JP2022175887A - Processing method - Google Patents

Abstract

To reduce manufacturing cost.SOLUTION: A processing method includes a heating step in which an end of a magnetic core passing through a spiral coil is disposed in a non-contact with and opposite to along an end face of a punched end of a steel plate, current is caused to flow through the steel plate to generate an induction electromotive force, thereby heating the end face.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a method for processing a steel plate.

A processing method is known in which a coil is inserted into a through hole formed in a work and high-frequency heating is performed by the coil (see, for example, Patent Document 1).

JP 2015-124430 A

However, in the above-described processing method, for example, when a coil is inserted into a small-diameter through-hole, an expensive coil made of a finer wire material is required to correspond to the small-diameter through-hole, which may lead to an increase in manufacturing costs. There is

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and a main object of the present invention is to provide a processing method capable of keeping manufacturing costs low.

One aspect of the present invention for achieving the above object is
The end of the magnetic core that penetrates the helical coil is arranged so as to face the end face of the stamped end of the steel plate in a non-contact state along the end face, and an electric current is applied to the steel plate by passing an electric current through the coil. A heating step of heating the end surface by generating an induced electromotive force,
processing method.
In this aspect, the end surface of the punched end of the steel plate is the inner peripheral surface of the through hole of the steel plate, and the end portion of the magnetic core penetrates the through hole and is in a state of non-contact with the inner peripheral surface. and may be arranged so as to face the inner peripheral surface.
In this aspect, the diameter of the through hole may be smaller than the diameter of the helical coil.
In this aspect, the magnetic core may be arranged so as to be relatively movable in the axial direction of the magnetic core with respect to the fixed coil.
In this aspect, the magnetic core is axially moved relative to the coil, the end of the magnetic core is inserted into the through-hole of the steel plate, and an electric current is applied to the coil. The inner peripheral surface of the through-hole may be heated by generating an induced electromotive force in the steel plate.
In this aspect, in the heating step, the steel plate punched in the punching step is placed on a heating jig and then heated by the coil, and the heating jig heats the steel plate punched in the punching step to a predetermined temperature. It may have a positioning guide for positioning, and the magnetic core and coil for heating the end face of the punched end of the steel plate positioned by the positioning guide.
In this aspect, the heating step may be performed during any step in the press.
This aspect further includes a stretch-flanging step of forming a stretch-flange on the punched end, and the heating step includes idling for adjusting a conveying pitch when conveying the steel plate from the punching step to the stretch-flanging step. It may be performed in steps.
In this aspect, at least the punching step and the idling step are continuously performed at a predetermined conveying pitch while the steel plate molded product is continuously conveyed by the gripping portion in the press machine, and the idling step The idling step may be replaced with the heating step by arranging the heating jig at a position corresponding to .

A main object of the present invention is to provide a processing method capable of keeping manufacturing costs low.

It is a schematic diagram which shows roughly the process of the processing method which concerns on this embodiment. It is a perspective view of a coil and a magnetic core according to the present embodiment. 3 is a side view of the coil and the magnetic core shown in FIG. 2 as viewed from the side; FIG. FIG. 4 is a diagram showing a configuration in which a pair of coils are arranged in a magnetic core so as to sandwich a through hole of a steel plate; It is a perspective view which shows the floor side member of a vehicle. 1 is a perspective view showing a rocker outer of a vehicle; FIG. It is a figure which shows the CAE analysis result at the time of heating the small diameter through-hole of a steel plate. It is a figure for demonstrating the case where the inner peripheral surface of the through-hole of a vertical wall is heated. It is a figure which shows an example of a heating jig. FIG. 4 is a diagram comparing the steps of the molding method according to the present embodiment and the steps of the conventional molding method. It is a figure which shows an example of the process in a press machine.

Embodiment 1
Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the scope of claims is not limited to the following embodiments. Moreover, not all the configurations described in the embodiments are essential as means for solving the problems.

FIG. 1 is a schematic diagram schematically showing the steps of the processing method according to this embodiment. In the processing method described below, a through hole 101 is provided in a steel plate 100 as a work, and the periphery of the through hole 101 is deformed to form a flange 102 .

The processing method according to the present embodiment includes, for example, as shown in FIG. and a stretch flanging step of forming the flange 102 against 103 .

The punching step is a step of punching out the steel plate 100 fixed to a punching die (not shown) with a punch 200 . The heating step, which will be described later in detail, is a step of heating the punched end 103 formed in the punching step.

In the heating step, the stamped steel plate 100 is placed on a heating jig. Then, as will be described later, the punched end 103 of the steel plate 100 is subjected to high-frequency induction heating. After the heating, the steel plate 100 is removed from the heating jig.

As shown in FIG. 1, the cooling step is a step of cooling the punched edge 103 heated in the heating step. Specifically, the steel plate 100 is left in a room temperature environment for a certain period of time. The stretch flanging step (burring step) is a step of inserting the flange mold 300 into the through hole 101 and plastically deforming the periphery of the through hole 101 to form the flange 102 .

Residual strain generated in the peripheral portion of the through-hole 101 by the punching process is removed by the heating process. Since it is introduced into the stretch-flanging process after standing to cool, it is possible to reduce the damage caused to the flange mold 300 as compared with the case where the steel plate 100 is heated. In particular, in this embodiment, as will be described later, the punched edge 103 can be locally heated, so that the residual strain can be satisfactorily removed, and the heating efficiency is also improved.

Next, the heating process described above will be described in detail. FIG. 2 is a perspective view of a coil and a magnetic core according to this embodiment. FIG. 3 is a side view of the coil and magnetic core shown in FIG. 2 as viewed from the side.

In the processing method according to the present embodiment, for example, as shown in FIGS. a heating step of heating the end face 104 by arranging the steel plates 104 to face each other along the end face 104 , and applying an electric current to the coil 1 to generate an induced electromotive force in the steel plate 100 .

The magnetic core 5 is a core material mainly composed of iron oxide, silicon, or the like, for example. The magnetic core 5 is formed in a substantially columnar shape, but is not limited to this. The magnetic core 5 may be formed into, for example, a prismatic shape, a conical shape, or the like. Moreover, although the magnetic core 5 is formed linearly, it is not limited to this. At least a portion of the magnetic core 5 may be formed in a curved shape corresponding to the position of the end face 104 of the punched end 103 of the steel plate 100 to be heated, for example.

The coil 1 is formed, for example, by spirally forming a metal wire such as copper. It is more preferable that the distance between the end peripheral surface of the magnetic core 5 and the end surface 104 of the punched end 103 of the steel plate 100 be as small as possible within a range where no spark occurs (for example, the thickness of the steel plate 100 or more). The end of the magnetic core 5 may be covered with an insulator. In this case, the insulator of the magnetic core 5 and the end face 104 of the punched end 103 of the steel plate 100 may be in contact with each other.

An induction heating power source is connected to the coil 1 . The induction heating power supply causes the magnetic core 5 to generate an alternating magnetic field by supplying current to the coil 1 . By arranging the ends of the magnetic core 5 so as to face each other along the end face 104 of the punched end 103 , an induced electromotive force is generated in the steel plate 100 .

As a result, an induced current is generated along the end face 104 of the punched end 103, and the end face 104 is self-heated by Joule heat due to this induced current, so that only the end face 104 can be locally heated. Since only the end face 104 of the punched end 103 can be locally heated, softening of the steel plate 100 as a whole can be suppressed.

In this embodiment, the number of turns of the coil 1 is, for example, 5 as shown in FIGS. By increasing the number of turns of the coil 1 and increasing the inductance of the coil 1, the end surface 104 of the punched end 103 can be heated at a higher temperature in a shorter time.

In this embodiment, a plurality of coils 1 may be arranged on the magnetic core 5 . As a result, the end face 104 of the punched end 103 can be heated at a higher temperature in a shorter time. For example, as shown in FIG. 4 , a pair of coils 1 may be arranged on the magnetic core 5 so as to sandwich the through hole 101 of the steel plate 100 . The direction of current flowing in the upper coil 1 and the direction of current flowing in the lower coil 1 are the same as indicated by the arrows in FIG.
In this case, after the through holes 101 of the steel plate 100 are arranged between the pair of coils 1 , the ends of the magnetic core 5 may be inserted into the through holes 101 of the pair of coils 1 and the steel plate 100 .

The heating temperature of the coil 1 is adjusted, for example, so that the punched end 103 is at 200° C. or more and less than Ac1 point. Heating within this temperature range can properly remove residual strain. In particular, if the steel sheet 100 is heated to the Ac point of 1 or more, the steel sheet 100 undergoes austenite transformation, and when it is air-cooled, it softens and its strength decreases. Therefore, it is preferable to keep Ac below 1 point.

A punched end 103 of the steel plate 100 is formed in a circular hole shape, for example, as shown in FIGS. 2 and 3 . In this way, when the punched end 103 has a hole shape, the induced current flowing through the end face 104 becomes a connected loop, so that the heating can be performed more efficiently. The hole shape of the punched edge 103 is not limited to a circular shape, and may be, for example, an elliptical shape, a square shape, a triangular shape, or the like.

By the way, in the conventional processing method, when a coil is inserted into a small-diameter through-hole formed in a steel plate and high-frequency heating is performed by the coil, an expensive coil made of a wire rod corresponding to the small-diameter through-hole is required. necessary. For this reason, there is a possibility that it will lead to an increase in manufacturing cost. For example, a thin coil wire must have a hollow structure for passing a coolant for cooling, and the thin hollow wire must be spirally formed. For this reason, it is very difficult to manufacture the thin coil wire while considering its durability, which may lead to an increase in cost.

On the other hand, in the processing method according to the present embodiment, for example, as shown in FIG. , is arranged so as to face the end face 104 of the punched end 103 of the steel plate 100 in a non-contact state along the end face 104, and the end face 104 is heated.

The end surface 104 of the punched end 103 of the steel plate 100 is, for example, the inner peripheral surface of the small-diameter through hole 101 formed in the steel plate 100 as shown in FIG. The diameter of through hole 101 is smaller than the diameter of spiral coil 1 . The end of the magnetic core 5 passes through the through hole 101 having a diameter smaller than the diameter of the coil 1 as described above, and faces along the inner peripheral surface without contacting the inner peripheral surface. placed in

As a result, even when the inner peripheral surface of the small-diameter through-hole 101 is to be heated, the end portion of the magnetic core 5 that is actually inserted into the through-hole 101 is aligned with the small-diameter through-hole 101 . It is only necessary to make the diameter smaller, and the wire itself of the coil 1 need not be thinned.

Reducing the diameter of the magnetic core 5 itself can be realized easily and at low cost. Therefore, in the heating step of the processing method according to the present embodiment, the expensive coil 1 made of fine wire is not required, so the manufacturing cost can be kept low.

The end face 104 of the punched end 103 of the steel plate 100 is not limited to the small-diameter through hole 101 formed in the steel plate 100 described above, and may be any end face 104 of the punched end 103 . For example, the punched edge 103 of the steel plate 100 may be a punched edge 103 with an open end face 104 . The ends of the magnetic core 5 may be arranged to face each other along the end face 104 of the punched open end 103 .

In the heating process of the processing method according to the present embodiment, for example, the end face 104 of the punched end 103 is hindered by other members, or the end face 104 of the punched end 103 has a complicated and intricate shape. This is particularly effective when it is difficult to bring a normal heating coil close to the device.

In the heating step of the processing method according to the present embodiment, as described above, it is only necessary to reduce the shape of the magnetic core 5 to be actually heated so as to correspond to the shape of the end face 104 of the punched end 103 to be heated. Reducing the shape of the magnetic core 5 itself can be realized easily and at low cost.

The heating step of the processing method according to this embodiment may be applied to improve the toughness of the small-diameter through-hole 101 . For example, automobile parts and the like often have small-diameter through holes 101 for various reasons such as reference holes and drain holes. On the other hand, high-strength steel sheets are often used for vehicle frame parts in order to reduce weight and increase strength.

These parts receive a large amount of input at the time of collision, and the concentration of stress at the end of the through-hole 101 often leads to cracks starting from the through-hole 101. Therefore, it is necessary to consider the diameter and arrangement of the through-hole 101 in the design. Become. Furthermore, in a high-strength steel plate, although the strength is increased, the toughness is decreased. Therefore, when stress is concentrated on the edge of the through-hole 101, cracks are more likely to occur.

Therefore, it is effective to locally heat the small-diameter through-hole 101 of the frame member using the high-strength steel plate and the portion where stress is likely to concentrate by the heating process of the processing method according to the present embodiment to improve the toughness. is.

FIG. 5 is a perspective view showing a floor side member of the vehicle. A plurality of small-diameter through holes 101 are formed in the floor side member. By the heating step of the processing method according to the present embodiment, these small-diameter through-holes 101 can be locally heated to improve their toughness.

FIG. 6 is a perspective view showing the rocker outer of the vehicle. Similarly, the rocker outer is formed with a plurality of small-diameter through holes 101 . By the heating step of the processing method according to the present embodiment, these small-diameter through-holes 101 can be locally heated to improve their toughness.

Next, analysis results when heating is performed in the heating step of the processing method according to the present embodiment will be described. In the main heating step, the magnetic core 5 is inserted into the inner peripheral surface of the small-diameter through hole 101 formed in the steel plate 100 of GA980 with a thickness of 2.9 mm, and the inner peripheral surface is heated under the following conditions. Is going.

・Initial temperature: 20 [°C]
・ Energization time: 3.0 [seconds]
・Frequency: 350 [kHz]
・Current: 750 [A]

FIG. 7 is a diagram showing CAE analysis results when a small-diameter through-hole of a steel plate is heated under the above conditions. As shown in FIG. 7, by the heating process according to the present embodiment, only the inner peripheral surface of the small-diameter through-hole 101 of the steel plate 100 can be locally heated, and softening of the steel plate 100 as a whole can be suppressed. In addition, in the small-diameter through-hole 101 of the steel plate 100, the maximum temperature is 794.1 ° C. and the minimum temperature is 740.2 ° C., the temperature difference is kept small, and it can be heated well. I understand.

Embodiment 2
In this embodiment, the magnetic core 5 may be arranged so as to be relatively movable in the axial direction of the magnetic core 5 with respect to the coil 1 fixed to a jig or the like. As a result, the end portion of the magnetic core 5 can be easily inserted into the through-hole 101 of the steel plate 100 and arranged by simply moving the magnetic core 5 in the axial direction.

For example, the steel plate 100 to be heated is placed on a jig to which the coil 1 is fixed at a predetermined position. Next, the magnetic core 5 is relatively moved in the axial direction of the magnetic core 5 with respect to the coil 1 , and the end of the magnetic core 5 is inserted into the through hole 101 of the steel plate 100 and arranged in the through hole 101 . do. Thereafter, an electric current is passed through the coil 1 to generate an induced electromotive force in the steel plate 100 , thereby heating the inner peripheral surface of the through hole 101 .

As a result, for example, as shown in FIG. 8, even when the inner peripheral surface of the through-hole 101 of the steel plate 100 of the vertical wall is heated, the steel plate 100 can be easily positioned on a jig or the like, and the magnetic core 5 can be moved to the magnetic core. The end of the magnetic core 5 can be easily inserted into the through-hole 101 of the steel plate 100 simply by relatively moving the magnetic core 5 in the axial direction, and the inner peripheral surface of the through-hole 101 can be locally heated.

For example, the heating process according to the present embodiment is particularly effective when it is difficult to bring the magnetic core 5 closer to the through hole 101 because another member or the like obstructs the through hole 101 of the steel plate 100. is.

Embodiment 3
In the present embodiment, the steel plate molded product punched in the punching step is placed on a heating jig in the heating step and heated. FIG. 9 is a diagram showing an example of a heating jig. The left side view of FIG. 9 shows the state before the steel plate molded product X is placed on the heating jig 400, and the right side view shows the state after the steel plate formed product X is placed on the heating jig 400. .

As shown in FIG. 9, the heating jig 400 includes a magnetic core 5 and a coil 1 for heating the punched end 103 of the steel plate X, a positioning guide 2 for positioning the steel plate X at a predetermined position, and a base portion 3. and have Each coil 1 is connected to an AC power supply 4 that supplies power to each coil 1 .

The shape and arrangement of the positioning guide 2 are set so that the position of the steel plate molded product X is automatically set by simply placing the steel plate molded product X on the positioning guide 2 . The magnetic core 5, the coil 1, and the positioning guide 2 are arranged on the base portion 3 so as to correspond to the shape of the steel plate molded product X and the position of the heating portion.

The positions, numbers, and shapes of the magnetic cores 5 and coils 1 are not limited to the example shown in FIG. 9, and can be set arbitrarily. Similarly, the position, number, and shape of the positioning guides 2 are not limited to the example shown in FIG. 9, and can be set arbitrarily.

By using the heating jig 400 according to the present embodiment, it is not necessary to heat the steel plate product X from above and below while the steel plate product X is gripped as in the conventional art, and the steel plate product X can be easily placed on the heating jig 400. can be heated.

The heating process according to the present embodiment may be performed in an idling process between the punching process and the stretch flanging process, as shown in FIG. The idling process is a process of adjusting the conveying pitch when conveying the steel plate molded product X from the punching process to the stretch flanging process, and is a standby process in which processing is not performed.

As a result, conventionally, after the punching process and before the stretch flanging process, the steel sheet molded product X can be efficiently heated using the idling process in which the stamped steel sheet molded product X is kept on standby. . Therefore, since there is no need to introduce an additional heating step, productivity is improved.

Further, according to this embodiment, by simply placing the heating jig 400 in the idling process in a normal press, the idling process can be converted into a heating process, so the number of processes is not increased. FIG. 11 is a schematic diagram showing an example of processes in the press.

In the press machine 500, for example, while the steel plate molded product X is continuously conveyed by fingers (gripping parts) 501 shown in the lower part of FIG. And the punching process is continuously performed at a predetermined conveying pitch. Therefore, by simply placing the heating jig 400 at a position corresponding to the idling process, the idling process in the press machine 500 can be easily replaced with the heating process.

Note that the heating process may be performed during any process in the press machine 500, such as a molding process or a punching process, as long as the heating jig 400 can be arranged.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1 coil, 2 positioning guide, 3 base part, 4 AC power supply, 5 magnetic core, 100 steel plate, 101 through hole, 102 stretch flange, 103 punching end, 104 end face, 200 punch, 300 flange mold, 400 heating cure tool, 500 press, 501 finger

Claims (9)

The end of the magnetic core that penetrates the helical coil is arranged so as to face the end face of the stamped end of the steel plate in a non-contact state along the end face, and an electric current is applied to the steel plate by passing an electric current through the coil. A heating step of heating the end surface by generating an induced electromotive force,
processing method. The processing method according to claim 1,
The end surface of the punched end of the steel plate is the inner peripheral surface of the through hole of the steel plate,
An end portion of the magnetic core passes through the through hole, is arranged in a non-contact state with the inner peripheral surface, and faces the inner peripheral surface.
processing method. The processing method according to claim 2,
the diameter of the through-hole is smaller than the diameter of the helical coil;
processing method. The processing method according to claim 2 or 3,
The magnetic core is arranged so as to be relatively movable in the axial direction of the magnetic core with respect to the fixed coil,
processing method. The processing method according to claim 4,
moving the magnetic core relative to the coil in the axial direction, inserting the end of the magnetic core into the through hole of the steel plate, and
An electric current is passed through the coil to generate an induced electromotive force in the steel plate, thereby heating the inner peripheral surface of the through hole.
processing method. The processing method according to any one of claims 1 to 5,
In the heating step, the steel plate punched in the punching step is placed on a heating jig and then heated by the coil,
The heating jig has a positioning guide for positioning the steel plate punched in the punching process at a predetermined position, and the magnetic core and coil for heating the end surface of the punched end of the steel plate positioned by the positioning guide. ,
processing method. The processing method according to claim 6,
The heating step is performed during any step in the press,
processing method. The processing method according to claim 7,
Further comprising a stretch-flange step of forming a stretch-flange on the punched end,
The heating step is carried out in an idling step for adjusting the conveying pitch when conveying the steel plate from the punching step to the stretch flanging step,
processing method. The processing method according to claim 8,
At least the punching step and the idling step are continuously performed at a predetermined conveying pitch while the steel plate molded product is continuously conveyed by the gripping portion in the press,
By arranging the heating jig at a position corresponding to the idling process, the idling process is replaced with the heating process,
processing method.

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