on an upper surface thereof, the second protruding tab 500a being inserted into the position fixing hole ma formed in the material m. Here, the position adjusting block 500 may position the material m at a specific position by the second protruding tab 500a.

[0021] The preliminary mold 300 is installed in the press body 200 and performs primary molding of the material m. The preliminary mold 300 will be described later with reference to FIG.

[0022] The variable die 100 is installed in the press body 200, and receives the material m primarily molded by the preliminary die 300, and performs second molding of the material m while correcting molding errors caused by spring back. The variable die 100 will be described later with reference to Figs. 3 to 7.

[0023] Further, the press apparatus according to the embodiment of the present invention includes a transfer unit 400. The transfer unit 400 is installed in the press body 200, adsorbs and fixes the material m, and moves the material m to the position adjustment block 500, the preliminary mold 300, and the adjustable mold 100 in sequence.

[0024] The material m is always provided at the same position on the position adjustment block 500 by the second protruding tab 500a. This allows the transfer unit 220 to always start moving the material m at the same position. This can improve the movement error of the material m.

[0025] 2 is a perspective view of a pre-mold 300 according to an embodiment of the present invention. Referring to the drawing, the pre-mold 300 includes a second lower mold part 310 and a second upper mold part 320.

[0026] The second lower die part 310 includes a second lower die center part 311 and a second lower die side part 312. The second lower die center part 311 is a member fixed to the lower part of the press body 200. The second lower die side part 312 is a member disposed outside the second lower die center part 311 and receives an upward elastic force from an expansion spring or the like. In addition, the second lower die side part 312 moves downward while being pressed downward by the downward movement of the second upper die part 320.

[0027] The second upper die part 320 includes a second upper die center part 321 and a second upper die side part 322. The second upper die center part 321 is a member that receives a downward elastic force from the expansion spring or the like. The second upper die center part 321 moves downward to contact the upper surface of the material m, and then moves upward while being pushed upward by the second lower die center part 311. The second upper die side part 322 is a member that is disposed outside the second upper die center part 321 and fixed to the upper part of the press body 200.

[0028] With this configuration, the central portion of the material m is tightly fixed between the second upper mold center portion 321 and the second lower mold center portion 311. Both side portions of the material m are molded while being bent toward the side surfaces of the second lower mold center portion 311 by the second upper mold side portion 322 moving downward.

[0029] FIG. 3 is a front view showing a variable mold 100 according to an embodiment of the present invention, FIG. 4 is an oblique view showing a first lower mold part 110 according to an embodiment of the present invention, and FIG. 5 is a plan view showing a first lower mold side part 112 according to an embodiment of the present invention.

[0030] Referring to the figure, the variable mold 100 may include a first lower mold part 110 and a first upper mold part 120 .

[0031] Here, the first lower mold part 110 includes a first lower mold center part 111 , a first lower mold side part 112 , and a second sensor part 118 .

[0032] The material m is placed on the first lower mold center portion 111. A first sensor unit 117 is provided on the first lower mold center portion. The first sensor unit 117 measures a molding distance B, which is a distance from the first sensor unit 117 to the material m. This will be described later with reference to FIGS. 6 and 7.

[0033] The first lower mold side part 112 is installed on a side of the first lower mold center part 111. The first lower mold side part 112 includes an inner member 114 and a driving part .

[0034] The inner member 114 has an inclined surface 114a that approaches the first lower mold center part 111 from the top to the bottom. The driving unit 116 moves the inner member 114 in a first direction x toward the first lower mold center part 111. The second sensor unit 118 measures a correction distance that is a moving distance of the inner member 114.

[0035] The first lower mold side part 112 according to the embodiment of the present invention may further include an outer member 113 and a wedge member 115.

[0036] The outer member 113 is a member disposed outside the inner member 114. The wedge member 115 is disposed between the inner member 114 and the outer member 113. The wedge member 115 is linked to the driving unit 116 and moved by the driving unit 116 in a second direction z intersecting with the first direction x. Here, the driving unit 116 is driven based on the forming distance to adjust the correction distance.

[0037] To this end, the wedge member 115 includes an outer surface 115a and an inner surface 115b. The outer surface 115a contacts the outer member 113 and is formed horizontally in the second direction z. The inner surface 115b contacts the inner member 114 and is formed inclined in the second direction z.

[0038] The movement of the wedge member 115 in the second direction z causes the inner member 114 to move in the first direction x.

[0039] Furthermore, the wedge member 115 minutely adjusts the distance by which the inner member 114 is moved depending on the degree to which it is sandwiched between the outer member 113 and the inner member 114. For this purpose, a wedge angle θ between the outer side surface 115a and the inner side surface 115b of the wedge member 115 according to the embodiment of the present invention is formed to be at least smaller than 45 degrees. That is, by forming the wedge angle θ to be smaller than 45 degrees, the movement distance of the inner member 114 in the first direction x can be made smaller than the movement distance of the wedge member 115 in the second direction z.

[0040] In addition, the wedge member 115 is configured to move linearly by being connected to the driving unit 116. Thus, the wedge member 115 finely adjusts the distance between the outer member 113 and the inner member 114.

[0041] Here, the driving unit 116 according to the embodiment of the present invention includes a step motor 116b and a screw rod 116a coupled to the step motor 116b. The wedge member includes a through hole 115c having a screw thread formed thereon along the second direction z. The screw rod 116a is inserted into the through hole 115c by screw coupling.

[0042] The moving distance of the wedge member 115 is precisely adjusted according to the rotation amount of the screw rod 116a rotated by the step motor 116b, so that the moving distance of the inner member 114 in the first direction x is adjusted to 0.1 mm or less.

[0043] The adjustable mold 100 may include a control unit 130 for controlling the first lower mold unit 110. To this end, the control unit 130 is connected to the first sensor unit 117, the second sensor unit 118 and the driving unit 116.

[0044] The control unit 130 adjusts the correction distance by driving the driving unit 116 based on the forming distance B. More specifically, the control unit 130 adjusts the correction distance based on a forming error value S that is a difference between a target distance T, which is a distance between a product to be finally formed and the first sensor unit 117, and the forming distance B. The forming distance B and the target distance T may refer to the contents illustrated in FIG. 7. Here, the product to be finally formed is the final target shape of the material m.

[0045] The forming error value S includes a spring back value, which is a value when the forming distance B is measured to be larger than the target distance T, or a spring go value, which is a value when the forming distance B is measured to be smaller than the target distance T. However, since most materials m generate spring back, the following description will be based on the case where spring back occurs.

[0046] The compensation distance is adjusted to further overbend the material m by the forming error value due to springback. That is, when springback occurs in the material m, the control unit 130 drives the driving unit 116 to move the inner member 114 in the first direction x and move it closer to the first lower mold center portion 111.

[0047] As an example, after the first material is formed, the control unit 130 moves the inner member 114 from the first position to the second position based on the forming error value S of the first material. At this time, since springback may occur in the first material, the second position is closer to the first lower mold center portion 111 than the first position.

[0048] Next, the control unit 130 maintains the inner member 114 at the second position while forming the second material that is drawn in after the first material. At this time, the second material is overbent more than the first material. Therefore, a certain portion of the forming distance B of the second material converges to the target distance T, and the forming error value S is reduced.

[0049] Furthermore, after the second material is formed, the control unit 130 moves the inner member 114 from the second position to the third position based on the forming error value S of the second material. Therefore, the forming error value S of the third material which is drawn in next to the second material is further reduced.

[0050] In this manner, the control unit 130 continuously corrects the forming error value S of the material m that is repeatedly supplied, whereby the forming error value S gradually decreases.

[0051] The first lower mold side part 112 according to the embodiment of the present invention is provided in a pair on both sides of the first lower mold center part 111. The control part 130 controls the driving parts individually. The driving parts 116 are individually controlled by the control part 130.

[0052] That is, a pair of first side parts 112a installed adjacent to one side of the first lower mold center part 111 and second side parts 112b installed adjacent to the other side of the first lower mold center part 111 are provided. The driving parts 116 provided in the first side part 112a and the second side part 112b are driven individually by the control part 130. As a result, the distances between the inner members 114 provided in the first side part 112a and the second side part 112b and the first lower mold center part 111 are individually adjusted. Also, the distances between the inner members 114 provided in the first side part 112a and the second side part 112b and the first lower mold center part 111 can be adjusted to be the same.

[0053] The first lower mold center portion 111 may have a first protruding tab 111b formed on an upper surface thereof to be inserted into the position fixing hole ma formed in the material m.

[0054] This makes it possible to improve forming errors caused by positional fluctuations of the material m when the material m is formed.

[0055] Although only one first protruding tab 111b and the corresponding position fixing hole ma may be formed, a plurality of first protruding tabs 111b and the corresponding position fixing hole ma may be formed, so that the position of the material m can be fixed more stably.

[0056] The second sensor unit 118 is installed on the outer member 113. As a result, the second sensor unit 118 measures the amount of change in the distance between the inner member 114 and the outer member 113. The amount of change in the distance between the inner member 114 and the outer member 113 is the same as the correction distance.

[0057] By providing the second sensor unit 118, the correction distance can be measured in real time.

[0058] The first upper mold part 120 molds the material m in cooperation with the first lower mold part 110. That is, the first upper mold part 120 moves in a direction y of the first lower mold part 110 and pressurizes and molds the material m. To this end, the first upper mold part 120 may be disposed above the first lower mold part 110.

[0059] Specifically, the first upper mold part 120 according to the embodiment of the present invention includes a first upper mold center part 121 and a first upper mold side part 122 .

[0060] The first upper mold center part 121 is disposed above the first lower mold center part 111, and moves downward toward the first lower mold center part 111. The first upper mold side part 122 is disposed on a side of the first upper mold center part 121, moves downward, is guided by the inclined surface 114a of the inner member 114, and rotates and moves to the side of the first lower mold center part 111.

[0061] The first upper mold center part 121 fixes a central part of the material m in cooperation with the first lower mold center part 111. Then, the first upper mold side part 122 molds the material m while pressing both side parts of the material m in a side direction x of the first lower mold center part 111.

[0062] The first upper mold center portion 121 has an arc-shaped guide hole 121a. The first upper mold side portion 122 includes a rotation pin member 122a. When the first upper mold side portion 122 descends along the inclined surface 114a, the rotation pin member 122a moves along the guide hole 121a. This causes the first upper mold side portion 122 to rotate.

[0063] Further, the first upper mold side part 122 may include a return spring 122b which is a contraction spring. The return spring 122b is provided such that both ends are coupled to the first upper mold side part 122 and the first upper mold center part 121, respectively. Thus, when the first upper mold part 120 moves away from the first lower mold part 110, the first upper mold side part 122 is driven by the return spring 122b to return to its original position while leaving the inclined surface 114a of the first lower mold side part 112.

[0064] 6 and 7 are front views showing a cross section of the first lower mold center part 110 according to an embodiment of the present invention. That is, Fig. 6 shows all of the first sensor parts 117 arranged toward both side surfaces of the first lower mold center part 111. And Fig. 7 shows an enlarged view of only the first sensor part 117 on one side, illustrating a state in which a forming error occurs in the material m due to springback.

[0065] Referring to the figure, the first lower mold center part 111 according to the embodiment of the present invention includes an observation hole 111a. The observation hole 111a is formed on a side surface of the first lower mold center part 111 and faces the material. The observation hole 111a is formed in a middle part of the first lower mold center part 111 in a height direction y. The first sensor unit 117 is disposed in the observation hole 111a.

[0066] As a result, the first sensor portion 117 is disposed in the middle portion of the first lower mold center portion 111 in the height direction y.

[0067] The first sensor unit 117 may be provided in pairs to measure the distance toward both sides of the first lower mold center part 111. However, the present invention is not limited thereto, and only one first sensor unit 117 may be provided to measure the distance toward one side of the first lower mold center part 111.

[0068] The first sensor unit 117 is provided at a middle portion of the first lower mold center portion 111 in the height direction y, thereby reducing an error in measuring the distance to the material m. That is, the material m is molded to include at least one bent portion mb. However, the bent portion mb is formed at an upper end or a lower end of the first lower mold center portion 111. In addition, the periphery of the bent portion mb is less likely to maintain flatness compared to other portions of the material m. Therefore, the first sensor unit 117 is provided at a middle portion of the first lower mold center portion 111 in the height direction y, where the influence of the bent portion mb is minimized. As a result, the first sensor unit 117 improves an error in the molding distance B caused by a difference in flatness of the material m.

[0069] The first sensor unit 117 measures a forming distance B, which is the distance between the material m and the first sensor unit 117, through the observation hole 111a.

[0070] 8 is a flowchart showing a pressing method according to an embodiment of the present invention. The pressing method includes pressing stages SP1 and SP2, a forming distance measurement stage SM, and a set distance correction stage SC. The pressing stages SP1 and SP2 include a first pressing stage SP1 and a second pressing stage SP2. The material includes a first material and a second material. The set distance A is a first set distance A. n , Second setting distance A n+1 The forming distance B is the first forming distance B n , second forming distance B n+1 Includes.

[0071] The first material is not limited to the initial material, but may be a material supplied after a plurality of press processes. n is not limited to the initial set distance A1, but is the set distance A determined after multiple pressing processes. n The first molding distance B n is not limited to the initial forming distance B1, but is the forming distance B determined after multiple pressing processes. nmay be also possible.

[0072] Here, the first pressing step SP1 is a first set distance A n The first set distance A is n In this step, the first material is molded by the variable die 100 under the molding conditions set by the first set distance A. n The position of the inner member 114 is determined based on the above.

[0073] The forming distance measurement stage SM is performed after the first pressing stage SP1. The forming distance measurement stage SM is performed to measure a first forming distance B, which is a distance between the first material and the first sensor unit 117 of the variable die 100. n That is, the forming distance measuring step SM is a step of measuring the first forming distance B based on the shape of the first material after springback occurs due to forming. n Measure.

[0074] The set distance correction step SC is performed after the forming distance measurement step SM. The set distance correction step SC is performed by measuring the first forming distance B n and the above first set distance A n Based on the difference between the next set distance A n+1 The second set distance A is n+1 This is the stage to determine the following.

[0075] However, the target distance T, which is the distance between the final product to be molded and the first sensor unit 117, and the first molding distance B n If the distance is the same, the first set distance A will be used for the next molding. n Therefore, there is no need to correct the target distance T and the first forming distance B n If the distances are the same, the set distance correction step SC need not be carried out.

[0076] In addition, the set distance correction step SC according to the embodiment of the present invention calculates the next set distance A by the following formula: n+1 Set.

[0077] A n+1 =T+(A n -B n )

[0078] Here, A is the set distance. B is the forming distance. n is the number of repetitions, "n=1, 2, 3...". T is the target distance, which is the distance between the final product to be formed and the first sensor unit. And the initial set distance A1 is the same as the target distance T.

[0079] As an example, if the target distance T is 10 mm, and springback occurs and the forming distance B1 measured in the first press step is 12 mm, the following is considered. In this case, the set distance A1 is 10 mm because it is the same as the target distance T. Therefore, the set distance A2 in the second press step is determined to be 8 mm by the above formula.

[0080] If the forming distance B2 measured in the second press step is 11 mm, the set distance A3 in the third press step is determined to be 7 mm according to the above formula. That is, the set distance A3 in the third press step is determined to be smaller than the set distance A2 in the second press step. The reason for this determination is that even if the correction based on the set distance in the second press step is performed, it is necessary to further correct the forming error due to springback.

[0081] In addition, if the forming distance B2 measured in the second press process is 10 mm, the set distance A3 in the third press process is determined to be 8 mm according to the above formula. That is, the set distance A3 in the third press process is determined to be the same as the set distance A2 in the second press process. The reason for this determination is that, due to the correction based on the set distance in the second press process, it is no longer necessary to correct the forming error due to springback.

[0082] In addition, if the forming distance B2 measured in the second press step is 9 mm, the set distance A3 in the third press step is determined to be 9 mm according to the above formula. That is, the set distance A3 in the third press step is determined to be larger than the set distance A2 in the second press step. The reason for this determination is that the correction based on the set distance in the second press step is excessive even when considering springback.

[0083] The second press step SP2 is performed after the set distance correction step SC. n+1 In other words, the second press stage SP2 is a stage in which the second material is molded in place of the first material by the variable die 100 under the molding conditions set by the first set distance A n Instead of the above second set distance A n+1 The only difference is that the material is molded using the variable die 100 under the molding conditions set forth in 1., but the material is molded by press working in the same manner as in the first pressing stage SP1.

[0084] Moreover, the second pressing stage SP2 is performed when the second material is supplied, and is therefore performed after confirming whether or not the second material has been supplied.

[0085] Therefore, after the second pressing step SP2, the forming distance measurement step SM, the set distance correction step SC, and the third pressing step for processing the third blank drawn in after the second blank can be performed in succession. That is, the pressing method according to the embodiment of the present invention is performed continuously while blanks are continuously supplied.

[0086] Here, the molding condition of the variable mold 100 to be changed is the second set distance A n+1 The position of the inner member 114 is changed based on the

[0087] Furthermore, the pressing method according to the embodiment of the present invention may include a preforming step SB. The preforming step SB is performed before the first pressing step SP1. The preforming step SB is a step of forming the first material with a preliminary mold 300.

[0088] Therefore, the variable die 100, the press device, and the press method according to the embodiment of the present invention can change the forming conditions to correct the forming error caused by the springback of the material m. Furthermore, such forming conditions can be changed in real time.

[0089] As a result, the variable die 100, press device, and press method according to the embodiment of the present invention can automatically minimize forming errors due to springback, regardless of the physical properties of the material m and the shape that the high-strength material had before forming.

[0090] As described above, an embodiment of the present invention has been described. However, the scope of the present invention is not limited to this, and it will be obvious to a person having ordinary knowledge in the art that various modifications and variations are possible without departing from the technical idea of ​​the present invention described in the claims. [Explanation of symbols]

[0091] 100: Variable mold 110: First lower mold section 111: First lower mold center section 112: First lower mold side part 113:Outer member 114: Inner member 115: Wedge member 116: Drive unit 117: First sensor section 118: Second sensor section 120: First upper mold section 121: First upper mold center section 122: First upper mold side part 200: Press body 130: Control unit 300: Spare mold 310: Second lower mold section 311: Second lower mold center section 312: Second lower mold side part 320: 2nd upper mold section 321: 2nd upper mold center section 322: Second upper mold side part 400:Transport unit 500: Position adjustment block

Claims

1. A first lower mold part; a first upper mold part disposed above the first lower mold part; The first lower mold part is a first lower mold center portion on which the material is placed and which is provided with a first sensor portion; a first lower mold side portion disposed on a side surface of the first lower mold center portion, The first lower mold side portion is an inner member having an inclined surface that approaches the first lower mold center portion from an upper portion toward a lower portion; an outer member disposed outside the inner member; a wedge member disposed between the inner member and the outer member; a driving unit that moves the wedge member in a second direction that intersects with a first direction that is a direction toward the first lower mold center portion, The first upper mold part is a first upper mold center portion disposed above the first lower mold center portion and moving downward toward the first lower mold center portion; a first upper mold side part that is installed on a side surface of the first upper mold center part, moves downward, and is guided by the inclined surface while moving downward to rotate and move to the side surface of the first lower mold center part, The first sensor unit measures a forming distance which is a distance from the first sensor unit to the material, the inner member is moved in the first direction by the movement of the wedge member in the second direction, the driving unit is driven based on the forming distance to adjust a correction distance which is a moving distance of the inner member; The wedge member is an outer surface that is in contact with the outer member and is formed horizontally in the second direction; an inner surface in contact with the inner member and inclined in the second direction such that the width of the inner surface gradually decreases along the second direction; If the angle between the outer surface and the inner surface is defined as a wedge angle, A variable mold, wherein the surface of the inner member in contact with the inner surface has a shape that is inclined at the wedge angle.

2. a control unit for controlling the first lower mold unit; The first lower mold side portion is a second sensor unit for measuring the correction distance; The variable mold according to claim 1 , wherein the control unit is connected to the first sensor unit, the second sensor unit, and the driving unit.

3. The variable mold according to claim 2 , wherein the control unit adjusts the correction distance based on a molding error value that is a difference between a target distance, which is a distance between a product to be finally molded and the first sensor unit, and the molding distance.

4. The control unit is After the first blank is formed, the inner member is moved from a first position to a second position based on a forming error value of the first blank; maintaining the inner member in the second position during forming of a second feedstock which is drawn subsequent to the first feedstock; The variable mold according to claim 3 , wherein after the second blank is molded, the inner member is moved from the second position to a third position based on a molding error value of the second blank.

5. The first lower mold center portion is an observation hole formed on a side surface of the first lower mold center portion toward the material, the observation hole being formed in a middle portion in a height direction of the first lower mold center portion; The variable mold according to claim 1 , wherein the first sensor portion is disposed in the observation hole.

6. The variable mold according to claim 1 , wherein the wedge angle is formed to be at least less than 45 degrees.

7. The drive unit is A step motor; a screw rod coupled to the stepper motor; The wedge member is A through hole having a screw thread formed along the second direction, The variable mold according to claim 1 , wherein the screw rod is inserted into the through hole by a threaded connection.

8. The first lower mold side portion is provided in a pair on both sides of the first lower mold center portion, The variable mold according to claim 2 , wherein the control unit controls the drive units individually.

9. The adjustable mold according to claim 1 , wherein the first lower mold center portion has a first protruding tab formed on an upper surface thereof, the first protruding tab being inserted into a position fixing hole formed in the material.

10. The press body, A preliminary mold that is installed in the press body and performs primary molding of a material; and a variable die according to any one of claims 1 to 9, which is installed on the press body and performs secondary forming of the material while compensating for forming errors due to springback.

11. The preliminary mold is A second lower mold portion on which the material is seated; The press apparatus of claim 10 including a second upper die part disposed above the second lower die part and movable downwardly toward the second lower die part.

12. The press apparatus according to claim 10 , further comprising a position adjustment block, the position adjustment block being installed on the press body and having a second protruding tab formed on an upper surface thereof, the second protruding tab being inserted into a position fixing hole formed in the material.

13. The press apparatus according to claim 12 , further comprising a transfer unit that is installed on the press body, suction-fixes the material, and moves the material to the position adjustment block, the spare die, and the variable die in that order.

14. a first press stage in which the first material is molded by a variable die having molding conditions determined by a first set distance; a forming distance measuring step of measuring a first forming distance, which is a distance between the first material and a first sensor unit of the variable mold; a set distance correcting step of determining a second set distance, which is a next set distance, based on a difference between the first set distance and the first forming distance; A second press stage in which a second material is molded by the variable die under molding conditions determined by the second set distance, the second material being drawn in next to the first material; The variable mold is a variable mold according to any one of claims 1 to 9, The set distance correction step is performed by the following formula: ｎ＋１ Determine the pressing method. A ｎ＋１ =T+(A ｎ -B ｎ ) Here, A is the set distance, B is the forming distance, n is the number of repetitions, "n = 1, 2, 3 ...", T is the target distance between the final product to be formed and the first sensor unit, and the initial set distance A １ is the same as the target distance.

15. The pressing method according to claim 14, further comprising a preforming step, performed before the first pressing step, of forming the first blank in a preforming die.

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