Patent Application
20200324360
This application is based upon and claims the benefit of priority from Japanese patent application No. 2019-077111, filed on Apr. 15, 2019, the disclosure of which is incorporated herein in its entirety by reference.
Japanese Unexamined Patent Application Publication No. 2013-066927 discloses a method for providing a cylindrical outer shape regulating fitting when steel bars are abutted against each other and pressure-welded.
The present inventors have found the following problem regarding the method for producing a steel plate member.
When the pressure welding method disclosed in Japanese Unexamined Patent Application Publication No. 2013-066927 is applied to steel plates, it is difficult to make the steel plates abut against each other and pressure-weld the steel plates, and even when an outer shape regulating fitting is provided at a pressure-welded part, undesired deformation such as buckling may occur at a part other than the pressure-welded part.
The present disclosure has been made in light of such circumstances. An object of the present disclosure is to provide a method for producing a steel plate member capable of pressure-welding a plurality of steel plates while effectively preventing deformation of a pressure-welded part and parts other than the pressure-welded part.
An example aspect is a method for producing a steel plate member including:
heating first and second steel plates; and
press-forming the heated first and second steel plates while sandwiching the first and second steel plates between an upper die and a lower die and cooling the first and second steel plates.
In the press-forming, end parts of the first and second steel plates are overlapped, and the overlapped end parts are pressure-welded by the press-forming.
In the method for producing a steel plate member according to the example aspect, in the press-forming, end parts of the first and second steel plates are overlapped, and the overlapped end parts are pressure-welded by the press-forming.
Since the steel plates are pressure-welded while being press-formed, it is possible to effectively prevent undesired deformation at a pressure-welded part and undesired deformation such as buckling at a part other than the pressure-welded part as compared with butt pressure welding.
In the press-forming, a compression rate of the overlapped end parts may be 30% or higher. Such a configuration enables more reliable pressure-welding.
A projection and a recess may be provided to at least one of the upper die and the lower die at a position where the projection and the recess are brought into contact with the overlapped end parts of the first and second steel plates. Alternatively, a projection and a recess may be provided to at least one of the overlapped end part of the first steel plate and the overlapped end part of the second steel plate. With such a configuration, an area of a contact interface between the end parts in the pressure-welded part can be increased, and the end parts can be joined more firmly.
The first and second steel plates may be made of different types of steel plates, a strength of the first steel plate after the press forming being different from a strength of the second steel after the process forming. Alternatively, a thickness of the first steel plate before the press-forming may differ from a thickness of the second steel plate after the press-forming. With such a configuration, both a high strength and excellent impact absorption characteristics can be achieved.
According to the present disclosure, it is possible to provide a method for producing a steel plate member capable of pressure-welding a plurality of steel plates while effectively preventing deformation of a pressure-welded part and parts other than the pressure-welded part.
The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure.
Hereinafter, specific embodiments to which the present disclosure is applied will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. Further, the following descriptions and drawings are simplified as appropriate for clarity of explanation.
First, a method for producing a steel plate member according to the first embodiment will be described with reference to
First, the heating process shown in
As shown in
In
The steel plates 11 and 12 are steel plates for hot stamping made of, for example, manganese boron steel having a thickness of about 1 to 4 mm, although the steel plates 11 and 12 are not limited in particular. The flat steel plates 11 and 12 before the heating process are, for example, soft materials including microstructures formed of ferrite and pearlite. Furthermore, by using different types of steel plates having a tensile strength after the press forming process different from each other as the steel plates 11 and 12, both a high strength and excellent impact absorption characteristics can be achieved. For example, the difference between a tensile strength of the steel plate 11 and that of the steel plate 12 is set to 500 MPa or greater.
Next, the press forming process shown in
The right-handed xyz orthogonal coordinates shown in
In the example of
As shown in the middle part of
The compression rate for pressure-welding the overlapped end parts 11a and 12a may be, for example, 30% or higher. Here, the formula “compression rate(%)=(plate thickness of pressure-welded part before press forming−plate thickness of pressure-welded part after press forming)/plate thickness of pressure-welded part before press forming×100” holds. When the steel plates 11 and 12 have the same thickness, an ideal value of the compression rate is 50%.
Here, in the press forming process shown in the temperature chart of
In this manner, by overlapping the end parts 11a and 12a of the steel plates 11 and 12 and then press-forming the end parts 11a and 12a of the steel plates 11 and 12, the steel plates 11 and 12 can be pressure-welded while being formed. In other words, the steel plates 11 and 12 can be pressure-welded and press formed at the same time during the press forming process. It is therefore not necessary to provide a pressure welding process and a pressure welding apparatus separately from a process and an apparatus for the press forming.
Further, since the steel plates are pressure-welded while being press-formed, it is possible to effectively prevent undesired deformation at a pressure-welded part and undesired deformation such as buckling at a part other than the pressure-welded part as compared with butt pressure welding.
The steel plate member 10 shown in the lower part of
Thus, as shown in
As described above, in the method for producing a steel plate member according to this embodiment, the steel plates 11 and 12 can be pressure-welded while being formed by overlapping the end parts 11a and 12a of the steel plates 11 and 12 and press-forming them. It is therefore not necessary to provide a pressure welding process and a pressure welding apparatus separately from a process and an apparatus for the press forming. Furthermore, since the steel plates are pressure-welded while being press-formed, it is possible to effectively prevent undesired deformation at a pressure-welded part and undesired deformation such as buckling at a part other than the pressure-welded part as compared with butt pressure welding.
Next, a configuration of a specific example of the steel plate member according to the first embodiment will be described with reference to
Note that the use and shape of the steel plate member 40 shown in
The steel plate member 40 shown in
In a manner similar to the steel plate member 10 shown in
Next, a method for producing a steel plate member according to the second embodiment will be described with reference to
In the example shown in
In the example shown in
Thus, the area of the contact interface between the end parts 11a and 12a in the pressure-welded part can be increased, and the end parts 11a and 12a can be joined more firmly.
Next, a method for producing a steel plate member according to a third embodiment will be described with reference to
In the example shown in
In the example shown in
Next, a configuration of a specific example of the steel plate member according to a fourth embodiment will be described with reference to
Note that the use and shape of the steel plate member 50 shown in
As shown in
As shown in
The main body 511 is slightly curved as a whole so as to project outward.
Furthermore, an upper end part and a lower end part of the main body 511 are formed in a T shape in a plan view extending in the width direction (front-rear direction). Here, the lower end part is extended in the width direction (front-rear direction) to be wider than the upper end part.
The upper flange part 512 includes a plate surface that rises outward from an upper end part of the main body part 511, and a plate surface that projects upward from an outer end part of the other surface (outward in longitudinal direction of main body part 511). That is, the upper flange part 512 is a part having an L-shaped cross section that extends in the width direction (front-rear direction).
The lower flange part 513 is a flat part projecting to be extended from a lower end part of the top plate 511a to a lower side (outer side in longitudinal direction and also extending in the width direction (front-rear direction).
In the steel plate member 50 shown in
As shown in
Hereinafter, experimental examples of the method for producing a steel plate member according to the embodiments will be described.
First, the steel plates 11 and 12 having a thickness of 2.0 mm and a width of 40 mm were held at 900° C. for 6 minutes to make the entire steel plates austenitic. After that, as shown in
As shown in Table 1, regarding the Experimental Examples 1 to 11, it was determined whether the steel plates 11 and 12 were joined under different conditions, with different types of the steel plates 11 and 12, plated plates or non-plated plates, different overlapped margins, and different press loads. Moreover, a compression rate was measured in each Experiment Example. As the types of steel, SPH steel or SA1D steel with a tensile strength before quenching of about 270 MPa was used for the low strength material, and manganese boron steel (22MnB5) with a tensile strength after quenching of about 1.5 GPa was used for the high strength material. For the condition of using plated plates or non-plated plates, an Al-Si-based plated steel plate or a non-plated steel plate was used.
As shown in Table 1, for the steel plates 11 according to the Experimental Examples 1 to 10, plated or non-plated low strength materials were used. For the steel plate 11 according to Experimental Example 11, a high strength material of an Al-Si-based plated steel plate was used. For the steel plate 12, in all the Experimental Examples 1 to 11, a high strength material of an Al-Si-based plated steel plate was used.
The overlapped margin was changed in three stages of 5 mm, 10 mm, and 20 mm. The press load was 100 t or 200 t. The compression rate was obtained by a formula “compression rate (%)=(plate thickness of pressure-welded part before press forming−plate thickness of pressure-welded part after press forming)/plate thickness of pressure-welded part before press forming×100”. The “plate thickness of pressure-welded part before press forming” and “plate thickness of pressure-welded part after press forming” were measured using a micrometer.
From the results of Experimental Examples 1 to 10 in Table 1, it has been found that the smaller the overlapped margin and the greater the press load, the compression rate is increased, regardless of the use of the plated steel plate or non-plated steel plate. From the result of comparison between Experimental Examples 11 and Experimental Examples 9 and 10, it has been found that the smaller the tensile strength of the steel plates, the compression rate becomes higher. As shown in Table 1, the steel plates were joined to each other in Experimental Examples 3 to 10 in which the compression rate was 30% or higher. When tensile tests were conducted in Experimental Examples 3 to 10, in Experimental Examples 3 to 9, a fracture occurred in the base material, not in the joining interface, and in Example 10, a peeling occurred in the joining interface.
On the other hand, in Experimental Examples 1, 2, and 11 in which the compression rate was less than 30%, the steel plates were not joined to each other.
From the results of Experimental Examples 1 to 11 shown above, it has been found that when the overlapped margin, press load, and the like are adjusted in such a way that the compression rate of the pressure-welded part are increased to some extent, the steel plates can be pressure-welded by overlapping and press forming the end parts of the steel plates. Since the steel plates are pressure welded while being press-formed, it is not necessary to provide a pressure welding process and a pressure welding apparatus separately from a process and an apparatus for the press forming. Further, as compared with butt pressure welding, it is possible to effectively prevent undesired deformation at a pressure-welded part and undesired deformation such as buckling at a part other than the pressure-welded part.
Note that the present disclosure is not limited to the above embodiments, modifications may be made as appropriate within a range not departing from the scope of the present disclosure.
From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-077111 | Apr 2019 | JP | national |
