JP5430968B2 - Press forming method of aluminum alloy sheet with excellent shape freezing property - Google Patents

Description

The present invention relates to a press forming method of an aluminum alloy sheet, and in particular, presses the wrinkle so that the punch load is within a predetermined range in press forming of an aluminum alloy sheet that is bent into a hat-shaped cross-section while applying a wrinkle holding load. The present invention relates to a press forming method for realizing a good shape freezing property by reducing a springback by controlling a load and a processing speed.

  In recent years, aluminum alloy sheet materials are being applied to automobile parts in order to reduce the weight of the vehicle body, but shape freeze defects (springback) that occur when aluminum alloy sheet materials are molded into automobile parts have become a problem. This shape freezing defect not only significantly deteriorates the appearance quality of the final product (including the problem of the uniformity of the building gap between parts), but also causes welding defects in the assembly work performed after molding. For this reason, improvement of the shape freezing defect at the time of press molding is anxious.

  Springback, which is a shape freezing failure observed in bending, is a phenomenon that occurs because the residual stress generated in the work in the mold during bending is elastically restored and deformed during unloading. This is caused by uneven distribution in the thickness direction.

  When a hat-shaped cross-sectional part is molded using a U-shaped bending mold, if the part is released from the mold, the angle change and wall warp occur due to the spring back of the workpiece. In order to solve this problem, Patent Document 1 discloses a wrinkle pressing force (corresponding to “wrinkle pressing load” in the present application) and a punch speed (corresponding to “processing speed” in the present application) during press molding. A molding method for obtaining a molded article with high dimensional accuracy (small spring back) by adjusting is disclosed.

JP 2006-61980 A

Patent Document 1 discloses an invention in which dimensional accuracy is improved (spring back is reduced) by adjusting a wrinkle pressing force and a punch speed. However, the inventors of the present application have conducted repeated experiments and as a result of studying it, as shown in Patent Document 1, even if only focusing on the wrinkle holding force and the punch speed and changing them in the middle of the stroke, It has been found that the springback may not be suppressed. That is, it has been found that it is necessary to pay attention to characteristics (viscosity, composition, etc.) of rust preventive oil or press oil used as a lubricant, and to consider them.

  Thus, the present inventors have found that the occurrence of springback is closely related to the punch load in press forming of an aluminum alloy sheet that is bent into a hat-shaped cross-section while applying a wrinkle holding load. Based on this knowledge, the spring back can be reduced and the good shape freezing property can be ensured by adjusting and controlling the wrinkle holding load and processing speed so that the punch load during press forming is within the predetermined range. The present invention has been clarified to be possible.

  In other words, in order to reduce the springback, it is effective to reduce the stress difference in the thickness direction generated during the bending process. It can be realized by loading. Since it is the punch load that directly corresponds to the workpiece to generate a tensile stress, it is reasonable to consider using the punch load to achieve this purpose. It can be said.

  Next, the punch load is not simply determined by the wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the processing speed (“punch speed” in Patent Document 1). Depending on the material properties of the plate, as well as the characteristics (viscosity, composition, etc.) of the lubricant (rust prevention oil, press oil, etc.), etc. This will be described below.

  In press forming of aluminum alloy sheet that is bent into a hat-shaped cross-section while applying a wrinkle holding load, the plastic deformation resistance load of the workpiece and the friction load due to wrinkle holding are applied to the flange, and the plastic deformation of the work is applied to the die shoulder. Resistance load, bending and bending back resistance load and friction load are generated. Those loads are propagated through the workpiece on the side wall, and are transmitted to the punch through a portion where the workpiece and the punch shoulder are in contact with each other. The combined load becomes the punch load. In other words, the punch load is a load received by the punch through a portion where the load generated in each of the above portions propagates through the workpiece on the side wall and the workpiece and the punch shoulder are in contact with each other.

  Among the various loads described above, the friction load due to the wrinkle presser is the product of the friction coefficient between the mold and the workpiece and the wrinkle presser load. The coefficient of friction depends on the sliding speed of the workpiece in the mold (that is, it is proportional to the machining speed (“punch speed” in Patent Document 1)), but not only that. It greatly depends on the viscosity and composition of the rust preventive oil or press oil used in the agent. For example, even with the same wrinkle pressing load and the same processing speed, a high-viscosity press oil has a low friction coefficient and a small friction load, but a low-viscosity rust preventive oil has a high friction coefficient and a large friction load. Therefore, even with the same wrinkle holding load and the same processing speed, the punch load is small with high viscosity press oil, but the punch load is large with low viscosity rust preventive oil.

  That is, the punch load is not simply determined by the wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the processing speed (“punch speed” in Patent Document 1). Depending on the characteristics of the lubricant as well as the characteristics (viscosity, composition, etc.) of the lubricant (rust preventive oil, press oil, etc.), these are comprehensively reflected and determined.

  That is, as explained in detail above, in order to suppress springback in press forming of an aluminum alloy sheet that is bent into a hat-shaped cross-section while applying a wrinkle holding load, control the focus by focusing on the punch load. It is important to do. In other words, among the factors that affect the punch load, only the wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the processing speed (“punch speed” in Patent Document 1) are considered. In addition to the material characteristics of aluminum alloy sheet, the characteristics (viscosity, composition, etc.) of the lubricant (rust preventive oil, press oil, etc.) are considered as other factors that affect the punch load. It is necessary to put in.

Specifically, the present invention is as follows.
(1) In a press forming method of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, the product of the cross-sectional area A0 of the wall portion and the tensile strength TS of the work is expressed as f In this case, the punch load P is controlled to be not more than A% of f (A ≦ 45) from the start of molding until reaching the 90% position of the full stroke, and exceeds the 90% position of the full stroke. The punch load P is B% of f (however, 77 ≦ B ≦ 90 and (B / A) ≧ 2) from the point of time until reaching the point of end of molding (including the point of end of molding). all SANYO controlled to increase,
The punch load P is controlled to A% or less of f (A ≦ 30) from the start of molding until reaching the 90% position of the full stroke, and from the time when the 90% position of the full stroke is exceeded. Control is performed so that the punch load P is increased to B% of f (77 ≦ B ≦ 90 and (B / A) ≧ 3) until the end point is reached (including the end point of molding). Is what
A press forming method for an aluminum alloy sheet material, characterized in that the means for controlling the punch load to a predetermined value is adjustment control of the wrinkle holding load and the processing speed .

( 2 ) The punch load is measured by a punch load measuring means, and the wrinkle holding load and the machining speed are adjusted and controlled based on the punch load measured so that the punch load becomes a predetermined value. ( 1 ) Press forming method of aluminum alloy sheet.

( 3 ) The press forming method of the aluminum alloy sheet according to ( 2 ), wherein the punch load measuring means is installed in the punch.

( 4 ) The press forming method for an aluminum alloy sheet according to any one of ( 1 ) to ( 3 ), wherein the adjustment control of the processing speed is realized by servo drive.

( 5 ) The press forming method of the aluminum alloy sheet according to any one of ( 1 ) to ( 4 ), wherein the adjustment control of the wrinkle holding load is realized by servo drive.

( 6 ) The rust preventive oil or press oil or both are used as a lubricant between the metal mold and the aluminum alloy plate material, as described in any one of (1) to ( 5 ) above Press forming method of aluminum alloy sheet.

( 7 ) The aluminum alloy sheet material used in the work described in any one of (1) to ( 6 ) above, wherein the aluminum alloy sheet material used for the workpiece is a 5000 series aluminum alloy or a 6000 series aluminum alloy .

According to the method of the present invention, in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, it is possible to reduce the springback and ensure a good shape freezing property.

It is a schematic diagram which shows schematic structure of the press machine used for the press molding of an Example and a comparative example. The hat type | mold cross section in press molding is shown. It is a schematic diagram which shows the structure of a punch load measuring apparatus. 3 is a graph showing wrinkle holding loads according to Example 1 of the present invention and Comparative Example 1. 3 is a graph showing the processing speed according to Example 1 of the present invention and Comparative Example 1 of Example 1. It is a graph which shows the value P / f which remove | divided the punch load P which concerns on Example 1 of this invention of Example 1 by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). It is a graph which shows the value P / f which remove | divided the punch load P which concerns on the comparative example 1 of Example 1 by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). 2 is a photograph showing the appearance of a panel molded in Example 1. FIG. 6 is a graph showing a processing speed according to Example 2 of the present invention in Example 2. It is a graph which shows the value P / f which remove | divided the punch load P which concerns on this invention example 2 of Example 2 by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). 4 is a photograph showing the appearance of a panel molded in Example 2. FIG. It is a graph which shows the value P / f which remove | divided the punch load P which concerns on this invention Example 3 of Example 3 by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). It is a graph which shows the value P / f which remove | divided the punch load P which concerns on the comparative example 2 of Example 3 by f (product sectional area A0 of a punch shoulder part, and the tensile strength TS of a workpiece | work). 4 is a photograph showing the appearance of a panel molded in Example 3. FIG. It is a graph which shows the value P / f which remove | divided the punch load P which concerns on this invention example 4 of Example 4 by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). 6 is a photograph showing the appearance of a panel molded in Example 4. FIG. It is a graph which shows the wrinkle pressing load concerning Comparative Examples 3-8 of a comparative example. It is a graph which shows the value P / f which remove | divided the punch load P which concerns on Comparative Examples 3-5 of a comparative example by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). It is a graph which shows the value P / f which remove | divided the punch load P which concerns on Comparative Examples 6-8 of a comparative example by f (product of the cross-sectional area A0 of the workpiece | work of a punch shoulder part, and the tensile strength TS of a workpiece | work). It is a photograph which shows the external appearance of the panel shape | molded by Comparative Examples 3-5. It is a photograph which shows the external appearance of the panel shape | molded by Comparative Examples 6-8.

  As described above, in order to reduce the spring back, it is effective to reduce the stress difference in the thickness direction generated in the bending process. However, it increases the punch load and loads the workpiece with tensile stress. It can be realized by doing.

  The timing when the punch load starts to increase is preferably at the end of the molding stroke at which the progress of the bending process can be regarded as almost completed. This is because even if tensile stress can be applied to reduce the stress difference in the plate thickness direction, the stress difference in the plate thickness direction will occur again in the workpiece if bending further proceeds thereafter. Because it will end up. Therefore, it is desirable to keep the punch load low until the slowest possible stage in order to complete the bending process as much as possible. As will be described later, keeping the punch load as low as possible as late as possible is preferable from the viewpoint of preventing the displacement.

  However, if the starting point at which the punch load starts to increase is too late, the punch load cannot be increased to a predetermined value even at the end of the stroke, that is, at the end of molding.

  As can be understood from the above-described circumstances, the punch load does not have to start increasing strictly, but it is preferable that the punch load starts to increase from about 90% of the total stroke. Considering the above two conflicting propositions that the starting point to start increasing the punch load is brought as late as possible in the molding stroke, and that the punch load can be reliably increased to a predetermined value at the end of molding. As a result of the examination, it was found that the time when the punch load starts to increase may be the time when the position exceeds 90% of the total stroke.

As a result of the investigation, it has been found that by setting the punch load P to 77% or more of f, the springback can be remarkably reduced and the purpose can be achieved.
However, even if the punch load P after the increase is 90% or more of f, the effect of suppressing the spring back is not improved any more, and an extreme reduction in the plate thickness at the punch shoulder may occur. Get higher.
Therefore, a tensile stress is applied to the workpiece for the purpose of reducing springback during the final stage of the forming stroke (from the time when 90% of the total stroke is reached to the end of forming (including the forming end time)). Therefore, the value of B when the punch load P is increased to B% of f is preferably controlled so as to satisfy 77 ≦ B ≦ 90.

  What is important here is that the punch load is increased as described above by keeping the punch load as low as possible until the end of the molding stroke to be increased. It is important to make it a way to raise it all at once. In other words, it is desirable to keep the punching load as low as possible so that the bending process proceeds as smoothly as possible, and the bending process is completed as much as possible. This is because, as described in the section explaining the timing of starting to increase the punch load above, even if the tensile stress is applied and the stress difference in the plate thickness direction can be reduced, the bending process further proceeds thereafter. This is because a stress difference in the thickness direction is generated again on the workpiece. Once the punch load is increased and a tensile stress is applied to the workpiece, it is preferable that the bending process no longer proceeds thereafter.

  Therefore, when the punch load is increased at the end of the molding stroke (from the time when 90% of the total stroke is reached to the time when the molding is completed (including the time when the molding is completed)), the entire stroke is started from the molding start time. The punch load P until reaching the 90% position is controlled to be not more than A% of f, and from the time when the 90% position of the full stroke is reached to the time when the molding is finished (the time when the molding is finished). If the punch load P is increased to B% of f (provided that 77 ≦ B ≦ 90), (B / A) ≧ 2, preferably (B / A) ≧ 3. In addition, it is desirable that a difference in size exists between A and B.

  As described above (paragraph 0028), if B is controlled to 77-90, in order to satisfy (B / A) ≧ 2, A must be at most 45, that is, A ≦ 45, In order to satisfy (B / A) ≧ 3, A must be at most 30, that is, A ≦ 30.

  By the way, when a hat-shaped cross-section part is press-molded using a U-shaped bending mold, an increase in punch load means an increase in friction load at the flange portion. This means that there is a high probability that an imbalance will occur between the friction loads on the left and right flanges on both sides of the mold. In other words, the inflow of the workpiece becomes asymmetric, and a phenomenon that the workpiece is formed while being displaced (hereinafter referred to as “offset”) tends to occur.

Once the offset occurs, the asymmetry is further amplified by the subsequent processing, so the offset is particularly serious as the offset occurs early in the stroke. Accordingly, it is desirable to keep the punch load at an early stage of the stroke as low as possible. When the punch load exceeds 30% of f, the offset tends to occur, and when the punch load exceeds 50% of f, the frequency of occurrence of the offset becomes extremely high. Therefore, it is desirable to control the punch load to 50% or less of f, preferably 30% or less of f, from the viewpoint of preventing deviation.
This value is a condition (A ≦ 45, preferably) that has been necessary to satisfy the above-described requirement for reducing the springback (B / A) ≧ 2, preferably (B / A) ≧ 3. Almost overlap with A ≦ 30).

  Speaking only from the point of prevention of slipping, it is safe to keep the punch load low, but if the punch load is kept low until the end of molding, the load of tensile stress on the workpiece is realized. As described above, the non-uniformity in the plate thickness direction of the residual stress generated in the work remains unresolved and the springback is caused. .

In addition, as described above, as a method for increasing the punch load at the end of the molding stroke for the purpose of reducing the springback, it is important to increase the punch load at once. This method is also preferable from the point of prevention of slipping, and the punch load is increased at once after increasing the wrinkle holding load of the flange portions on both sides of the mold at the same time to suppress the inflow of the work at the same time. The way is desirable. This is because if the punch load is increased little by little at this time, the offset tends to occur.
It is.

  In the present invention, since the ratio of the punch load to the product f of the workpiece cross sectional area A0 of the punch shoulder bearing the inflow resistance and the tensile strength TS of the workpiece is controlled, a load cell is provided under the punch, etc. It is necessary to be able to measure the load.

  In press forming of an aluminum alloy sheet, when rust preventive oil or press oil is used as the lubricant, the punch load can be increased by increasing the wrinkle holding load or decreasing the processing speed.

In order to realize these, it is preferable to variably control the processing speed during molding and the wrinkle holding load by servo drive having excellent responsiveness.

Hereinafter, the present invention will be specifically described by way of examples.

■ Invention Example 1
The press machine used is a link servo press that controls a link mechanism as shown in FIG. 1 with a servo motor, and is accompanied by a servo die cushion using the servo motor as a drive source. After the slide with the die attached is lowered from the top dead center and a part of the work is held between the blank holder and the die connected to the cushion pad, a wrinkle presser load is generated on the work, then the slide and cushion The workpiece is formed by the die and the die fixed at the lower position of the workpiece while holding the wrinkle holding load of the workpiece by lowering the pad at the same time. Can be variably controlled.

  The molding test was performed by bending a hat-shaped section having a width of 150 mm and a height of 80 mm as shown in FIG. Note that the clearance between the punch having a height of 80 mm and the die is 1.4 mm. Further, as shown in FIG. 3, a load cell for punch load measurement was installed at the lower part of the punch, and the punch load during press molding was measured.

  In the above [Means for Solving the Problems], in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-section while applying a wrinkle holding load, the plastic deformation resistance load of the workpiece is Friction load due to wrinkle holding, and plastic deformation resistance load, bending bending return resistance load and friction load are generated at the die shoulder, and these loads propagate through the workpiece on the side wall and The load is transmitted to the punch through the part where the punch shoulder is in contact.The combined load becomes the punch load.In other words, the load generated at each of the above parts propagates through the workpiece on the side wall. And then, the load that the punch received through the part where the workpiece and punch shoulder contacted. ”

Here is a remark on this. The “side wall portion” corresponds to the “80 mm height portion” of the hat-shaped cross section, and the clearance between the punch and the die is 1.4 mm as described above. Accordingly, when an aluminum alloy plate material having a thickness of 1 mm is press-formed, a clearance margin of 0.4 mm exists between the aluminum alloy plate material and the mold, so that the friction load derived from this “80 mm height portion”. Is considered to hardly occur. Therefore, it can be said that the punch load measured using the load cell is the sum of loads generated at the flange portion and the die shoulder portion. That is, in [Means for Solving the Problems], “the plastic deformation resistance load of the workpiece and the friction load due to the wrinkle at the flange portion, and the plastic deformation resistance load and the bending-bending return resistance load of the workpiece at the die shoulder portion. "These frictional loads are generated. These loads propagate through the workpiece on the side wall and are transmitted to the punch through the portion where the workpiece and the punch shoulder are in contact with each other."

Table 1 shows the characteristics of the 6000 series aluminum alloy sheet material used as the workpiece of the forming test of Example 1 of the present invention.

The shape of the molded specimen is a strip shape with a plate thickness of 1 mm, a plate width of 100 mm, and a plate length of 350 mm.
Table 2 shows the specifications of the rust preventive oil preton R-303P manufactured by Sugimura Chemical Co., Ltd. used as the lubricant of Invention Example 1. (For convenience, Table 2 also shows the specifications of a rust preventive oil preton RS-962 manufactured by Sugimura Chemical Industries, Ltd., which is a lubricant used in Comparative Example 1 described later.)

Press molding was performed using the wrinkle pressing load control pattern shown in FIG. 4 and the speed control pattern shown in FIG.
The wrinkle holding load was fixed at 50 kN up to a molding height of 75 mm (that is, 94% of the total stroke), and was controlled to 350 kN after the molding height of 75 mm. The molding speed was about 110 mm / s at the start, and thereafter the molding was performed while constantly reducing the speed.

The value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) is shown in percentage in FIG.
By controlling the P / f to be 30% or less up to a molding height of 75 mm (that is, 94% of the total stroke), and adjusting the wrinkle holding load to 350 kN after the molding height of 75 mm. The P / f at the end of molding was controlled to 84%.

The punch load P from the start of molding to the 90% position of the entire stroke (that is, the molding height of 72 mm) is 19% or less of f. That is, A described in claim 1 is “19” in this case.
In addition, the punch load P is increased to 84% of f from the time when the position exceeds 90% of the total stroke to the time when the molding ends (including the molding end time). That is, B described in claim 1 is “84” in this case, and therefore satisfies the condition of 77 ≦ B ≦ 90.
Further, (B / A) = 4.4.

The results of this molding test will be described in detail later in comparison with the case of Comparative Example 1 described below, but showed a good shape freezing property.

■ Comparative Example 1
Except for using Preton R-303P used in Example 1 of the present invention as a lubricant, the same conditions as in Example 1 of the present invention were used except that a rust preventive oil Preton RS-962 manufactured by Sugimura Chemical Co., Ltd. was used. (Press machine, hat-shaped cross-sectional shape, aluminum alloy sheet (6000 series aluminum alloy) used as a workpiece, shape of molded specimen, wrinkle holding load control pattern in FIG. 4, speed control pattern in FIG. 5, etc.) Was done.

The specifications for Preton RS-962 were already shown in Table 2. In addition, Preton RS-962 is an intermediate oil between the rust preventive oil and the press oil, in which a rust preventive additive and a lubricating additive are added to the refined mineral oil.

A value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) is shown in FIG.
In spite of being controlled with the same wrinkle holding load control pattern and the same speed control pattern as in Example 1 of the present invention, the lubricant used was different, so P / f at the end of molding was 40%. Note that the P / f up to a molding height of 75 mm (that is, 94% of the entire stroke) is 30% or less.

The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 9% or less of f. That is, A described in claim 1 is “9” in this case.
In addition, the punch load P is increased to 40% of f during the period from when the 90% position of the full stroke is reached to when the molding is completed (including the molding completion time). That is, since B described in claim 1 is “40” in this case, the condition of 77 ≦ B ≦ 90 is not satisfied.
Note that (B / A) = 4.4.

The results of this molding test are described in detail below, but the springback was large.

(1) Comparison of shape freezing properties of Invention Example 1 and Comparative Example 1 Table 3 shows a comparison of shape freezing properties of Invention Example 1 and Comparative Example 1.

In order to quantitatively evaluate the springback, the forming width W at a position 65 mm in height from the punch bottom surface of the workpiece is measured, and the deviation ratio (W−W0) / W0 from the design width W0 is defined as the width opening ratio. Thus, it was used as an index of shape freezing property.

FIG. 8 shows the appearance of the molded panel.
In the hat-type bending molding of Invention Example 1, the width opening ratio was small and the shape freezing property was good, whereas in Comparative Example 1, the width opening ratio was large. In addition, in the invention example 1 and the comparative example 1, no offset occurred.

Thus, in the press forming method of an aluminum alloy sheet material that is bent into a hat-shaped cross-section while applying a wrinkle pressing load, the same wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the same processing are performed. Despite processing under the condition of speed (“punch speed” in Patent Document 1), the shape freezing property may be good or poor.
Despite being processed under the same processing conditions, the shape freezing property was good in Example 1 of the present invention, but it was inferior in Comparative Example 1 because the lubricant was different. Based.

(1) Conversion of Wrinkle Pressing Load into Description Style of Patent Document 1 Here, the wrinkle pressing load of Invention Example 1 and Comparative Example 1 is converted to the description style related to “wrinkle pressing force” of Patent Document 1.

  According to [0 0 2 8] of Patent Document 1, a value obtained by dividing the wrinkle pressing force by the plate cross-sectional area is set as a “value converted to tension”.

  First, the wrinkle pressing load 50 kN (constant) up to a molding height of 75 mm (that is, 94% of the total stroke) in Invention Example 1 and Comparative Example 1 is as follows.

The plate cross-sectional area is a plate thickness of 1 mm and a plate width of 100 mm, and in the case of bending a hat-shaped cross section, there are workpieces on two sides of the mold,
Plate cross-sectional area = 2 places × plate thickness 1 mm × plate width 100 mm = 200 mm ²
It is. Therefore, as a value corresponding to “a value obtained by converting the wrinkle pressing force into tension” described in Patent Document 1, the wrinkle pressing load 50 × 10 ³ N is divided by the plate cross-sectional area 200 mm ² and 250 [N / mm ² = MPa]. This is “98%” of the tensile strength TS of the workpiece (corresponding to “tensile strength TS” of the present application, 256 MPa).

Further, the wrinkle holding load 350 kN after the molding height 75 mm (that is, 94% of the total stroke) in Invention Example 1 and Comparative Example 1 is described in “Wrinkle” described in Patent Document 1 according to the method described above. When the pressing force is converted to a value converted to tension, the pressure is 1750 MPa. This is “684%” of the tensile strength TS (256 MPa) of the workpiece.

(3) Relation to the condition that Patent Document 1 says is preferable By the way, with respect to the “wrinkle holding force” at the start of molding, Patent Document 1 states that 5% or more is preferable. ([Claim 1] and [0016])

The wrinkle holding load at the start of forming in Invention Example 1 and Comparative Example 1 is “98%” of the tensile strength (TS) of the metal thin plate as calculated above, which is satisfied.

  On the other hand, with respect to the “wrinkle pressing force” at the end of molding, Patent Document 1 states that 50% or more is preferable. ([Claim 4] (... the wrinkle holding force after the increase is 50% or more of the tensile strength (TS) in terms of tension) and [0058].)

The wrinkle holding load at the end of forming in Invention Example 1 and Comparative Example 1 is “684%” of the tensile strength (TS) of the metal thin plate as calculated above, which is satisfied.

  As for the “punch speed”, Patent Document 1 describes that 500 mm / sec or less is preferable at the start of molding, and it is preferable to lower to 0.5 to 50 mm / sec in the middle of the stroke. Claim 4).

The processing speed at the start of molding in Invention Example 1 and Comparative Example 1 is about 110 mm / s as can be seen from the speed control pattern of FIG.
Further, in the invention example 1 and the comparative example 1, since the molding is performed while the speed is constantly reduced, it is not a method of reducing the speed to a certain value as in Patent Document 1, but the speed control pattern of FIG. As can be seen, after the molding height of 66 mm (that is, 83% of the entire stroke), the machining speed is 50 mm / s or less.

  In other words, the processing speeds of Invention Example 1 and Comparative Example 1 satisfy the condition of “punch speed” that is preferable in Patent Document 1.

  That is, both Example 1 and Comparative Example 1 processed under exactly the same conditions except that the lubricant is different are the wrinkle pressing load ("wrinkle pressing force" in Patent Document 1) and the processing speed (Patent Document 1). The condition that Patent Document 1 states is preferable for both of the “punch speed”.

Nevertheless, one (Invention Example 1) has good shape freezing properties, while the other (Comparative Example 1) has a poor shape. The fact that the shape freezing property is inferior in Comparative Example 1 (that is, the width opening ratio is large) is actually P / f at the end of molding (that is, the punch load P is f (the cross-sectional area A0 of the workpiece at the punch shoulder). This is because the value divided by the product of the tensile strength TS of the workpiece is 40%, which is out of the range of the present invention (77% to 90%).
That is, even if it is within the range preferred by Patent Document 1, those that fall outside the scope of the present invention have a poor shape freezing property.

  As described above ([]), Patent Document 1 states that the lower limit of “wrinkle holding force” at the end of molding is preferably 50%.

Regarding the upper limit, although Patent Document 1 does not particularly define in the claims, in [0024] to [0028] of “Detailed Description of the Invention”, “... ... increase the wrinkle holding force ... increase the wrinkle holding force when the punch shoulder comes into contact with the metal sheet, ... adjust wrinkle holding force and speed in the press forming described in (4) above An example is shown in Fig. 4. This shows how much the wrinkle holding force of the invention according to the above (1) is raised and how much the punch speed is lowered to obtain the best effect. F1 is a value converted into a tension by dividing by the cross-sectional area of the plate, and a sufficient effect can be obtained if it is 50% or more of the tensile strength (TS) of the thin metal plate. 120% or less of the tensile strength (TS) It described and it is preferable to. ", And that it is preferable that the upper limit is" 120% ".

However, as is clear from the results of Example 1 of the present invention (the wrinkle holding load is “684%” of TS), the value is much larger than the upper limit value (“120%” of TS) recommended by Patent Document 1. Even within the range of the wrinkle holding load, it is possible to ensure a sufficiently good shape freezing property in hat-type bending. In Example 1 of the present invention, the shape freezing property is good (that is, the width opening ratio is small). The P / f at the end of molding is 84%, within the range of the present invention (77% to 90%). It is because it controlled so that it might become.
That is, even if it is in the range which patent document 1 makes unpreferable, if it is in the range of this invention, it is possible to obtain favorable shape freezing property.

  The above explanation can be summarized as follows. Even if the wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the processing speed (“punch speed” in Patent Document 1) are within the recommended range of Patent Document 1, the punch load is in accordance with the present invention. Those outside the range have poor shape freezing properties, and conversely, even if they are outside the recommended range of Patent Document 1, it is good if the punch load is within the range of the present invention. It is possible to obtain a shape freezing property.

That is, in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, in order to reduce the spring back and realize a good shape freezing property, the “punch load” of the present invention It can be said that the use of the determination criterion is more accurate and appropriate than the determination criterion (wrinkle pressing force, punch speed) proposed by Patent Document 1.

■ Invention Example 2
Under substantially the same conditions as in Comparative Example 1 (press machine, hat-shaped cross-sectional shape, aluminum alloy plate (6000 series aluminum alloy) used as a workpiece, shape of a molded test piece, wrinkle holding load control pattern in FIG. 4, etc.). The hat-shaped cross-section bending test was conducted. As for the lubricant, Preton RS-962 was used as in Comparative Example 1.

However, with respect to the speed control pattern, after the molding height of 74 mm (that is, 93% of the entire stroke) so that the punch load at the end of molding can be controlled within the range of 77% to 90% of f. Was rapidly decelerated so that the speed was 5 mm / s or less. FIG. 9 shows a speed control pattern in Example 2 of the present invention.

  FIG. 10 shows a value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) in percentage display. P / f up to a molding height of 75 mm (that is, 94% of the total stroke) is 30% or less, and P / f at the end of molding is 83%.

The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 23% or less of f. That is, A described in claim 1 is “23” in this case.
In addition, the punch load P is increased to 83% of f from the time when the position exceeds 90% of the total stroke to the time when the molding ends (including the molding end time). That is, B described in claim 1 is “83” in this case, and therefore satisfies the condition of 77 ≦ B ≦ 90.
Further, (B / A) = 3.6.

Table 4 shows the shape freezing property in Example 2 of the present invention. The meaning of (W−W0) / W0 is the same as that in the first embodiment.

FIG. 11 shows the appearance of the molded panel.
In the hat-type bending molding of Example 2 of the present invention, the width opening ratio was reduced, the shape freezing property was good, and no offset occurred.

■ Relationship between Invention Example 2 and Comparative Example 1 As described in Example 1, the invention Example 1 had good shape freezing property despite being processed under the same processing conditions. Moreover, the reason why it was inferior in Comparative Example 1 was that the lubricants were different.

  On the other hand, in Example 2 of the present invention, the shape freezing property could be improved in spite of using the same lubricant as in Comparative Example 1. This is not limited to the viewpoint of “wrinkle holding load” (“wrinkle holding force” in Patent Document 1) and “processing speed” (“punch speed” in Patent Document 1). This is because attention has been paid to the viewpoint of “punch load” and, from that viewpoint, the “wrinkle holding load” and “machining speed” are changed to be controlled.

That is, in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, in order to reduce the spring back and realize a good shape freezing property, the “punch load” of the present invention It can be said that the use of the determination criterion is more accurate and appropriate than the determination criterion (wrinkle pressing force, punch speed) proposed by Patent Document 1.

■ Invention Example 3
Except that the aluminum alloy sheet used as a workpiece is a 5000 series aluminum alloy sheet shown in Table 5, the same conditions as in Example 1 of the present invention (press machine, hat-shaped cross-sectional shape, molded specimen shape, lubricant preton R- 303P, the wrinkle pressing load control pattern of FIG. 4, the speed control pattern of FIG.

A value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) is shown in FIG.
The P / f up to a molding height of 75 mm (ie 94% of the total stroke) is 30% or less, and after the molding height of 75 mm, the wrinkle holding load is controlled to 350 kN, so that the P / f at the end of molding is 77%.

The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 20% or less of f. That is, A described in claim 1 is “20” in this case.
In addition, the punch load P is increased to 77% of f from the time when it exceeds 90% of the total stroke to the time when the molding ends (including the molding end time). That is, B described in claim 1 is “77” in this case, and therefore satisfies the condition of 77 ≦ B ≦ 90.
Further, (B / A) = 3.9.

The results of this molding test will be described in detail later in comparison with the case of Comparative Example 2 described below, but showed a good shape freezing property.

■ Comparative Example 2
In place of Preton R-303P used in Invention Example 3, the same conditions as in Invention Example 3 except that rust preventive oil Preton RS-962 manufactured by Sugimura Chemical Industry Co., Ltd. was used as a lubricant ( (Press machine, hat-shaped cross-sectional shape, aluminum alloy sheet (5000 series aluminum alloy) used as a workpiece, shape of molded specimen, wrinkle holding load control pattern in FIG. 4, speed control pattern in FIG. 5, etc.). I did it.

A value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) is shown in percentage in FIG.
Despite being controlled with the same wrinkle holding load control pattern and the same speed control pattern as Example 3, the P / f at the end of molding was 33% because the lubricant used was different. Note that the P / f up to a molding height of 75 mm (that is, 94% of the entire stroke) is 30% or less.

The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 10% or less of f. That is, A described in claim 1 is “10” in this case.
In addition, the punch load P is increased to 33% of f during the period from when the 90% position of the full stroke is reached to when the molding end time is reached (including the molding end time). That is, since B described in claim 1 is “33” in this case, the condition of 77 ≦ B ≦ 90 is not satisfied.
Note that (B / A) = 3.3.

The results of this molding test are described in detail below, but the springback was large.

(3) Comparison of shape freezing properties of Invention Example 3 and Comparative Example 2 Table 6 shows a comparison of shape freezing properties of Invention Example 3 and Comparative Example 2. The meaning of (W−W0) / W0 is the same as that in the first embodiment.

FIG. 14 shows the appearance of the molded panel.
In the hat-type bending molding of Invention Example 3, the width opening ratio was small and the shape freezing property was good, whereas in Comparative Example 2, the width opening ratio was large. In addition, in the inventive example 3 and the comparative example 2, no offset occurred.

  Thus, in the press forming method of an aluminum alloy sheet material that is bent into a hat-shaped cross-section while applying a wrinkle pressing load, the same wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the same processing are performed. Despite processing under the condition of speed (“punch speed” in Patent Document 1), the shape freezing property may be good or poor.

Despite processing under the same processing conditions, the shape freezing property was good in Example 3 of the present invention, but it was poor in Comparative Example 2 because the lubricant was different. Based.
It can be said that it was confirmed that the phenomenon confirmed for the 6000 series aluminum alloy sheet in Example 1 also occurred in the present 5000 series aluminum alloy sheet.

(2) Conversion of Wrinkle Pressing Load into Description Style of Patent Document 1 Here, the wrinkle pressing load of Invention Example 3 and Comparative Example 2 is converted to the description style related to “wrinkle holding force” of Patent Document 1.

  Since the wrinkle pressing load control pattern of Example 3 of the present invention is exactly the same as that of Example 1 of the present invention, the description in Example 1 of the present invention is applied almost as it is. However, since the aluminum alloy plate used as the workpiece is changed from the 6000 series aluminum alloy to the 5000 series aluminum alloy, the tensile strength TS of the workpiece (corresponding to the “tensile strength TS” in the present application) is changed from 256 MPa to 272 MPa. Yes.

  That is, for the wrinkle pressing load 50 kN (constant) up to a molding height of 75 mm (that is, 94% of the total stroke) in Invention Example 3 and Comparative Example 2, the “wrinkle pressing force is tensioned” described in Patent Document 1. The value corresponding to “converted value” is 250 MPa. This is “92%” of the tensile strength TS of the workpiece (corresponding to the “tensile strength TS” in the present application) 272 MPa.

For the wrinkle pressing load 350 kN after the molding height of 75 mm (that is, 94% of the total stroke) in Invention Example 3 and Comparative Example 2, “value obtained by converting the wrinkle pressing force into tension” described in Patent Document 1. The value corresponding to “is 1750 MPa. This is “643%” of the tensile strength TS of the workpiece (corresponding to “tensile strength TS” in the present application) 272 MPa.

(3) Relation to the condition that Patent Document 1 is preferable According to Patent Document 1, the “wrinkle holding force” at the start of molding is preferably 5% or more as described above.

The wrinkle pressing load at the start of forming in Invention Example 3 and Comparative Example 2 is “92%” of the tensile strength (TS) of the metal thin plate as calculated above, and thus satisfies this.

On the other hand, regarding the “wrinkle pressing force” at the end of molding, Patent Document 1 states that 50% or more is preferable as described above.
The wrinkle pressing load at the end of forming in Invention Example 3 and Comparative Example 2 is “643%” of the tensile strength (TS) of the metal thin plate as calculated above, which is satisfied.

Regarding the “punch speed”, Patent Document 1 describes that, as described above, 500 mm / sec or less is preferable at the start of molding, and it is preferable to lower to 0.5 to 50 mm / sec in the middle of the stroke ( Claims 1 and 4).
The processing speed at the start of molding in Invention Example 3 and Comparative Example 2 is about 110 mm / s as can be seen from the speed control pattern of FIG.

Further, in the present invention example 3 and the comparative example 2, since the molding is performed while the speed is constantly reduced, it is not a method of lowering to a certain value as in Patent Document 1, but the speed control pattern of FIG. As can be seen, after the molding height of 66 mm (that is, 83% of the entire stroke), the machining speed is 50 mm / s or less.

  In other words, the processing speeds of Invention Example 3 and Comparative Example 2 satisfy the condition of “punch speed” that is preferable in Patent Document 1.

  That is, both Example 3 and Comparative Example 2 processed under exactly the same conditions except that the lubricant is different are the wrinkle pressing load ("wrinkle pressing force" in Patent Document 1) and the processing speed (Patent Document 1). The condition that Patent Document 1 states is preferable for both of the “punch speed”.

Nevertheless, one (Invention Example 3) is good in shape freezing property, while the other (Comparative Example 2) is inferior. The fact that the shape freezing property is inferior in Comparative Example 2 (that is, the width opening ratio is large) is actually P / f at the end of molding (that is, the punch load P is f (the cross-sectional area A0 of the workpiece at the punch shoulder). This is because the value divided by the product of the tensile strength TS of the workpiece is 33%, which is out of the range of the present invention (77% to 90%).
That is, even if it is within the range that is preferable in Patent Document 1, those that deviate from the present invention have poor shape freezing properties.

  As described above, in Patent Document 1, although the upper limit of “wrinkle holding force” at the end of molding is not particularly defined in the claims, it is described as “120%” in “Detailed Description of the Invention”. "Is preferable.

However, as is clear from the results of Example 3 of the present invention (the wrinkle pressing load is “643%” of TS), the value is much larger than the upper limit value (“120%” of TS) recommended by Patent Document 1. Even within the range of the wrinkle holding load, it is possible to ensure a sufficiently good shape freezing property in hat-type bending. In Example 1 of the present invention, the shape freezing property is good (that is, the width opening ratio is small). The P / f at the end of molding is 77%, within the range of the present invention (77% to 90%). It is because it controlled so that it might become.
That is, even if it is in the range which patent document 1 makes unpreferable, if it is in the range of this invention, it is possible to obtain favorable shape freezing property.

  Thus, the situation confirmed in Example 1 (Invention Example 1 and Comparative Example 1) is also the same in Example 3 (Invention Example 3 and Comparative Example 2) in which the target aluminum alloy sheet was changed. It was confirmed that.

  That is, even if the wrinkle pressing load (“wrinkle pressing force” in Patent Document 1) and the processing speed (“punch speed” in Patent Document 1) are within the recommended range of Patent Document 1, the punch load is What deviates from the scope of the invention results in poor shape freezing, and conversely, even if they are outside the recommended range of Patent Document 1, if the punch load is within the scope of the present invention. It is possible to obtain a good shape freezing property.

That is, in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, in order to reduce the spring back and realize a good shape freezing property, the “punch load” of the present invention It can be said that the use of the determination criterion is more accurate and appropriate than the determination criterion (wrinkle pressing force, punch speed) proposed by Patent Document 1.

■ Invention Example 4
Under substantially the same conditions as in Comparative Example 2 (press machine, hat-shaped cross-sectional shape, aluminum alloy plate material (5000 series aluminum alloy) used as a workpiece, shape of molded specimen, wrinkle holding load control pattern in FIG. 4 and the like). The hat-shaped cross-section bending test was conducted. As the lubricant, Preton RS-962 was used as in Comparative Example 2.

However, with respect to the speed control pattern, after the molding height of 74 mm (that is, 93% of the entire stroke) so that the punch load at the end of molding can be controlled within the range of 77% to 90% of f. Was rapidly decelerated so that the speed was 5 mm / s or less. FIG. 9 shows a speed control pattern in Example 4 of the present invention.

  FIG. 15 shows a value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder and the tensile strength TS of the workpiece) in percentage display. P / f up to a molding height of 75 mm (that is, 94% of the total stroke) is 30% or less, and P / f at the end of molding is 78%.

The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 20% or less of f. That is, A described in claim 1 is “20” in this case.
In addition, the punch load P is increased to 78% of f during the period from when the 90% position of the full stroke is reached to when the molding end time is reached (including the molding end time). That is, B described in claim 1 is “78” in this case, and therefore satisfies the condition of 77 ≦ B ≦ 90.
Further, (B / A) = 3.9.

Table 7 shows the shape freezing property in Example 4 of the present invention. The meaning of (W−W0) / W0 is the same as that in the first embodiment.

FIG. 16 shows the appearance of the molded panel.
In the hat-type bending of Example 4 of the present invention, the width opening ratio was reduced, the shape freezing property was good, and no offset occurred.

■ Relationship between Invention Example 4 and Comparative Example 2 As described in Example 3, the invention Example 3 had good shape freezing property despite being processed under the same processing conditions. Moreover, the reason why the comparative example 2 was inferior was based on the fact that the lubricant was different.

  On the other hand, in Example 4 of the present invention, the shape freezing property could be improved in spite of using the same lubricant as in Comparative Example 2. This is not limited to the viewpoint of “wrinkle holding load” (“wrinkle holding force” in Patent Document 1) and “processing speed” (“punch speed” in Patent Document 1). This is because attention has been paid to the viewpoint of “punch load” and, from that viewpoint, the “wrinkle holding load” and “machining speed” are changed to be controlled.

That is, in the press forming of an aluminum alloy sheet material that is bent into a hat-shaped cross-sectional shape while applying a wrinkle holding load, in order to reduce the spring back and realize a good shape freezing property, the “punch load” of the present invention It can be said that the use of the determination criterion is more accurate and appropriate than the determination criterion (wrinkle pressing force, punch speed) proposed by Patent Document 1.

■ Comparative Examples 3-5
Except that the wrinkle holding load control pattern was changed, the same conditions as in Example 1 of the present invention (press machine, hat-shaped cross-sectional shape, aluminum alloy sheet (6000 series aluminum alloy) used as a workpiece, and shape of a molded specimen , Lubricant Preton R-303P, the speed control pattern of FIG.

  As shown in FIG. 17, the wrinkle holding load was fixed at 50 kN (Comparative Example 3), 100 kN (Comparative Example 4), and 150 kN (Comparative Example 5).

A value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder portion and the tensile strength TS of the workpiece) is shown in percentage in FIG.
<Comparative Example 3>
The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 21% or less of f. That is, A described in claim 1 is “21” in this case.
In addition, the punch load P is increased to 28% of f from the time when the position exceeds 90% of the total stroke to the time when the molding ends (including the molding end time). That is, since B described in claim 1 is “28” in this case, it does not satisfy the condition of 77 ≦ B ≦ 90.
Note that (B / A) = 1.3.
<Comparative Example 4>
From FIG. 18, when examined in the same manner as in Comparative Example 3, A = 42, B = 53 (that is, the condition of 77 ≦ B ≦ 90 is not satisfied), and (B / A) = 1.3. is there.
<Comparative Example 5>
From FIG. 18, when examined in the same manner as in Comparative Example 3, A = 59, B = 73 (that is, the condition of 77 ≦ B ≦ 90 is not satisfied), and (B / A) = 1.2. is there.

In Comparative Example 3, P / f was 30% or less including the end of molding.
In Comparative Example 4, P / f exceeded 30% at a molding height of about 25 mm (that is, 31% of the total stroke).
In Comparative Example 5, P / f exceeded 30% at a molding height of about 15 mm (that is, 18% of the total stroke).

Table 8 shows the shape freezing property. The meaning of (W−W0) / W0 is the same as that in the first embodiment.

FIG. 20 shows the appearance of the molded panel.
In all of Comparative Examples 3 to 5, the reduction of the width opening ratio was insufficient, and in Comparative Example 5, offset was also generated.

■ Comparative Examples 6-8
Except that the wrinkle holding load control pattern was changed, exactly the same conditions as in Example 3 of the present invention (press machine, hat-shaped cross-sectional shape, aluminum alloy sheet (5000 series aluminum alloy) used as a workpiece, molded specimen) The shape, the lubricant Preton R-303P, the speed control pattern in FIG.

  As shown in FIG. 17, the wrinkle pressing load was fixed at 50 kN (Comparative Example 6), 100 kN (Comparative Example 7), and 150 kN (Comparative Example 8).

A value P / f obtained by dividing the punch load P during molding by f (product of the cross-sectional area A0 of the workpiece at the punch shoulder portion and the tensile strength TS of the workpiece) is shown in percentage in FIG.
<Comparative Example 6>
The punch load P from the start of molding to the 90% position of the full stroke (that is, the molding height of 72 mm) is 20% or less of f. That is, A described in claim 1 is “20” in this case.
In addition, the punch load P is increased to 28% of f from the time when the position exceeds 90% of the total stroke to the time when the molding ends (including the molding end time). That is, since B described in claim 1 is “28” in this case, it does not satisfy the condition of 77 ≦ B ≦ 90.
Note that (B / A) = 1.4.
<Comparative Example 7>
From the examination in the same manner as in Comparative Example 6 from FIG. 19, A = 40, B = 55 (that is, the condition of 77 ≦ B ≦ 90 is not satisfied), and (B / A) = 1.4. is there.
<Comparative Example 8>
When examined in the same manner as in Comparative Example 6 from FIG. 19, A = 57, B = 75 (that is, the condition of 77 ≦ B ≦ 90 is not satisfied), and (B / A) = 1.3. is there.

In Comparative Example 6, P / f was 30% or less.
In Comparative Example 7, P / f exceeded 30% at a molding height of about 50 mm (that is, 63% of the total stroke).
In Comparative Example 8, P / f exceeded 30% at a molding height of about 18 mm (that is, 23% of the total stroke).

Table 9 shows the shape freezing property. The meaning of (W−W0) / W0 is the same as that in the first embodiment.

FIG. 21 shows the appearance of the molded panel.
In all of Comparative Examples 6 to 8, the reduction of the width opening ratio was insufficient, and in Comparative Example 8, offset was also generated.

As described above, in Comparative Examples 3 to 5 and Comparative Examples 6 to 8 in which the wrinkle holding load was kept constant over the entire stroke, the shape freezing property was not good.
This is because, when the wrinkle holding load is kept constant over the entire stroke, “from the time when the 90% position of the entire stroke is exceeded until the end of molding (including the end of molding). This is because it was impossible to satisfy the condition (Claim 1) that the punch load P is controlled to increase to B% of f (provided that 77 ≦ B ≦ 90).

Moreover, although the offset occurred in Comparative Example 5 and Comparative Example 8, in these experimental examples, from a very early stage of the stroke (Comparative Example 5: 18% of the total stroke, Comparative Example 8: 23% of the total stroke). The punch load exceeded 30% of f.

1 ... work, 2 ... punch, 3 ... die, 4 ... blank holder, 5 ... slide, 6 ... plunger,
7 ... link mechanism, 8 ... carrier, 9 ... ball nut, 11 ... ball screw, 12 ... driven pulley,
13 ... Timing belt, 14 ... Drive pulley, 15 ... Servo motor, 16 ... Control part,
17 ... Memory part, 18 ... Bolster, 19 ... Cushion pin, 20 ... Cushion pad, 21 ... Hydraulic room,
22 ... Pressure sensor, 23 ... Ball nut, 24 ... Ball screw, 25 ... Large pulley,
26 ... pulse coder, 27 ... timing belt, 28 ... small pulley, 29 ... servo motor,
30 ... Control unit, 31 ... Storage unit, 32 ... Linear scale

Claims (7)

In the press forming method of an aluminum alloy sheet material that is bent into a hat-shaped cross-section while applying a wrinkle holding load, when the product of the cross-sectional area A0 of the wall and the tensile strength TS of the work is f The punch load P is controlled to not more than A% of f (A ≦ 45) from the start of molding until reaching the 90% position of the full stroke, and from the time when the 90% position of the full stroke is exceeded. The punch load P is increased to B% of f (77 ≦ B ≦ 90 and (B / A) ≧ 2) until reaching the molding end time (including the molding end time). all SANYO to control,
The punch load P is controlled to A% or less of f (A ≦ 30) from the start of molding until reaching the 90% position of the full stroke, and from the time when the 90% position of the full stroke is exceeded. Control is performed so that the punch load P is increased to B% of f (77 ≦ B ≦ 90 and (B / A) ≧ 3) until the end point is reached (including the end point of molding). Is what
A press forming method for an aluminum alloy sheet material, characterized in that the means for controlling the punch load to a predetermined value is adjustment control of the wrinkle holding load and the processing speed . Aluminum alloy sheet of claim 1, the punch load was measured by a punch load measuring means, it and adjusting controlling blank holding load and processing speed on the basis of the punch load was measured to a predetermined value Press molding method. 3. The press forming method for an aluminum alloy sheet according to claim 2 , wherein the punch load measuring means is installed in the punch. Press forming method for an aluminum alloy sheet according to any one of claims 1 to claim 3 adjustment control processing speed is characterized in that operation realized by the servo drive. Press forming method for an aluminum alloy sheet according to any one of claims 1 to claim 4 adjustment control blank holding load is characterized in that operation realized by the servo drive. The aluminum alloy sheet material press according to any one of claims 1 to 5 , wherein rust preventive oil or press oil or both are used as a lubricant between the mold and the aluminum alloy sheet material. Molding method. The aluminum alloy sheet material according to any one of claims 1 to 6 , wherein the aluminum alloy sheet material used for the workpiece is a 5000 series aluminum alloy or a 6000 series aluminum alloy.