WO2014068494A1

WO2014068494A1 - Die-quenching apparatus and method of an aluminum alloy material

Info

Publication number: WO2014068494A1
Application number: PCT/IB2013/059771
Authority: WO
Inventors: Kiyohito Kondo; Yuji Yamashita
Original assignee: Aisin Takaoka Co., Ltd.
Priority date: 2012-10-31
Filing date: 2013-10-30
Publication date: 2014-05-08
Also published as: WO2014068494A4; JP5808724B2; JP2014087837A

Abstract

A die-quenching apparatus and method of an aluminum alloy material contributing to improvement of a formability of the aluminum alloy material is desirable. The die-quenching apparatus comprises a forming die(s) cooling concurrently with forming a heated aluminum alloy material, a holder mechanism clamping the aluminum alloy material for setting the material in the forming die(s), and a heating mechanism heating a holder mechanism.

Description

DIE-QUENCHING APPARATUS AND METHOD OF AN ALUMINUM ALLOY MATERIAL

(Cross-Reference to Related Applications)
The present application claims priority based on JP Patent Application 2012-240525 filed in Japan on Oct. 31, 2012, whose entire disclosure is incorporated therein by reference. This invention relates to a die-quenching apparatus and method of an aluminum alloy material.

Background

For a fuel consumption improvement and environmental protection, lightweight automobile components are strongly desired. Therefore, substitution of steel materials with lightweight aluminum alloy materials is in progress.

Currently, the automobile components made of aluminum alloy materials are usually formed by a cold press method. Aluminum alloy materials have drawbacks of lower strength and lower formability due to their lower ductility compared to steel materials. Thus the aluminum alloy materials for automobile components are produced as follows.

(1) T4 materials are used as a blank, i.e., T4 materials obtained by solution heating H materials followed by natural aging are used as a blank;
(2) T4 materials are cold pressed with multiple steps, since it is difficult to form T4 materials which have been processed to provide high-strength;
(3) Cold pressed T4 materials are assembled and coat-baked.

The above multi-stepped cold pressing method has many steps for forming, thus causing deterioration of productivity and increase in cost. To solve such problems, forming methods in which the heated aluminum alloy materials are formed, are proposed.

Patent Literature 1 proposes a forming apparatus in which a heated aluminum alloy material is conveyed into cold dies and formed within less than 0.15 seconds after conveyance.

Patent Literature 2 proposes a forming apparatus in which an aluminum alloy material clamped by water-cooled cavity die(s) is die-quenched using a water-cooled core die.

Patent Literature 3 proposes a multi-stepped forming method of an aluminum alloy material having the steps of firstly hot pressing and secondly die-quenching.

JP Patent Kokai (TOKUHYO) JP2012-510565A (claim 1, WO2010/032002) JP Patent Kokai JP2011-63868 (Fig. 2, Paragraphs 0022 and 0023) WO2011-58332A1 (Fig. 1)

Summary

The disclosures of the above mentioned Patent Literatures are incorporated herein by reference. The following analysis is given by the present invention.

The forming apparatus of Patent Literature 1 performs forming in a very short time. However, at the start of forming, the aluminum alloy material has been cooled by the dies and the temperature of the material already fall, since a heat capacity of the dies is larger than those of the material to be die-quenched. Therefore, according to the forming apparatus of Patent Literature 1, formability of aluminum alloy materials is not improved so much. Additionally, for performing the forming in a very short time, there is a problem in installation that requires a special pressing apparatus capable of performing high-speed operation.

The forming apparatus of Patent Literature 2 has a problem that the temperature of the material already falls at the start of forming so that a formability of the aluminum alloy material is not improved so much, likewise the forming apparatus of Patent Literature 1.

The processing method of Patent Literature 3 has problems that the method needs many steps and two kinds of apparatuses, i.e., hot pressing apparatus and die-quenching apparatus.

It is desired to provide a die-quenching apparatus and method for an aluminum alloy material that contribute to improve formability of aluminum alloy material.

In a first aspect, there is provided a die-quenching apparatus of an aluminum alloy material, the apparatus comprising:
a forming die(s) that cools concurrently with forming a heated aluminum alloy material;
a holder mechanism that clamps the aluminum alloy material for setting the material in the forming die(s); and
a heating mechanism that heats the holder mechanism.

In a second aspect, there is provided a die-quenching method of an aluminum alloy material, the method comprising the steps of:
heating an aluminum alloy material;
clamping the heated aluminum alloy material;
locally heating a clamping portion(s) of the aluminum alloy material or suppressing a temperature decrease of the clamping portion; and
die-quenching the aluminum alloy material under a condition that the clamping portion(s) is locally heated or is suppressed from the temperature decrease.

Effect of the Invention

The first and second aspects contribute to the following effects:
The heated aluminum alloy material is set in the forming die(s) and further heated therein by the holder mechanism, so that, at a start of the forming, a temperature of the material is maintained at a predetermined temperature or more, preferably in a range of a solution treatment temperature, thus securing a good formability.
Additionally, the die-quenching or rapid-cooling of the aluminum alloy material by the forming die(s) is started in a setting condition that the aluminum alloy material is maintained at a sufficiently high temperature due to the heating via the holder mechanism, so that a portion requiring a high strength is sufficiently quenched.

Fig. 1 is a flow diagram showing a die-quenching method of an aluminum alloy material, the method performing in a die-quenching apparatus of aluminum alloy material according to an exemplary embodiment. Fig. 2 is a schematic perspective view showing a structure of a die-quenching apparatus of aluminum alloy material according to an example. Fig. 3 is a schematic operation view showing the die-quenching apparatus of Fig. 2. Fig. 4 is an operation view following Fig. 3.

Outline of the present disclosure will be explained with reference to drawings and exemplary examples. Accordingly, the reference signs referring to the figures are given for assisting examples and understanding by way of examples to be regarded as illustrative in nature, and not as restrictive.

Referring to Fig. 2, a die-quenching apparatus 1 of an aluminum alloy material according to the present disclosure comprises a forming die(s) 3 cooling concurrently with forming a heated aluminum alloy material (blank), a holder mechanism 4 clamping the aluminum alloy material for setting the material in the forming die(s), and a heating mechanism 5 heating the holder mechanism 4.

Referring to Fig.s 1 and 2, a die-quenching method of an aluminum alloy material according to the present disclosure comprises the steps of: heating an aluminum alloy material (1)-(2); clamping the heated aluminum alloy material (3a) and setting it in a forming die(s); locally heating a clamping portion of the aluminum alloy material or suppressing the clamping portion from a temperature decrease (4a); and die-quenching the aluminum alloy material under a condition that the clamping portion(s) is locally heated or the temperature decrease of the clamping portion(s)is suppressed (4).

According to the die-quenching apparatus 1 and method, at a start of die-quenching, the aluminum alloy material 2 has a sufficiently high temperature due to a heating via the holder mechanism 4, so that there is no more necessity of completing the forming in a very short time. Therefore, even if using a general pressing machine, which is operated at a relatively low speed, the quenching by the forming die(s) is securely performed with stable quality.

In addition, at the start of die-quenching, the aluminum alloy material 2 is maintained at a sufficiently high temperature, thus providing a formability of the aluminum alloy material in the die-quenching step. A heat capacity of the forming die(s) 3 is larger than those of the material 2 or the holder mechanism 3. Therefore, even if the aluminum alloy material 2 is locally heated by the holder mechanism 4, a strength-required portion in the aluminum alloy material 2 can be sufficiently quenched by the rapid-cooling using the forming die(s) 3.

Thus according to the present disclosure, a product which has high strength, high precision without generation of spring-back and high flexibility (freedom) in the shape can be manufactured at low cost.

Each of the steps of Fig. 1 is described in detail as follows. Steps (1) and (2) are a solution treatment step that heats the aluminum alloy material (blank) 2 and maintains the temperature of the aluminum alloy material 2 in a range of the solution treatment temperature. In the steps (1) and (2), each of elements contained in the aluminum alloy material is uniformly in solid-solution. Just before die-quenching, the solution treatment is performed so that, there is no need for preparing an aluminum alloy material as a blank on which the solution treatment has been applied. Instead of the solution treated aluminum alloy material, as the blank, inexpensively manufacturable rolled aluminum alloy materials (H materials regulated by JIS H 0001 or ISO 2107) can be used.

Step (3) is a feeding step that feeds the solution-treated aluminum alloy material 2 from the heating furnace into the forming die(s) 3. While feeding, the temperature of the aluminum alloy material 2 decreases. However the heating via the holder mechanism heat the aluminum alloy material 2 up to a high temperature approximately equal to a temperature at which the material 2 has been maintained in the heating furnace. Thus at a time point of setting the aluminum alloy material 2 in the forming die(s) 3, i.e., at a time point of setting a blank, the temperature of the aluminum alloy material 2 is maintained in the range of the solution treatment temperature.

Step (4) is a die-quenching step that die-quenches or forms and rapidly cools by the forming die(s) 3 the aluminum alloy material 2 whose temperature is maintained in the range of the solution treatment temperature. At a time point (4a) of starting to form, the temperature of the aluminum alloy material 2 is prevented from decreasing, so that the temperature is maintained in the range of the solution treatment temperature.

Step (5) is a feedout step in which the aluminum alloy material 2 is taken out of the forming die(s), with opening the forming die(s).

Step (6) is an artificial-aging step that artificial-ages the aluminum alloy material 2 which has been feedouted from the forming die(s) 3. The step (6) may be started in the middle of cooling in the step (4) or (5).

Further, after the step (6), a surface treatment step is preferably performed with heating the materials, for example, a coat-baking is performed so that the aluminum alloy material 2 is aged again, thus improving a strength of a final product.

In one preferred exemplary embodiment, the die-quenching apparatus 2 comprises a heat insulating portion(s) 6 insulating between the forming die(s) 3 and the holder mechanism 4. The heat insulating portion(s) 6 secures to effectively rapid- cooling by the forming die(s) 3 in the die-quenching step.

In one preferred exemplary embodiment, the holder mechanism 4 clamps a disposal portion(s) of the aluminum alloy material which does not become a product. For the clamping portion(s) 2c clamped by the holder mechanism 4, there is no need to be rapidly cooled or quenched, thus such clamping portion(s) 2c is easy to cut.

In one preferred exemplary embodiment, when the aluminum alloy material 2 is formed, the holder mechanism 4 clamps a peripheral portion(s) of the aluminum alloy material 2, allowing for a displacement of the peripheral portion in a direction which is perpendicular to the opening and closing direction of the forming die(s) 3, so that an accumulation of excessive strain in a portion with a large deformation quantity is prevented.

In one preferred exemplary embodiment, when the aluminum alloy material 2 is set in the forming die(s) 3, the holder mechanism 4 clamps the aluminum alloy material 2, avoiding a contact of the aluminum alloy material 2 with the forming die(s) 3. Thus a temperature decrease at the start of forming is prevented.

In one preferred exemplary embodiment, the forming die(s) 3 comprises upper and lower dies 3a, 3b, the holder mechanism 4 comprises an upper holder 4a which is integrally supported by the upper die 3a and capable of coming into contact on an upper surface of the aluminum alloy material 2, and a lower holder 4b which is elastically supported by the lower die 3b and capable of coming into contact on a lower surface of the aluminum alloy material 2. The holder mechanism 4 may be easily applied to the forming die(s) 3 which has, generally, a structure of having the upper and lower dies 3a, 3b.

In one preferred exemplary embodiment, the die-quenching apparatus 1 comprises a cooling passage(es) arranged in the forming die(s) 3 for cooling the forming die(s) 3 and a heater(s) 5 arranged in the holder mechanism 4 for heating the holder mechanism 4 thus securing to perform both of the rapidly cooling by the forming die(s) 3 and the heating by the holder mechanism 3. If the forming die(s) 3 is ensured to be sufficiently cooled, the forming die(s) 3 may be only naturally cooled.

According to the aspects of the present disclosure, in die-quenching step, forming starts during a state where (under a condition that) a temperature of the aluminum alloy material is maintained in a range of the solution treatment temperature, i.e., the heated aluminum alloy materials of high temperature by the solution treatment are used for the die-quenching; so that re-heating for the die-quenching is no more needed, thus energy saving is achieved. Preferably, the solution treatment temperature is a range of 475-580 degrees, particularly 500-560 degrees, considering a temperature decrease caused by transferring from the solution step to the die-quenching step or a temperature decrease just before die-quenching in the die-quenching press (e.g. caused by touching a cold die).

In one preferred exemplary embodiment, as the aluminum alloy material (blank), aluminum alloy materials which contribute to obtain high strength by heating, for example, 2000, 6000, or 7000 series (according to JIS H 4000 or ISO 6361) are selected. According to desired product strength, other kinds of materials may be selected.

In one preferred exemplary embodiment, preferred condition of heating and forming are described by way of examples as follows:
(a) range of the solution treatment temperature: 450-600 degrees, preferably 475-580 degrees, more preferably 500-560 degrees;
(b) solution treatment time: several tens of seconds to five minutes or more;
(c) rapid quenching rate in the die-quenching: at or above 10 degrees/sec, preferably at or above 50 degrees/sec, more preferably at or above 100 degrees/sec;
(d) interval of time between the die-quenching step and the artificial-aging step: five minutes or less;
(e) artificial-aging temperature: 70-250 degrees, preferably 200 degrees or less, more preferably 100-200 degrees;
(f) artificial-aging time: 5 minutes or more
(g) cooling in the artificial-aging step: for example, natural cooling in the atmosphere.

The present disclosure will be explained in detail with reference to drawings and exemplary examples. Accordingly, the reference signs referring to the figures are given for assisting examples and understanding by way of examples to be regarded as illustrative in nature, and not as restrictive.

Fig. 2 is a schematic perspective view showing a structure of a die-quenching apparatus of aluminum alloy material according to an example.

Referring to Fig. 2, a die-quenching apparatus 1 of an aluminum alloy material according to one example comprises forming dies 3 (3a,3b) cooling concurrently with forming the aluminum alloy material (blank) which is heated, left and

right holder mechanism

4,4 clamping the aluminum alloy material for setting the material in the forming die(s) and

heating mechanisms

5,5 heating the

holder mechanisms

4,4, respectively.

The forming dies 3 comprise upper and lower dies 3a, 3b. Cooling passages through which cooling fluid flows are formed in the upper and lower dies 3a, 3b. Upon die-quenching, the aluminum alloy material 2 is formed and rapidly cooled at the same time.

The

holder mechanisms

4,4 are arranged on the left and right side, respectively. Both the left and

right holder mechanisms

4,4 and the

heating mechanisms

5,5 have symmetric structures, therefore both one side of the holder mechanism 4 and the heating mechanisms 5 are mainly described. The holder mechanism 4 has an upper holder 4a which is integrally supported by the upper die 3a and capable of coming into contact on a upper surface of the aluminum alloy material 2, and a lower holder 4b which is elastically supported by the lower die 3b and capable of coming into contact on a lower surface of the aluminum alloy material 2. The holder mechanism 4 may be made of steel. Heaters 5 are buried in the upper and lower dies 3a,3b, as the heating mechanisms 5. The upper holder 4a is basically fixed to the upper die 3a. The lower holder 4b is elastically supported by the lower die 3b via a cushion 4c. A spring or cylinder may be adapted as the cushion 4c. Additionally, the upper holder 4a is mounted on a lower surface of the upper die 3a and the lower holder 4b is mounted on a upper surface of the lower die 3b so that a contacting area between the heated holder mechanism 4 and the cooled dies 3 is minimized as possible or a distance between the heated holder mechanism 4 and the cooling passages 3c in the cooled dies 3 is increased, thus contributing to minimize the temperature decrease of the clamping (disposal) portion 2c to be cut and secure a good formability of the other (product)

portions

2a,2b.

Additionally, an insulator sheet 6a is sandwiched between the upper die 3a and the upper holder 4a. An insulator sheet 6b is sandwiched between the lower die 3b and the lower holder 4a. For example, the

insulator sheets

6a,6b may be made of low heat conductive ceramics, whose thickness may be about 5-20 mm.

Next, an operation of the die-quenching apparatus 1 is described. Fig. 3 is a schematic operation view showing the die-quenching apparatus of Fig. 2. Fig. 4 is an operation view following Fig. 3.

Referring to steps (1) and (2) in Fig. 1, a heating furnace (unillustrated) heats aluminum alloy material up to the range of a solution treatment temperature. Referring to step (3) in Fig. 1, the solution treated aluminum alloy material is transferred into the die-quenching apparatus 1. During transferring, the temperature of aluminum alloy material slightly decreases, however the temperature is still maintained in the range of the solution treatment temperature.

Referring to Fig. 2, the left and

right holder mechanisms

4,4 clamp peripheral portions of the aluminum alloy material 2 and sets the material in the forming dies 3 (referring to a setting point (3a) in Fig. 1). The portions clamped by the left and

right holder mechanisms

4,4 are called clamping

portions

2c,2c below. The clamping

portions

2c,2c are brought to abut on the upper and

lower holders

4a,4b, with being pressed by the cushions 4c which are compressed or reduced. The left and

right holder mechanisms

4,4 are heated by the heaters 5. Thus the decrease in temperature of the aluminum alloy material 2 is prevented so that the temperature of the aluminum alloy material 2 is still maintained in the range of the solution treatment temperature.

Referring to Fig.s 2 and 3, at a start point of forming (4a), a die-quenching step (4) starts using the forming dies 3, in detail, the upper die 3a is lowered toward the lower die 3b. Accordingly, the cushions 4c are further compressed. At this time, the temperature of the aluminum alloy material 2 is maintained at high temperature, since the clamping

portions

2c,2c thereof are heated by the heaters 5 integrated in the left and right holder mechanisms. In particular, the clamping

portions

2c,2c, in addition,

middle portions

2b,2b arranged between the clamping

portions

2c,2c and the central portion 2a, are maintained in a state easy to stretch in the high temperature.

Referring to Fig. 3, when the upper die 3a is further lowered so that the aluminum alloy material 2 comes into enough contact on the upper and lower dies 3a,3b which are cooled, particularly, the central portion 2a of the aluminum alloy material 2 is rapidly cooled to become hard or not easy to stretch. Whereas the clamping

portions

2c,2c heated and the

middle portions

2b,2b conductively heated via the clamping

portions

2c,2c are easy to stretch in the high temperature or to form. Thus the clamping

portions

2c,2c of the aluminum alloy material 2 are allowed for a displacement thereof in a direction which is perpendicular to an opening and closing direction of the forming dies 3, so that an accumulation of excessive strain in a portion with large deformation quantity is prevented, or developments of cracks are prevented.

Referring to Figs. 3 and 4, when the upper die 3a is further lowered so that the peripheral portion (outer peripheral portion) of the aluminum alloy material 2 displaces toward the center and is released to be clamped by the

holder mechanisms

4,4, and the whole portion of the aluminum alloy material 2 including the

middle portions

2b,2b and

portions

2c,2c is formed and cooled. Thus a crack concentration is prevented due to allowing for the displacement of the aluminum alloy material 2.

After completing the forming, the upper die 3a is elevated and the aluminum alloy material 2 is taken out (referring to a step (5) in Fig. 1), the clamping

portions

2c,2c corresponding to disposal portions are cut. An artificial-aging step (6) and further a surface treatment step with re-aging treatment for example, a coat-baking step etc. are performed.

This invention is not limited to the exemplary embodiments or examples described above. It should be noted that other objects, features and aspects of the present invention will become apparent in the entire disclosure and that modifications may be done without departing the gist and scope of the present invention as disclosed herein and claimed as appended herewith.

The disclosures of known technical literatures, including the aforementioned Patent Literatures, are to be incorporated herein by reference. The particular exemplary embodiments or examples may be modified or adjusted within the gamut of the entire disclosure of the present invention, inclusive of claims, based on the fundamental technical concept of the invention. Moreover, a variety of combinations or selection of elements herein disclosed, inclusive of various elements of the claims, exemplary embodiments, examples or figures, may be made within the concept of the claims. It is to be understood that the present invention is to include a variety of changes or modifications that may occur to those skilled in the art in accordance with the entire disclosures inclusive of the claims and the technical concept of the invention. Inter alia, if the ranges of numerical values are indicated herein, they should be construed as indicating any arbitrary numerical values or sub-ranges comprised within such ranges even if such effect is not stated explicitly.
Particularly, any numerical range disclosed herein should be interpreted that any intermediate values or subranges falling within the disclosed range are also concretely disclosed even without specific recital thereof. It should be noted that symbols for having reference to the drawings, as used in the present Application, are exclusively for assisting in understanding and are not intended to restrict the invention to the mode(s) illustrated.

An aluminum alloy material according to the present invention is suitable for body panels, pillars and beams of automobiles.

1 die-quenching apparatus
2 aluminum alloy material (blank)
2a central portion
2b,2b middle portion
2c,2c clamping portion
3 forming die
3a upper die
3b lower die
3c cooling passage
4 holder mechanism
4a upper holder
4b lower holder
4c cushion
5 heating mechanism, heater
6 insulating portion
steps (1) and (2) solution step
step (3) feeding or supplying and setting step
point (3a) point of setting a blank
point (4a) point of starting to form
step (4) die-quenching step
step (5) feeding out step
step (6) artificial-aging step (pre-aging step)
H H treated materials regulated by JIS H 0001 or ISO 2107, for example, rolled and non solution treated materials
T4 T4 treated materials regulated by JIS H 0001 or ISO 2107, solution heat treated and natural aged materials

Claims

A die-quenching apparatus of an aluminum alloy material, comprising:
a forming die(s) that cools concurrently with forming a heated aluminum alloy material;
a holder mechanism that clamps the aluminum alloy material for setting the material in the forming die(s); and
a heating mechanism that heats the holder mechanism.
The die-quenching apparatus according to claim 1, further comprising:
a heat insulating portion insulating between the forming die(s) and the holder mechanism.
The die-quenching apparatus according to claim 1, wherein
the holder mechanism clamps a disposal portion(s) of the aluminum alloy material which does not become a product.
The die-quenching apparatus according to claim 1, wherein
when the aluminum alloy material is formed, the holder mechanism clamps a peripheral portion of the aluminum alloy material, allowing for a displacement of the peripheral portion(s) in a direction which is perpendicular to an opening and closing direction of the forming die(s).
The die-quenching apparatus according to claim 1, wherein
when the aluminum alloy material is set in the forming die(s), the holder mechanism clamps the aluminum alloy material, so as to avoid a contact of the aluminum alloy material with the forming die(s).
The die-quenching apparatus according to claim 1, wherein
the forming die(s) comprises upper and lower dies,
the holder mechanism comprises an upper holder which is integrally supported by the upper die and capable of coming into contact on an upper surface of the aluminum alloy material, and a lower holder which is elastically supported by the lower die and capable of coming into contact on a lower surface of the aluminum alloy material.
The die-quenching apparatus according to claim 1, further comprising:
a cooling passage(es) arranged in the forming die(s) for cooling the forming die(s); and
a heater(s) arranged in the holder mechanism for heating the holder mechanism.
A die-quenching method of an aluminum alloy material, comprising the steps of:
heating an aluminum alloy material;
clamping the heated aluminum alloy material;
locally heating a clamping portion(s) of the aluminum alloy material or suppressing a temperature decrease of the clamping portion(s); and
die-quenching the aluminum alloy material under a condition that the clamping portion(s) is locally heated or is suppressed from the temperature decrease.
The die-quenching method according to claim 8, wherein
in the die-quenching step, forming starts under a condition that the temperature of the aluminum alloy material is maintained in a range of a solution treatment temperature.