JP2008173686A - Press forming apparatus for sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform good press forming by easily evaluating variation in the characteristics of a base material, deterioration with time of a die in a blanking stage or the like. <P>SOLUTION: This press forming apparatus for sheets comprises a blanking means and a press forming means having a blank holding pressure adjusting part and/or a forming speed adjusting part. In this press forming apparatus for sheets, the blanking means includes a working reaction force measuring part for measuring working reaction force of the sheet in the blanking work and a punch position measuring part and the press forming means includes a press forming condition control part for controlling the blank holding pressure and/or a forming speed on the basis of the working reaction force measured with the reaction force measuring part, the punch position measured with the punch position measuring part, the tensile strength of a blank, a workhardening exponent (n-value), elongation, the circumference and the thickness. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a press forming apparatus for various metal materials such as ferrous, non-ferrous, and laminated materials, and more particularly to a press forming apparatus capable of good processing regardless of variations in various material characteristics.

  Conventionally, when deep drawing processing, bending processing, cutting processing, etc. are performed on a metal material using a press forming apparatus, appropriate molding conditions for each material, that is, mold shape, lubrication conditions, molding speed, wrinkle suppression, etc. Usually, actual production is carried out after the force, mold and temperature of the workpiece are determined in advance by empirical or experimental trial production, simulation by a finite element method, or the like.

  On the other hand, various metal materials used as raw materials are plate materials, pipe materials, bar materials, wire materials, and granular materials obtained from raw materials and scrap through multiple processes such as melting, refining, casting, rolling, heat treatment, and secondary processing. Due to variations in process conditions such as variations in chemical components and temperature non-uniformity, it is inevitable that there is some variation in the mechanical property values of the product. For this reason, even if appropriate molding conditions are determined in advance as described above, moldability may differ depending on the material part and production lot, and molding defects may occur. In order to avoid this, quality control in the material manufacturing process is of course made more stringent, but excessive tightening leads to an increase in material cost, which is not preferable.

  Also, even if the mechanical properties of the material are the same, molding defects may occur due to environmental changes during processing, such as changes in mold temperature due to continuous processing, wear of the mold, changes in ambient temperature and humidity, etc. is there.

  On the other hand, various inventions are disclosed in the molding method for controlling the processing conditions in accordance with the conditions of the material and the mold. For example, Patent Document 1 discloses the shape, mechanical properties, chemical properties of the press material. The relationship between physical properties such as properties, lamination characteristics such as plating, surface conditions such as oil amount, and appropriate wrinkle holding load to obtain a predetermined press quality is obtained in advance, and the appropriate wrinkle is determined according to the actual physical amount from the relationship. An apparatus has been disclosed that obtains a holding load and adjusts the air pressure of the air cylinder so that pressing is performed with the appropriate wrinkle holding load.

  Patent Document 2 discloses an apparatus for adjusting press conditions based on material conditions specified for each material, maximum load during bending, and the like.

In addition, as shown in Patent Documents 3 to 5, the present inventor has molding variations caused by environmental fluctuations during machining, for example, mold temperature change due to continuous machining, mold wear, atmospheric temperature and humidity fluctuations, and the like. In order to compensate for this, an invention has already been disclosed in which the wrinkle holding load and the molding speed are controlled using the mold distortion during processing in addition to the material characteristics.
JP 7-266100 A JP 58-103918 A JP 2004-249365 A JP 2005-161399 A JP 2006-75884 A

  Patent Document 1 discloses an invention for controlling a wrinkle holding load based on material characteristics, information unique to a processing apparatus, and mold information. However, a synergistic effect of fluctuations in material characteristics, changes in processing apparatus, and mold conditions is disclosed. As a result, the lubrication characteristics of the mold, in particular, vary from moment to moment, and it is extremely difficult to predict this in advance.

  It is also described that physical quantities such as work hardening index (n value), r value, TS (tensile strength), YS (yield strength), E (Young's modulus) may be measured and input. However, for example, in parts with stretch flange deformation that is liable to crack at the end face, the effect of the cut end face properties after blanking is very large. It is necessary to consider degradation.

  Patent Document 2 discloses a method of controlling the bending process by measuring the plate thickness for each material and the maximum load during the bending process to obtain the tensile strength of the material. In order to prevent cracking during the forming process, it is necessary to consider the ductility (elongation) of the material, and it is difficult to predict this with the tensile strength.

  In addition, Patent Documents 3 to 5 disclose inventions for adjusting press molding conditions using material properties. Generally, if material properties are a production lot, for example, a thin metal plate, the representative value of a coil is disclosed. While mechanical test results at one point in the coil, that is, data such as yield stress, tensile strength, and elongation, are provided, in reality, the material is not necessarily constant in the coil longitudinal direction and width direction, and there are some fluctuations Is inevitable. Therefore, in order to accurately consider the material characteristics, it is desirable to obtain at least the material characteristics for each blank, but it is impractical to perform a mechanical test on all blanks.

  On the other hand, not a rigorous mechanical test such as a tensile test, but also a simple method such as hardness measurement has been devised, but the hardness corresponds to the tensile strength, but for example press formability It is difficult to easily obtain elongation that has a large effect. Further, it is not possible to take into account the deterioration of the mold over time in the blanking process, which can cause stretch flange cracks.

  The present invention has been made in view of the above points, and it is an object of the present invention to easily evaluate variations in material characteristics and aging deterioration of a mold in a blanking process, and to enable favorable press molding processing. And

In order to solve the problem, means of the present invention are as follows.
(1) A thin plate press forming apparatus comprising a blanking means and a press forming means having a wrinkle holding pressure adjusting portion and / or a forming speed adjusting portion, wherein the blanking means is a processing of the thin plate in the blanking processing. It has a processing reaction force measuring unit and a punch position measuring unit for measuring a reaction force, and the press molding means includes a processing reaction force measured by the processing reaction force measuring unit and a punch position measured by the punch position measuring unit, A thin plate press characterized by having a press forming condition control unit for controlling the crease pressing pressure and / or forming speed based on the tensile strength, work hardening index (n value), elongation, circumference and plate thickness of the blank. Molding equipment.
(2) The machining reaction force measured by the machining reaction force measurement unit and the punch position measured by the punch position measurement unit are the machining reaction for each punch position (Xi (i = 1 to N)) in blanking. It is force history data (Ri (i = 1 to N)), the thin plate press forming apparatus according to (1). N is the number of data.
(3) The machining reaction force measured by the machining reaction force measurement unit is the maximum value (A) of the machining reaction force in blanking, and the punch position measured by the punch position measurement unit is the machining reaction force measurement. Punch position (B) where the processing reaction force during processing measured by the part is maximum, and punch position (C) when the processing reaction force is reduced to 50% to 70% of the maximum value, and the press molding In addition to the maximum value (A), the punch position (B), and the punch position (C), the condition control unit further records processing reaction force history data (R0i (i) when there is no wear immediately after the die update. = 1 to N)) and the function of controlling the wrinkle pressing pressure and / or the forming speed based on the standard deviation (D) of the history data (Ri (i = 1 to N)) of the processing reaction force in the blanking process. (2) characterized by having Press-forming device of the plate.
(4) The thin plate press forming apparatus according to (3), wherein the press forming condition control unit has a function of controlling wrinkle holding pressure and / or forming speed by a regression equation.
(5) The thin plate press forming apparatus according to any one of (1) to (4), wherein the processing reaction force measuring unit is a piezoelectric element embedded in a punch or a die.
(6) The processing reaction force measurement unit is a piezoelectric element embedded in a punch or a die mold along a blank shape, and is described in any one of (1) to (5) Thin plate press forming equipment.
(7) The punch position measurement unit includes a non-contact displacement meter that measures the displacement of the protrusion provided on the side surface of the punch. (1) to (6), Thin plate press forming equipment.
(8) The punch position measuring unit calculates the punch stiffness k [kN / mm] in advance, the displacement measurement value of the punch projecting portion is xt [mm], and the machining reaction force during xt measurement is calculated. When F [kN] is set, punch position xp [mm]
xp = xt − F / k
(7) The thin plate press forming apparatus according to (7).

  According to the present invention, appropriate processing conditions can be obtained regardless of variations in material characteristics, and a good molded product can always be obtained.

  Details will be described below with reference to the drawings.

  One embodiment of the present invention is shown in FIG. The thin plate press forming apparatus according to the present invention includes a blanking means 2 having a processing reaction force measuring unit (not shown) and a punch position measuring unit 5 for measuring a punch position, a wrinkle holding pressure adjusting unit 13 and / or The press forming means 7 includes a forming speed adjusting unit 14 and includes a press forming condition control unit (not shown) that controls the wrinkle pressure and / or forming speed.

  In general, a thin plate material for press forming is provided as a coil or a rectangular cut plate from a manufacturer or a primary processing manufacturer. In order to press-mold into a predetermined part shape, blanking ( The blank that has been cut and then cut is press-formed in the next step.

  Blanking is performed by punching a blank 6 having a predetermined shape with a pair of upper and lower molds (punch (upper mold) 3 and die (lower mold) 4) with appropriate clearances. Simultaneously measure the position (displacement) of the punch.

  The processing reaction force during the blanking process can be measured with high accuracy as an elastic strain of the die or punch for each location by using piezoelectric elements embedded in a plurality of locations along the cutting edge of the die or punch as a sensor. Also, the total processing reaction force can be obtained as the sum of all sensor outputs. The total machining reaction force can be measured using a load cell sandwiched in the machining force transmission path or a strain gauge installed in the machine frame, but blanking is a fast machining process of less than 1 second. Therefore, accurate measurement is difficult due to responsiveness, looseness of the entire device, elastic deformation, and the like. As shown in FIGS. 3 and 4, for example, by directly embedding a piezoelectric element in the punch 3, It is preferable to measure with high accuracy.

  The punch position can be measured as the slide displacement or crank angle of the blanking device, but there is a large error due to the deformation of the mold or the backlash of the device, and it can be measured directly with the displacement meter attached to the punch 3. Is desirable.

  FIG. 2 shows an example of a change in machining reaction force with respect to the punch position during blanking. As a result of measuring the reaction force for various materials in the same manner, the maximum value (A) of the reaction force is the tensile strength of the material and the punch position (B) where the reaction force is maximum. It is clear that the work hardening index (n value) of the material and the punch position (C) where the work reaction force rapidly decreases to 50% to 70% of the maximum value substantially correspond to the elongation of the material. became. Hereinafter, they are referred to as indexes A, B, and C.

In addition, when blanking is repeatedly performed, the cutting edge of the die gradually wears out, the sharpness decreases and the cutting end surface becomes rough, but a change appears in the history (waveform) of the processing reaction force against the punch position. Therefore, this is detected and used for monitoring the worn state and adjusting the next process. As a method for indicating the change in the waveform, for example, history data (R _i (i) of machining reaction force for each punch position (X _i (i = 1 to N)) in blanking after wear shown by a solid line in FIG. = 1 to N)) and the history data of machining reaction force in the standard state without wear immediately after the mold update shown by the dotted line in FIG. 2 (R0 _i (i = 1 to N)) (where N is the number of data points) From the machining reaction force standard deviation (also called machining reaction force waveform standard deviation) (D),
D = √ {Σ (R _i −R0 _i ) ² / (N−1)} (i = 1 to N) (1)
Is used as an indicator of mold wear.

  Moreover, since the distribution of the processing reaction force along the blank shape can be obtained by using a plurality of sensors, a portion corresponding to a stretch flange crack that may cause a problem in the next press forming step, for example, FIG. By measuring the processing reaction force of the stretch flange portion 20 shown in Fig. 5, it is possible to adjust appropriate press molding processing conditions in advance and prevent cracking.

  Next, a method for setting optimum press forming conditions for the next process for each blank using the indexes A, B, C, and D measured in the blanking process will be described.

First, each index A, B, C, D is normalized as follows.
A ′ = A / (L × t) / A0 (2)
B ′ = (B / t) / {b− (B / t)} / B0 (b is a coefficient, 1 ≦ b ≦ 2) (3)
C ′ = C / t / C0 (4)
D ′ = D / (ΣR0 _i / N) (i = 1 to N) (5)
Here, A: Maximum value of processing reaction force [N]
B: Punch position where processing reaction force is maximum [mm]
C: Punch position where the processing reaction force suddenly decreases to 50% to 70% of the maximum value [mm]
D: Machining reaction force waveform standard deviation [N]
A ′: normalized A value [−]
B ′: normalized B value [−]
C ′: normalized C value [−]
D ′: normalized D value [−]
L: Blank circumference [mm]
t: Blank plate thickness [mm]
A0: Blank tensile strength [MPa]
B0: Blank n value [-]
C0: Blank elongation [-]
R0 _i : Processing reaction force history [N] (i = 1 to N) in the standard state without wear immediately after the mold update
N: Number of reaction force history data [-]
The blank circumferential length L is the outer circumferential length of the blank 6 shown in FIG. In addition, the tensile strength (A0), n value (B0), and elongation (C0) of the blank were each tested by the method described in JISG0202 (1.1) tensile test for the same sample as the blank material. Are defined as tensile strength, n value, and elongation.

Next, with respect to the preset standard setting value P0 [N] of the wrinkle pressing pressure and the standard setting value V0 [mm / sec] of the molding speed, respectively, the normalization index (A ′, B ′, C ′) is set. , D ′), for example, the wrinkle holding pressure P [N] and the forming speed V [mm / sec] are adjusted using a first-order model formula. That is,
P = P0 × (p0 + p1 × A ′ + p2 × B ′ + p3 × C ′ + p4 × D ′) (6)
Here, p0 to p4 are coefficients, and are preferably in the ranges of −1.0 ≦ p0, p1, p2, p3 ≦ + 1.0, and −50 ≦ p4 ≦ + 50, respectively.
V = V0 × (v0 + v1 × A ′ + v2 × B ′ + v3 × C ′ + v4 × D ′) (7)
Here, v0 to v4 are coefficients, and are preferably in the ranges of −1.0 ≦ v0, v1, v2, v3 ≦ + 1.0, and −50 ≦ v4 ≦ + 50, respectively.

  Each coefficient can be obtained by creating a regression equation from experimental results obtained by artificially changing molding processing conditions using various samples whose material properties were directly measured by a tensile test in advance. In addition, it is possible to further improve accuracy by adding a function of automatically learning and adjusting a coefficient from a quality inspection result at the time of mass production.

  Usually, the contact displacement meter is cheaper and can be expected to have higher resolution than the non-contact displacement meter. However, if the space for installing the contact displacement meter is not available due to the shape of the punch, or the vibration of the mold When the displacement is high speed and large, the displacement meter may not be directly attached to the punch, and the punch displacement may have to be measured with a non-contact displacement meter. In such a case, in order to avoid the influence of the bending of the press device due to the reaction force as much as possible, a protrusion is provided on the side surface of the punch as the punch position measurement unit, and the displacement of the protrusion is measured with a non-contact displacement meter (see above). Invention according to (7)). At this time, it is desirable that the non-contact sensor has a high response frequency of 30 kHz or higher, such as an optical fiber displacement meter or a laser Doppler displacement meter.

The amount of displacement of the punch protrusion measured by the non-contact displacement meter as described above is affected by the punch deflection due to the processing reaction force, although it is very small compared to the deflection of the entire press device. When the variation in the machining reaction force is large, the influence of the machining reaction force becomes a problem for accurate punch displacement measurement. In such a case, in the invention according to (7), the punch position measurement unit The punch stiffness k [kN / mm] is calculated in advance, and the punch position xp [mm]
xp = xt − F / k (13)
xt: measured displacement of punch protrusion [mm]
F: Machining reaction force during xt measurement [kN]
It is possible to measure the punch displacement force more accurately (the invention according to the above (8)).

  Based on the above-described invention, as an example of the present invention, as shown in FIG. 1, the blanking means 2 including the machining reaction force measuring unit (not shown) and the punch position measuring unit 5, the wrinkle holding pressure adjusting unit 13, and the molding A prototype of a thin plate press forming apparatus constituted by the press forming means 7 provided with the speed adjusting unit 14 was produced. As shown in FIGS. 3 and 4, strain sensors using a total of five piezoelectric elements are embedded in the blanking punch 3 along the blank shape to form a processing reaction force measurement unit 12. . The piezoelectric elements were respectively installed at positions 20 mm from the surface of the blanking punch 3 and 20 mm from the side surface. Further, as shown in FIG. 1, the punch position measuring unit 5 recorded the relative displacement between the blanking punch 3 and the blanking die 4 in synchronism with the output of the strain sensor using a contact displacement sensor. The contact-type displacement sensor was fixed by providing scissors on the side surfaces of the blanking punch 3 and the blanking die 4.

The thin steel plate used as a raw material is a cold rolled steel plate provided as a coil from a raw material manufacturer and having a plate thickness (t) of 1.4 mm and a tensile strength of 590 MPa. Typical values for mechanical properties are
Tensile strength (A0): 620 [MPa]
n value (B0): 0.18 [-]
Elongation (C0): 0.30 [-]
Met. In this example, a T-shaped part (6) shown in FIG. The delivered coils are sequentially punched into the outer shape shown in FIG. 1 by the blanking means 2, and then pressed into the molded product 11 having the shape shown in FIG. 1 by the press molding means 7. The peripheral length L of the blank corresponds to the peripheral length of the plan view of the punch 3 shown in FIG. 3 and is about 1357 mm (= 400 + 150 × 2 + 200 + 2 × (50 + 25π + 100)).

  In order to investigate the influence of mechanical property fluctuations and blanking mold wear, as shown in Table 1 and Table 2, a total of 40 blanking processes were performed, of which 20 were new molds. The remaining 20 sheets were punched out using a mold that was used about 10,000 times, and the history of processing reaction force was measured for each using the above-described sensor.

  Next, from the measured machining reaction force history at each punch position, the maximum value (A) of the machining reaction force, the punch position (B) where the reaction force is maximized, and the punch where the machining reaction force rapidly decreases to 60% of the maximum value. The results obtained for the position (C) and the standard deviation (D) of the processing reaction force are shown in Tables 1 and 2 together.

Here, the maximum value (A) of the processing reaction force is expressed as the maximum value of the sum of the respective processing reaction forces measured by a total of five piezoelectric elements. That is,

(I = 1 to N, N: number of sampling points = 1000) (8)
In addition, the punch position (B) where the machining reaction force becomes maximum and the punch position (C) where the machining reaction force rapidly decreases to 60% of the maximum value averaged sensor outputs at five locations.

Further, the machining reaction force waveform standard deviation (D) is the standard state R0 of the reaction force histories R ⁽¹⁾ and R ⁽²⁾ of the ^two sensors 12 'in FIG. ⁽¹⁾ The standard deviation with R0 ⁽²⁾ was averaged. That is,
D = [√ {Σ {R ⁽¹⁾ _i −R ₀ ⁽¹⁾ _i ) ² / (N−1)} + √ {Σ (R ⁽²⁾ _i −R ₀ ⁽²⁾ _i ) ² / (N−1 )}] / 2 (i = 1 to N, N: number of sampling points = 1000) (9)
Next, using A ′, B ′, C ′, and D ′ obtained by normalizing the indicators A, B, C, and D for each measured blank, press forming processing conditions and wrinkle holding pressure P for the next step are used. The molding speed V was set as follows.

P / P0 = (0.59 × A ′ + 0.50 × B ′ + 0.29 × C′−25 × D ′) (10)
V = V0 (P / P0 ≧ 0.85) (11)
V0 × 0.9 (P / P0 <0.85) (12)
Here, P0 and V0 were 200 [kN] and 200 [mm / sec], respectively, under the standard conditions of wrinkle pressing pressure and molding speed.

  In addition, each coefficient of the equation (10) is prepared by preparing two types of materials with the same steel type and different production lots, and two types of dies with different clearances, and blanking according to the above-described procedure. After that, press molding is performed based on the experimental design method (material 2 level x mold 2 level x wrinkle pressing pressure 2 level x molding speed 2 level = 16 levels) in which wrinkle pressing pressure and molding speed are changed by 2 levels each. The shape of the molded product and the presence / absence of cracks (evaluated by the plate thickness reduction rate of the stretch flange portion) were measured and obtained from an experimental regression equation based on the experimental results.

  Table 1 shows the result of molding by the method described above. Here, with respect to the molded product, the presence or absence of cracks and the torsion angle of the T-shaped portion using a check tool were checked visually, and those in which both were within the allowable range were determined as non-defective products.

  When the method according to the present invention was used, it was possible to mold without defects regardless of whether the material characteristics fluctuated or the blanking mold was worn.

  On the other hand, as a comparative example, Table 2 shows the results of press molding processing under the same conditions for all blanks. In this case, 40% of defective molding occurred due to twisting due to the spring back and cracking of the edge portion. In particular, when blanking was performed with a mold used 10,000 times, cracks frequently occurred during press molding.

  In order to confirm the effect of the present invention, an apparatus shown in FIG. 5 was made as an experiment, and an experiment was conducted in which flange-up forming was performed after blanking by the apparatus of FIG. 5 using the plate material used in Example 1. The apparatus shown in FIG. 5 includes a blanking punch 17, a die 20, and a crease presser 16 that generates pressure by hydraulic pressure. The die 20 is formed with a concave portion at the center so as to correspond to the punch 17, and has a rectangular opening that is slightly movable in the direction of the punch 17 (leftward in the drawing). It is fixed to the frame by screws 23. An optical fiber type non-contact displacement meter is used for the punch position measurement unit 15, and as shown in FIG. 5, a pole 22 is raised and fixed to a frame 19 on which a blanking mold is installed, The displacement of the part 24 was measured. The measured displacement of the protrusion 24 is corrected by the deflection of the punch 17 calculated by the equation (13). The punch stiffness was calculated in advance as k = 11.3 [kN / mm] by the elastic finite element method. In order to make the effects of the present invention easy to understand, the above-described apparatus is configured such that the die fixing type of the blanking mold is a screw type, and the clearance is easily spread through blanking 500 times by intentionally loosening the tightening torque of the screw 23. The conditions were set (the initial clearance was 0.12 [mm]).

  The shape of the cut surface 21 after blanking is the shape shown in FIG. 6, and in this embodiment, the flange portion 21 is subjected to a test for flange-up molding so that the final product shape becomes the shape shown in FIG. Repeated 500 times, the molding defect rate of the final product was compared for the case where wrinkle holding force control was performed during blanking and the case where it was not performed.

  For the processing reaction force measuring unit 25, one embedded load cell using a piezoelectric element was used, and it was installed in the punch 17 in the configuration as shown in FIG.

  The molding speed was the same as the standard conditions in Example 1.

  Next, wrinkle pressure control will be described.

In order to grasp the relationship between the molding defect rate and the wrinkle holding pressure, as a preliminary experiment, trials of blanking and flange-up were carried out using a device in which the tightening torque of the screw 23 is appropriate and the clearance is hardly changed. As a result, the relational expression of the maximum machining reaction force A [kN] during blanking, the punch position B [mm] that gives the maximum machining reaction force, and the wrinkle holding pressure P [kN] is

P> 600A ^-0.6 +520 (0.12-B) [KN]

Then, cracks did not occur during flange-up molding with a probability of 90% or more. In addition, the above empirical formula is estimated by performing the above trial with six kinds of clearance amounts of 0.06, 0.12, 0.18, 0.24, 0.36, and 0.6 [mm] (A and B change depending on the clearance). Used to do).

In view of this result, the wrinkle holding pressure P in this embodiment,

Control was performed. The initial wrinkle pressure is 32.1 [kN] obtained by substituting the average value 160 [kN] of A and the average value 0.1 [mm] of B measured during the preliminary experiment with a clearance of 0.12 [mm] into equation (14). It is.

  The molding defect rate causing cracks during flange-up molding is as shown in FIG. 9, and when the wrinkle holding pressure was controlled, the defect rate was 10% or less despite a gap in clearance. On the other hand, when the wrinkle holding pressure is not controlled, the defect rate is about 15%, and this result proves that the device according to the present invention is effective.

It is a conceptual diagram which shows one Embodiment of the press molding processing apparatus of the thin plate of this invention. The relationship between the machining reaction force during blanking and the punch displacement is shown. It is an example of the punch metal mold | die which has a process reaction force measuring means. It is sectional drawing (AA of FIG. 3) of the punch metal mold | die which has a process reaction force measurement means. It is a conceptual diagram which shows another form of the press molding processing apparatus of the thin plate of this invention.

(A) A side view is shown. (B) A top view is shown.
The top view of the steel plate after blanking is shown. It is a perspective view which shows a final product shape. It is sectional drawing which shows one Embodiment of a punch position measurement part. Shows the molding defect rate that caused cracks during flange-up molding.

Explanation of symbols

1 Coil 2 Blanking means 3, 17 Blanking punch 4, 20 Blanking die 5 Displacement sensor (punch position measuring unit)
6, 18 Blank 7 Press molding means 8 Die for press molding (upper mold)
9 Punch for press molding (lower mold)
10, 16 Wrinkle presser 11 Molded product 12 Piezoelectric element 12 'Stretch flange part piezoelectric element 13 Wrinkle presser pressure adjusting part 14 Molding speed adjusting part 15 Punch position measuring part (non-contact displacement meter)
19 Frame 21 After forming, a portion 22 that becomes an elongated flange portion 22 Pole 23 Screw 24 Projection portion 25 Processing reaction force measurement portion (piezoelectric element)

Claims (8)

  A thin plate press forming apparatus comprising a blanking means, and a press forming means having a wrinkle holding pressure adjusting portion and / or a forming speed adjusting portion, wherein the blanking means generates a processing reaction force of the thin plate in blanking processing. The press forming means includes a machining reaction force measured by the machining reaction force measurement unit, a punch position measured by the punch position measurement unit, and a blank tension. A thin plate press forming apparatus characterized by having a press forming condition control unit that controls wrinkle holding pressure and / or forming speed based on strength, work hardening index (n value), elongation, circumference and plate thickness . The machining reaction force measured by the machining reaction force measurement unit and the punch position measured by the punch position measurement unit are history of machining reaction force for each punch position (Xi (i = 1 to N)) in blanking. It is data (Ri (i = 1-N)), The press molding processing apparatus of the thin plate of Claim 1 characterized by the above-mentioned.
N is the number of data.   The machining reaction force measured by the machining reaction force measurement unit is the maximum value (A) of the machining reaction force in blanking, and the punch position measured by the punch position measurement unit is measured by the machining reaction force measurement unit. The punch position (B) where the reaction force during machining is maximized and the punch position (C) when the machining reaction force is reduced to 50% to 70% of the maximum value, and the press molding condition control unit In addition to the maximum value (A), the punch position (B), and the punch position (C), the history data (R0i (i = 1 to 1) of machining reaction force when there is no wear immediately after the die update) N)) and a function of controlling the wrinkle pressing pressure and / or the forming speed based on the standard deviation (D) of the history data (Ri (i = 1 to N)) of the processing reaction force in the blanking process. The thin plate according to claim 2 Press-forming apparatus.   4. The thin plate press forming apparatus according to claim 3, wherein the press forming condition control unit has a function of controlling a wrinkle holding pressure and / or a forming speed by a regression equation.   The thin plate press forming apparatus according to any one of claims 1 to 4, wherein the processing reaction force measuring unit is a piezoelectric element embedded in a punch or a die.   The thin plate press molding according to any one of claims 1 to 5, wherein the processing reaction force measurement unit is a piezoelectric element embedded in a punch or a die mold along a blank shape. Processing equipment.   The thin plate press molding according to any one of claims 1 to 6, wherein the punch position measuring unit is composed of a non-contact displacement meter for measuring a displacement of a protrusion provided on a side surface of the punch. Processing equipment. The punch position measuring unit calculates the punch stiffness k [kN / mm] in advance, the displacement measurement value of the punch protrusion is xt [mm], and the machining reaction force during xt measurement is F [kN]. ], Punch position xp [mm]
xp = xt − F / k
The thin plate press forming apparatus according to claim 7, having a function of calculating as follows.

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