JP6229223B2 - Method for manufacturing thin three-dimensional body - Google Patents

Description

  The present invention relates to a method for manufacturing a thin three-dimensional body having regions with different strengths.

  Conventionally, thin three-dimensional bodies having regions with different strengths in one member have been used for automobile parts and the like. As a method of manufacturing this thin three-dimensionally shaped body, a method of forming regions having different strengths by heat-treating a member made of a single steel material is known.

  For example, Patent Document 1 below proposes a method of manufacturing a member having regions having different strengths by hot press forming in which cooling is performed while press forming after heating. In this Patent Document 1, a coolant is sprayed on a partial region of the molding material during energization heating, and the quenching region is limited by maintaining the region below the quenching temperature, and then cooling while performing press molding. A thin three-dimensional body having regions with different strengths was manufactured.

  In the following Patent Document 2, a press working method capable of quenching a partial region of a molded product is proposed. In Patent Document 2, the current density is varied depending on the shape of the plate material to be pressed, and after heating a part of the plate to a temperature equal to or higher than the quenching temperature, the member is pressed and cooled to manufacture a member having regions having different strengths. .

  It has been conventionally performed to improve the toughness and the like by tempering the entire quenched member. In that case, the tempering process was heat-treated by being housed in a heating furnace set at a predetermined temperature, heated to a predetermined tempering temperature range, and cooled.

JP 2010-179317 A Japanese Patent No. 4563469

However, as in Patent Documents 1 and 2, it is known that the heating method in which a pair of electrodes are brought into contact with each other to be heated by electric current easily varies in temperature. For example, if the cross-sectional area changes between the pair of electrodes at an intermediate position, the current density becomes non-uniform accordingly, resulting in variations in the heating temperature. Further, when a temperature difference occurs in the energization path, a difference occurs in the resistance value, resulting in a large variation in the heating temperature.
In the quenching treatment, it is sufficient that the melting point is equal to or lower than the melting point and equal to or higher than the A1 or A3 transformation point. Therefore, even if the temperature is somewhat varied by heating by energization heating, it is possible to perform quenching accompanying press working. However, in the case of tempering, the properties are likely to vary depending on the tempering temperature, and the allowable range of variation in the heating temperature is narrow. For this reason, conventionally, it is common to heat and cool by a heating furnace maintained at a predetermined temperature instead of energization heating.
However, a heating apparatus using a heating furnace is likely to be larger than a heating apparatus that performs current heating. In particular, when a large number of workpieces are manufactured with a short tact time as in an automobile part, a larger heating furnace is required, and the equipment for tempering is significantly enlarged.

  Then, an object of this invention is to provide the manufacturing method of a thin-walled solid-shaped body which can form a tempering area | region with simple equipment.

The manufacturing method of a thin three-dimensional body of the present invention that achieves the above object is to energize a workpiece having a thin three-dimensional shape by quenching a workpiece to form a quenching region, and bringing a pair of electrodes into contact with the continuous surface of the quenching region. In the method of manufacturing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempering region by heating at least a part of the quenching region to a predetermined tempering temperature range and tempering the workpiece, A pair of electrodes, each of which has a pair of electrodes facing each other, and the pair of electrodes are spaced apart from each other in the axial direction of the workpiece to sandwich the workpiece, Touch the surface.

In this manufacturing method, it is preferable to perform the tempering process by bringing a pair of electrodes into contact with a continuous region of the workpiece having a constant cross-sectional shape.
In this manufacturing method, a plurality of tempering regions can be formed by heating a plurality of portions of the quenching region to different tempering temperature ranges.
The method for producing a thin three-dimensional body of the present invention includes quenching a workpiece having a thin three-dimensional shape to form a quenching region, bringing a pair of electrodes into contact with a continuous surface of the quenching region, and energizing the workpiece. In a method of manufacturing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempering region by heating a part to a predetermined tempering temperature range and performing a tempering treatment, a plating treatment was performed after quenching Tempering treatment can also be performed on the workpiece.

The method for producing a thin three-dimensional body of the present invention includes quenching a workpiece having a thin three-dimensional shape to form a quenching region, bringing a pair of electrodes into contact with a continuous surface of the quenching region, and energizing the workpiece. In the method of manufacturing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempering region by heating a part to a predetermined tempering temperature range and performing tempering treatment, at least of quenching treatment and tempering treatment On the other hand, the post-processing region may be formed by suppressing the temperature rise in the region corresponding to the heat removal member by arranging and heating the heat removal member on the surface of the workpiece. In that case, it is preferable to keep the temperature of the region corresponding to the heat removal member below the quenching temperature range in the quenching process and below the tempering temperature range in the tempering process.

According to the present invention, since a part of the region is heated by bringing a pair of electrodes into contact with the surface of the quenching region and energizing, the tempering region is formed so that the shape change is small and the shape change is a monotonous region. If it sets, even if it is a solid | 3D-shaped workpiece | work, the area | region can be accurately heated to the desired tempering temperature range, and can be tempered. Therefore, a desired tempering region can be formed in a part of the quenching region in a three-dimensional workpiece.
In addition, since the work is energized from the pair of electrodes, it is not necessary to use a large facility such as a heating furnace. As a result, it is possible to provide a method for manufacturing a thin three-dimensional body that can form a tempering region with simple equipment.

In 1st Embodiment of this invention, it is a conceptual diagram explaining the hardening process of a workpiece | work. In 1st Embodiment of this invention, it is a conceptual diagram explaining the tempering process of a workpiece | work. In 2nd Embodiment of this invention, it is a conceptual diagram explaining the tempering process of a workpiece | work. In 3rd Embodiment of this invention, it is a conceptual diagram explaining the tempering process of a workpiece | work.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
In order to manufacture a thin three-dimensional body in the first embodiment, a workpiece W having a thin three-dimensional shape is prepared, the workpiece W is subjected to quenching treatment to form a quenching region Rh, and tempering to a part of the quenching region Rh. By performing the treatment, the tempering region Rt is formed.

The workpiece W used in this manufacturing method is made of a steel material that can be electrically heated and hardened, and has a thin three-dimensional shape. The thin wall may be any thickness that does not cause a temperature distribution in the thickness direction during quenching and tempering.
Although the shape of the workpiece | work W is not specifically limited, What has the area | region which continues in one direction with a fixed cross-sectional shape is good. The workpiece W of the first embodiment is a cylindrical body such as a square pipe in which a pair of side walls continuous in the longitudinal direction is formed with a substantially uniform thickness and a constant width.

As shown in FIG. 1, the heating device used in the manufacturing method according to the first embodiment supplies a pair of electrodes 11 and 12 that are spaced apart from each other and supplies power between the pair of electrodes 11 and 12. Power supply facility 15. The power supply facility 15 is configured such that current, voltage, and the like can be adjusted.
The pair of electrodes 11, 12 is composed of a pair of counter electrodes 11, 11 or counter electrodes 12, 12 that are arranged opposite to each other and have the same polarity. The surfaces of the electrodes 11 and 12 that come into contact with the workpiece W have shapes corresponding to the surface shape of the workpiece W, and the workpiece W can be clamped so as to be in close contact with the outer surfaces of the pair of side walls of the workpiece W. It has become. The pair of electrodes 11 and 12 according to the first embodiment are arranged in a direction intersecting with the longitudinal direction of the workpiece W and cross the entire width of both side walls of the workpiece W. In contact.

In the manufacturing method of the first embodiment, the workpiece W is first quenched by using the above-described apparatus.
The quenching method may be performed by heating the whole using a heating furnace, but here, as shown in FIG. 1, by energizing the pair of electrodes 11 and 12 in contact with both ends of the workpiece W, Heat to a predetermined temperature or higher. In the quenching treatment, the workpiece W is heated to a temperature above the quenching temperature range, that is, the A1 transformation point or the A3 transformation point to austenite, and then rapidly cooled to change the main structure into a martensite phase, a bainite phase, or a martensite and bainite phase. do it.
The rapid cooling method can be performed, for example, by bringing a coolant into contact therewith.
Here, the electrodes 11 and 12 are respectively brought into contact with the entire width of both ends of the work W and energized, so that the entire work W is heated and brought into contact with the cooling liquid, and is hardened at both ends. A quenching region Rh is formed in the workpiece W in a state where the region Rm is provided. The material region Rm may be used as a post-processing region for performing post-processing such as press processing such as trim processing, piercing processing, and welding processing or mechanical processing in a post-process.

  Next, the workpiece W that has been quenched is subjected to a plating treatment such as galvanization, and the entire surface is covered with a plating layer. Although the plating treatment is optional, in the first embodiment, galvanization is performed for the purpose of rust prevention.

Thereafter, tempering is performed on the plated workpiece W.
In the tempering process, as shown in FIG. 2, the pair of electrodes 11 and 12 are brought into contact with each other so as to sandwich a predetermined region of the continuous surface of the quenching region Rh. Since the cross section perpendicular to the longitudinal direction of the workpiece W is continuous in a substantially constant shape with a substantially uniform thickness along the longitudinal direction, the pair of electrodes 11 and 12 are brought into contact with positions spaced apart from each other in this region. As a result, a part of the quenching region Rh can be energized with a substantially uniform current density and can be heated substantially uniformly. And a tempering process is performed by cooling after a heating.

At the time of energization heating, it is preferable to energize between the pair of electrodes 11 and 12 under a milder condition than the quenching process, and to heat the temperature in the range of the preset region Rt as uniform as possible. Here, the length in which one electrode 11 is in contact with the workpiece W and the length in which the other electrode 12 is in contact with the workpiece W are the same, and are arranged so as to be orthogonal to the longitudinal direction of the workpiece W and to be parallel to each other. ing. Therefore, when energized from the pair of electrodes 11 and 12, the current density can be made substantially uniform throughout the preset region Rt, and the region Rt can be heated as uniformly as possible.
Further, the pair of electrodes 11, 12 has a pair of counter electrodes 11, 11 or counter electrodes 12, 12 facing each other, and the counter electrodes 11, 11 or the counter electrodes 12, 12 are the axes of the workpiece W. The side surfaces are in contact with each other so as to sandwich the workpiece W at positions separated in the direction. Therefore, it is possible to heat the counter electrode 11 or 11 or the counter electrode 12 or 12 with the same potential on the upper surface and the potential on the lower surface. Furthermore, the side surface where the electrodes 11 and 12 are not in contact can also be heated.

  During this energization heating, it is desirable that the temperature of the entire preset tempering region Rt is within the tempering temperature range. The tempering temperature range is a temperature range in which the effect of tempering is obtained at a temperature lower than the quenching temperature range, for example, lower than the A1 transformation point. Since the tempering effect is greatly influenced by the temperature in the tempering treatment, the tempering is accurately heated to a temperature at which desired physical properties can be obtained.

Since the temperature range for obtaining desired physical properties by tempering is narrower than the allowable range of the reached temperature in the quenching process, the temperature of the region Rt is adjusted with higher accuracy than in the quenching process. In the first embodiment, the region Rt can be arbitrarily set in order to bring the pair of electrodes 11 and 12 into contact with a part of the workpiece W, and the region Rt is set so that the current density is as uniform as possible. Then, the entire region Rt is heated to a desired tempering temperature range.
Thus, after heating to the tempering temperature range, the tempering area | region Rt is formed by carrying out rapid cooling or air cooling.

In the first embodiment, the tempering regions Rt can be formed at a plurality of positions by moving the pair of electrodes 11 and 12 to arbitrary positions and repeating such a tempering process. At that time, in the tempering process at different positions, it is possible to form a plurality of tempering regions Rt having different strengths by supplying different currents supplied from the power supply facility 15.
Then, a plurality of tempering regions Rt are formed in the quenching region Rh, and then post-processing is performed as necessary, thereby completing the production of the thin three-dimensional body.

In the thin three-dimensional body manufactured in this way, the quenching region Rh and the tempering region Rt are formed at different positions in the longitudinal direction, and the strength in the plurality of regions is different from each other, so that there is an intensity distribution in the longitudinal direction. doing.
Since a portion with different strength is provided at any position of a single thin three-dimensional body, an appropriate strength distribution according to the application can be realized, such as providing a portion that is easily deformed while ensuring strength. . For example, if a thin three-dimensionally shaped body is used as it is or covered with a covering material and used as a bumper of a vehicle, it is possible to efficiently secure shock absorbing performance.

  According to the manufacturing method of the thin three-dimensional body as described above, the pair of electrodes 11 and 12 are brought into contact with a part of the surface of the quenching region Rh and energized and heated. , Even in the case of a three-dimensional workpiece W, the region can be accurately heated and tempered to a desired tempering temperature range, and a desired tempered region Rt is formed in a part of the quenched region Rh. it can.

In addition, since the work W is energized by the pair of electrodes 11 and 12, there is no need to use a large facility such as a heating furnace, and a thin three-dimensional body having a quenching region Rh and a tempering region Rt is a simple facility. Can be manufactured.
In particular, when the tempering process is performed by energizing the workpiece W with the pair of electrodes 11 and 12, the tempering process can be performed in a very short time. As a result, when manufacturing a large number of thin three-dimensional bodies, a tempering process can be performed even if the tact time is short, and the manufacturing equipment for the thin three-dimensional bodies can be made compact.

  In this manufacturing method, the tempering process is performed after the plating layer is provided on the workpiece W. However, since the pair of electrodes 11 and 12 can be accurately heated to the tempering temperature range, a part of the temperature is excessively increased. And high temperature conditions do not last for a long time. Therefore, deterioration of the plating layer due to peeling of the plating or alloying can be prevented, for example, the antirust effect by the plating layer can be maintained, and the degree of freedom in setting the order of the production process is great.

Note that the above-described embodiment can be appropriately changed within the scope of the present invention.
In the embodiment, the example in which the workpiece W having a constant cross-sectional shape continuous in the longitudinal direction has been heat treated has been described. However, the workpiece W whose shape monotonously changes in one direction, for example, the width and thickness gradually change along the longitudinal direction. Even so, the present invention is applicable. This monotonous change is a shape in which the cross-sectional area increases or decreases along one direction and there is no inflection point in the middle.

  In that case, while the pair of electrodes 11 and 12 are in contact with the surface of the workpiece W and are energized, one or both of the electrodes 11 and 12 are moved corresponding to the shape change of the workpiece W, By adjusting the energization amount, the tempering can be performed by heating the range of each tempering region Rt within a predetermined tempering temperature range.

In the embodiment, the quenching process, the plating process, and the tempering process are continuously performed. However, the tempering process may be performed using the workpiece W that has been subjected to the quenching process and the plating process in advance.
In the above description, the same electrode is used in the quenching process and the tempering process. For example, by using an electrode having a short length during the tempering process, the widths of the quenching region Rh and the tempering region Rt can be made different.

  In the embodiment, the quenching process is performed on substantially the entire work W to form the entire quenching region Rh. However, when the quenching process is performed by bringing the pair of electrodes 11 and 12 into contact with each other and conducting heating, The quenching treatment Rh may be formed on a part of the workpiece W by appropriately selecting the arrangement positions of the electrodes 11 and 12. In this way, regions that are not subjected to quenching treatment can be formed, and more regions having different strengths can be formed.

[Second Embodiment]
The second embodiment is an example in which the quenching process and the tempering process are performed on the same region of the intermediate portion of the workpiece W, and the heat treatment is not performed on both ends.
As shown in FIG. 3, the heating device used in the second embodiment is the same as the first embodiment except that a heat removal member 14 is provided at a position adjacent to the pair of electrodes 11 and 12.

The heat removal member 14 is a member that suppresses the temperature rise in a region set in advance on both ends of the workpiece W during heating, has a shape corresponding to the region, and is formed of a nonconductive member such as ceramics. Yes.
Here, the corresponding shape may be a shape that can contact the entire region when the region that suppresses the temperature increase generates heat, and heat transfer from other regions adjacent to the region that suppresses the temperature increase. In the case where the heating is performed, the shape may be a shape that can contact only a portion adjacent to another region among the regions that suppress the temperature rise.

  In the present embodiment, the heat removal member 14 is composed of a plurality of pads that are in contact with the entire surface of a region set in advance on both ends of the workpiece W in the longitudinal direction. Each pad of the heat removal member 14 is provided with a cooling passage through which a coolant can flow.

In order to manufacture a thin three-dimensional body in the second embodiment using this heating device, first, the workpiece W is subjected to a quenching process. In the quenching process, the pair of electrodes 11 and 12 are brought into contact with both sides of a predetermined intermediate portion of the workpiece W, and the heat removal members 14 are disposed on both ends of the workpiece W adjacent to the pair of electrodes 11 and 12. In the same manner as in the first embodiment, the pair of electrodes 11 and 12 are energized and heated and rapidly cooled while contacting the four surfaces and passing the coolant through the heat removal member 14.
At the time of heating, the heat transferred from the region between the pair of electrodes 11 and 12 is absorbed by the heat removal member 14, thereby suppressing the temperature rise in the region corresponding to the heat removal member 14, and The region is kept at a temperature below the quenching temperature range. By this quenching process, a quenching region is formed between the pair of electrodes 11 and 12 and a material region Rm is formed on both ends.

Next, after forming a plating layer on the entire surface, a tempering treatment is performed. In the tempering process, a pair of electrodes 11 and 12 and a heat removal member 14 are disposed at the same position as in the quenching process, and a coolant is passed through the heat removal member 14, and a pair of electrodes is formed in the same manner as in the first embodiment. The electrodes 11 and 12 are energized under milder conditions than the quenching process, heated to the tempering temperature range, and cooled.
Even at the time of heating in the tempering process, the heat transferred from the region between the pair of electrodes 11 and 12 is absorbed by the heat removal member 14, so that the temperature rise in the region corresponding to the heat removal member 14 is suppressed. Region Rm is kept at a temperature below the tempering temperature range.
Therefore, by this tempering process, the tempering region Rt is formed between the pair of electrodes 11 and 12 while maintaining the material region Rm on both ends.
After the tempering process, a thin three-dimensional body is manufactured by performing press processing such as trim processing, piercing processing, and welding processing or machining on the material region Rm and the tempering region Rt.

In the manufacturing method of the thin three-dimensional body as described above, the same effects as those of the first embodiment can be obtained.
Furthermore, in this embodiment, during the quenching process and the tempering process, a heat treatment structure is prevented from being generated by a relatively simple method of arranging the heat removal member 14 in a preset post-processing area of the workpiece W. It is possible to perform post-processing easily.
Moreover, since heating is started in a state in which the heat removal member 14 is in contact, even when the temperature is raised in a short time by energization heating, the temperature rise on both ends of the workpiece W can be efficiently suppressed. Therefore, the processing time of the quenching process and the tempering process can be shortened without complicating the apparatus configuration.

[Third Embodiment]
The third embodiment is an example in which a quenching process is performed on an intermediate part of the workpiece W, a tempering process is performed on a part thereof, and heat treatment is not performed on both ends.
As shown in FIG. 4, the heating device used in the third embodiment is configured in the same manner as in the second embodiment except that it includes a heat removal member 16 that can contact a pair of side walls between the pair of electrodes 11 and 12. Has been.

  The heat removal member 16 is a member that removes heat from the surface of the workpiece W so as to suppress the temperature rise in a part of the quenching region Rh during heating in the tempering process, and the pair of heat removal members 16 between the pair of electrodes 11 and 12. It is composed of a pair of pads having a shape corresponding to the side wall. Others are the same as the heat removal member 14.

In order to manufacture the thin three-dimensionally shaped body of the third embodiment using this heating device, first, a quenching process and a plating process are performed as in the second embodiment.
Thereafter, the heat removal member 16 is disposed and brought into contact with a pair of opposed side walls that do not contact the pair of electrodes 11 and 12 so as to be positioned between the pair of electrodes 11 and 12, and the heat removal members 14 and 16 are cooled. A tempering process is performed by energizing, heating and cooling between the pair of electrodes 11 and 12 while passing the liquid.

At the time of heating, the pair of side walls in contact with the electrodes 11 and 12 between the pair of electrodes 11 and 12 are heated to the tempering temperature range. On the other hand, in the other pair of side walls where the electrodes 11 and 12 are not in contact with each other between the pair of electrodes 11 and 12, since the heat generated by the current heating is absorbed by the heat removal member 16, the temperature rise is suppressed and the tempering temperature. Keep temperature below range.
Therefore, in this tempering process, among the quenching region Rh formed by the quenching process, the pair of side walls with which the electrodes 11 and 12 are in contact are tempered to form the tempering region Rt and the other pair with which the electrodes 11 and 12 are not in contact with each other. Are not tempered as in the tempering region Rt, and the quenching region Rh remains.
Otherwise, the thin three-dimensional body in the third embodiment is manufactured in the same manner as in the second embodiment.

In the manufacturing method of the thin three-dimensional body as described above, the same operational effects as those of the second embodiment can be obtained.
Furthermore, in this embodiment, the heat removal member 14 is disposed on both ends of the workpiece W during the quenching process to suppress the temperature rise, and the heat removal member 16 is disposed on the pair of side walls between the electrodes 11 and 12 during the tempering process. By arranging and processing while suppressing the temperature rise, a material region Rm is formed on both ends, a quenching region Rh is formed on a pair of side walls between the material regions Rm, and a tempering region Rt is formed on the other pair of side walls. It is possible to manufacture a solid member having a large number of formed regions.

W Work Rh Quenching area Rt Tempering area 11, 12 Electrodes 14, 16 Heat removal member 15 Power supply equipment

Claims (6)

A workpiece having a thin wall three-dimensional shape by quenching to form a hardened region, energized by contacting a pair of electrodes in continuous surface of該焼insertion region, in a predetermined tempering temperature range at least a portion of said hardening region In a method for producing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempered region by heating and tempering,
The workpiece is formed of a cylindrical body, and the pair of electrodes has a pair of opposed electrodes that face each other, and the pair of electrodes are spaced apart in the axial direction of the workpiece to sandwich the workpiece. A method for producing a thin three-dimensional body, wherein the counter electrode is brought into contact with both side surfaces of the workpiece. A workpiece having a thin wall three-dimensional shape by quenching to form a hardened region, energized by contacting a pair of electrodes in continuous surface of該焼insertion region, in a predetermined tempering temperature range at least a portion of said hardening region In a method for producing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempered region by heating and tempering,
A method for producing a thin three-dimensional body, wherein the tempering treatment is performed on the workpiece that has been plated after the quenching. A workpiece having a thin wall three-dimensional shape by quenching to form a hardened region, energized by contacting a pair of electrodes in continuous surface of該焼insertion region, in a predetermined tempering temperature range at least a portion of said hardening region In a method for producing a thin three-dimensional body having a plurality of regions having different strengths by forming a tempered region by heating and tempering,
In at least one of the quenching process and the tempering process, a heat removal member is disposed on the surface of the workpiece and heated, thereby suppressing a temperature rise in a region corresponding to the heat removal member and forming a post-processing region. A method for producing a thin three-dimensional body.   The method for producing a thin three-dimensional body according to claim 3, wherein the temperature of the region corresponding to the heat removal member is kept below the quenching temperature range in the quenching treatment and below the tempering temperature range in the tempering treatment.   The method for producing a thin three-dimensional body according to any one of claims 1 to 4, wherein the tempering treatment is performed by bringing the pair of electrodes into contact with a continuous region of the workpiece having a constant cross-sectional shape.   The method for producing a thin three-dimensional body according to any one of claims 1 to 5, wherein a plurality of tempering regions are formed by heating a plurality of portions of the quenching region to different tempering temperature ranges.

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