JPH0472010A - High strength pressing formed product - Google Patents

Abstract

PURPOSE:To manufacture a pressing formed product having a light wt. and high accuracy in spite of high strength by radiating high energy source at least to position needing the high strength in the untreating pressing formed product and forming plural bead-state quenching hardened parts being apart at the prescribed intervals. CONSTITUTION:For example, at the time of manufacturing a front side member, at first, the untreated press formed product 1 obtd. with the ordinary forming method by using a steel plate of SGAC 45-45/45 having about 1.4mm thickness, is prepared. On high stress part decided with vehicle collision test result and FEM analysis, etc., in this untreated press formed product 1, CO2 laser beam is radiated to form the bead-state quenching hardened parts 2. Then, the irradia tion condition of laser beam is about 2Kw output, about 5m/min velocity, about -1mm focus point, about 8mm nozzle height and about 20l/min gas flow rate as the quenching condition. By this method, the front side member having the quenching hardened part 2 is obtd., and the quenching hardened part 2 having bainitic structure and martensitic structure of steel plate structure is obtd. with the laser beam irradiation and is hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-strength press-formed product, and more particularly to a high-strength press-formed product suitable for use in automobile tenon panels and the like.

[Prior Art] Conventional high-strength press-formed products, such as automotive podium panels, are known to be made of high-strength steel plates or thick steel plates.

[Problem to be Solved by the Invention 1] However, the above-mentioned conventional high-strength press-molded products have been met with various practical limitations.

That is, a high-strength press-formed product made of a high-strength steel plate had extremely poor press formability during manufacture because the elongation rate of the steel plate decreased in inverse proportion to the increase in strength of the steel plate. In addition, this high-strength press-formed product has a large springback and high dimensional accuracy because the steel plate itself is high strength.
Hard to get qused.

For this reason, high-strength press-formed products with good formability and high precision can be produced by forming high-strength steel sheets using high-energy speed processing methods such as explosion forming, electrical discharge forming, electromagnetic forming, and impact hydraulic forming. However, these molding methods inevitably lead to high costs due to decreased productivity.

In addition, high-strength press-formed products made of thick steel plates,
As the thickness of the plate increases, the weight increases, which goes against the desire to reduce the weight of automobile podiums, for example.
After all, it is necessary to increase the size of the press machine, resulting in a decrease in productivity.

In order to solve such problems such as decreased productivity, increased costs, and increased weight, it may be possible to quench the entire untreated press-formed product after forming. Warpage, twisting, etc. are likely to occur, making it difficult to obtain high dimensional accuracy.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a high-strength press-formed product that can be obtained with good productivity, is lightweight, and has high precision.

[Means for Solving the Problems 1] The high-strength press-formed product of the present invention is formed by irradiating a high-density energy source at least to a portion of an untreated press-formed product that is spaced at predetermined intervals. It is characterized by having a plurality of bead-shaped hardened parts.

This high-strength press-formed product can be obtained by forming a quench-hardened part on an untreated press-formed product.

The untreated press-formed product can be obtained by using a material such as a steel plate or a non-ferrous metal plate and pressing this material with a press machine in a conventional manner.

In the case where this untreated press-formed product requires at least strength, for example, if it is a high-strength press-formed product or is used in an automobile, high stress is analyzed by vehicle collision tests, FEM (finite element method), etc. Department.

The quench-hardened portion is formed into a bead shape by irradiating at least a portion of the untreated press-formed product where strength is required with a high-density energy source. A laser, plasma, etc. can be used as the high-density energy source. The quench-hardened parts are a plurality of parts spaced apart at predetermined intervals in a sushi-like or lattice-like shape. The distance between each quench-hardened portion can be determined depending on the material, desired strength, etc.

[Operation] When the material is irradiated with a high-density energy source, a beet-shaped hardened part is formed. Although this quench-hardened part varies depending on the material of the material, it can be expected that both hardness and tensile strength will increase by 50% or more compared to the material. Therefore, if a quench-hardened part is formed by irradiating an untreated press-formed product with a high-density energy source, it is possible to produce a high-strength press-formed product without increasing the strength of the material or increasing the plate thickness. is obtained. In addition, since multiple quench-hardened parts are formed at predetermined intervals in the areas where strength is required in the untreated press-formed product, compared to the case where the entire part is quenched, the high-strength press-formed product or the thermal distortion In addition to being resistant to damage, it also has toughness by absorbing displacement between adjacent quench-hardened parts while maintaining strength due to the quench-hardened parts.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings. In this example, a front side member of an automobile body panel is applied as a high-strength press-molded product.

This front side member, as shown in Figure 1,
The untreated press-formed product 1 has bead-like quench hardened portions 2 formed in a sushi shape and a lattice shape.

This front site member was obtained as follows. First, an untreated press-formed product 1 was prepared by using a steel plate made of 5GAC45-45/45 and having a thickness of 1.4T'rL7/m by a normal molding method. Then, a CO2 laser was irradiated onto high-stress areas determined by vehicle collision test results, FEM analysis, etc. in this untreated press-formed product 1, to form beet-shaped quenched hardened areas 2.

Laser irradiation conditions are: output 2kW, speed 5m/'min
, focal point -11nIn, nozzle height 8m, gas flow rate 2CH2/min, and quenched state. In this way, a front side member having a hardened portion 2 was obtained.

In this front sight member, the quench hardened part 2 is
The steel plate structure became a bainitic structure and a martensitic structure by laser irradiation and was hardened. The quench-hardened parts 2 are formed in a sushi-like and lattice-like shape with respect to the soft steel plate portion of the untreated press-formed product 1 between adjacent quench-hardened parts 2. Compared to press-formed product 1, it had improved strength and toughness. Additionally, this front side member was less susceptible to thermal distortion and had higher precision compared to a case where the entire front side member is hardened.

[Test] Next, test 1 was conducted to confirm one effect of the present invention.
2.3 will be explained with reference to the drawings.

(Test 1) A JIS No. 5 tensile test was conducted using JIS No. 5 test piece 11 shown in Figure 2 as an untreated press-formed product, and the strain (ε
The relationship between (%>) and stress (σ(K3/#2)) was investigated.

As implementation survey 1, JIS No. 5 test piece (SGAC45-
4,5/45) A specimen No. 11 was used in which three quench hardened portions 21 were formed in the length direction under the same conditions as in the previous example.

As comparative survey 1, JIS5 which does not form a quench hardened part
No. 1 test piece was used.

The results are shown in Figure 3. From this figure, it can be seen that the stress in the actual survey 1 was improved by about 25% compared to the comparative survey 1.

From this test 1 it can be seen that the actual survey 1 is hardened compared to the comparative survey 1.

(Test 2) Using the hat-shaped panel 3 shown in FIG. 4 as an untreated press-formed product, the relationship between the number of quench-hardened parts and buckling strength and bending strength was tested for two types of materials.

The hat-shaped panel 3 consists of a horn-shaped upper plate 31 and a lower plate 32 fixed to the bottom surface of the upper plate 31.

The material of this hat-shaped panel 3 is 5HP28 (carbon (C) nominal value = 0.049%) SH
P45 (carbon (C) nominal value -0,167%).

Moreover, the dimensions of this hat-shaped panel 3 are as follows: thickness i>-1
, 4m Height h) = 78 Layer width wl > -80 Regular length ρ) = 300m Bottom width W2>=120M.

The quench-hardened parts were formed in the length direction (three pieces each on the top surface and both sides of each hat-shaped panel 3 (total of nine pieces)), and the number of quench-hardened parts formed on the top surface in the horizontal direction was changed as follows.

Δ pattern: 0 lines B pattern: 3 lines C pattern: 21 lines Further, each hardened portion was formed using a CO2 laser under the following conditions.

Output...3. Qkw Speed -3m/m+n Focus point...-1m Nozzle height...8# Waste flow rate...20j/mln Molten state, medium density, and hat shape with A to C patterns made of the above two types of materials As shown in FIG. 4, two panels 3 each were loaded from the Pl direction in the buckling test and from the P2 direction in the bending test using a gold material 5QtOn universal testing machine.

The buckling strength is determined by the maximum load (Pmax (ton)) and the energy absorption amount (Ea (xl to 00!j-rrt>
) was evaluated. The results are shown in FIGS. 5 and 6. From FIG. 5, it can be seen that the maximum load for both 5HP28.5HP45 tends to increase slightly depending on the number of quench-hardened parts.

Moreover, from FIG. 6, it can be seen that the energy absorption amount increases by about 16% in 5HP28 and by about 13% in 5HP45.

Further, the bending strength was evaluated using the maximum load (Pmax (ton)). The results are shown in FIG. From Figure 7, 5HP28
．． The maximum load for either 5HP45 is approximately 20% compared to the case where there are no quenched parts in the lateral direction (pattern A).
It can be seen that the maximum load tends to increase depending on the number of quenched and hardened parts.

From this test 2, even if the high-strength press-formed product of the present invention is manufactured using conventional materials and plate thickness, the required strength is 10 to 20%.
It can be seen that a weight reduction of 10 to 20% can be expected.

(Test 3) JIS5185 shown in Figure 8 as an untreated press-formed product
Using the No. 1 test, the relationship between the pattern of the quench hardened portion 5, hardness, tensile strength, maximum load, and total elongation was tested for two types of materials.

JIS5185 test material is 5GAC45-45/45 (carbon (C) nominal value = 0.
05%) SGACE-45/45 (carbon (C) nominal value -0,0
3%).

Moreover, the JIS5185 test board thickness is 1.6 m.

As shown in FIG. 8, the quench hardened portion 5 was formed in a DH pattern on the upper surface of each JIS No. 5 test piece 4 symmetrically with the center line (CL). In addition, JIS that does not form a quench hardened part
A No. 5 test piece (Noma I) was also prepared. In addition, the interval Δ of the quench hardened parts 5 in the E pattern is 13INn,
The interval Δ of the hardened parts 5 in the F pattern is 6.5#
, the interval Δ1 between the hardened parts 5 in the longitudinal direction in the G pattern is 6°51+11, the interval Δ2 between the hardened parts 5 in the lateral direction is 20IrIIn, and the interval Δ3 between the hardened parts 5 in the lateral direction in the H pattern is 6.5#, same horizontal 45°
The interval Δ4 between the hardened parts 5 in the (θ) direction is 9 mm.

Further, each quench hardened portion 5 was formed using a CO2 laser under the following conditions. Other conditions were the same as Test 2.

Output...2.5kw Nozzle height...6IrI! 11 Then, D to H batons and N made of the above two types of materials
A test was conducted using a tensile test using two Oma+ pattern JIS No. 5185 tests.

Distance from the center line (CL) of each JIS No. 5 test piece 4 (
Figure 9 shows the relationship between the hardness (mHV) at 0.2 mm from the surface and the hardness at the center in the thickness direction (mHv). Figure 9 also shows a cross-sectional view of the JIS 5185 test.
In this cross-sectional view, the measurement position is indicated by an X mark. In addition, each quench hardened part pattern and tensile strength (TS (Ng/Mn2
) is shown in Figure 10, and the relationship between each quench hardened part pattern and the maximum load (Pmax (ton)) is shown in Figure 11.
The figure shows each quench hardened part pattern and total elongation (EL (%)
)) is shown in FIG.

Roughly, the metal structure of the quench hardened part 5 formed by JIS 5185 test consisting of 5GACE is 30 times, 100 times, 4
00x micrographs are shown in Figures 13, 14, and 15, and the metal structure of the quench hardened part 5 formed by JIS 5185 test consisting of 5GAC45 is 30x, 100x, and 4x.
16, 17, and 18 show micrographs at 00x magnification.

These evaluations show that the more quench-hardened parts 5 are formed, the better the hardness, tensile strength, maximum load, and total elongation are.

In addition, the hardness, tensile strength, maximum load, and total elongation are all 5G.
It can be seen that AC45 is extremely superior to 5GACE. This is because 5GAC45 has a metal structure close to a hardened state, while 5GACE has a carbon content of 5G.
This is because it is smaller than AC45, so it only becomes enlarged.

From this Test 3, it was found that the strength of the high-strength press-formed product of the present invention can be arbitrarily selected by appropriately selecting the number of irradiations, position, direction, etc. of a high-density energy source such as a laser, and the degree of freedom in product design is increased. I know it's expensive.

[Effect of the invention 1 As detailed above, the high-strength press-formed product of the present invention has
Since the press molding method can be a conventional method, productivity can be maintained and the product is lightweight.

Furthermore, since high-strength press-formed products are obtained by irradiation with a high-density energy source, the structure of the quench-hardened parts is stable and stable product strength can be obtained.

In general, this high-strength press-formed product is made by irradiating a high-energy source such as a laser onto only a portion of the untreated press-formed product in the form of a beat, making the high-strength press-formed product less susceptible to heat effects. Compared to the case of whole hardening, dimensional errors due to thermal distortion can be reduced, resulting in high precision.

Therefore, this high-strength press-formed product has high strength, light weight, and high precision, so when it is used, for example, in a car panel, it can make the car lighter and stronger, making it practical. It can also produce excellent effects.

In addition, this high-strength press-formed product can be produced by quenching in a short time, simple and continuous operation, and whether the untreated press-formed product is a single item or assembled with other parts, As long as it is possible to irradiate the necessary areas with a high-density energy source, it is possible to increase the strength of the uncured press-formed product, which can also be applied to line work processes.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a front side member according to an embodiment of the present invention. 2 and 3 relate to Test 1, FIG. 2 is a plan view of a JIS No. 5 test piece with a quench-hardened portion formed thereon, and FIG. 3 is a graph showing the relationship between strain and stress. Figures 4 to 7 relate to Test 2, Figure 4 is a perspective view showing the hat-shaped panel, Figure 5 is a graph showing the relationship between the quench hardened part pattern and the maximum load in the measurement of buckling strength, and Figure 6 Figure 7 is a graph showing the relationship between the quench-hardened part pattern and the amount of energy absorbed in measuring buckling strength, and Figure 7 is a graph showing the relationship between the quench-hardened part pattern and maximum load in measuring bending strength. . Figures 8 to 18 relate to Test 3, Figure 8 is a plan view of a JIS No. 5 test piece with a quench-hardened part formed, and Figure 9 is a cross-sectional view showing the relationship between the distance from the center line of the test piece and hardness. and graphs, Figure 10 is a graph showing the relationship between the quench-hardened part pattern and tensile strength, Figure 11 is a graph showing the relationship between the quench-hardened part pattern and maximum load, and Figure 12 is the quench-hardened part slam and total elongation. A graph showing the relationship between 5G and Figure 13 is
A 30x micrograph showing the metal structure targeting ACE, Figure 14 is 1 showing the metal structure targeting 5GACE.
00x micrograph, Figure 15 is a 400x micrograph showing the metal structure of 5GACE, and Figure 16 is 5GACE.
A 30x photomicrograph showing the metallographic structure of GAC45, Figure 17 is a 100x photomicrograph showing the metallographic structure of 5GAC4,5, and Fig. 18 is a 100x photomicrograph showing the metallographic structure of 5GAC45.
This is a 400x micrograph showing the metal structure of the target. 1... Untreated press-molded product 11.4... JJS No. 5 test piece (untreated press-molded product) 3... Hat-shaped panel (untreated press-molded product) 2.2
1.5... Quench hardened part patent applicant Toyota Motor Corporation agent
Patent Attorney Mizuo Okawa 1 Figure 3 Figure 4 Figure 5 Figure 12 ★ P pattern buckling strength Ea (xlOOkglm)

Claims (1)

[Claims] (1) It is characterized by having a plurality of bead-shaped quench hardened parts spaced apart at a predetermined interval, which are formed by irradiating a high-density energy source to at least a portion of the untreated press-formed product where strength is required. High strength press molded product.