JP2008045183A - Method for hardening thin steel sheet-formed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for highly efficiently hardening a thin steel sheet-formed article utilizing heating with low electric power consumption with the use of a small-scaled high frequency electric source. <P>SOLUTION: A method for hardening the thin steel sheet-formed article is provided for induction-heating a hardening objective region 11 of the thin steel sheet-formed article being a material 10 to be treated then rapidly cooling the hardening objective region 11. The method is characterized in that the plurality of bodies 13, 14 of the materials 10 are mutually coupled (16) with conductive relation (15) such as forming a closed circuit in which the respective hardening objective regions 11 of the bodies 13, 14 are continued as a series-endless state and such that positional relation between the respective bodies are fixed, and the plurality of bodies 13, 14 temporarily assembled in a form of materials 13+14 to be treated, then the high frequency induction current is conducted to an inductor 17 generating magnetic flux in the same direction as the axis of the assembly by disposing the inductor 17 outside the assembly, thereby the induction current circulating the closed circuit is generated in such a state that a coupling coefficient as an index of the coupling degree of the inductor with the materials is increased and the plurality of the hardening objective regions 11, 11 are simultaneously hardened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for quenching a thin steel sheet molded article, for example, a thin steel sheet molded article constituting an automobile body is used as an object to be processed, and heating to a quenching temperature and subsequent quenching are applied to a region requiring strengthening. It relates to a quenching method for a thin steel sheet molded product.

Regarding quenching of thin steel sheet molded products, when induction heating is performed up to the quenching temperature using a pressed product made of a thin steel sheet with a thickness of 0.6 mm to 3.2 mm as the object to be processed, the entire heated area is induction heated at the same time. A technique for induction heating by arranging an inductor having a zigzag circuit configuration has been developed so that the heat input distribution can be easily adjusted even by a heating method (see, for example, Patent Document 1).
Also, a technology for temporarily stopping or temporarily reducing high-frequency energization so that uneven temperature rise is reduced even with a single heating method when induction heating to a quenching temperature, using a press-formed product made of a thin steel plate as a workpiece, It has been developed (see, for example, Patent Document 2).

  Furthermore, a single article to be processed is heated once in order to heat a heated region on the article to be processed, such as a molded article or plate-like body made of a thin steel sheet having a thickness of 3.2 mm or less. When applying induction heating of the system, the end of the heated area is connected by a conductive member placed outside the object to be processed so that the induced current is concentrated in the heated area. A technique for forming a circulation electric circuit that provides the above has been developed (see, for example, Patent Document 3). Incidentally, the current flowing through the short-circuited portion of the circulation circuit does not contribute to induction heating and only brings about copper loss. In this technique, when there are a plurality of heated regions, these regions are connected in series with a conductive member to form a closed circuit (closed circuit), or a clamping tool is provided at the end of the conductive member. It has also been proposed to make the conductive member detachable from the thin steel sheet molded product. That is, in this technique, not only when the heating area is single, but also when the heating area (quenching target area) is plural, the object to be heated at a time is single.

JP 2004-353035 A JP-A-2005-015906 JP 2005-054225 A

By the way, the induction heating in the above-mentioned patent documents 1 to 3 is referred to as a “transverse magnetic flux method” in which the inductor is operated in an electromagnetic mode in which the magnetic flux is disposed so as to penetrate the plate surface of the workpiece. This is induction heating.
In this transverse induction heating, since the coupling coefficient between the inductor and the object to be processed (representing the strength of electromagnetic coupling and governing the ratio of induced current to inductor current) is low, Some of these become reactive currents that do not contribute to induction heating. Therefore, it is necessary to energize an extra current that is considerably larger than the current required for heat input, and therefore it is necessary to set the scale of the high-frequency power source larger than that of the high coupling coefficient method, resulting in an increase in equipment cost. . Power consumption is also increased by increasing copper loss. These are disadvantageous factors in the processing of press-formed products that are mass-produced.

Therefore, induction heating of the region to be quenched (heated region) can be performed not by a transverse method but by a method with a higher coupling coefficient between the inductor and the object to be processed, so that the scale and power consumption of the high-frequency power source can be reduced. This is a basic issue.
Moreover, in the conventional quenching method for a thin steel sheet molded product as described above, the object to be treated is single in any case. For this reason, when processing a large number of articles, it takes time to process one by one, and simply increasing the number of processing and performing parallel processing or parallel processing increases the equipment cost. End up.
Therefore, it is a further problem to simultaneously process a plurality of objects to be processed for improving efficiency.

  The method of quenching a thin steel sheet molded article of the present invention (Claim 1) was devised in order to solve such a problem. The thin steel sheet molded article is defined as an object to be processed, and is defined in the object to be processed. A quenching method for a thin steel sheet molded article, in which an induction current is generated in the region by induction heating to be heated to a quenching temperature and then rapidly cooled, and the heating to the quenching temperature is performed on the to-be-quenched region. A plurality of processed objects are connected to each other so as to form a closed circuit in which the quenching target regions belonging to the respective bodies are connected in a series endless manner, and the positional relationship between the bodies is fixed. By interconnecting and temporarily assembling in the form of an assembly to be processed, an inductor that generates magnetic flux in the same direction as the axis of the assembly is placed outside the assembly, and high-frequency current is passed through the inductor, The closed circuit is configured by generating an induced current that circulates around the closed circuit. The performed quenching target area to induction heating that, characterized in that.

  Moreover, the quenching method for a steel sheet molded product according to the present invention (Claim 2) embodies the above solution by a single heating method, and specifically, the steel sheet molding according to Claim 1 above. Further, the quenching target area is defined as an elongated shape in the workpiece, and the ring-shaped closed circuit is formed so as to face the ring-shaped closed circuit formed continuously in the longitudinal direction. An inductor is arranged, and the induction heating is performed in a state where the inductor is allowed to stand with respect to the closed circuit.

  Furthermore, the method for quenching a thin steel sheet molded product according to the present invention (Claim 3) is one in which the above solution is embodied by a moving heating method. Specifically, the thin steel plate molded product according to Claim 1 above. Further, the quenching target area is an entire area of the workpiece to be processed except for an end portion to be used for the interconnection, and a cylindrical closed circuit formed by connecting the entire area. A ring-shaped inductor or a multi-winding inductor is arranged facing each other, and the induction heating is performed while the inductor is caused to travel relatively in the axial direction with respect to the cylindrical closed circuit. And

  Moreover, the quenching method for a thin steel sheet molded product according to the present invention (Claim 4) is one in which the above-mentioned solution means is embodied by the use of a connector, and specifically, the interconnection in the conductive connection is performed. It is characterized in that it is carried out using a connecting tool provided with a clamping force gripping function part at both ends of the crossing conductor.

In the quenching method of the thin steel sheet molded article of the present invention (claim 1), the idea is to induction heat the processed object assembly in which a plurality of processed objects are connected endlessly, Inductive heating in an electromagnetic mode in which the direction of the magnetic flux of the inductor coincides with the axis of the workpiece assembly to be heated, in other words, the heated body is arranged in an endless ring surrounding the magnetic flux of the inductor As a result, induction heating with a high coupling coefficient method (so-called “coaxial magnetic flux method”) that ensures strong electromagnetic coupling is realized, and the scale and power consumption of the high-frequency power source can be reduced. Problems are solved. Moreover, since it was set as the structure which heats a to-be-processed object in a mutually fixed state, it will be able to heat a multiple body simultaneously and the said further subject is also solved collectively.
Therefore, according to the present invention, it is possible to realize a quenching method for a thin steel sheet molded product with high productivity, which is a small-scale power supply facility and high-efficiency processing with low power consumption.

In the case of the configuration of the present invention that realizes induction heating in the coaxial magnetic flux electromagnetic mode, the engagement coefficient of the inductor with the workpiece is usually a high value such as 0.6 to 0.8, although it depends on the shape. . On the other hand, it is difficult to secure 0.5 even by induction heating in the transverse magnetic flux electromagnetic mode. That is, the fact that coaxial magnetic flux heating can be realized means that the required power supply scale and power consumption are nearly half that of transverse induction heating.
When the present invention is applied to quenching by the moving heating method, the required power supply scale can be further reduced, but at the cost of longer processing time. However, the price is reduced by a fraction of the simultaneous processing of multiple bodies. The moving heating has the advantage that the heat input distribution in the traveling direction can be adjusted by adjusting the traveling speed and the input power, but this advantage can also be utilized in the method of the present invention.

  It will be described in detail with numerical examples. Assuming that the typical thickness of the workpiece to which the present invention is applied is 0.6 mm to 3.2 mm, the preferred frequency of high-frequency energization in the quenching method for thin steel sheet molded products of the present invention is 1 kHz to 50 kHz. . This frequency region is different from 0.1 MHz to 5 MHz, which is a suitable frequency region for surrounding induction heating, in which a single plate is sandwiched from the front and back by an inductor and induction heating is performed. Since it is an easy range, the problem of high equipment costs due to frequency does not occur.

  In the present invention, 2 to 4 bodies that can easily maintain the shape of the aggregate are recommended as the number of bodies to be processed that constitute the aggregate of objects to be processed, but are not limited thereto. Furthermore, it is useful for improving productivity to multistage the assembly in the axial direction. As a method of connection between a plurality of bodies, for example, a method in which adjacent long sides are brought into direct contact and connected in an electrically conductive state, or an electrically conductive state is indirectly set by interposing a rigid transition conductor or the like. A method of connecting adjacent long sides while being established can be exemplified.

In the present invention, since there is no or minimal interposition of the connection conductor in the electric circuit around which the induced current circulates, there is substantially no concern that a copper loss due to the interconnection is newly added.
That is, in the case of mutual connection by direct contact, the induced current flows only in the quenching target area of the object to be processed, so that no extra power is consumed by the conductive member for connection.
In addition, even in the case of interconnection with a crossing conductor interposed as a conductive member for connection, since the connection points of the workpieces are close enough to allow direct contact, the path length of the induced current in each individual quenching target area Since it is easy to shorten or increase the path length of the induced current in the transition conductor, for example, it is easy to reduce the circuit resistance by orders of magnitude, for example, 1/10 or less, so that the copper loss in the transition conductor is sufficiently reduced. be able to.

  The procedure and the like of an embodiment (first embodiment) of the method for quenching a thin steel sheet molded product of the present invention will be described with reference to the drawings. 1A is a perspective view of the concave side of the workpiece 10, FIGS. 1B and 1C are perspective views of the convex side of the workpiece 10, and FIG. (E) is a longitudinal sectional view of the workpiece assembly 13 + 14 and the support mechanism 16, and (f) is a plan view of the workpiece assembly 13 + 14 and the induction heating device 17 + 18. g) is a plan view of an object assembly and induction heating apparatus made up of three objects to be processed, and (h) is a plan view of an object assembly made up of four objects to be processed and an induction heating apparatus. . Note that the high-frequency power source is simplified by symbols.

  The workpiece 10 (see FIGS. 1 (a) and 1 (b)) is, for example, a press-formed product having a chevron-shaped cross section made of a carbon steel plate suitable for quenching used for a part of an automobile body, and has a thickness of 2 mm. With a height of around 50 mm and a length of 800 mm, the width of the flat part at the top of the mountain is 20 mm, the width on the lower end side is 80 mm including the flanges on both sides (each 10 mm wide), and the entire area is subject to quenching This is a region 11 (see the double hatched portion in FIG. 1C). The long side portion 12 and the inclined portion between the long side portion 12 and the quenching target region 11 are not heated.

  In such an object 10 to be processed, a plurality of bodies 13 and 14 are assembled in the form of an object to be processed 13 + 14 (see FIG. 1D). At that time, for example, two flexible conductors 15 having a large current cross-sectional area in which a plurality of twisted copper wires are arranged in parallel are used, and one end of the quenching target region 11 of the workpiece 13 and the quenching target region 11 of the workpiece 14 are used. One end of the workpiece 13 is connected by the first conductor 15, and the other end of the quenching target region 11 of the workpiece 13 and the other end of the quenching target region 11 of the workpiece 14 are connected by the second conductor 15. The As long as electrical continuity is obtained, the connection may be performed by using a sandwiching tool (see, for example, Patent Document 3) or by another method. By interconnecting the objects to be processed 13 and 14 by such conduction connection, a closed circuit (11 + 15 + 11 + 15) is formed in which the quenching target regions 11 belonging to each of the multiple bodies 13 and 14 are connected in series endlessly. . That is, the plurality of quenching target regions 11 and 11 are connected in the longitudinal direction to form a ring-shaped closed circuit (11 + 15 + 11 + 15).

  When the multiple bodies 13 and 14 of the workpiece 10 are temporarily assembled in the shape of the workpiece aggregate 13 + 14, the workpieces 13 and 14 are arranged to face each other and the positional relationship between the bodies is fixed. To interconnect. The opposing arrangement is intended to make the temperature distribution uniform when the heating target area 11 is heated by inducing induction current in the quenching target area 11 by induction heating and the heating state and heat dissipation state are uniform. Then, the quenching target area 11 is kept away and the long side 12 side is brought close to face each other. Since the conductor 15 is a flexible transition conductor and is not useful for fixing the positional relationship, in order to fix the positional relationship between the bodies 13 and 14, for example, the pair of the long side portions 12 does not cause conduction between the pair. It is preferable to use a support mechanism 16 that holds and grips with (see FIG. 1E).

An induction heating apparatus including an inductor 17 and a high-frequency power source 18 is used to induction-heat such an object assembly 13 + 14 by a single heating method (see FIG. 1 (f)). The inductor 17 is made of, for example, a water-coolable copper tube and is disposed outside the workpiece assembly 13 + 14. For example, it is formed in a ring shape so as to face each other in the vicinity of about 5 mm to 10 mm.
The inductor 17 is arranged with the inductor 17 facing the closed circuit (11 + 15 + 11 + 15).

At that time, the inductor 17 is disposed in a state where a magnetic flux is generated in the same direction as the axis of the workpiece assembly 13 + 14 and the inductor 17 is left stationary with respect to the narrow closed circuit (11 + 15 + 11 + 15). To do. Then, a high frequency of, for example, about 10 to 20 kHz based on the thickness of the quenching target region 11 is supplied from the high frequency power source 18 and the inductor 17 is energized with a high frequency.
As a result, an induced current that circulates around the closed circuit (11 + 15 + 11 + 15) is generated, and the two quenching target regions 11 and 11 that constitute the closed circuit are induction-heated simultaneously.
In this way, induction heating for the two workpieces 10 is performed quickly and accurately in one shot.

In addition, when three to-be-processed objects 10 as mentioned above are collectively heated by induction, the to-be-processed object 10 is arrange | positioned at each edge | side of an equilateral triangle, and the conductor 15 is arrange | positioned at each vertex of an equilateral triangle (FIG. 1). (See (g)). As a result, a closed circuit (11 + 15 + 11 + 15 + 11 + 15) is formed in which the quenching target regions 11, 11, 11 belonging to each of the plurality of bodies are connected in a series endless manner.
Further, in the case where four of the above-described objects to be processed 10 are collectively heated by induction, the objects to be processed 10 are arranged on each side of the square, and the conductors 15 are arranged on each vertex of the square (FIG. 1 (h )reference). This also forms a closed circuit (11 + 15 + 11 + 15 + 11 + 15 + 11 + 15) in which the quenching target regions 11, 11, 11, 11 belonging to each of the plurality of bodies are connected in series endlessly.

In any case, after the workpieces 10 are fixed to each other, the ring-shaped closed circuit is formed so that the elongated quenching target region 11 is opposed to the ring-shaped closed circuit formed continuously in the longitudinal direction. Inductive heating is performed in a state where the inductor 17 is placed and the inductor 17 is allowed to stand against a narrow closed circuit. Thereby, since the flow path of the induced current is regulated by the proximity effect by the opposing inductor, the induced current is accurately concentrated even if the quenching target region is elongated. Moreover, a plurality of objects to be processed can be processed efficiently. For example, in the case of FIGS. 1D to 1F, the heating operation for raising the quenching target region 11 to a temperature of slightly higher than 900 ° C. set as the quenching temperature in a short time of less than 1 minute is a high frequency of 20 kVA. This can be done by operating the power supply with a margin in output.
After the heating, the entire heating unit is rapidly cooled at the same time by a method such as water cooling (see, for example, Patent Documents 1 to 4), and then the interconnects of the objects to be processed are released to finish the heat treatment of each object 10 to be processed.

  The procedure and the like of another embodiment (second embodiment) of the method for quenching a thin steel sheet molded product of the present invention will be described with reference to the drawings. 2A and 2B are perspective views of the convex side of the object 20 to be processed, FIG. 2C is a perspective view of an object assembly 23 + 24 made up of two objects 23 and 24, and FIG. Is a perspective view showing an example of the connection of the long side portions 22, 22, (e) is a perspective view of the workpiece assembly 23 +24 and the induction heating device 27 +28, and (f) is an end view thereof.

In this embodiment, the workpiece 20 is a thin steel plate molded product obtained by bending a rectangular flat plate into a bowl shape, the plate thickness is 1.2 mm, the height is 60 mm, the length is 600 mm, the top width is 80 mm, and the lower end side is The width (including the flange) is 105 mm. Interconnection in conduction coupling is performed by direct contact, and induction heating is performed by a moving heating method instead of a single heating method.
The workpiece 20 (see FIG. 2A) has the same cross-sectional shape everywhere in the longitudinal direction. The quenching target region 21 is the entire area of the workpiece 20 excluding the long side portion 22 that is an end portion provided for interconnection (see the double hatched portion in FIG. 2B).

When the two objects 23 and 24 of the object to be processed 20 are assembled in the form of the object to be processed 23 + 24, the objects to be processed 23 and 24 are arranged to face each other as in the above example (see FIG. 2C). Unlike the example, it is performed until the positional relationship between each body is fixed by the conductive connection in the direct contact state described below. In order to perform the mutual connection in the continuity connection in a direct contact state (see FIG. 2D), the long side portions 22 and 22 of the pair of workpieces 20 and 20 provided for the connection, that is, the quenching target region 21. For example, the long side portions 22, 22 of the long side portions 22, 22 are overlapped with each other by using a pinching tool 26 (detailed structure not shown) of a spring pressure sandwiching type in which end portions on both sides of each other are overlapped with each other and, for example, pressurizing ridges are arranged at multiple points. It is good to make a multipoint contact along the longitudinal direction and interconnect. Such interconnection by the clamping tool 26 also serves to maintain the temporarily assembled shape of the workpiece assembly 23 + 24 in addition to the electrical connection of the workpiece assembly 23 + 24.
Then, when the long sides 22 of the workpieces 23 and 24 are directly attached and provisionally assembled by such a connecting method, the workpiece aggregates 23 + 24 are cylindrical in which all of the quenching target areas 21 and 21 are connected. Closed circuit (21 + 21) is formed.

  Although only the inductor 27 and the high frequency power supply 28 are shown here as the induction heating device (see FIGS. 2E and 2F), a moving mechanism (not shown) is also provided. It is made to run relatively in the axial direction, that is, the longitudinal direction with respect to the closed electric circuit (21 + 21). The inductor 27 is formed in a ring shape so as to face the quenching target region 21 of the workpiece 23 and the quenching target region 21 of the workpiece 24 close to a place where an induced current can be induced, It is opposed to the cylindrical closed circuit (21 + 21), specifically, is disposed outside the closed circuit so as to be opposed to the annular portion in one transverse section of the closed circuit.

  The inductor 27 is made of a copper tube and has a water cooling structure in which the hollow portion is a cooling water channel. Further, the inductor 27 is provided with a large number of small holes in a stepping stone shape (not shown). Quenching proceeds in a moving manner by following the cooling of the heating part by the inductor 27 with water jetted from the hole. In this case, it is preferable to perform vertical movement so that draining is easy. Note that this water cooling may be performed at once after moving heating over the entire length, but in that case, it is desirable to perform program heat input so as to compensate for the inclination of the heating temperature due to heat radiation during moving heating. .

While the inductor 27 is energized with high frequency from the high frequency power supply 28, the inductor 27 is caused to travel from one end side to the other end side of the workpiece assembly 23 + 24 at a constant speed or a variable speed based on the heat input distribution specification. . Then, a magnetic flux in the same direction as the axis of the workpiece assembly 23 + 24 is generated, thereby generating an induced current circulating around the closed circuit in the annular portion of the closed circuit (21 + 21) facing the inductor 27. Of the two quenching target areas 21 and 21 that are configured, the part facing the inductor 27 is simultaneously induction-heated.
Then, when the inductor 27 finishes traveling from end to end of the workpiece assembly 23 + 24, induction heating for the two workpieces 20 is completed.

  Even in the moving heating method, since the current density of the induced current flowing in the annular portion facing the inductor 27 is as large as in the one-shot heating method, overheating due to contact resistance is likely to occur in the interconnected portion. That worry is useless. This is because by increasing the spacing between the inductor 27 and the object to be processed in the vicinity of the interconnecting portion, the induced current flow path regulating action by the inductor 27 is weakened, and the induced current is distributed over the entire length of the long side portion 22. This is because the current density in the interconnecting portion can be remarkably reduced by removing the flow path.

The procedure and the like of another embodiment (third embodiment) of the method for quenching a thin steel sheet molded product of the present invention will be described with reference to the drawings. 3A and 3B are perspective views of the workpiece assembly and the inductor 27 including four workpieces 20 and FIG. 3C is an enlarged view of a portion C surrounded by a two-dot chain line. is there.
In this embodiment (see FIGS. 3A and 3B), the interconnection in the continuity connection is performed with the crossing conductor 29 interposed. The workpiece 20 is the same as that of the second embodiment described above, but four bodies are processed together. Induction heating is performed by a moving heating method.

  The transition conductor 29 (see FIG. 3 (c)) is formed by connecting an outer conductor 29a and an inner conductor 29b made of metal or the like with a small bolt (not shown) facing each other and using this to be processed When connecting the long side portions 22 of the object 20, the long conductors 22 are inserted into the gap from both sides in a state where a gap is formed between the outer conductor 29a and the inner conductor 29b, and the outer conductor is then tightened by bolting or the like. By narrowing the gap between the inner conductor 29b and the inner conductor 29b, the workpiece 20 is clamped and gripped on both sides. In the illustrated example, the four workpieces 20 are temporarily assembled in a cylindrical shape so that each conductor 29 grips the workpieces 20 on both sides substantially orthogonally, but the cross-section perpendicular to the longitudinal direction. Since the moving heating can be appropriately performed if the shape is the same everywhere in the longitudinal direction, the present invention can be applied even if the workpiece 20 is three bodies or five bodies or more.

When the output of the high-frequency power source 18 is small, the ring-shaped inductor 27 made by only one winding is arranged outside the workpiece assembly (20 + 20 + 20 + 20) to perform moving heating (see FIG. 3A). When there is a margin in the output of the high-frequency power source 18, the inductor 27 wound in a solenoid shape or a multi-stage ring shape is placed outside the workpiece assembly (20 + 20 + 20 + 20) to perform moving heating (FIG. 3 ( b)).
Also in the case of this moving heating method, it is desirable to perform the moving type quenching as a moving type in which the rapid cooling after heating is followed by heating. After quenching, the workpiece aggregate is disassembled to obtain a plurality of reinforced molded products.

[Others]
In the case of moving heating and quenching in the case of FIG. 2, the quenching process at a quenching temperature of over 900 ° C. and a moving speed of 3.3 mm / s (required time: 3 minutes) by 20 to 50 kHz high-frequency energization is shown in FIG. ~ (F) can be performed with a high-frequency power supply of 20 kVA and FIG.
The connection between the objects to be processed 20 is convenient using the detachable type as described above, but may be a fixed type such as crimping or welding as long as disassembly can be performed in a short time.

  A typical application of the present invention is a quenching method in which a press-molded product for automobile body construction is subjected to quenching after induction heating.

About one Embodiment (1st form) of this invention, the quenching method of a thin steel plate molded article is shown, (a) is the concave side perspective view of a to-be-processed object, (b) and (c) are the convex sides of a to-be-processed object. (D) is a perspective view of a workpiece assembly composed of two workpieces, (e) is a longitudinal sectional view of a workpiece assembly consisting of two workpieces, and a support mechanism. (f) is a plan view of a workpiece assembly and induction heating apparatus made up of two workpieces; (g) is a plan view of a workpiece assembly and induction heating device consisting of three workpieces; h) is a plan view of an object assembly including four objects to be processed and an induction heating device. About other embodiment (2nd form) of this invention, the quenching method of a thin steel plate molded article is shown, (a) And (b) is a convex side perspective view of a to-be-processed object, (c) is two to-be-processed The perspective view of the to-be-processed object assembly which consists of a thing, (d) is a perspective view which shows an example of a long side part connection, (e) is the perspective view of the to-be-processed object assembly which consists of two to-be-processed objects, and an induction heating apparatus FIG. 4F is an end view thereof. About other embodiment (3rd form) of this invention, the hardening method of a thin steel plate molded article is shown, The perspective view of the to-be-processed object aggregate | assembly and inductor which (a) and (b) consist of four to-be-processed objects FIG. 4C is an enlarged view of a portion C surrounded by a two-dot chain line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... To-be-processed object (thin steel plate molded product), 11 ... Quenching object area | region, 12 ... Long side part,
13, 14 ... object to be processed (processed object aggregate), 15 ... flexible conductor,
16 ... support mechanism, 17 ... inductor, 18 ... high frequency power supply,
20 ... object to be treated (thin steel plate molded product), 21 ... quenching target area, 22 ... long side part,
23, 24 ... object to be processed (processed object aggregate), 26 ... pinching tool (direct contact conduction means),
27 ... Inductor, 28 ... High frequency power supply, 29 ... Transition conductor

Claims (4)

  A thin steel plate molded article which is formed by using a thin steel plate molded article as an object to be processed, and heating a quenching target area defined in the object to be processed by induction heating to the quenching temperature by induction induction in the area. In this quenching method, heating to the quenching temperature is performed so that a plurality of the objects to be processed form a closed electric circuit in which the regions to be quenched that belong to each of the plurality of bodies are connected in series endlessly. The inductors are connected to each other so that the positional relationship between the bodies is fixed and connected to each other and temporarily assembled into a workpiece assembly, and an inductor generating a magnetic flux in the same direction as the axis of the assembly is provided. The induction hardening is performed by inductively heating the region to be quenched that forms the closed circuit by generating an induced current that circulates the closed circuit by applying high-frequency current to the inductor by placing the inductor outside the body. Quenching method for thin steel sheet molded products.   The quenching target region is elongated and defined in the workpiece, and a ring-shaped inductor is disposed so as to face a ring-shaped closed circuit formed in a continuous manner in the longitudinal direction of the region. The method for quenching a thin steel sheet molded article according to claim 1, wherein the induction heating is performed in a state where the steel sheet is left stationary with respect to the closed circuit.   The quenching target area is the entire area of the workpiece except for the end portion used for the interconnection, and a ring-shaped inductor facing the cylindrical closed circuit formed by connecting the entire area. The thin coiled inductor according to claim 1, wherein a plurality of wound inductors are arranged, and the induction heating is performed while the inductors travel relatively in the axial direction with respect to a cylindrical closed circuit. A quenching method for steel sheet molded products.   4. The thin connection according to claim 1, wherein the connection in the conductive connection is performed using a connection tool provided with a clamping gripping function portion at both ends of the crossing conductor. A quenching method for steel sheet molded products.

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