JP6939765B2 - A method of joining a plate set in which a steel plate and a light metal plate are superposed, a method of joining a plate set in which a metal plate and a CFRP plate are superposed, and a method of manufacturing a plate set using the joining method. - Google Patents

Description

The present invention relates to a plate assembly in which a steel plate (for example, a normal steel plate, a high tension steel plate, etc.) and a light metal plate (for example, an aluminum plate, an aluminum alloy plate, etc.) are superposed, and a metal plate (for example, a steel plate, an aluminum plate, an aluminum alloy plate, etc.). Etc.) and a plate material made of a non-metal material (for example, resin, CFRP, GFRP, etc.) are overlapped with each other to join a plate assembly, and a plate assembly manufacturing method using the joining method.

In recent years, research to deal with environmental problems such as global warming has been carried out in various fields. In the automobile industry, technologies for reducing fuel consumption (so-called fuel efficiency improvement) and, by extension, CO ₂ emissions have been developed. By increasing the amount, technologies for reducing the amount of steel plate used and reducing the weight of the vehicle body have been put into practical use.

Further, in the automobile industry, in order to achieve further weight reduction of the vehicle body, a technique of adopting a light metal (for example, aluminum alloy, etc.) or CFRP (that is, carbon fiber reinforced plastic) for the vehicle body is being studied. In order to mass-produce such a car body on a production line, a technique for firmly joining a steel frame forming the skeleton of the car body and a lightweight material (that is, light metal, CFRP, etc.) is required.

Conventionally, since a steel plate was used for the outer plate, a general-purpose melt welding method (for example, arc welding, resistance spot welding, etc.) was widely used. The conventional hot-dip welding method cannot be adopted. For example, when an attempt is made to join a steel plate and an aluminum alloy plate by a hot-dip welding method, an intermetallic compound of Fe and Al is generated, and as a result, there arises a problem that the joint portion becomes remarkably embrittled. Further, when an attempt is made to join a steel plate and a CFRP plate by a melt welding method, there arises a problem that the CFRP plate melts or burns.

Therefore, a joining technique that enables joining of steel sheets and dissimilar materials is being studied. A typical example thereof is a technique called SPR (Self Pierce Riveting). The technology is to stack multiple metal plates into a plate assembly, place the plate assembly on a die, and drive in a flanged tubular rivet to plasticize the rivet inside the plate assembly. It is a technique of deforming and joining, and is generally called caulking.

In addition, a technique called FDS (Flow Drilling Screw) is also being studied. The technique is a technique in which a screw with a sharp tip is rotated at a high speed to be perforated and pushed into a plate assembly, and the plate assembly is penetrated and joined.
In addition, a technique called ImpAcT (Impulse Accelerated Tracking) is a technique in which a rivet is pushed into a plate set at high speed to make a hole, and then the rivet is further penetrated and joined.

Since all of these techniques are techniques for plastically deforming (that is, drilling or caulking) the metal plates constituting the plate assembly to join them, the strength of the metal plates has a great influence on the joining of the plate assembly. For example, when a high-strength steel plate is used as a metal plate, the deformation resistance of the high-strength steel plate is large, so it is difficult to apply the above SPR, FDS, and ImpAcT to join the platework.

Therefore, a technique for joining a plate set in which a high-strength steel plate and a lightweight material are superposed is being studied. For example, Patent Documents 1 and 2 disclose a technique in which electric current is supplied from the upper surface to the lower surface of a plate assembly to perform energization heating to soften the joint portion of the plate assembly and drive rivets.

All of the techniques disclosed in Patent Documents 1 and 2 are joining techniques called caulking, and when the plate assembly includes a high-strength steel plate having a tensile strength of 980 MPa or more, the rivet is a plate assembly. Since it does not penetrate the joint, a significant improvement in the strength of the joint cannot be expected. Further, when the plate assembly is composed of the high-strength steel plate and the CFRP plate, the current cannot be supplied from the upper surface to the lower surface of the plate assembly, so that the high-strength steel plate does not soften. That is, it is difficult to join a plate set composed of a high-strength steel plate and a CFRP plate.
This problem occurs not only in high-strength steel plates but also in plate sets composed of metal plates and CFRP plates.

JP-A-2018-126752 International Publication WO2017 / 002976

The present invention solves the problems of the prior art and enables a joining method capable of firmly joining a steel plate in which a steel plate and a light metal plate are superposed, in particular, the steel plate is a high-tensile steel plate (tensile strength of 980 MPa or more). It is an object of the present invention to provide a joining method that can be applied to a sheet steel assembly. Further, the present invention also applies to a joining method capable of firmly joining a plate assembly in which a metal plate and a CFRP plate are overlapped, particularly a plate assembly including a high-tensile steel plate having a tensile strength of 980 MPa or more as a metal plate. It is an object of the present invention to provide an applicable joining method.

The present inventor first, in order to establish a joining technique capable of solving the above-mentioned problems, first
(A) Technology for joining plate sets (two or more layers in total) in which various metal plates (for example, steel plates, light metal plates, etc.) are superposed.
Consider, especially
(B) Technology for joining a plate set (two or more layers in total) in which a steel plate and various light metal plates are superposed.
Was examined in detail. resulting in,
(C) By heating and softening (that is, reducing deformation resistance) the steel plates that make up the plate assembly, the screws or pins extend from the upper surface to the lower surface of the plate assembly (that is, all the steel plates and light metal plates). It will be possible to penetrate,
(D) As a means for heating the steel sheet, energization heating, high frequency heating, and laser heating are preferable.
(E) If at least one of the layer arranged on the upper surface and the layer arranged on the lower surface of the plate set is a steel plate, the steel plate can be easily heated.
I got the knowledge.

Next, the present inventor
(F) Technology for joining a plate assembly (total of 2 layers) in which metal plates and CFRP plates are stacked one by one.
As well,
(G) Technology for joining one metal plate and two or more CFRP plates, or a plate set in which two or more metal plates and one CFRP plate are superposed (three or more layers in total).
Moreover,
(H) A technique for joining a plate set in which the metal plate is a steel plate when there is only one metal plate (see (F) and (G) above).
(I) A technique for joining a plate set in which at least one metal plate is a steel plate when there are two or more metal plates (see (G) above).
(J) Technology for joining a plate assembly (see (H) (I) above) in which the steel plate is a high-strength steel plate with a tensile strength of 980 MPa or more.
Was examined.

Then, the common technology that enables the joining of the plates described in (F) to (J) above was studied in detail. resulting in,
(K) By heating the metal plates that make up the sheet metal to soften (that is, reduce the deformation resistance), the screws or pins can be extended from the upper surface to the lower surface of the sheet metal (that is, the metal plate and the CFRP plate). All) can be penetrated,
(L) As a means for heating the metal plate, energization heating, high frequency heating, and laser heating are preferable.
(M) If at least one of the layer arranged on the upper surface and the layer arranged on the lower surface of the plate set is a metal plate, the metal plate can be easily heated.
(N) The above effects (K) to (M) can be obtained even in a sheet metal assembly using a steel plate as a metal plate.
I got the knowledge.
In the following, the layer arranged on the upper surface and the layer arranged on the lower surface of the plate assembly are collectively referred to as the outermost layer.

The present invention has been made based on such findings.
That is, in the present invention, one or more steel plates and one or more light metal plates are superposed to form a plate assembly, and the steel plates are heated or after heating, and screws or pins are passed through the plate assembly to form a plate assembly. It is a joining method of a plate set for joining.

In the method for joining a steel plate and a light metal plate of the present invention, when the total number of steel plates and light metal plates constituting the plate is 3 or more, the steel plate is arranged on one or both of the outermost layers of the plate. Is preferable. Further, it is preferable to use any one of energization heating, high frequency heating, and laser heating as a means for heating the steel sheet, and join the sheets by any one of the following methods (a) to (c). ..
(a) While heating the steel plate, pass a screw or pin through the plate assembly.
(b) Immediately after the heating of the steel plate is completed, the screws or pins are passed through the steel plate.
(c) After the steel plate has finished heating, the screws or pins are passed through the plate assembly at a predetermined temperature during cooling.

Further, in the present invention, one or more metal plates and one or more CFRP plates are superposed to form a plate assembly, and the metal plates are heated or after heating, and screws or pins are passed through the plate assembly. This is a method of joining a metal plate and a CFRP plate to join a plate set.

In the method of joining the metal plate and the CFRP plate of the present invention, when the total number of the metal plate and the CFRP plate constituting the plate is 3 or more, the metal plate is attached to one or both of the outermost layers of the plate. It is preferable to arrange it. Further, as a means for heating the metal plate, any one of energization heating, high frequency heating, and laser heating can be used, and the plate assembly can be joined by any one of the following methods (d) to (f). preferable.
(d) While heating the metal plate, pass the screw or pin through the plate assembly.
(e) Immediately after the heating of the metal plate is completed, a screw or pin is passed through the plate assembly.
(f) After the metal plate has finished heating, a screw or pin is passed through the plate assembly at a predetermined temperature during cooling.

Further, when there is one metal plate constituting the plate assembly, the metal plate may be a steel plate, and when there are two or more metal plates constituting the plate assembly, at least one of the metal plates may be a steel plate. preferable. Further, it is preferable that the steel plates constituting the plate assembly are heated by any one of energization heating, high frequency heating, and laser heating, and the plate assembly is joined by any one of the following methods (g) to (i). ..
(g) While heating the steel plate, screw or pin is passed through the steel plate.
(h) Immediately after the heating of the steel plate is completed, the screws or pins are passed through the steel plate.
(i) After the steel sheet has finished heating, a screw or pin is passed through the sheet steel at a predetermined temperature during cooling.

The method for joining plates of the present invention can be applied not only to ordinary carbon steel but also to high-strength steel plates having a tensile strength of 980 MPa or more.

According to the present invention, a plate set in which a steel plate and a light metal plate (for example, an aluminum plate) are overlapped, particularly a plate set in which a high-strength steel plate (tensile strength of 980 MPa or more) and a light metal plate are overlapped is firmly joined. It becomes possible. In addition, it is possible to firmly join a plate assembly in which a metal plate and a CFRP plate are overlapped, and in particular, it is possible to join a plate assembly in which a high-strength steel plate (tensile strength of 980 MPa or more) and a CFRP plate are overlapped. Become. In other words, a high-strength steel plate with a tensile strength of 980 MPa or more and another metal plate or non-metal plate can be superposed and joined, which is extremely effective in industry.

It is sectional drawing which shows typically the example of the apparatus which joins a plate assembly by applying this invention. It is sectional drawing which shows typically the example that the screw shown in FIG. 1 penetrated a plate set.

FIG. 1 is a cross-sectional view schematically showing a main part of an apparatus for joining a plate structure 1 to which the present invention is applied. Here, first, referring to FIG. 1, the metal plate 2 and the CFRP plate 3 are superposed one by one to form a plate assembly 1 (two layers in total), and energization heating is adopted as a means for heating the metal plate 2. An example will be described. The joining of the plate set in which the steel plate and the light metal plate are superposed will be described later.

In the two-layer plate assembly 1 shown in FIG. 1, both the metal plate 2 and the CFRP plate 3 are the outermost layers. That is, this is an example in which the metal plate 2 is arranged on one of the outermost layers of the plate assembly 1. Such a plate set 1 is placed on the two electrodes 4. At this time, the metal plate 2 which is the outermost layer on the lower side of the plate assembly 1 is brought into contact with the electrode 4. When energized in this way, the current flows from one electrode 4 through the metal plate 2 to the other electrode 4, so that energization heating is possible even in the plate assembly 1 in which the metal plate 2 and the CFRP plate 3 are overlapped. That is, the metal plate 2 located between the two electrodes 4 is heated and softened. The region is indicated by reference numeral 5.

Even in a plate assembly of three or more layers (not shown), if a metal plate is arranged on one or both of the outermost layers, the electrode can be brought into contact with the metal plate. Therefore, the metal plate can be energized and heated even in a plate set having three or more layers having at least one CFRP plate.

When laser heating is adopted as a means for heating the metal plate 2 of the two-layer plate assembly 1 shown in FIG. 1, the metal plate 2 is irradiated with laser light. Since the metal plate 2 is arranged on the outermost layer, it can be easily irradiated with laser light. Even in a plate set of three or more layers, if a metal plate is arranged on one or both of the outermost layers, the metal plate can be easily heated by irradiating the metal plate with laser light.

Further, when high frequency heating is adopted as a means for heating the metal plate 2 of the two-layer plate assembly 1 shown in FIG. 1, an eddy current is not generated in the CFRP plate 3, so that only the metal plate 2 can be heated. can.

When high-frequency heating is adopted as a means for heating a metal plate of three or more layers, if a metal plate is placed on one or both of the outermost layers and an electromagnetic coil is placed in the vicinity thereof, the metal plate can be placed at high frequency. Can be heated. When two types (or two or more types) of metal plates with different electromagnetic or mechanical characteristics and CFRP plates are stacked to form a plate assembly, the current and voltage supplied to the electromagnetic coil are adjusted to increase the tensile strength. Set so that eddy current is generated in the highest metal plate.

As described above, with reference to FIG. 1, various combinations of the metal plate and the CFRP plate in the plate assembly to which the present invention is applied, and heating for softening the metal plate have been described. The present invention can also be suitably applied to a plate assembly in which a steel plate is used as a metal plate and superposed on a CFRP plate. Even if the steel sheet is a high-strength steel sheet, there is no problem.

As described above, the screw 6 is screwed in while heating the metal plate 2 of the plate assembly 1. Since the CFRP plate 3 is significantly softened by heating, the screw 6 easily advances in the direction of arrow A. Further, since the heated region 5 of the metal plate 2 is softened, the screw 6 also penetrates the metal plate 2 and proceeds. Even if the metal plate 2 is a steel plate (or a high-strength steel plate), the screw 6 can be easily penetrated from the upper surface of the CFRP plate 3 to the lower surface of the steel plate (or the high-strength steel plate). An example thereof is shown in FIG.

Further, when a steel plate (or a high-strength steel plate) and a light metal plate are used as the metal plate 2 and the plate assembly 1 (three or more layers in total) overlapped with the CFRP plate 3 is joined, the light metal plate and the CFRP plate 3 are formed. Since it is a soft material, only the steel sheet (or high-strength steel sheet) needs to be heated to soften it. Therefore, if the steel plate (or high-strength steel plate) is arranged in the outermost layer of the plate assembly 1, energization heating, high-frequency heating, and laser heating can be easily performed.

When screwing the screw 6 into the plate assembly 1, it is preferable to dispose the clamp 7 so that the positions of the metal plate 2 and the CFRP plate 3 do not shift, and sandwich the plate assembly 1 between the electrode 4 and the clamp 7. ..

However, if the metal plate 2 and the CFRP plate 3 are superposed and joined in multiple layers, the positions of the metal plate 2 and the CFRP plate 3 are likely to shift even if the clamp 7 is used. Further, since it is necessary to use a long screw 6, the screw 6 is easily deformed (for example, buckling, bending, breaking, etc.). Therefore, the plate assembly 1 preferably has a range of 2 layers (see FIGS. 1 and 2) or more and 4 layers or less.

In this way, the joining work of the plate assembly 1 is completed. Even if the excess protruding portion of the screw 6 is cut off, the joint strength of the plate assembly 1 is not adversely affected.

It is also possible to use pins (not shown) instead of screws. While heating the metal plate by the means described above, the plate assembly can be joined by driving the pin through the pin from the upper surface of the CFRP plate to the lower surface of the metal plate. The excess protrusion of the pin may be cut off or deformed into a rivet shape.

Next, joining of a plate set in which a steel plate (or a high-strength steel plate) and a light metal plate are superposed will be described.

In the two-layer plate set 1 shown in FIGS. 1 and 2, if the plate sets are arranged so that reference numeral 2 is a steel plate and reference numeral 3 is a light metal plate, the steel plate is heated from the upper surface of the light metal plate to the bottom of the steel plate. The series of techniques for penetrating a screw to the surface is the same as the mechanism already described with reference to the figure. Even in a plate assembly having three or more layers, the steel plate can be energized and heated by arranging the steel plate on the outermost layer of the plate assembly and bringing the electrodes into contact with each other. Further, by arranging the steel plate in the outermost layer, the laser beam can be easily irradiated, so that laser heating is also possible. Since a light metal plate such as an aluminum plate or an aluminum alloy plate is a non-magnetic material, it is possible to heat only the steel plate by high frequency heating.

The technique of driving a steel plate (or metal plate) while heating it has been described above, but it can be used for a sheet metal set that has been heated in advance and cooled as necessary (for example, air cooling, quenching by forced cooling, or slow cooling by atmosphere control). You may drive in screws or pins. Further, after the heating of the steel plate (or metal plate) is completed, screws or pins may be driven into the plate assembly at a predetermined temperature during cooling. The term “during cooling” as used herein includes a state in which the temperature of the steel sheet (or metal plate) has dropped to room temperature or lower after the start of cooling.

That is, one of energization heating, high frequency heating, and laser heating is used as a means for heating the steel plate (or metal plate), and the steel plate (or metal plate) is driven and penetrated by any one of the following methods (1) to (3). Let me.
(1) While heating the steel plate (or metal plate), pass the screws or pins through the plate assembly.
(2) Immediately after the heating of the steel plate (or metal plate) is completed, the screws or pins are passed through the plate assembly.
(3) After the heating of the steel plate (or metal plate) is completed, the screws or pins are passed through the plate assembly at a predetermined temperature during cooling.

The above (1) to (3) are steel sheets that utilize the softening phenomenon of steel sheets (or metal plates) caused by the decrease in deformation resistance caused by heating, or steel sheets that have the same effect as tempering. It is a technology that utilizes the softening phenomenon of (or metal plate).

The present invention will be described in more detail by way of examples. It should be noted that the following examples do not have properties that limit the present invention, and all of them are included in the technical scope of the present invention as long as the gist of the present invention is satisfied.

A joining experiment was conducted in which a high-strength steel plate having a tensile strength of 980 MPa or more and a 5000-series aluminum alloy plate were superposed one by one (two layers in total). The procedure will be described.

The high-strength steel plate constituting the plate assembly was used as the lower plate (corresponding to reference numeral 2 in the figure) of the two layers, and the aluminum alloy plate was used as the upper plate (corresponding to reference numeral 3 in the figure). The high-strength steel plate and aluminum alloy plate used are as shown in Table 1.

The plate set was placed on an electrode and further clamped. At this time, the high-strength steel plate, which is the lower plate, came into contact with the electrodes. In this way, energization heating was performed to heat the high-tensile steel plate, and after sufficient cooling was performed, a screw was screwed in to penetrate from the upper surface of the aluminum alloy plate to the lower surface of the high-tensile steel plate. Table 2 shows the electrodes used in the energization heating, the supplied current, and the energization time. As the shape of the electrode, for example, the one described in JIS standard C9304: 1999 can be used. As an example, in Table 2, the tip of each electrode has a flat shape (that is, the tip has an infinite radius of curvature) as a DF type.

In this way, the high-strength steel plates of each plate assembly (see Table 1) were energized and heated (see Table 2), and the screws were screwed in after sufficient cooling was performed. The setting conditions for screwing the screw are as shown in Table 3. The rotation speed in Table 3 is the number of rotations of the screw per minute, and the pressing force is the pressure for pressing the screw in the direction of arrow A.

After the joining of the plate assembly was completed, the appearance of the plate assembly was visually observed, and the plate assembly in which the screw penetrated from the upper surface to the lower surface of the plate assembly was evaluated as ◯, and the plate assembly that did not penetrate was evaluated as x. The results are shown in Table 3 as the appearance of the board.

_{Next, the length L USED} (mm) of the screw screwed into the plate assembly was measured, and the ratio (= 100 × L _USED / L _{PRIMARY ) to the length L PRIMARY} (mm) of the new screw was calculated. The results are shown in Table 3.

Then, the joint state was evaluated based on the presence or absence of screw penetration and the ratio of screw length. That is, the case where the appearance of the plate assembly is 〇 and the ratio of the screw length is 95% or more is excellent (A), and the case where the appearance of the plate assembly is 〇 and the ratio of the screw length is 80% or more and less than 95% is good (B). Table 3 shows an example in which the appearance of the plate assembly is 〇 and the ratio of the screw length is less than 80% is good (C), and an example in which the appearance of the plate assembly is × is not possible (D).

As is clear from Table 3, in all the examples of the invention (that is, the example in which the high-strength steel plate was heated), the appearance of the plate assembly was ◯, and the joint states were evaluated as A to C. On the other hand, in the comparative example (that is, the example in which the high-strength steel plate was not heated), the appearance of the plate assembly was ×.

That is, under the condition that the lower plate strength was 980 MPa and the energization time was sufficiently secured, punching was easy and the judgment was excellent (A). Under the condition that the energizing time was insufficient, the tempering was insufficient due to insufficient heating, and the difficulty of punching increased, so the judgment was good (B) or good (C). On the other hand, under the condition without energization and heating, punching becomes difficult, so it was judged as impossible (D).

1 Plate set 2 Metal plate 3 CFRP plate 4 Electrode 5 Heated area 6 Screw 7 Clamp

Claims (4)

One or more steel plates and one or more light metal plates are superposed to form a plate assembly.
The steel sheet is a high-strength steel sheet with a tensile strength of 980 MPa or more.
The steel plate is used as the outermost layer on the lower side of the plate assembly.
Energization heating is used as a means for heating the steel plate, the electrode of the energization heating is brought into contact with the steel plate which is the outermost layer on the lower side of the plate assembly, and energization heating is performed between the electrodes of the energization heating. after heating pressure to the steel plate,
A method for joining a steel plate, characterized in that the steel plate is joined by penetrating a screw or a pin through the steel plate in a state where the temperature of the steel plate is lowered to room temperature or lower. The plate according to claim 1, wherein when the steel plate constituting the plate assembly and the light metal plate are three or more in total, the steel plate is arranged on one or both of the outermost layers of the plate assembly. How to join a pair. One or more metal plates and one or more CFRP plates are superposed to form a plate assembly.
When there is one metal plate constituting the plate assembly, the metal plate is a steel plate, and when there are two or more metal plates constituting the plate assembly, at least one of the metal plates is a steel plate. ,
The steel sheet is a high-strength steel sheet with a tensile strength of 980 MPa or more.
Using the steel plate as the outermost layer on the lower side of the plate assembly,
When heating the steel plate constituting the plate assembly by energization heating, the electrode of the energization heating is brought into contact with the steel plate which is the outermost layer on the lower side of the plate assembly, and energization heating is performed between the electrodes of the energization heating. Then, after heating the steel sheet,
A method for joining a steel plate, characterized in that the steel plate is joined by penetrating a screw or a pin through the steel plate in a state where the temperature of the steel plate is lowered to room temperature or lower. A method for manufacturing a plate assembly joined by using the plate assembly joining method according to any one of claims 1 to 3.

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