JP4808678B2 - Thin plate press die apparatus and press molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press die apparatus and a press-forming method, capable of obtaining a press-formed product having excellent dimensional precision by accurately detecting, at the time of press-forming, whether the pressurization required for proper transfer to or proper formation of a sheet is conducted. <P>SOLUTION: A press die apparatus performs press-forming of a sheet 5 through relative straight movements of a punch 1 and a die 2. A strain measuring means 10 for measuring elastic strain generated in a normal direction of the sheet 5 is arranged inside near at least one of the pressurizing faces of the punch 1 and the die 2. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

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, a press die capable of determining and controlling the dimensional accuracy of a molded product by detecting the pressure applied to the thin plate at the bottom dead center. The present invention relates to a 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.

  For example, Patent Document 1 discloses a method of calculating a load applied to a slide from a pressure sensor of a hydraulic cylinder, and Patent Document 2 discloses a method of measuring a load applied to the slide. Both provide a method for detecting a double blank for mold protection.

  Non-Patent Document 3 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 10-193199 A Japanese Patent Laid-Open No. 11-58097 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, for example, when unevenness formed on the pressing surface of the punch is transferred and shaped on a thin plate, the load distribution applied to the entire thin plate is difficult to be uniform. In both Patent Document 1 and Patent Document 2, only the slide load is detected. However, with this alone, the processed portion of the thin plate is reliably pressed, and accurate transfer / modeling of the pressing surface unevenness and the like is performed. Cannot determine whether or not.

  In addition, when different press mold apparatuses are used, even if the load applied to the slide is the same, the load applied to the thin plate may be locally different due to different bending of the apparatus and the mold. For this reason, whether or not sufficient pressurization has been applied to the processed portion of the thin plate cannot be determined without looking at the shape of the molded product after pressing, and conventionally, an appropriate output is obtained by trial and error for each press die device. Had to set.

  Further, even when the frictional force between the die and the crease presser mold was measured as in Non-Patent Document 3, it was still impossible to know the contact state between the thin plate and the mold in the transfer / modeling portion.

  Therefore, an object of the present invention is to provide a press-molded product with excellent dimensional accuracy by accurately detecting at the time of press molding whether or not pressurization for proper transfer and modeling to a thin plate is performed. It is providing the press die apparatus and press molding method which are obtained.

  In order to solve the above problem, according to the present invention, there is provided a press mold apparatus for press-molding a thin plate by a relative linear movement of a punch and a die, in the vicinity of a pressing surface of at least one of the punch and the die. There is provided a thin plate press mold apparatus characterized in that a strain measuring means for measuring elastic strain generated in the normal direction of the thin plate is disposed therein.

  By providing strain measuring means in the vicinity of the pressing surface of the punch or die, it is possible to detect the strain caused by the reaction force of the compressive force applied to the thin plate from the punch or die at the bottom dead center of press molding. Therefore, the contact state between the pressing surface and the thin plate can be accurately detected.

  In this press mold apparatus, the strain measuring means is, for example, a piezo element or a strain gauge.

  Further, according to the present invention, there is provided a press forming method for a thin plate using the press mold apparatus, wherein the strain measured by the strain measuring means is within a predetermined range at the bottom dead center of press molding. There is provided a press molding method characterized in that press molding is performed by previously adjusting the pressing force of the punch or the die.

  Further, according to the present invention, there is provided a press forming method for a thin plate using the press mold apparatus, wherein the strain measured by the strain measuring means at a bottom dead center of the press molding exceeds a predetermined range, or a predetermined When the pressure falls below the range, the press molding is temporarily interrupted, the pressing force of the punch or the die is adjusted so that the strain is within a predetermined range, and then the press molding is restarted. A press molding method is provided.

  Furthermore, according to the present invention, there is provided a thin plate press molding method using the press mold apparatus, wherein the strain measured by the strain measuring means at a bottom dead center of the press molding exceeds a predetermined range, or Provided is a press molding method characterized in that a molding abnormality is determined when the value falls below a predetermined range.

  According to the present invention, it is possible to accurately detect the pressing force at the bottom dead center of press molding by measuring the strain in the normal direction of the thin plate generated near the pressing surface of the punch or die at the bottom dead center. It becomes. That is, by detecting the contact state between the thin plate and the punch or die at the bottom dead center at the time of molding, it can be determined whether or not the pressure molding to the thin plate of the mold is correctly performed. Further, by detecting a contact force abnormality at the bottom dead center, it is possible to prevent the thin plate from being broken. As a result, a press-formed product having excellent dimensional accuracy can be obtained without breaking the thin plate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 and FIG. 2 are schematic explanatory views of a press die apparatus according to the first embodiment of the present invention. This press mold apparatus is a system that performs drawing without using a crease 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 shown in FIG. 1, 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, as shown in FIG. 1, a thin plate 5 as a molding material is placed on a die 2, and the punch 1 and the die 2 are moved relatively straight in the vertical direction. In accordance with the relative linear movement of the punch 1 and the die 2, the thin plate 5 is drawn into the cavity 20 of the die 2 and is press-molded into a shape along the pressing surface 11 of the punch 1 as shown in FIG. . In the present embodiment, as shown in FIG. 3, a molded product having an opening toward one side and a depression 51 on the bottom surface by the convex portion 22 of the pressing surface 21 of the die 2 and the concave portion 12 of the pressing surface 11 of the punch 1. 50 can be made. In addition, FIG. 3 is the figure seen from the bottom face side. Of course, in the press molding, the punch 1 may be lowered or the die 2 may be raised.

  The strain measuring means 10 is provided to measure the strain generated in the normal direction of the thin plate 5 in the punch 1 and the die 2 at the time of the above press forming. In the press die apparatus shown in FIGS. 1 and 2, the strain measuring means 10A for measuring the strain generated in the normal direction of the thin plate 5, that is, the vertical direction in the figure, is provided in the center of the concave portion 12 of the punch 1. One strain measuring means 10B for measuring strain generated in the normal direction of the thin plate 5, that is, in the vertical direction in the figure, is provided in the center of the two convex portions 22 one by one. Both strain measuring means 10A and 10B are provided in the vicinity of the pressurizing surfaces 11 and 21 of the punch 1 or die 2. The strain measuring means 10 can detect a strain caused by a reaction force of a compressive force applied to the thin plate 5 from the concave portion 12 of the punch 1 and the convex portion 22 of the die 2 during press molding. The strain measuring means 10 may be provided inside both the punch 1 and the die 2 as shown, or may be provided only in one of them.

  As the strain measuring means 10 provided inside the punch 1 and the die 2 as described above, for example, a piezoelectric element or a strain gauge can be used. FIG. 4 shows an example of attachment of the measuring means 10 composed of such a piezo element or a strain gauge to the inside of the die 2.

  As shown in FIG. 4, the strain measuring means 10B is inserted into the bottom of the hole formed in the die 2 to place the strain measuring means 10B inside the convex portion 22 of the die 2, and then the hole is formed by the bolt 9. It has a closed configuration. A lead wire 19 for taking out a detection signal from the strain measuring means 10B passes through the bolt 9 and is drawn to the outside. The strain measuring means 10B is preferably disposed at a position of, for example, a depth of about 4 to 30 mm from the pressing surface 21 on the surface of the convex portion 22.

  As described above, by providing the strain measuring means 10 for measuring the strain generated in the normal direction of the thin plate 5 inside the concave portion 12 of the punch 1 and the convex portion 22 of the die 2, it is possible to form the middle or bottom dead center. The contact state between the thin plate 5 and the pressing surfaces 11 and 21 of the punch 1 or the die 2 can be accurately detected, and it can be determined whether or not the press molding is correctly performed. In addition, the thin plate 5 can be prevented from being broken by setting an upper limit of the detection value and detecting a 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. Furthermore, detection of contact force abnormality by setting an upper limit is also effective for detecting defects such as double blanks and wrinkle overlap.

  Further, for example, when the strain 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, it is possible to cope by temporarily interrupting the press molding and adjusting the pressing force of the punch 1 or the die 2 so that the strain falls within a predetermined range. 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. 5 and FIG. 6 are schematic explanatory views of a press die apparatus according to the second embodiment of the present invention. In this press mold apparatus, a die 2 is disposed on the upper side, and a punch 1 is disposed on the lower side so as to face the die 2. Further, by providing wrinkle presser molds 6 and 6 on both sides of the punch 1, the drawing process is performed while applying a wrinkle presser load to the flange portion of the thin plate 5. Thus, by using the wrinkle presser mold 6, the flow of the material can be controlled, and it becomes easy to obtain a press-formed product having an excellent shape without wrinkles even if there is a shrinkage deformed portion.

  In such a press mold apparatus, as shown in FIG. 5, in the initial state, the crease presser molds 6 and 6 on both sides and the upper end surface of the punch 1 are arranged flush with each other, and the thin plate 5 which is a molding material is disposed thereon. Put on. Thereafter, the punch 1 and the die 2 are moved relatively straight in the vertical direction, whereby the thin plate 5 is drawn into the cavity 20 of the die 2 and along the pressurizing surface 11 of the punch 1 as shown in FIG. Press molded into shape.

  The strain measuring means 10 includes a strain measuring means 10 </ b> A for measuring strain generated in the normal direction of the thin plate 5 in the center of the concave portion 12 of the punch 1, and a method for the thin plate 5 in the center of the convex portion 22 of the die 2. One strain measuring means 10B for measuring strain generated in the line direction is provided one by one. Both strain measuring means 10A and 10B are provided in the vicinity of the pressurizing surfaces 11 and 21 of the punch 1 or die 2. The strain measuring means 10 detects the strain generated by the reaction force of the compressive force applied to the thin plate 5 from the concave portion 12 of the punch 1 and the convex portion 22 of the die 2 during press molding. In other words, as in the above-described embodiment, the contact state between the thin plate 5 and the pressurization surfaces 11 and 21 of the punch 1 or die 2 in the middle of molding or at the bottom dead center can be accurately detected. It is possible to determine whether or not a press-formed product with excellent dimensional accuracy is obtained. In this case as well, the strain measuring means 10 may be provided on both the punch 1 and the die 2 as shown in the figure, or may be provided on only one of them.

  FIG. 7 is a schematic explanatory view of a press die apparatus according to the third embodiment of the present invention. This is a mold apparatus in which V bending is performed, and is used, for example, in a press brake or the like.

  7, the strain measuring means 10 is provided inside the vicinity of the tip of the punch 7 so as to measure the strain generated in the radius of curvature at the radius of the tip of the V-bending portion of the thin plate 5, that is, the strain generated in the vertical direction in FIG. Is provided. Thereby, since the pressurization state at the time of V bending of a molded article can be detected correctly, a press molded article excellent in dimensional accuracy can be obtained. The strain measuring means 10 may be disposed inside the die 8 that faces the tip of the punch 7.

  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.

  A press mold device that does not have a crease presser mold as described above with reference to FIG. 2 and a wrinkle presser load applied to the flange portion of the thin plate 5 by the crease presser mold 6 as previously described with reference to FIG. For the two types of press mold apparatuses that perform press forming, the thin plate 5 was press formed, and the strain ε was detected at the bottom dead center.

  In each press mold apparatus, as shown in FIGS. 2 and 6, a piezoelectric element is used as the strain measuring means 10 in the inside of the center of the concave portion 12 of the punch 1 and inside the center of the convex portion 22 of the die 2. Strain generated in the normal direction of the thin plate 5 was measured in the vicinity of the pressure surfaces 11 and 21 (each 5 mm from the surface). For each of the presence / absence of the wrinkle presser die 6, press molding was performed with respect to two kinds of applied pressure.

  Table 1 was obtained as a result of examining the radius of curvature of the ridgeline 52 (see FIG. 3) for the molded product 50 thus press-formed.

  From Table 1, according to the strain measuring means arranged in Example 1, when the detected strain value at the bottom dead center exceeds 80 μm, the curvature radius of the ridge line becomes the standard value of 5.0 mm, which passes the quality standard. I found out that Further, the applied pressure at which the strain reached 80 μm was different depending on the presence or absence of the wrinkle presser mold.

  Next, the thin plate 5 was press-molded by a press mold apparatus B different from that in Example 1. The configuration of the apparatus is the same as that of apparatus No. 4 of Example 1, and a strain gauge is provided as a strain measuring means at the same position as apparatus A.

  First, without performing control by strain, when press-molding with a pressure of 2800 kN similar to No. 4 that passed the quality standard in Example 1, the detected value of strain at the bottom dead center is 87μ, and the curvature radius of the ridge line is It was larger than the standard value and was rejected.

  Then, when the pressure is controlled so that the strain value at the bottom dead center is 100 με, a molded product is obtained in which the applied pressure is 3130 kN and the curvature radius of the ridge line is 5.0 mm as a reference value. It was.

  As a result, if the device is controlled only by the applied pressure, an appropriate molded product may not be obtained due to differences in device rigidity, etc., but the thin plate method at the bottom dead center of the punch or die It was found that accurate quality control can be achieved by controlling the strain in the linear direction.

  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 at the time of press completion. It is a perspective view of the molded product shape | molded by FIG. It is explanatory drawing of the attachment structure of the strain measurement means arrange | positioned inside a 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 before a press. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Punch 2 Dies 3 Punch holder 4 Die holder 5 Thin plate 6 Wrinkle presser mold 10 Strain measuring means 11, 21 Pressurizing surface 12 Recess 20 Recess 20 Cavity 22 Protrusion 50 Molded product

Claims (5)

A press mold apparatus for press-molding a thin plate by a relative straight movement of a punch and a die,
A thin plate press mold characterized in that a strain measuring means for measuring elastic strain generated in the normal direction of the thin plate is disposed in the vicinity of the pressing surface of at least one of the punch and the die. apparatus.   The thin plate pressing die apparatus according to claim 1, wherein the strain measuring means is a piezo element or a strain gauge.   A thin plate press forming method using the press mold apparatus according to claim 1 or 2, wherein a strain measured by the strain measuring means is within a predetermined range at the bottom dead center of press forming. A press molding method, wherein press molding is performed by adjusting a pressing force of the punch or the die.   A thin plate press molding method using the press die apparatus according to claim 1 or 2, wherein the strain measured by the strain measuring means at a bottom dead center of the press molding exceeds a predetermined range, or a predetermined range. The press forming is temporarily interrupted, the pressing force of the punch or the die is adjusted so that the strain is within a predetermined range, and then the press forming is restarted. Molding method.   A thin plate press molding method using the press die apparatus according to claim 1 or 2, wherein the strain measured by the strain measuring means at a bottom dead center of the press molding exceeds a predetermined range, or a predetermined range. A press molding method characterized in that a molding abnormality is determined when the value is less than.

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