JP5187010B2 - Method and apparatus for hot bending of metal material - Google Patents

Description

  The present invention relates to a hot bending method and apparatus for a metal material, in particular, a metal material having a low-strength portion whose strength is relatively lower than other portions in the middle of the length direction. Belongs.

  Conventionally, a heating device such as an induction heating coil disposed between two jigs while feeding a metal material made of steel or the like through a fixed jig and a movable jig constituted by a pair of rollers, for example. By heating the bending part preset in the metal material and tilting the movable jig with respect to the metal material feeding direction of the fixed jig, a bending stress is applied to the bending part and the bending process is performed. A metal material that bends a part and quenches the bent part by jetting a coolant such as water from a nozzle disposed immediately after the heating device to increase the strength by quenching the bent part. Is known (see Patent Document 1).

  On the other hand, in recent years, tailored tubes in which a plurality of metal materials having different properties such as strength and thickness are joined together are attracting attention as materials for structural members or skeletal members such as side frames, reinforcements or cross members. ing. This tailored tube has the advantage that it can respond to different requirements for each part of the automobile to which it is assembled.

  And such a tailored tube is manufactured by abutting and welding the end faces of a plurality of metal plates having different characteristics to form a tailored blank, and then forming the tailored blank into a pipe and welding the abutted end faces to each other. Is done. As a result, in the middle of the length direction of the tailored tube, there is a portion where the welded portion between adjacent metal materials extending in the circumferential direction of the tailored tube intersects with the welded portion at the time of pipe forming extending in the lengthwise direction. In this intersection part, intensity is relatively lower than other parts.

JP2007-83304A

  Therefore, like the tailored tube, there is a low-strength portion whose strength is relatively lower than other portions in the middle of the length direction, and a predetermined range including the low-strength portion is a bending portion. When hot bending a metal material by the bending technique, there is a problem that cracks and wrinkles are likely to occur at the low strength portion. To solve this problem, it is conceivable to increase the strength of the low-strength portion in advance by quenching the low-strength portion before bending the metal material. However, in this case, a quenching operation is added before the bending work of the metal material, which increases the operation and decreases the productivity.

  Accordingly, the present invention provides a hot metal material in which a low-strength portion having a relatively lower strength than other portions exists in the middle of the length direction, and a predetermined range including the low-strength portion is a bent portion. An object of the present invention is to suppress the occurrence of cracks and wrinkles in the low-strength portion without adding extra work when bending.

  In order to solve the above problems, the present invention uses the following means. In the disclosure of the following means, reference numerals corresponding to embodiments of the invention described later are added for reference.

  First, in the invention according to claim 1 of the present application, there is a low strength portion C whose strength is relatively lower than other portions in the middle of the length direction, and a predetermined range including the low strength portion C is bent. While feeding the metal material W made into the part R through the fixed jig 12 and the movable jig 15, the bending part R is heated by the heating device 13 disposed between the jigs 12 and 15. At the same time, the bending jig R is bent by tilting the movable jig 15 with respect to the metal material feeding direction of the fixed jig 12, and the quenching apparatus 14 disposed immediately after the heating apparatus 13 is used. A method of hot bending a metal material W in which the bending portion R is quenched by quenching the bending portion R, and the low strength portion C passes through the heating device 13 and the rapid cooling device 14. During the period, the low strength portion of the bending portion R The movable jig 15 tilted to bend the part before C is fed in the metal material of the fixing jig 12 at the same speed as the feeding speed of the metal material W in the tilted posture. It is characterized by moving in the same direction as the feeding direction (S2).

  Next, the invention according to claim 2 of the present application is the method for hot bending a metal material W according to claim 1, wherein the metal material W is a tailored tube in which different metal materials are joined together. The low-strength portion C is an intersecting portion between a circumferential weld portion A between adjacent metal materials and a longitudinal weld portion B at the time of pipe forming.

  Next, the invention described in claim 3 of the present application is the hot bending method for the metal material W according to claim 1 or 2, wherein the low-strength portion C is the heating device 13 and the rapid cooling device. After passing through 14, the metal material W and the movable jig 15 are fed back at the same speed to the position before the low-strength portion C passes through the heating device 13 (S4). The continuation of the bending process is resumed (S6).

  Next, in the invention according to claim 4 of the present application, there is a low strength portion C whose strength is relatively lower than other portions in the middle of the length direction, and a predetermined range including the low strength portion C is bent. While feeding the metal material W, which has been set as the processing site R, through the fixed jig 12 and the movable jig 15, the bending unit R is heated by the heating device 13 disposed between the jigs 12 and 15. At the same time, the movable jig 15 is tilted with respect to the metal material feeding direction of the fixed jig 12 to bend the bending portion R, and the quenching device 14 disposed immediately after the heating device 13. In the hot bending apparatus 1 for the metal material W for quenching the bending portion R by quenching the bending portion R, the low-strength portion C includes the heating device 13 and the rapid cooling device. 14 during the period of passing 14 The movable jig 15 tilted to bend the part before the strength part C is kept in the tilted posture at the same speed as the feeding speed of the metal material W, and the metal of the fixed jig 12 is moved. Control means 20 (S2) for moving in the same direction as the material feeding direction is provided.

  Next, the invention according to claim 5 of the present application is the hot bending apparatus 1 for the metal material W according to claim 4, wherein the low-strength portion C is the heating device 13 and the rapid cooling device 14. After passing, the reverse feed means 20 (S4) reversely feeds the metal material W and the movable jig 15 to the position before the low-strength portion C passes the heating device 13 at the same speed. ), And then restarting means 20 (S6) for restarting the continuation of the bending process.

  First, according to the first and fourth aspects of the present invention, the metal material is fed through the fixed jig and the movable jig, and the bending portion preset in the metal material is bent. In addition, in the hot bending process technology for metal materials to be hardened, tilting is performed in order to bend the bent part before the low-strength part during the period when the low-strength part passes through the heating device and the quenching device. Since the movable jig that has been moved is moved in the same direction as the metal material feeding direction of the fixed jig at the same speed as the metal material feeding speed in the tilted posture, the low strength portion is Without being subjected to bending stress due to the movable jig, only the heating by the heating device and the rapid cooling by the rapid cooling device are received, and as a result, only quenching is performed.

  Therefore, it is possible to increase the strength of the low-strength part in advance of the bending process in the bending work process without adding a separate quenching work for the low-strength part, and as a result, without reducing the productivity, It is possible to suppress the occurrence of cracks and wrinkles at low strength sites.

  As described above, the feature of the present invention is that the metal material can be heated without causing bending stress due to the movable jig in the conventionally known hot bending technology for the metal material that performs bending and quenching simultaneously. It is focused on that quenching can be performed only without quenching the metal material. And in that case, as a configuration for temporarily stopping the bending stress caused by the movable jig tilted to bend the bending portion before the low-strength portion, as in the first and fourth aspects, In addition to moving the movable jig in synchronization with the metal material while maintaining the tilting posture, the tilting posture can be gradually returned to the original state in conjunction with the passage of the metal material without moving the movable jig. Possible (2nd plan). When these two configurations are compared, both are effective as a configuration that temporarily eliminates the bending stress of the movable jig. In particular, the configurations of claims 1 and 4 are capable of moving without causing the metal member to bend. There is an advantage that it can be realized simply, speedily and easily than the second plan for returning the tilting posture of the tool.

  Next, according to the second aspect of the invention, the bent portion is bent and quenched while feeding the tailored tube in which different metal materials are joined together through the fixed jig and the movable jig. When it does, it becomes possible to suppress generation | occurrence | production of a crack and a wrinkle in the cross | intersection site | part of the weld part extended in the circumferential direction of a tailored tube, and the weld part extended in a length direction.

  In the first and fourth aspects of the invention, the metal material may be a plate-shaped or bar-shaped tailored blank. In that case, the low-strength portion is a welded portion between adjacent metal materials (the circumferential welded portion A). It may be a welded part corresponding to the above.

  Next, according to the invention described in claim 3 and claim 5, after the low-strength portion passes through the heating device and the quenching device, that is, after the low-strength portion is only quenched, the metal material and the movable jig Are fed back at the same speed to the position before the low-strength portion passes through the heating device, and then the continuation of the bending process is resumed. By simply setting the metal material once in the hot bending machine, the pre-quenching of the low-strength part and the bending and quenching of the bending part including the low-strength part can be performed efficiently and finished in a short time. The product can be finished. Hereinafter, the present invention will be described in more detail through the best mode for carrying out the invention.

  FIG. 1 is a perspective view showing the overall configuration of a hot bending apparatus 1 for a metal material W according to the best embodiment of the present invention.

  The hot bending apparatus 1 includes a metal material holding device 10 that holds a terminal portion of a metal material W extending in the horizontal direction. The holding device 10 is configured to be movable on the track 11. In front of the holding device 10, fixed rollers 12 to 12, an induction heating coil 13, a cooling water injection device 14, and movable rollers 15 and 15 are arranged in this order from the upstream side.

  The fixing rollers 12... 12 as fixing jigs determine the feeding direction of the metal material W by sandwiching the metal material W from both sides in two stages.

  The induction heating coil 13 as a heating device has a shape that surrounds the metal material W, and locally heats the metal material W to a predetermined temperature (temperature at which the metal material W can be plastically deformed and quenched) in the surrounding area and the periphery thereof. .

  The cooling water injection device 14 as a quenching device surrounds the metal material W, and cools the metal material W by locally injecting cooling water from the nozzle to the metal material W in and around the surrounded area.

  The movable rollers 15 and 15 as movable jigs are accommodated in the housing 16 and sandwich the metal material W from both sides. And it is movable in the same direction (x-axis direction) as the metal material feeding direction of the fixed rollers 12... 12, and the direction (y-axis direction) perpendicular to the metal material feeding direction of the fixed rollers 12. Movable in the direction perpendicular to the metal material feeding direction (z-axis direction) of the fixed rollers 12... 12, rotatable about the y-axis, and rotatable about the z-axis. Has been. Then, by combining these movements, the movable rollers 15, 15 tilt with respect to the metal material feeding direction of the fixed rollers 12... 12, thereby applying a bending stress to the metal material W, and the metal material W Is bent at a portion heated by the induction heating coil 13 (bending portion R as will be described later).

  FIG. 2 is a manufacturing process diagram of the metal material W before bending. In this embodiment, the metal material W is a tailored tube in which different metal materials are joined together. That is, tailored blanks are prepared by butting the end faces of a plurality of metal plates having different characteristics (two metal plates in the illustrated example) and welded to each other. Manufactured by. As a result, in the middle of the length direction of the tailored tube W, a welded portion A between adjacent metal materials extending in the circumferential direction of the tailored tube W intersects with a welded portion B at the time of pipe forming extending in the lengthwise direction. There is a part C to be performed, and at this intersection part C, the strength is relatively lower than other parts. In the tailored tube W, a predetermined range including the low-strength portion C is preset in the bending portion R.

  FIG. 3 is a control system diagram of the hot bending apparatus 1. The bending apparatus 1 includes a tailored tube feeding actuator 21 for moving the holding device 10 on a track 11 (in other words, feeding a metal material W), the induction heating coil 13, and the cooling water. Injector 14, actuators 22, 23, and 24 for moving movable rollers 15 and 15 in the x-axis direction, y-axis direction, and z-axis direction, and actuator 25 for rotating around y-axis and z-axis , 26, and a control unit 20 that controls the hot bending operation (hot bending method of the metal material W) of the metal material W performed by the bending apparatus 1.

  The control unit 20 includes a memory 20a in which the positions of the lateral welded portion A and the longitudinal welded portion B of the metal material W, and thus the position of the low strength portion C, are registered. In addition, the memory 20a also stores the range of the bending portion R and the like.

  FIG. 4 is a plan view of the metal material W after bending. In this embodiment, the metal material W is bent in two opposite directions in the opposite direction, and finished into an S-shaped final product. In particular, in the subsequent bending process, the bending process part R includes a low-strength part C, which is an intersection part of the lateral welded part A and the vertical welded part B. This S-shaped product is used, for example, as a material for automobile structural members or skeleton members such as side frames, reinforcements, or cross members.

  FIG. 5 is a flowchart showing a specific example of the hot bending operation (the hot bending method for the metal material W) of the metal material W performed by the bending apparatus 1.

  In step S <b> 1, it is determined whether or not the lateral welding portion A of the metal material W has come to a position immediately before the induction heating coil 13. Since the low-strength portion C of the metal material W is at the same position as the lateral welded portion A in the feeding direction of the metal material W, this determination eventually results in the low-strength portion C of the metal material W being the induction heating coil 13. It is determined whether or not it has come to the position immediately before.

  This determination is made based on the position of the low-strength portion C registered in the memory 20a, the position of the induction heating coil 13, the feeding speed of the metal material W, and the like. Of course, the low-intensity part C may be directly detected by a sensor as appropriate.

  In addition, by the time this determination is made, the bending portion R before the low-strength portion C has already passed through the induction heating coil 13, and the induction heating coil 13 has a temperature at which the metal material W can be plastically deformed and quenched. The movable rollers 15 and 15 are tilted so that the heated bending portion R can be bent.

  As a result, when it comes, at step S2, the fixed roller 12 ... is fed at the same speed as the feeding speed of the work (tailored tube, which is the metal material W) while maintaining the tilting posture of the movable rollers 15, 15. The movable rollers 15 and 15 are moved in the same direction (x-axis direction) as the 12 workpiece feeding directions.

  That is, since the low strength portion C is included in the bending portion R, the movable rollers 15 and 15 bend the portion located before the low strength portion C in the bending portion R as described above. In order to achieve this, the movable rollers 15 and 15 are moved forward in synchronization with the metal material W in a state where the tilt has already been tilted and the tilted posture is maintained.

  Next, in step S <b> 3, it is determined whether or not the lateral welding portion A of the metal material W, that is, the low-strength portion C has passed through the cooling water injection device 14. That is, it is determined whether or not the low-strength portion C is heated to the quenchable temperature by the induction heating coil 13, cooled by the cooling water injection device 14, and quenched.

  This determination is also made based on the position of the low strength portion C registered in the memory 20a, the position of the cooling water injection device 14, the feeding speed of the metal material W, and the like. Of course, the low-intensity part C may be directly detected by a sensor as appropriate.

  As a result, when it has passed, in step S4, the workpiece (tailored tube, which is a metal material W) and the movable rollers 15, 15 are moved at the same speed while maintaining the tilting posture of the movable rollers 15, 15. Then, reverse feed is made in the x axis direction.

  Next, in step S <b> 5, it is determined whether or not the lateral welding portion A of the metal material W, that is, the low-strength portion C has returned to the position immediately before the induction heating coil 13.

  As a result, when it returns, the continuation of the bending process is resumed in step S6. That is, the second half of the bending portion R including the quenched low-strength portion C is again heated by the induction heating coil 13 and bent by the tilted movable rollers 15 and 15 (this time, the movable rollers 15 and 15 are It does not move), and cooling by the cooling water injection device 14 is performed.

  FIG. 6 is a process diagram showing a specific example of the hot bending operation (the hot bending method of the metal material W) of the metal material W performed by the bending apparatus 1.

  As shown in FIG. 6A, the metal material W is fed through the fixed rollers 12... 12 and the movable rollers 15, 15, and the low strength portion C is transferred to the induction heating coil 13 along with the feeding. Coming closer.

  Next, as shown in FIG. 6 (b), when the front end portion of the bending portion R enters the induction heating coil 13, the induction heating coil 13 is activated, and only the bending portion R is locally made of metal. The material W is heated to a temperature at which plastic deformation is possible and quenching is possible (parts with dots in the figure).

  Next, as shown in FIG. 6C, when the low-strength portion C comes to a position immediately before the induction heating coil 13 (step S1: At this time, the movable rollers 15 and 15 are in the low-strength portion C of the bending portion R. As shown in FIG. 6D, the movable rollers 15 and 15 are synchronized with the metal material W while maintaining the tilting posture. Then, it moves forward (step S2).

  When the low-strength portion C passes through the cooling water injection device 14 (step S3), as shown in FIG. 6E, the movable rollers 15 and 15 are synchronized with the metal material W while maintaining the tilting posture. Then, it is sent backward (step S4).

  When the low-strength portion C returns to the position immediately before the induction heating coil 13 (step S5), the continuation of the bending process is resumed (step S6), and the low-strength portion C is included as shown in FIG. The latter half of the bending portion R is bent.

  In the above, although the heating temperature by the heating device 13 depends on the metal material W, particularly in the case of an iron-based material, both the bending temperature and the quenching temperature are preferably 800 ° C. to 1050 ° C., and about 850 ° C. Is more preferable.

  If it is 800 degrees C or less, a quenching effect will not fully appear and the improvement of the tensile strength in a molded article will become inadequate. On the other hand, when heated above 1050 ° C., the improvement in tensile strength saturates or tends to decrease (the reason is thought to be that the bonding of the crystal structure becomes coarse due to the coarsening of the metal crystal accompanying excessively high temperature) However, it has little profit for energy cost.

The cooling rate of the start of hardening by quenching apparatus 14, it is preferable to cool below the A ₁ transformation point. The A ₁ transformation point, with the exception of retained austenite or the like, pearlite transformation from austenite is at a temperature of approximately terminated during cooling. In addition, it does not specifically limit as a cooling method and cooling conditions of a steel pipe, It is possible to employ | adopt a general cooling method and cooling conditions.

  The coolant is preferably a coolant such as water, particularly water containing a rust inhibitor.

  Further, the feeding speed of the metal material W is preferably about 150 mm / second or less from the viewpoint of the accuracy of bending.

  And as a combination of the dissimilar materials of the tailored tube W, basically, dissimilar materials having different plate pressures are preferably used.

  As described above, according to this embodiment, while bending the metal material W through the fixed jig 12 and the movable jig 15, the bending portion R set in advance on the metal material W is bent. In addition, in the hot bending technology of the metal material W to be hardened, during the period when the low strength portion C passes through the heating device 13 and the quenching device 14, the portion of the bending portion R that precedes the low strength portion C is selected. The movable jig 15 tilted for bending is moved in the same direction as the metal material feeding direction of the fixing jig 12 at the same speed as the feeding speed of the metal material W in the tilted posture. Therefore, the low-strength portion C is subjected only to heating by the heating device 13 and rapid cooling by the rapid cooling device 14 without being subjected to bending stress by the movable jig 15, and is only quenched as a result. It becomes.

  Therefore, the strength of the low-strength portion C can be increased in advance of the bending process in the bending process step (see FIG. 6) without adding a separate quenching operation for the low-strength portion C. It is possible to suppress the occurrence of cracks and wrinkles in the low-strength portion C without reducing the properties.

  As a configuration for temporarily stopping the bending stress caused by the movable jig 15 tilted to bend the bending portion R before the low strength portion C, a chain line (a) in FIG. As indicated by, it is conceivable that the tilting posture is gradually returned to the original state in conjunction with the passage of the metal material W without moving the movable jig 15. Compared with this, this embodiment has an advantage that it can be realized more simply, speedily and easily than returning the tilting posture of the movable jig 15 without causing the metal member W to twist.

  Further, when the bent portion R is bent and quenched while feeding the tailored tube W in which different metal materials are joined together through the fixed jig 12 and the movable jig 15, the tailored tube W Generation of cracks and wrinkles can be suppressed at the intersection C between the welded portion A extending in the circumferential direction and the welded portion B extending in the length direction.

  In addition, after the low-strength portion C passes through the heating device 13 and the quenching device 14, that is, after the low-strength portion C is only quenched, the metal material W and the movable jig 15 are moved at the same speed. Since the low-strength portion C is fed back to the position before passing through the heating device 13 (S4), and then the continuation of the bending process is resumed (S6), in one bending process, that is, a metal material By simply setting W in the hot bending apparatus 1 once, the pre-quenching of the low-strength portion C and the bending and quenching of the bending portion R including the low-strength portion C can be efficiently performed. It is possible to finish the final product in time.

  The metal material W may be a plate-shaped or bar-shaped tailored blank instead of the tailored tube. In this case, the low-strength portion is a welded portion between adjacent metal materials (weld corresponding to the circumferential weld A). Part) itself.

  As described above in detail with reference to specific examples, the present invention includes a low-strength portion whose strength is relatively lower than other portions in the middle of the length direction, and a predetermined range including the low-strength portion is present. Since it is a technology that can suppress the occurrence of cracks and wrinkles in the low-strength portion without adding extra work when hot bending a metal material that has been made into a bent portion, tailored Extensive industrial applicability is expected in the technical field of metal processing of metal materials such as tubes.

It is a perspective view which shows the whole structure of the hot bending apparatus of the metal material which concerns on the best embodiment of this invention. It is a manufacturing-process figure of the metal material (tailored tube) before a bending process. It is a control system figure of the said hot bending apparatus. It is a top view of the metal material after a bending process. It is a flowchart which shows one specific example of the hot bending operation (hot bending method) which the said hot bending apparatus performs. It is process drawing which shows one specific example of the hot bending operation (hot bending method) which the said hot bending apparatus performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot-bending apparatus of metal material 10 Metal material holding apparatus 11 Track 12 Fixing jig (fixed roller)
13 Heating device (induction heating coil)
14 Quenching device (cooling water injection device)
15 Movable jig (movable roller)
16 Movable jig housing 20 Control means, reverse feed means, resumption means (control unit)
A Circumferential weld (lateral weld)
B Longitudinal weld (longitudinal weld)
C Low strength part (crossing part)
R Bending part W Metal material (tailored tube)

Claims (5)

In the middle of the length direction, there is a low-strength portion whose strength is relatively lower than other portions, and a metal material in which a predetermined range including the low-strength portion is a bent portion, a fixed jig and a movable jig The bending portion is heated by heating the bending portion with a heating device disposed between the two jigs and tilting the movable jig with respect to the metal material feeding direction of the fixed jig. A method of hot bending a metal material, wherein the bending part is quenched by quenching the bending part by quenching the bending part with a quenching device disposed immediately after the heating device.
During the period when the low-strength portion passes through the heating device and the quenching device, the movable jig tilted to bend the portion of the bending portion before the low-strength portion is tilted. The method of hot bending a metal material, wherein the metal material is moved in the same direction as the metal material feeding direction of the fixing jig at the same speed as the feeding speed of the metal material in the posture. A hot bending method for a metal material according to claim 1,
The metal material is a tailored tube in which different metal materials are joined together,
The method of hot bending a metal material, wherein the low-strength portion is a crossing portion between a welded portion in the circumferential direction between adjacent metal materials and a welded portion in the length direction during pipe forming. A hot bending method for a metal material according to claim 1 or 2,
After the low-strength portion passes through the heating device and the quenching device, the metal material and the movable jig are reversed to the position before the low-strength portion passes through the heating device at the same speed. A method of hot bending of a metal material, characterized in that the bending process is resumed after feeding. In the middle of the length direction, there is a low-strength portion whose strength is relatively lower than other portions, and a metal material in which a predetermined range including the low-strength portion is a bent portion, a fixed jig and a movable jig The bending portion is heated by heating the bending portion with a heating device disposed between the two jigs and tilting the movable jig with respect to the metal material feeding direction of the fixed jig. An apparatus for hot bending of a metal material for quenching a bent portion by bending the processed portion and quenching the bent portion by a quenching device disposed immediately after the heating device. And
During the period when the low-strength portion passes through the heating device and the quenching device, the movable jig tilted to bend the portion of the bending portion before the low-strength portion is tilted. Hot bending of a metal material characterized by comprising control means for moving in the same direction as the metal material feeding direction of the fixing jig at the same speed as the feeding speed of the metal material in the posture Processing equipment. The metal material hot bending apparatus according to claim 4,
After the low-strength portion passes through the heating device and the quenching device, the metal material and the movable jig are reversed to the position before the low-strength portion passes through the heating device at the same speed. Reverse sending means to send,
Thereafter, a hot bending apparatus for a metal material, comprising restarting means for restarting the continuation of the bending process.

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