JP4870018B2 - Thin plate press die apparatus and press molding method - Google Patents

Description

  The present invention relates to a press mold apparatus and a press molding method using a thin plate as a molding material, and in particular, by detecting the deformation behavior of the thin plate within the clearance during molding, the dimensional accuracy and fracture of the molded product can be determined and controlled. The present invention relates to a press mold apparatus and a press molding method.

  The press forming of a thin plate using a press die apparatus is widely used in the field of manufacturing automobile parts. In the field of press molding, various measures have been conventionally taken in order to improve the dimensional accuracy of a molded product and prevent material breakage. For example, in Patent Documents 1 and 2, a so-called reverse bending is generated by setting the size of the clearance formed between the punch and the die during molding within a predetermined range with respect to the plate thickness. A technique for eliminating a shape defect is disclosed. Patent Document 2 also discloses a technique for reducing the spring back by so-called ironing, in which the clearance is made smaller than the plate thickness, instead of reverse bending.

  Further, for example, in Patent Document 3, the friction force between the die and the thin plate generated between the die and the crease presser mold is measured at the time of draw forming while pressing the thin plate with the crease presser die. Techniques for controlling are disclosed.

Furthermore, Non-Patent Document 4 discloses a technique in which a piezoelectric element is built in the vicinity of the shoulder portion of the die and the sliding characteristics of the thin plate are measured based on the compressive strain generated in the die shoulder.
JP 56-1117831 A JP 2004-237360 A JP 2004-249365 A Development of integrated high-strength steel sheet forming technology (development of mold friction sensor) ”, Proceedings of the 57th Joint Conference on Plastic Working (October 31 to November 2, 2006, Takaoka Chamber of Commerce and Industry Building) Published by Japan Society for Technology of Plasticity (October 17, 2006), pp. 165-166.

  However, the size of the clearance formed between the punch and the die at the time of molding varies due to changes in the thickness of the thin plate to be press-molded, wear of the die (die, punch), misalignment of the die, and the like. For this reason, even if it is going to set the magnitude | size of clearance to the predetermined range like the said patent documents 1 and 2, it is difficult to always press-mold on the same conditions. Moreover, according to these patent documents 1 and 2, it cannot be confirmed whether the reverse bending has generate | occur | produced appropriately at the time of shaping | molding.

  Further, even when the frictional force between the die and the crease presser die is measured as in Patent Document 3 and Patent Document 4, the contact state between the thin plate and the mold in the clearance has not been known. .

  Here, when the present inventors repeated various studies, in press molding, a punch in which a clearance is formed during molding and a strain in a normal direction (a direction perpendicular to the vertical wall portion) generated in the vertical wall portion of the die. However, it has been found that this is a very important factor for improving the dimensional accuracy of the molded product and preventing the material from breaking. That is, the inventors of the present invention have a straight line in the molding direction (the direction of relative straight movement of the punch and the die) with respect to the vertical wall surface of the molded product that is molded in contact with the vertical wall portion of the punch and the die during press molding. I examined the sex. As a result, when the normal direction distortion generated in the vertical wall portion of the punch and the die is within a predetermined range, the vertical wall surface of the molded product is substantially linear with respect to the molding direction. It has been found that when the distortion of the material deviates from the predetermined range, the curvature of the wall surface of the molded product increases with respect to the molding direction, or the material breaks during molding. The present invention has been obtained on the basis of such knowledge, and by accurately knowing the contact state between the thin plate and the mold within the clearance during press forming, press forming excellent in dimensional accuracy without breaking the thin plate The purpose is to obtain goods.

To achieve the above object, according to the present invention, there is provided a press die apparatus for press-molding the sheet by the relative linear movement of the punch and die, said punch to form a clearance face each other at the time of molding and A thin plate characterized in that a strain measuring means for measuring strain generated in the normal direction of the vertical wall portion is disposed inside at least one of the vertical wall portions parallel to the linearly moving direction of the die. A press mold apparatus is provided.

  In this press mold apparatus, for example, the strain measuring means is a piezo element or a strain gauge. A plurality of strain measuring means may be arranged at different positions in the relative movement direction of the punch and the die. Furthermore, a wrinkle presser mold and / or a pad interlocking with the punch may be provided.

  Further, according to the present invention, there is provided a press forming method for a thin plate using the above press mold apparatus, wherein the strain measured by the strain measuring means during press molding exceeds a predetermined range or falls below a predetermined range. A press forming method is provided in which it is determined that the forming is abnormal.

  Further, according to the present invention, there is provided a press forming method for a thin plate using the above press mold apparatus, wherein the strain measured by the strain measuring means during press molding exceeds a predetermined range or falls below a predetermined range. A press forming method is provided, wherein the wrinkle presser load or the pad pressure is adjusted so that the strain falls within a predetermined range.

  In this press molding method, press molding can be performed while causing reverse bending of the thin plate within the clearance.

  According to the present invention, it is possible to accurately detect the deformation behavior of the thin plate within the clearance during press forming by measuring the normal strain generated in the vertical wall portion of the punch and die. That is, according to the present invention, when the spring back is suppressed by utilizing the contact between the material in the clearance and the vertical wall portion of the punch and the die as in reverse bending or ironing, a thin plate in the clearance during molding is used. By detecting the contact state between the vertical wall portion and the vertical wall portion, it is possible to determine whether reverse bending or ironing is correctly performed within the clearance. Further, by detecting an abnormality in contact force during ironing, the thin plate can be prevented from breaking. As a result, the thin plate can be molded without breaking, and a press-molded product with excellent dimensional accuracy can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. 1 to 3 are schematic explanatory views of a press die apparatus according to the first embodiment of the present invention. The press mold apparatus of FIGS. 1-3 is a system which performs a drawing process without using a wrinkle presser mold. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  In the press mold apparatus, a punch 1 disposed above and a die 2 disposed below are disposed to face each other. The punch 1 is supported by the punch holder 3 of the press mold apparatus, and the die 2 is supported by the die holder 4 of the press mold apparatus.

  In such a press mold apparatus, a thin plate 5 as a molding material is placed on the die 2 and the punch 1 and the die 2 are moved relatively straight in the vertical direction as shown in FIGS. In accordance with the relative linear movement of the punch 1 and the die 2, the thin plate 5 is drawn into the cavity 2 a of the die 2 and is press-formed into a shape along the punch 1. In this case, it goes without saying that the punch 1 may be lowered or the die 2 may be raised. Alternatively, the punch 1 and the die 2 may be installed upside down and the die 2 may be lowered.

  In the press mold apparatus, the punch 1 is inserted into the cavity 2a of the die 2 at the time of molding, and the vertical wall portion 1 ′, which is the outer peripheral surface of the punch 1, and the vertical surface, which is the inner peripheral surface of the cavity 2a of the die 2. Wall part 2 'will be in the state which mutually opposed with the predetermined space | interval. A space formed by the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 is called a clearance.

  In the press mold apparatus shown in FIGS. 1 to 3, this clearance (interval between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2) c (mm) is the thickness t ( mm). That is, t> c. Therefore, during press molding, the thin plate 5 is squeezed between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 in the clearance c. By the action of ironing between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2, the spring back generated in the product after molding is canceled to obtain a desired product shape.

  However, for example, when the thin plate 5 is a hard material, or when the thin plate 5 is not sufficiently squeezed within the clearance c, there is a concern that a spring back may occur after molding and a desired product shape cannot be obtained. is there. Further, the force applied to the thin plate 5 by ironing also changes due to the influence of the fluctuation of the clearance c caused by the change in the thickness of the thin plate 5, the wear of the mold (punch 1 and die 2), the displacement of the mold, and the like. . Furthermore, if the force applied to the thin plate 5 due to ironing in the clearance c is excessive, there is a concern that the thin plate 5 may be broken during molding.

On the other hand, the force for squeezing the thin plate 5 within the clearance c is generated by compressing the thin plate 5 between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. For example, if the clearance c is relatively large, the force applied to the thin plate 5 by ironing is reduced. Conversely, if the clearance c is relatively small , the force applied to the thin plate 5 by ironing is increased. Therefore, the compressive force applied to the thin plate 5 from the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 should be an index of the force applied to the thin plate 5 by ironing.

  On the other hand, the strain ε generated in the normal direction of the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 is thin from the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. This is caused by the reaction force of the compression force applied to 5. Since the strain ε is proportional to the compressive force applied to the thin plate 5 within the clearance c, the strain ε is an index of the force applied to the thin plate 5 by ironing as well as the compressive force applied to the thin plate 5 within the clearance c. It should be.

  Therefore, in the present invention, the strain for measuring the strain ε generated in the normal direction of the vertical wall portions 1 ′ and 2 ′ in at least one of the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. A measuring means is provided. In the press die apparatus shown in FIGS. 1 to 3, as an example, the strain measuring means 10 that measures the strain ε generated in the normal direction of the vertical wall portion 1 ′ inside the vertical wall portion 1 ′ of the punch 1. Are provided in the relative movement direction (up and down direction on the paper surface) of the punch 1 and the die 2, and a strain ε generated in the normal direction of the vertical wall portion 2 ′ is generated inside the vertical wall portion 2 ′ of the die 2. One strain measuring means 10 for measuring is provided.

  During press molding, the thin plate 5 is drawn into the clearance c immediately after passing through the shoulder 2b of the die 2. At that time, the greatest force is applied to the thin plate 5 by ironing. Therefore, the strain ε generated in the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 immediately after the thin plate 5 passes the shoulder 2 b of the die 2 is the most indicative of the force applied to the thin plate 5 by ironing. It is considered appropriate. Therefore, in the press die apparatus shown in FIGS. 1 to 3, one strain measuring means 10 is arranged inside the vertical wall 2 'of the die 2 just below the shoulder 2b. On the other hand, with respect to the punch 1, as the punch 1 is inserted into the cavity 2 a of the die 2, the position where the largest force is applied to the thin plate 5 by ironing sequentially moves upward. Therefore, in the press die apparatus shown in FIGS. 1 to 3, a plurality of strain measuring means 10 are arranged at different heights inside the vertical wall portion 1 ′ of the punch 1 so that the thin plate 5 is the die 2. The strain ε generated immediately after passing through the shoulder 2b can be detected a plurality of times during press molding.

  Here, with reference to FIG. 4, the mounting direction of the strain measuring means 10 provided inside the vertical wall portion 2 ′ of the die 2 will be described. In FIG. 4, the strain measuring means 10 a is arranged in a direction for measuring the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 (arrow pointing leftward on the paper surface). On the other hand, the strain measuring means 10b is arranged in a direction for measuring the strain ε 'generated in the surface direction of the vertical wall portion 2' of the die 2 (the direction perpendicular to the normal direction: an arrow pointing downward on the paper surface). According to the strain measuring means 10a, it is possible to measure the strain ε generated in the normal direction of the vertical wall portion 2 'of the die 2 as an index of the force applied to the thin plate 5 by ironing. On the other hand, the strain measuring means 10b can measure the strain ε ′ due to the frictional force between the vertical wall portion 2 ′ of the die 2 and the thin plate 5, but the vertical wall portion 2 of the die 2 that is an index of the force applied to the thin plate 5 by ironing. The strain ε generated in the normal direction of 'cannot be measured. Therefore, in the present invention, the mounting direction of the strain measuring means 10 is set to a direction in which the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 can be measured like the strain measuring means 10 a. However, the mounting direction of the strain measuring means 10 may not be exactly perpendicular to the surface of the vertical wall portion 2 ′ of the die 2. From the viewpoint of improving the sensitivity, it is desirable that the measurement axis direction of the strain measuring means 10 coincides with the normal direction of the vertical wall portion 2 ′ of the die 2, but even if it is slightly inclined, the vertical direction of the die 2 is practically achieved. It is sufficient if the strain ε generated in the normal direction of the wall 2 ′ can be measured.

  Note that the mounting direction of the strain measuring means 10 provided inside the vertical wall portion 2 ′ of the die 2 has been described, but the same applies to the strain measuring means 10 provided inside the vertical wall portion 1 ′ of the punch 1.

  As the strain measuring means 10 provided inside the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 as described above, for example, a piezo element or a strain gauge can be used. FIG. 5 is an explanatory diagram in the case where the measuring means 10 composed of such a piezo element, a strain gauge or the like is attached to the inside of the vertical wall portion 2 ′ of the die 2.

  In FIG. 5, the strain measuring means 10 is inserted into the bottom of the hole formed in the die 2 so that the strain measuring means 10 is arranged inside the vertical wall portion 2 ′ of the die 2, and then the holes are formed by bolts 11. It is a closed configuration. A lead wire 12 for taking out a detection signal from the strain measuring means 10 passes through the bolt 11 and is drawn to the outside. In this case, the strain measuring means 10 is preferably arranged at a position of a depth of about 4 to 30 mm from the surface of the vertical wall 2 '.

  Although the attachment structure of the strain measuring means 10 provided inside the vertical wall portion 2 ′ of the die 2 has been described, the same applies to the strain measuring means 10 provided inside the vertical wall portion 1 ′ of the punch 1.

  As described above, the strain measuring means 10 for measuring the strain ε generated in the normal direction of the vertical wall portions 1 ′ and 2 ′ inside the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. By providing this, it is possible to detect the contact state between the thin plate 5 and the vertical wall portions 1 ′ and 2 ′ within the clearance c during molding, and it is possible to determine whether or not the ironing process is correctly performed within the clearance c. Moreover, the breakage of the thin plate 5 can be prevented by detecting the contact force abnormality. As a result, the thin plate 5 can be molded without breaking, and a press-molded product with excellent dimensional accuracy can be obtained.

  Further, for example, when the strain ε measured by the strain measuring means 10 during press molding exceeds a predetermined range or falls below a predetermined range, it can be determined that the molding is abnormal. In such a case, when the next molding is performed, it is possible to cope by adjusting the clearance c, such as repairing the mold. Also, quality control during mass production, such as countermeasures by detecting defective products and correcting press conditions, can be facilitated by detecting molding abnormalities.

  FIG. 6 is a schematic explanatory view of a press die apparatus according to the second embodiment of the present invention. The press mold apparatus shown in FIG. 6 is a system that performs drawing while applying a wrinkle pressing load to the flange portion of the thin plate 5 by the wrinkle pressing mold 15. Similar to the press mold apparatus shown in FIGS. 1 to 3, the clearance c (mm) of the press mold apparatus of FIG. 6 is set slightly smaller than the plate thickness t (mm) of the thin plate 5 (t> c). ) During the press molding, within the clearance c, the thin plate 5 is squeezed between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. Thus, by using the crease presser mold 15, an excellent press-molded product having a wrinkle-free shape on the flange portion can be obtained.

  FIG. 7 is a schematic explanatory view of a press die apparatus according to the third embodiment of the present invention. The press die apparatus shown in FIG. 7 is a system that performs drawing while pressing the thin plate 5 between the pad 16 and the punch 1. In the press mold apparatus of FIG. 7 as well, the clearance c (mm) is set slightly smaller than the thickness t (mm) of the thin plate 5 (t> c). The punch 1 is squeezed between the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. Thus, stable pressing can be performed by pressing the thin plate 5 with the pad 16 between the punch 1 and the punch 1.

  Next, FIG. 8 is a schematic explanatory view of a press die apparatus according to a fourth embodiment of the present invention. In the press die apparatus of FIG. 8, the clearance c (mm) is set larger than the plate thickness t (mm) of the thin plate 5. That is, t <c. In the press mold apparatus shown in FIG. 8, during press molding, the cross-sectional shape of the thin plate 5 is changed to an S-curve in the clearance c, so that a so-called reverse bending is generated and the shape defect due to the spring back can be eliminated. Done. Note that the press mold apparatus of FIG. 8 is a system in which press forming is performed while a wrinkle presser load is applied to the flange portion of the thin plate 5 by the wrinkle presser mold 15.

  In the press die apparatus shown in FIG. 8, within the clearance c, the thin plate 5 comes into contact with the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2 only at specific locations. Therefore, in the present invention, the strain for measuring the strain ε generated in the normal direction of the vertical wall portions 1 ′ and 2 ′ in at least one of the vertical wall portion 1 ′ of the punch 1 and the vertical wall portion 2 ′ of the die 2. A measuring means is provided. In the press die apparatus shown in FIG. 8, as an example, strain measurement is performed to measure strain ε generated in the normal direction of the vertical wall portion 2 ′ at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2. Means 10 are provided.

  As described above, by providing the strain measuring means 10 for measuring the strain ε generated in the normal direction of the vertical wall portion 2 ′ at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2, In the clearance c, the thin plate 5 bulges outward at a substantially middle height of the vertical wall portion 2 ′ of the die 2, and the thin plate 5 correctly contacts the almost middle height of the vertical wall portion 2 ′ of the die 2. Can be detected. When the thin plate 5 does not bulge outward at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2, the strain measuring means 10 does not detect the strain ε, so that the thin plate 5 is not in the vertical direction of the die 2. It can be seen that the wall 2 'is not in contact with the almost middle height. As a result, the molding state of the thin plate 5 in the clearance c can be detected. Further, when it is determined that the thin plate 5 does not bulge outward at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2, the thin plate 5 has a substantially intermediate height of the vertical wall portion 2 ′ of the die 2. The occurrence of defective products can be avoided by adjusting the wrinkle presser load so as to make a proper contact.

  Next, FIG. 9 is a schematic explanatory view of a press die apparatus according to a fifth embodiment of the present invention. In the press mold apparatus of FIG. 9, the clearance c (mm) is set larger than the plate thickness t (mm) of the thin plate 5 (t <c), and the cross-sectional shape of the thin plate 5 is within the clearance c during press forming. By making S into an S-shaped curve, so-called reverse bending is generated to eliminate the shape defect due to springback. The press mold apparatus of FIG. 9 is a system in which press forming is performed while pressing the thin plate 5 between the punch 1 and the pad 16 while applying a wrinkle press load to the flange portion of the thin plate 5 by the wrinkle press die 15. Thus, stable press molding can be performed by pressing the thin plate 5 with the pad 16 between the punch 1 and the punch 1 while using the crease presser die 15. Further, when it is determined that the thin plate 5 does not bulge outward at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2, the thin plate 5 has a substantially intermediate height of the vertical wall portion 2 ′ of the die 2. By adjusting the wrinkle presser load and the presser load (pad pressure) by the pad 16 so as to make a proper contact, it is possible to avoid the occurrence of defective products.

  Next, FIG. 10 is a schematic explanatory view of a press die apparatus according to a sixth embodiment of the present invention. In the press mold apparatus of FIG. 10 as well, the clearance c (mm) is set larger than the plate thickness t (mm) of the thin plate 5 (t <c), and the cross-sectional shape of the thin plate 5 is within the clearance c during press forming. By making S into an S-shaped curve, so-called reverse bending is generated to eliminate the shape defect due to springback. The press mold apparatus shown in FIG. 10 is a system that performs press molding while applying a wrinkle press load to the flange portion of the thin plate 5 by the wrinkle press mold 15.

  In the press die apparatus of FIG. 10, strain measuring means for measuring strain ε generated in the normal direction of the vertical wall portion 2 ′ at three heights of the upper, middle and lower portions of the vertical wall portion 2 ′ of the die 2. 10 is provided. In this way, by providing a plurality of strain measuring means 10 at different heights, the thin plate 5 bulges outside at any position in the clearance c during molding, and the thin plate 5 is the vertical wall portion 2 of the die 2. It is possible to detect at which position it is in contact with '. As a result, the molding state of the thin plate 5 within the clearance c can be detected, and the shape of the molded product can also be determined. In addition, when it is determined that the thin plate 5 does not bulge outward at the correct height, the occurrence of defective products can be avoided by adjusting the wrinkle presser load so as to have a correct shape.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  In the first embodiment, as described above with reference to FIG. 6, a press mold apparatus (No. 11 to 15) that performs drawing while applying a wrinkle pressing load to the flange portion of the thin plate 5 by the wrinkle pressing mold 15, As described in FIGS. 1 to 3, the press mold apparatus (No. 16 to 18) having neither the wrinkle presser mold 15 nor the pad 16 and the wrinkle presser mold as previously described in FIG. 9. A press mold apparatus (No. 19 to 21) that performs press molding while pressing the thin plate 5 between the punch 1 and the pad 16 while applying a wrinkle pressing load to the flange portion of the thin plate 5 with the pad 15, and the pad 16 shown in FIG. Measurement was performed on four types of press forming apparatuses (No. 22) that perform press forming using a thin film, and the thin plate 5 was press formed under each condition. In Example 1, the clearance c (mm) is set slightly smaller than the plate thickness t (mm) of the thin plate 5 (t> c), and the thin plate 5 is the punch 1 in the clearance c during press forming. The vertical wall portion 1 ′ and the vertical wall portion 2 ′ of the die 2 are squeezed. In Example 1, as shown in FIG. 11, a strain for measuring a strain ε generated in the normal direction of the vertical wall portion 2 ′ inside the vertical wall portion 2 ′ of the die 2 immediately below the shoulder portion 2 b. Measuring means A is arranged (not shown in FIG. 9). Further, a strain measuring means B for measuring the strain ε generated in the normal direction of the vertical wall portion 2 ′ is disposed inside the vertical wall portion 1 ′ at almost the intermediate height of the punch 1 (FIG. 9). The illustration is omitted in FIG. Further, all strain measuring means C for measuring the friction force generated between the flange portion of the thin plate 5 and the upper surface of the die 2 are arranged inside the upper surface of the die 2 (FIGS. 1 to 3 and FIG. 6). (The illustration is omitted in FIG. 9). The strain measuring means C is arranged in a direction to measure strain generated in the surface direction (normal direction and normal direction) of the upper surface of the die 2 in the vicinity of the shoulder 2b. The thin plate 5 is a high-tensile steel plate having a thickness of 1.21 to 1.50 mm, and a hat cross-section beam (length 150 mm) having a web width of 90 mm and a depth of 80 mm is formed. Each strain measuring means was arranged at the center in the longitudinal direction of the mold, and the maximum output value during the stroke was measured.

  About the vertical wall surface of the press-molded product in Example 1, the linearity in the molding direction (the direction of relative straight movement of the punch 1 and the die 2) was examined. As a result, Table 1 was obtained. Strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A and generated in the normal direction of the vertical wall portion 1 ′ of the punch 1 measured by the strain measuring means B. When all the strains ε were in the range of 100 to 200 (μ), the curvature (1 / m) of the vertical wall surface of the molded product with respect to the molding direction was 1.0 or less, and a substantially linear shape was obtained. On the other hand, the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A and the normal direction of the vertical wall portion 1 ′ of the punch 1 measured by the strain measuring means B. When either one of the generated strains ε is out of the range of 100 to 200 (μ), the curvature (1 / m) of the vertical wall surface of the molded product with respect to the molding direction exceeds 1.0, and the curvature becomes large. It was. No15 is the strain ε generated in the normal direction of the vertical wall 2 ′ of the die 2 measured by the strain measuring means A and the method of the vertical wall 1 ′ of the punch 1 measured by the strain measuring means B. All of the strains ε generated in the linear direction exceeded the range of 100 to 200 (μ), and the material broke during molding. Note that the strain generated in the surface direction of the upper surface of the die 2 measured by the strain measuring means C was not an index for determining a molded product.

  FIG. 12 is a schematic explanatory diagram of a press die apparatus according to the second embodiment of the present invention. In the press mold apparatus of FIG. 12, the clearance c (mm) is set larger than the plate thickness t (mm) of the thin plate 5 (t <c), and the cross-sectional shape of the thin plate 5 is within the clearance c during press forming. A so-called reverse bending was generated by making S into a curved curve, and shape defects due to springback were eliminated (No. 31 to 35). In addition, press molding was performed while applying a wrinkle pressing load to the flange portion of the thin plate 5 by the wrinkle pressing mold 15. In the press mold apparatus shown in FIG. 12, the strain measuring means A for measuring the strain ε generated in the normal direction of the vertical wall portion 2 ′ is arranged at a substantially intermediate height of the vertical wall portion 2 ′ of the die 2. Furthermore, in the press die apparatus of FIG. 12, the strain measuring means D for measuring the strain generated in the normal direction of the upper surface of the die 2 in the vicinity of the shoulder 2b is arranged. The thin plate 5 is a high-tensile steel plate with a plate thickness of 1.4 mm, and a hat cross-section beam (length 100 mm) with a web width of 80 mm and a depth of 80 mm was formed. Each strain measuring means was arranged at the center in the longitudinal direction of the mold, and the maximum output value during the stroke was measured.

  For the vertical wall surface of the press-molded product in Example 2, the linearity in the molding direction (the direction of relative straight movement of the punch 1 and the die 2) was examined. As a result, Table 2 was obtained. When the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A is 40 (μ) or more, the curvature (1 / m) of the vertical wall surface of the molded product with respect to the molding direction Became 1.0 or less, and became a substantially linear shape. On the other hand, when the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A is less than 40 (μ), the curvature of the vertical wall surface of the molded product with respect to the molding direction (1 / m) exceeded 1.0, or reverse warping occurred as in No. 32. The strain generated in the normal direction of the upper surface of the die 2 measured by the strain measuring means D was not an index for determining the molded product. Further, in No. 34 in Table 2, the strain ε measured by the strain measuring means A was excessive and the curvature (1 / m) was 1.7. However, as shown in No. 35, it was measured by the strain measuring means A. The curvature (1 / m) could be reduced to 1.0 or less by adjusting the wrinkle holding load low so that the strain ε to be 40 (μ) or more.

  FIG. 13 is a schematic explanatory diagram of a press die apparatus according to Example 3 of the present invention. In the press mold apparatus of FIG. 13, the clearance c (mm) is set larger than the plate thickness t (mm) of the thin plate 5 (t <c), and the cross-sectional shape of the thin plate 5 is within the clearance c during press forming. A so-called reverse bending was generated by making S into a curved curve, and the shape defect due to the springback was eliminated (No. 41 to 47). In addition, press forming was performed while pressing the thin plate 5 between the punch 1 and the pad 16 while applying a wrinkle pressing load to the flange portion of the thin plate 5 by the wrinkle pressing die 15. In the press die apparatus of FIG. 13, strain measuring means A1 and A2 for measuring strain ε generated in the normal direction of the vertical wall portion 2 ′ are arranged at a plurality of heights of the vertical wall portion 2 ′ of the die 2. . Further, in the press die apparatus of FIG. 13, a strain measuring means D for measuring the strain generated in the normal direction between the flange portion and the upper surface of the die 2 is disposed in the vicinity of the shoulder portion 2b. The thin plate 5 is a high-tensile steel plate with a plate thickness of 1.4 mm, and a hat cross-section beam (length 100 mm) with a web width of 80 mm and a depth of 80 mm was formed. Each strain measuring means was arranged at the center in the longitudinal direction of the mold, and the output value at a stroke of 55 mm was measured.

  For the vertical wall surface of the molded product press-molded in Example 3, the linearity in the molding direction (the direction of relative straight movement of the punch 1 and the die 2) was examined. As a result, Table 3 was obtained. The strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A1 is less than 40 (μ), and the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A2 When the strain ε generated in the normal direction is 40 (μ) or more, the curvature (1 / m) of the vertical wall surface of the molded product with respect to the molding direction is 1.0 or less, which is almost linear. On the other hand, the strain ε generated in the normal direction of the vertical wall portion 2 ′ of the die 2 measured by the strain measuring means A1 is 40 (μ) or more, or the vertical wall of the die 2 measured by the strain measuring means A2. When the strain ε generated in the normal direction of the portion 2 ′ was less than 40 (μ), the curvature (1 / m) of the vertical wall of the molded product with respect to the molding direction exceeded 1.0. The strain generated in the normal direction of the upper surface of the die 2 measured by the strain measuring means D was not an index for determining the molded product. In No. 45 in Table 3, the strain ε measured by the strain measuring means A2 is too small and the curvature (1 / m) is 1.4, but the strain ε measured by the strain measuring means A2 is 40 ( μ) The curvature (1 / m) could be reduced to 1.0 or less by adjusting both the pad pressure in No46 and the pad pressure and the wrinkle holding load in No47.

  The present invention can be applied to the field of press forming thin plates.

It is a schematic explanatory drawing of the press die apparatus concerning the 1st Embodiment of this invention, and has shown the state before a press. It is a schematic explanatory drawing of the press die apparatus concerning the 1st Embodiment of this invention, and has shown the state in the middle of a press. It is a schematic explanatory drawing of the press die apparatus concerning the 1st Embodiment of this invention, and has shown the state at the time of press completion. It is explanatory drawing of the attachment direction of the distortion measurement means provided in the inside of the vertical wall part of die | dye. It is explanatory drawing of the attachment structure of the strain measurement means provided in the inside of the vertical wall part of die | dye. It is a schematic explanatory drawing of the press die apparatus concerning the 2nd Embodiment of this invention, and has shown the state at the time of press completion. It is a schematic explanatory drawing of the press die apparatus concerning the 3rd Embodiment of this invention, and has shown the state at the time of press completion. It is a schematic explanatory drawing of the press die apparatus concerning the 4th Embodiment of this invention, and has shown the state at the time of press completion. It is a schematic explanatory drawing of the press die apparatus concerning the 5th Embodiment of this invention, and has shown the state at the time of press completion. It is a schematic explanatory drawing of the press die apparatus concerning the 6th Embodiment of this invention, and has shown the state at the time of press completion. FIG. 2 is a schematic explanatory diagram of one type of press mold apparatus in Example 1, showing a state at the end of pressing. It is a schematic explanatory drawing of the press die apparatus of Example 2, and has shown the state at the time of press completion. It is a schematic explanatory drawing of the press die apparatus of Example 3, and has shown the state at the time of press completion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Punch 1 'Vertical wall part 2 Die 2' Vertical wall part 2a Air cavity 3 Punch holder 4 Die holder 5 Thin plate c Clearance 10 Strain measuring means 15 Wrinkle presser mold 16 Pad

Claims (7)

A press mold apparatus for press-molding a thin plate by a relative straight movement of a punch and a die,
Strain measurement for measuring strain generated in the normal direction of the vertical wall portion inside at least one of the punch and the vertical wall portion parallel to the linearly moving direction of the die that form a clearance facing each other during molding A thin plate press mold apparatus, characterized in that means are arranged.   The thin plate pressing die apparatus according to claim 1, wherein the strain measuring means is a piezo element or a strain gauge.   The thin plate press die apparatus according to claim 1 or 2, wherein a plurality of the strain measuring means are arranged at different positions in the relative movement direction of the punch and the die.   The thin plate pressing die apparatus according to any one of claims 1 to 3, further comprising a wrinkle pressing die and / or a pad interlocking with the punch.   A thin plate press molding method using the press die device according to any one of claims 1 to 4, wherein the strain measured by the strain measuring means during press molding exceeds a predetermined range, or A press molding method characterized in that a molding abnormality is determined when it falls below a predetermined range.   5. A thin plate press molding method using the press die apparatus according to claim 4, wherein the strain measured by the strain measuring means during press molding exceeds a predetermined range or falls below a predetermined range. And a wrinkle presser load or a pad pressure is adjusted so that the strain falls within a predetermined range.   The press molding method according to claim 5 or 6, wherein press molding is performed while causing reverse bending of the thin plate within the clearance.

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