JP2023140799A - Cooling device and cooling method - Google Patents

Abstract

To provide a cooling device that can perform effective cooling while avoiding interference with a hollow stock when performing normal bending or shear bending, and a cooling method.SOLUTION: A cooling device is used for a hollow bent component manufacturing apparatus comprising a feeder, a heating coil, a cooling unit having a plurality of nozzle holes for injecting cooling water to a hollow stock Pm, and a shear force applying unit. In this cooling device, at least one injection center line c of each nozzle hole crosses so as to incline with respect to an outer peripheral surface of the hollow stock Pm on a cross section orthogonal to a longer direction of the hollow stock Pm at a third position.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cooling device and a cooling method for cooling a hollow material when the hollow material is subjected to shear bending or normal bending.

As is well known, metal strength members, reinforcing members, or structural members having a hollow and curved shape used in automobiles, various machines, etc. are required to be lightweight and have high strength. Conventionally, this type of hollow bending part has been manufactured by, for example, cold bending, welding of a pressed product, punching of a thick plate, or even forging. However, these manufacturing methods have limitations in reducing the weight and increasing the strength of the manufactured hollow bending parts, and it has not been easy to achieve this goal.

In view of the current situation, the present inventors previously disclosed an invention related to a hot bending device in Patent Document 1. FIG. 11 shows an embodiment of the invention disclosed in Patent Document 1, and is an explanatory diagram schematically showing a schematic configuration of this hot bending apparatus 100.
As shown in FIG. 11, in this hot bending apparatus 100, a steel pipe (hereinafter referred to as a hollow material Pm) supported movably in the axial direction by a support means 101 (a pair of support means 101a, 101b) is placed on the upstream side. The bending process is performed at a position downstream of the supporting means 101a, 101b while the hollow bending part Pp made of steel is manufactured while being fed by a feeding device (not shown) toward the downstream side in the direction of the arrow F. That is, at the downstream position of the support means 101a, 101b, the hollow material Pm is rapidly heated to a temperature range where it can be partially quenched by the high-frequency heating coil 102, and the hollow material Pm is heated by the water cooling device 103 disposed downstream of the high-frequency heating coil 102. Rapidly cool down Pm. Then, the tip of the hollow material Pm is gripped by the gripping means 104 (a pair of gripping means 104a, 104b), and the position of the gripping means 104 is changed to a three-dimensional direction (in some cases, a two-dimensional direction) to heat the hollow material Pm. By applying a bending moment to the bent portion, the hollow material Pm is bent. According to this hot bending apparatus 100, it becomes possible to manufacture a high-strength hollow bent part Pp with high work efficiency.

International Publication No. 2011/024741 Japanese Patent Application Publication No. 55-8473

By the way, in the hot bending apparatus 100, the hollow material Pm is cooled by the water cooling device 103, but it is possible to effectively cool the hollow material Pm while avoiding interference with the hollow material Pm that deforms during bending. It wasn't easy. In particular, when shear bending is performed, the hollow material Pm undergoing shear bending tends to interfere with the cooling means because a bent portion is formed with a smaller bending radius than when performing normal bending.
For example, as a device for cooling a pipe material, a cooling device for steel pipe quenching is disclosed in Patent Document 2 (see FIG. 12). However, even with this device, interference problems during bending cannot be avoided. In the first place, this equipment is intended for use in straight pipe hardening, and the problem is that cooling water enters from the pipe end. In other words, since this device focuses on cooling problems at the tube ends, it does not take into consideration its application to devices that perform hot bending or hot shear bending at intermediate positions in the longitudinal direction of steel tubes. Therefore, even if this device is applied to the above-mentioned hot bending device 100 of Patent Document 1, for example, since the jet body including the jet nozzle is long and large in the tube axis direction, interference will occur as soon as the tube material bends even slightly. I end up. Therefore, when trying to apply this device, it is not possible to perform not only the essential shear bending process but also normal bending process.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cooling device and a cooling method that can perform effective cooling while avoiding interference with a hollow material during normal bending or shear bending. shall be.

In order to solve the above problems, the present invention employs the following means.
(1) A cooling device according to one aspect of the present invention includes:
a feeding mechanism that feeds a metal hollow material while supporting it at a first position along its longitudinal direction;
a heating coil that heats the hollow material at a second position downstream of the first position;
a cooling device having a plurality of nozzle holes that inject a cooling medium into the hollow material at a third position downstream from the second position;
a bending section that grips the hollow material at a fourth position downstream from the third position and moves the gripping position in a two-dimensional direction or three-dimensional direction to form a bent part in the hollow material;
The cooling device used in a hollow bending component manufacturing device comprising:
In a cross section perpendicular to the longitudinal direction at the third position, at least one jetting center line of each nozzle hole intersects with the outer circumferential surface of the hollow material so as to be inclined.

According to the cooling device described in (1) above, the cooling medium injected from the nozzle hole whose injection center line is inclined is blown obliquely to the outer circumferential surface of the hollow material. Here, this nozzle hole is defined as a first injection hole, a nozzle hole whose spraying position with respect to the outer circumferential surface is downstream than the first injection hole is defined as a second injection hole, and a cross section orthogonal to the longitudinal direction is defined at a third position. I will explain the case seen in . In this aspect, the injection center line of the first injection hole intersects with the outer circumferential surface of the hollow material so as to be inclined. That is, when the angle of this inclination is φ, the angle φ is made smaller than 90 degrees so that the injection center line of the first injection hole lies close to the outer circumferential surface. Thereby, the cooling medium injected from the first injection hole can avoid interference with the cooling medium injected from the second injection hole and furthermore, the other cooling medium sprayed downstream from other injection holes. . Since interference between the coolants can be avoided in this way, the coolant ejected from the first injection holes is less likely to flow back upstream in the feeding direction. Therefore, when viewed in a cross section that includes the center axis of the hollow material at the third position, the angle θ that the injection center line of the first injection hole makes with respect to the outer peripheral surface of the hollow material is set to be large, and the injection center line is You can stand it up without having to lie it down like before. By setting a large angle θ in this way, even if the first injection hole is located far from the outer circumferential surface of the hollow material, the spraying position of the cooling medium injected from the first injection hole can be adjusted to the upstream side in the feeding direction. It can be moved closer to the heated part. As a result, it is possible to shorten the dimension of the heated portion along the feeding direction to prevent wrinkles from forming at the bent portion, and it is also possible to prevent the cooling device from interfering with the hollow material.

(2) In the cooling device described in (1) above,
The injection center line may obliquely intersect with the bent inner surface of the bent portion, which is the outer peripheral surface.
In the case of the cooling device described in (2) above, the cooling medium sprayed against the bent inner surface hits the bent inner surface while heading in the approximate width direction of the hollow material and cools the bent inner surface, and then immediately leaves the hollow material to cool the bent inner surface. It is discharged in the width direction. Here, in the conventional structure, the bent inner surface is likely to interfere with the cooling device. However, in this cooling device, for the reason mentioned above, it is possible to secure a larger clearance between the bent inner surface and the nozzle hole than in the conventional structure, so that interference between them can be reliably avoided.

(3) In the cooling device described in (2) above,
The injection center line may obliquely intersect with the bent inner surface of the bent portion formed by shear bending.
In the case of the cooling device described in (3) above, the cooling medium sprayed onto the bent inner surface formed by the shear bending process hits the bent inner surface while heading in the approximate width direction of the hollow material and cools it. , it is immediately separated and discharged in the substantially width direction. Here, in the case of shear bending, since the hollow material is bent at a steeper angle than in the case of normal bending, interference with the nozzle hole is likely to occur. However, in this cooling device, interference between the bent inner surface and the cooling device can be reliably avoided even during shear bending for the reasons described above.

(4) In the cooling device described in (2) or (3) above, the following may be used:
the bent inner surface is one of a pair of outer surfaces of the hollow material;
When the hollow material is viewed in the cross section at the third position, the jetting center line intersects the one outer surface diagonally downward.
In the case of the cooling device described in (4) above, the cooling medium sprayed against the outer surface, which is the bent inner surface, hits the outer surface and cools it, and then immediately separates and is discharged downward. At this time, the cooling medium is subjected to a downward force due to gravity, so that it can be discharged more reliably.

(5) In the cooling device described in (2) or (3) above, the following may be used:
the bent inner surface is the upper surface of the hollow material;
When the hollow material is viewed in the cross section at the third position, the jetting center line obliquely intersects the upper surface.
In the case of the cooling device described in (5) above, the cooling medium sprayed against the top surface, which is the inside surface of the bend, hits the top surface and cools it, then immediately leaves the top surface to the side and then flows downward due to gravity. It is ejected towards. Therefore, also in this form, the cooling medium can be discharged more reliably.

(6) The cooling method according to one aspect of the present invention includes:
a feeding step of feeding the metal hollow material while supporting it at a first position along its longitudinal direction;
a heating step of heating the hollow material at a second position downstream from the first position;
a cooling step of injecting a cooling medium from a plurality of nozzle holes toward the hollow material at a third position downstream from the second position;
a bending step of gripping the hollow material at a fourth position downstream from the third position and moving the gripping position in a two-dimensional direction or three-dimensional direction to form a bent part in the hollow material;
A cooling method used in the cooling step in a method for manufacturing a hollow bent part, comprising:
In a cross section perpendicular to the longitudinal direction at the third position, the cooling medium is supplied so that at least one jetting center line of each nozzle hole intersects the outer circumferential surface of the hollow material at an angle. Inject.

According to the cooling method described in (6) above, the cooling medium injected from the nozzle hole whose injection center line is inclined is blown obliquely to the outer circumferential surface of the hollow material. Here, this nozzle hole is defined as a first injection hole, a nozzle hole whose spraying position with respect to the outer circumferential surface is downstream than the first injection hole is defined as a second injection hole, and a cross section orthogonal to the longitudinal direction is defined at a third position. I will explain the case seen in . In this aspect, the injection center line of the first injection hole intersects with the outer circumferential surface of the hollow material so as to be inclined. That is, when the angle of this inclination is φ, the angle φ is made smaller than 90 degrees so that the injection center line of the first injection hole lies close to the outer circumferential surface. Thereby, the cooling medium injected from the first injection hole can avoid interference with the cooling medium injected from the second injection hole and furthermore, the other cooling medium sprayed downstream from other injection holes. . Since interference between the coolants can be avoided in this way, the coolant ejected from the first injection holes is less likely to flow back upstream in the feeding direction. Therefore, when viewed in a cross section that includes the center axis of the hollow material at the third position, the angle θ that the injection center line of the first injection hole makes with respect to the outer peripheral surface of the hollow material is set to be large, and the injection center line is You can stand it up without having to lie it down like before. By setting a large angle θ in this way, even if the first injection hole is located far from the outer circumferential surface of the hollow material, the spraying position of the cooling medium injected from the first injection hole can be adjusted to the upstream side in the feeding direction. It can be moved closer to the heated part. As a result, it is possible to shorten the dimension of the heated portion along the feeding direction to prevent wrinkles from forming at the bent portion, and it is also possible to prevent the cooling device from interfering with the hollow material.

(7) In the cooling method described in (6) above,
The cooling medium may be injected so that the injection center line obliquely intersects the bent inner surface of the bent portion, which is the outer circumferential surface.
In the case of the cooling method described in (7) above, the cooling medium sprayed onto the bent inner surface hits the bent inner surface while heading in the approximate width direction of the hollow material and cools the bent inner surface, and then immediately leaves the hollow material to cool the bent inner surface. It is discharged in the width direction. Here, in the conventional structure, the bent inner surface tends to interfere with the nozzle hole. However, in this cooling device, for the reason mentioned above, it is possible to secure a larger clearance between the bent inner surface and the nozzle hole than in the conventional structure, so that interference between them can be reliably avoided.

(8) In the cooling method described in (7) above,
The cooling medium may be injected onto the bent inner surface of the bent portion formed by shear bending so that the injection center line intersects with the inclination.
In the case of the cooling method described in (8) above, the cooling medium sprayed onto the bent inner surface formed by the shear bending process hits the bent inner surface while heading in the approximate width direction of the hollow material and cools it. , it is immediately separated and discharged in the substantially width direction. Here, in the case of shear bending, since the hollow material is bent at a steeper angle than in the case of normal bending, interference with the nozzle hole is likely to occur. However, in this cooling device, for the reason mentioned above, interference between the bent inner surface and the nozzle hole can be reliably avoided even in the shear bending process.

(9) In the cooling method described in (7) or (8) above, the following may be used:
the bent inner surface is one of a pair of outer surfaces of the hollow material;
When the hollow material is viewed in the cross section at the third position, the cooling medium is injected onto the one outer surface so that the injection center line intersects diagonally downward.
In the case of the cooling method described in (9) above, the cooling medium sprayed against the outer surface, which is the bent inner surface, hits the outer surface and cools it, and then immediately separates and is discharged downward. At this time, the cooling medium is subjected to a downward force due to gravity, so that it can be discharged more reliably.

(10) In the cooling method described in (7) or (8) above, the following may be used:
the bent inner surface is the upper surface of the hollow material;
When the hollow material is viewed in the cross section at the third position, the cooling medium is injected to the upper surface so that the injection center line obliquely intersects with the upper surface.
In the case of the cooling method described in (10) above, the cooling medium sprayed against the upper surface, which is the inside surface of the bend, hits the upper surface and cools it, and then immediately separates to the side of the upper surface and then flows downward due to gravity. It is ejected towards. Therefore, also in this form, the cooling medium can be discharged more reliably.

According to the cooling device and cooling method according to each of the above aspects of the present invention, effective cooling can be performed while avoiding interference with the hollow material during normal bending or shear bending.

FIG. 1 is a plan view of a manufacturing apparatus including a cooling device according to an embodiment of the present invention. (a) is a diagram showing the main parts of the same manufacturing apparatus, and is a longitudinal cross-sectional view of section A in FIG. 1. 2(b) is a diagram showing the cooling device provided in the same manufacturing apparatus, and is a view taken along the line BB in FIG. 2(a). (a) is a diagram showing the same cooling device, and is an enlarged view of section C in FIG. 2(b). (b) is a diagram showing the cooling device, and is a view taken along the line DD in FIG. 3(a). It is a perspective view explaining the direction of cooling water injected from one nozzle hole with which the same cooling device is equipped. (a) is a diagram showing the same cooling device, and is an enlarged view of section E in FIG. 3(a). 3(b) is a diagram showing the cooling device, and is an enlarged view of section F in FIG. 3(b). (a) to (g) are diagrams each illustrating a cooling water injection pattern when viewed in the direction of the arrow BB in FIG. 2(a). Of these, (a) to (e) are invention examples, and (f) and (g) are comparative examples for comparison. It is a figure which shows the modification of the cooling device shown in FIG. 1, Comprising: It is an enlarged plan view of the part corresponding to the A part of FIG. (a) shows a state in which straight pipe hardening is performed, and (b) shows a state in which shear bending is performed. It is a figure showing an example of the cooling device concerning reference technology. Of these, (a) is a view corresponding to section A in FIG. 1, and (b) is a view taken along the line GG in FIG. 8(a). FIG. 8 is a diagram showing a cooling device according to the reference technology shown in FIGS. 8(a) and 8(b). Of these, (a) is a GG arrow view in FIG. 8(a), (b) is an enlarged view of the H section in FIG. 8(a), and (c) is a It is an enlarged view of part I. (a) to (e) are diagrams for explaining the embodiment, and are diagrams corresponding to the BB arrow view in FIG. 2(a). FIG. 1 is a schematic diagram of a hot bending apparatus equipped with a conventional cooling device. FIG. 2 is a schematic diagram showing another conventional cooling device.

A cooling device and a cooling method according to an embodiment of the present invention will be described below with reference to the drawings. The cooling device is applied to a manufacturing apparatus 10 for hollow bent parts shown in FIG. In the following explanation, the manufacturing apparatus 10 will first be explained using FIG. 1, then details of the cooling device will be explained using FIGS. 2 to 5, and modified examples of the cooling device will be explained using FIGS. 6 and 7. explain. For better understanding, the problems of the conventional cooling device will first be explained using FIGS. 8 and 9, and then the technical effects of the cooling device of this embodiment will be summarized again. Finally, each example in which technical effects were verified will be described with reference to FIG. 10 and Tables 1 to 4.

[Manufacturing equipment for hollow bending parts]
The manufacturing apparatus 10 shown in FIG. 1 uses a hollow square steel tube with a rectangular cross-sectional shape as a workpiece (hereinafter referred to as hollow material Pm), and manufactures a hollow bent part Pp by applying shear bending to this. do. The hollow material Pm is a long square tube made of steel and has a closed cross-sectional shape of a hollow rectangle in a cross section perpendicular to its longitudinal direction. Note that the hollow material Pm to be processed in this embodiment is not limited to a square tube, but may be a tube having a circular, elliptical, or even various irregular cross-sectional shapes, for example. The hollow material Pm having a rectangular cross section may have either a square or rectangular cross-sectional shape. Furthermore, the hollow material Pm may be a polygonal tube other than a rectangular cross-sectional shape or a tube having an arbitrary curved surface shape. The hollow material Pm may be a metal pipe other than a steel pipe. Further, in this embodiment, the cooling device and the cooling method will be described below by exemplifying a case where shear bending is performed, but the cooling device and the cooling method may be applied to a case where normal bending is performed.

As shown in FIG. 1, this manufacturing apparatus 10 includes a feeding device (feeding mechanism) 11, a supporting device (supporting means) 12, a heating device 13, a cooling device 14, a shearing force applying device 15, and a control device. 16.
(1) Feeding device 11
As shown in FIG. 1, the feeding device 11 feeds the hollow material Pm supported by the supporting device 12 in its longitudinal direction (to the left in the paper along arrow F) at a predetermined feeding speed. The feeding device 11 is exemplified by a type using an electric servo cylinder, but it is not limited to a specific type, and a type using a ball screw, a timing belt or a chain, etc. can also be adopted.
After the portion of the hollow material Pm where the support device 12 is installed passes the first position A, the hollow material Pm is further sent in the direction of arrow F by the feeding device 11.

(2) Support device 12
The support device 12 includes a plurality of sets (two sets in the example of FIG. 1) of rolls 12a and 12b. A set of rolls 12a sandwich and support the hollow material Pm between them. Similarly, the set of rolls 12b also supports the hollow material Pm by sandwiching it therebetween. Another set of rolls 12a is arranged downstream of one set of rolls 12b, adjacent to the other set of rolls 12a. The hollow material Pm is supported at the first position A by these rolls 12a and 12b.
Note that the supporting device 12 only needs to be able to support the hollow material Pm so that it can be fed along the feeding direction F, and supporting devices with other configurations may be adopted. For example, the support device 12 may be configured to be slidably supported without the rolls 12a, 12b.
The support device 12 is fixedly arranged on a mounting table (not shown). However, the present invention is not limited to this embodiment, and, for example, the support device 12 may be supported by an end effector (not shown) of an industrial robot.
Further, by rotating the rolls 12a and 12b, the supporting device 12 may have a feeding function for feeding the hollow material Pm, and the feeding device 11 may be omitted. In this case, the support device 12 serves both as a feeding mechanism for moving the hollow material Pm in its longitudinal direction and as a support means for supporting the hollow material Pm.

(3) Heating device 13
The heating device 13 is arranged to heat the hollow material Pm at a second position B located downstream in the feeding direction F from the first position A. The heating device 13 heats the entire circumference of the cross section of the hollow material Pm sent through the support device 12 in a portion in the longitudinal direction. An induction heating device is used as the heating device 13. This induction heating device has a heating coil 13a that heats the hollow material Pm by high frequency induction.
The heating coil 13a of the heating device 13 is arranged at a predetermined distance from the outer surface of the hollow material Pm so as to surround the entire circumference of the cross section of the hollow material Pm in a part of the longitudinal direction. The hollow material Pm is partially rapidly heated in its heated portion H by the heating device 13. The position of the highest temperature in the heated part H is slightly downstream of the position of the downstream end face of the heating coil 13a, and may be slightly upstream depending on various conditions such as how to apply cooling water from the cooling device 14, which will be described later. move to the side or downstream. Therefore, the downstream end position P1 of the heating coil 13a is used as the reference position corresponding to the position of the highest temperature in the heated portion H. The most downstream end position P1 is the most downstream position in the feeding direction F when the outer shape of the heating coil 13a is viewed along the central axis CL.
The installation means (not shown) of the heating device 13 may be such that the heating coil 13a can be arranged at the second position B so that the inclination angle can be freely adjusted. That is, the installation means of the heating device 13 may include a rotation means (not shown) that tilts the heating coil 13a at a set angle with respect to the feeding direction F of the hollow material Pm.

The heating coil 13a of the heating device 13 preferably has a circular cross-sectional shape when the hollow material Pm is a round tube. Specifically, the shape of the heating coil 13a when viewed from oppositely along the central axis CL along the longitudinal direction of the hollow material Pm becomes a concentric circular shape having a uniform clearance with respect to the outer peripheral surface of the hollow material Pm. It is preferable. On the other hand, when the hollow material Pm has an irregular cross-sectional shape including a rectangle, the shape of the heating coil 13a when viewed from oppositely along the central axis CL of the hollow material Pm is suitable for heating the outer peripheral surface of the hollow material Pm. It is preferable that the shape has a certain clearance. Note that the central axis CL is the central axis of the hollow material Pm at the position of the support device 12.

As the installation means for the heating device 13, for example, a well-known and commonly used end effector of an industrial robot can be used, but other installation means can also be employed. A single-arm robot or an off-the-shelf device with an arm and a motor can also be used.

(4) Cooling device 14
The cooling device 14 of this embodiment is particularly characterized by the direction in which cooling water is injected from each nozzle hole, and the details will be described later with reference to FIG. 2 and subsequent figures. Before that, the schematic configuration of the cooling device 14 will be explained first.
This cooling device 14 cools the hollow material Pm at a third position C located downstream from the second position B along the feeding direction F of the hollow material Pm. The cooling device 14 rapidly cools a portion of the hollow material Pm located downstream of the portion heated at the second position B. Due to this cooling, in the hollow material Pm, a deformation region where the temperature is high and the deformation resistance is significantly reduced between the heated part H heated by the heating device 13 and the cooled part cooled by the cooling device 14 is created. becomes.

Of the heated portion H heated by the heating device 13 in the hollow material Pm, the portion located downstream thereof is rapidly cooled by the cooling water injected from the cooling device 14. By this cooling, it is also possible to increase the strength of the bent portion or the entire hollow material Pm to, for example, a tensile strength of 1500 MPa or more.

The installation means for the cooling device 14 may be any means that can place the cooling device 14 at the third position C, and is not limited to a specific installation means. In order to manufacture the hollow bending member Pp with high dimensional accuracy using the manufacturing apparatus 10 of this embodiment, by setting the distance between the second position B and the third position C as short as possible, the heating device 13 It is desirable to set the area between the heated part H heated by the cooling device 14 and the cooled part cooled by the cooling device 14 to be as small as possible. For this purpose, it is desirable to arrange the cooling water injection nozzle 14a close to the heating coil 13a. Therefore, it is desirable to arrange the cooling water injection nozzle 14a at a position immediately after the heating coil 13a. Furthermore, the cooling device 14 may be fixed to the installation means of the heating device 13. In this case, it is also possible to incline both the cooling water injection nozzle 14a and the heating coil 13a at the same inclination angle while maintaining the relative positional relationship between the cooling water injection nozzle 14a and the heating coil 13a.

The installation means for the cooling device 14 may be provided separately from the installation means for the heating device 13. In this case, the installation means (not shown) of the cooling device 14 can arrange the cooling water injection nozzle 14a at the third position C so that the inclination angle can be adjusted. That is, the installation means of the cooling device 14 can tilt the cooling device 14 at a set angle with respect to the feeding direction F of the hollow material Pm.
As an example of the installation means for the cooling device 14, an end effector of a conventional industrial robot can be used, but other installation means can also be adopted. It is also possible to adopt a single-arm robot or an existing device having a rotation means such as an arm and a motor.
Moreover, the cooling water injection nozzle 14a shown in FIG. 1 may be used as a primary cooling device, and a secondary cooling device may be further provided on the downstream side thereof. When the feeding speed of the hollow material Pm is low or when the mass of the hollow material Pm is small, cooling may be performed only by the primary cooling device without providing the secondary cooling device.

(5) Shearing force applying device 15
The shearing force applying device 15 is arranged downstream of the third position C along the feeding direction F of the hollow material Pm. The shearing force applying device 15 grips a midway position in the longitudinal direction of the hollow material Pm, and moves this gripping position in a two-dimensional direction or a three-dimensional direction. Specifically, the gripping position of the hollow material Pm in the shearing force applying device 15 is viewed from a cross section including the central axis CL, and is relative to the feeding direction F along the longitudinal direction of the hollow material Pm and the longitudinal direction of the hollow material Pm. and the orthogonal direction. As a result, the shearing force applying device 15 applies shear to at least a portion of the region between the heated portion H heated by the heating device 13 and the cooled portion cooled by the cooling device 14 in the hollow material Pm. A force is applied to perform shear bending on the hollow material Pm.

As shown in FIG. 1, the shearing force applying device 15 includes an arm 15A and a base (not shown).
The arm 15A supports gripping means 15a, 15b that grips the hollow material Pm at a fourth position D downstream from the third position C along the feeding direction F of the hollow material Pm, and the gripping means 15a, 15b. and an arm portion 15c that moves the position in two or three dimensions. The arm portion 15c is supported by the base. The gripping means 15a, 15b grip the hollow material Pm between them by approaching each other. On the other hand, the gripping means 15a and 15b release their grip on the hollow material Pm by separating from each other.

A cross section in a part of the longitudinal direction of the hollow material Pm is heated by the heating device 13, and the deformation resistance is significantly reduced. Therefore, the positions of the pair of gripping means 15a and 15b are moved in two-dimensional or three-dimensional directions at a fourth position D that is downstream of the third position C along the feeding direction F of the hollow material Pm. Accordingly, shearing force can be applied to the region between the heated part H heated by the heating device 13 and the cooled part cooled by the cooling device 14 in the hollow material Pm.
When a shearing force is applied to the hollow material Pm, an intermediate position in the longitudinal direction thereof is bent as shown in FIG. In this embodiment, a shearing force is applied to the heated portion of the hollow material Pm instead of applying a bending moment as in the invention disclosed in Patent Document 1. For this reason, hollow bending parts are manufactured that have a bending portion with an extremely small bending radius, for example, 1 to 2 times the diameter of the metal tube (the length of the side in the bending direction in the case of a rectangular cross section) or less. be able to.

(6) Control device 16
The control device 16 controls various operations of the above-mentioned feeding device 11, support device 12, heating device 13, cooling device 14, and shearing force applying device 15. Note that when a sliding type or the like that does not require operation control is used as the support device 12, the support device 12 is excluded from the control target.
The control device 16 controls the feeding amount and feeding speed of the hollow material Pm by giving instructions to the feeding device 11. On the other hand, when the feeding device 11 is omitted and the feeding function is provided to the supporting device 12, the control device 16 gives instructions to the supporting device 12 to control the amount and speed of rotation of the rolls 12a and 12b. Thereby, the feed amount and feed speed of the hollow material Pm are controlled.
The control device 16 controls the temperature of the heated portion H by controlling the power output that flows through the heating coil 13a. The control device 16 may control the heating coil 13a to be inclined with respect to the hollow material Pm, as necessary.
The control device 16 controls the temperature of the cooled portion by controlling the supply pressure or supply flow rate of the cooling water supplied to the cooling water injection nozzle 14a. The control device 16 may control the cooling water injection nozzle 14a to be inclined with respect to the hollow material Pm, as necessary.
The control device 16 controls the positions and inclinations of the gripping means 15a and 15b by controlling the arm portion 15c. Further, the control device 16 controls the opening and closing operations (gripping state and gripping release state) of the gripping means 15a and 15b.
The above is an example of the control device 16, and when mass producing the same hollow bent parts Pp, it is also possible to set the control amount to a predetermined pattern.

[Details of cooling device]
Details of the cooling device 14 will be described below with reference to FIGS. 2 to 5. In the following description, when the hollow material Pm is viewed in the cross-sectional view of FIG. 2(b), the horizontal direction on the paper surface may be referred to as the width direction, and the vertical direction on the paper surface may be referred to as the height direction. Further, regarding the width direction, the left direction when looking from the upstream side to the downstream side along the feeding direction F of the hollow material Pm at the third position D3 is sometimes called the left direction, and the right direction is sometimes called the right direction.
The cooling water injection nozzle 14a of the cooling device 14 has a square frame shape when viewed from the front, as shown in FIGS. 2(a) and 2(b). The cooling water injection nozzle 14a has a width dimension (in the feed direction) in a vertical cross-sectional view shown in FIG. dimension along F) is smaller.
The cooling water injection nozzle 14a has an internal space formed therein, through which the hollow material Pm is coaxially inserted. This internal space has a rectangular shape defined by a left inner wall 14a1 and a right inner wall 14a2 that face each other, and an upper inner wall 14a3 and a lower inner wall 14a4 that face each other. A plurality of nozzle holes are formed in each of the left inner wall 14a1, right inner wall 14a2, upper inner wall 14a3, and lower inner wall 14a4.

That is, in the upper inner wall 14a3, as shown in FIG. 2(b), a plurality of nozzle holes are lined up along the width direction to form a row. Each nozzle hole is formed at the center of the upper inner wall 14a3 in the width direction. As shown in FIG. 2(a), when viewed in a longitudinal section including the central axis CL, a plurality of rows of nozzle holes are lined up along the feeding direction F. Therefore, when the upper inner wall 14a3 is viewed from below, a plurality of nozzle holes are formed at equal intervals along each of the width direction and the feeding direction F of the hollow material Pm.
Similarly, in the lower inner wall 14a4, as shown in FIG. 2(b), a plurality of nozzle holes are lined up along the width direction to form a row. Each nozzle hole is formed at the center of the lower inner wall 14a4 in the width direction. As shown in FIG. 2(a), when viewed in a longitudinal section including the central axis CL, a plurality of rows of nozzle holes are lined up along the feeding direction F. Therefore, when the lower inner wall 14a4 is viewed from above, a plurality of nozzle holes are formed at equal intervals along each of the width direction and the feeding direction F of the hollow material Pm.

Further, in the left inner wall 14a1, as shown in FIG. 2(b), a plurality of nozzle holes are lined up along the height direction to form a row. Each nozzle hole is formed in the upper part of the left inner wall 14a1 in the height direction. When the left inner wall 14a1 is viewed from the opposite side, a plurality of rows of nozzle holes are lined up along the feeding direction F. That is, when the left inner wall 14a1 is viewed from the opposite side, a plurality of nozzle holes are formed at equal intervals along each of the height direction and the feeding direction F.
Similarly, in the right inner wall 14a2, as shown in FIG. 2(b), a plurality of nozzle holes are lined up along the height direction to form a row. Each nozzle hole is formed in the upper part of the right inner wall 14a2 in the height direction. When the right inner wall 14a2 is viewed from the opposite side, a plurality of rows of nozzle holes are lined up along the feeding direction F. That is, when the right inner wall 14a2 is viewed from the opposite side, a plurality of nozzle holes are formed at equal intervals along each of the height direction and the feeding direction F.

Each of the nozzle holes is formed such that an injection center line c, which is a center line of the cooling water injected from each nozzle hole, intersects with the outer peripheral surface of the hollow material Pm. Here, "intersection" means that the injection center line c intersects with the outer peripheral surface at a predetermined angle (an angle of more than 0 degrees), and the injection center line c with respect to the outer peripheral surface except when they touch at 0 degrees (tangential direction).
When viewed in FIG. 3(a), which is a cross section perpendicular to the longitudinal direction at the third position D, the injection center line c of all the nozzle holes formed in the right inner wall 14a2 is within the outer peripheral surface of the hollow material Pm. It intersects the right side of the road so that it slopes downward. Here, if the angle that each injection center line c makes with the left side surface of the hollow material Pm is φ, this angle φ is less than 90 degrees and can be appropriately selected from within the range of 20 degrees to 85 degrees. . Therefore, the cooling water injected from each nozzle hole of the right inner wall 14a2 is sprayed onto the right side surface of the hollow material Pm at an angle φ that proceeds diagonally downward from above.

On the other hand, when the hollow material Pm is viewed in plan, it is as shown in FIG. formed to intersect. That is, the injection center lines c of all the nozzle holes formed in the right inner wall 14a2 intersect with the right side surface of the outer peripheral surface of the hollow material Pm so as to be inclined slightly downward. Here, if the angle that each injection center line c makes with respect to the left side surface of the hollow material Pm is θ, this angle θ is 90 degrees or less and can be appropriately selected from within the range of 45 degrees to 90 degrees. . Therefore, the cooling water injected from each nozzle hole of the right inner wall 14a2 is sprayed onto the right side surface of the hollow material Pm at an angle θ that advances obliquely from the upstream side to the downstream side.

The relationship between the angle φ and the angle θ will be explained using FIG. 4. FIG. 4 is a perspective view showing a jetting center line c of cooling water sprayed from one nozzle hole h in the right inner wall 14a2 to the right side surface of the hollow material Pm. The XY plane means the right side of the hollow material Pm, the XZ plane means the cross section perpendicular to the feeding direction F (or the cross section perpendicular to the longitudinal direction of the hollow material Pm), and the YZ plane means the horizontal plane (or the XZ plane and a plane perpendicular to both the XZ plane). Point O indicates the intersection point perpendicularly lowered from the nozzle hole h to the right side surface of the hollow material Pm.

As shown in FIG. 4, the angle φ is the angle that a line obtained by projecting the injection center line c onto the XZ plane makes with the X axis. Further, the angle θ is the angle that a line obtained by projecting the injection center line c onto the YZ plane makes with the Y axis.
On the other hand, the injection center line when cooling water is injected from a cooling device having a conventional structure is indicated by the symbol cc. The conventional injection center line cc is the center line of the cooling water sprayed onto the right side surface of the hollow material Pm from a position closer to the nozzle hole h of the present embodiment. This jetting center line cc is not inclined in the X-axis direction, and its spraying position is located on the Y-axis and downstream of the jetting center line c of this embodiment. The angle θc between the injection center line cc and the Y-axis is smaller than the angle θ in this embodiment. Conversely, in the injection center line c of this embodiment, the angle θ between the projection line on the YZ plane and the Y axis is larger than the conventional angle θc. That is, in the conventional injection center line cc, the angle θc is intentionally set small for the purpose of preventing backflow of cooling water, so that the injection center line cc is placed close to the XY plane so as to lie flat. On the other hand, since the angle θ is set to be large, the injection center line c of this embodiment is raised with respect to the XY plane.

On the other hand, when viewed from the projection line onto the XZ plane, the injection center line c of this embodiment has an angle φ intentionally smaller than the conventional injection center line cc since the spray destination is set in the X direction. By doing so, it is placed close to the XY plane so that it lies flat. As a result, the jetting center line c of this embodiment maintains approximately the same length as the conventional jetting center line cc, while making it possible to move the nozzle hole h away from the XY plane. In other words, the nozzle hole h can be moved to a position farther away from the right side of the hollow material Pm than the position of the conventional nozzle hole hc, and as a result, the right inner wall 14a2 of the cooling water injection nozzle 14a can be moved from the right side of the hollow material Pm. It is now possible to move away from By keeping it away from the right inner wall 14a2 in this manner, the right inner wall 14a2 becomes less likely to interfere with the right side surface of the hollow material Pm, for example, when forming a bent portion in which the right side surface of the hollow material Pm is a concave surface. Further, by moving the right inner wall 14a2 away from the right side surface of the hollow material Pm, it is also possible to reduce the radiant heat that the right inner wall 14a2 receives from the right side surface of the hollow material Pm. Therefore, the health of the cooling water injection nozzle 14a can be maintained at a high level.

Further, since the jetting center line c of this embodiment has almost the same length as the conventional jetting center line cc, the spraying force of the cooling water to the right side surface of the hollow material Pm can be made the same. Therefore, the same cooling capacity is ensured while avoiding interference with the hollow material Pm.
Furthermore, when the most upstream end position along the Y axis of the deformation area in the right inner wall 14a2 is hu, the injection center line c of this embodiment has a spraying destination on the Y axis compared to the conventional injection center line cc. It is possible to approach the most upstream end position hu in the direction. Therefore, since the dimension of the deformation region along the Y-axis direction can be shortened, it is possible to suppress the generation of wrinkles when forming a concave bent portion on the right inner wall 14a2. Therefore, a high-quality hollow bent part Pp with few processing wrinkles can be manufactured.

The relationship between the angle φ and the angle θ will be further explained using FIG. 5. FIG. 5(a) is an enlarged view of section E in FIG. 3(a). Further, FIG. 5(b) is an enlarged view of the F section in FIG. 3(b).
In FIG. 5(a), among the nozzle holes adjacent to each other in the vertical direction, the center line of the cooling water jetted from the nozzle hole located at a relatively high position is indicated by the symbol ch, and the nozzle hole located at a relatively low position is indicated by the symbol ch. The injection center line of the cooling water injected from the center is designated by the symbol cl. When viewed from the line of sight in FIG. 5(a), the cooling water is injected along the injection center line ch and flows down while cooling the right side of the hollow material Pm, while the cooling water flows down along the injection center line cl next to it. Although it appears to be blocking the path of the cooling water that is injected toward the right side of the hollow material Pm, it is not actually blocking it. That is, since the cooling water on the jetting center line ch flows down toward the front side of the paper on the right side surface of the hollow material Pm, it does not interfere with the cooling water on the jetting center line cl flowing on the back side thereof.

Furthermore, in FIG. 5(b), the injection center line of the cooling water injected from the nozzle hole located at the relatively upstream position among the nozzle holes adjacent to each other along the feeding direction F is denoted by the symbol cu, and the relative The center line of the injection of cooling water injected from the nozzle hole located on the downstream side is denoted by the symbol cd. When viewed from the line of sight in FIG. 5(b), since the angle θ is large for both jet center lines cu and cd, the force component toward the feeding direction F is small, and the cooling water flowing along the jet center line cu is small. The cooling water flowing along the injection center line cd does not interfere with each other.
As described above, in the cooling water injection nozzle 14a, it is possible to suppress the possibility that the cooling water flowing from each nozzle hole of the right inner wall 14a2 interferes with each other and reduces the cooling efficiency. In addition, although the above description was about the right inner wall 14a2, the same effect can be obtained also for the left inner wall 14a1. That is, although each nozzle hole of the left inner wall 14a1 has a cooling water injection direction that is symmetrical with respect to the right inner wall 14a2 as shown in FIG. Since they are similar to each nozzle hole 14a2, their repeated explanation with respect to FIGS. 2 to 5 will be omitted.

Further, in this embodiment, as shown in the plan view of FIG. 1, since the bent portion is formed by shear bending in the horizontal direction, the left inner wall 14a1 and the right inner wall 14a1 and the right Regarding the inner wall 14a2, in a cross section perpendicular to the longitudinal direction at the third position D, each injection center line c is configured to intersect with the outer circumferential surface of the hollow material Pm at an angle. On the other hand, since the hollow material Pm is not subjected to shear bending in the vertical direction, the upper inner wall 14a3 and the lower inner wall 14a4, where there is a low possibility of interference, can be formed using nozzle holes of the conventional structure as shown in FIG. 2(b). good.

[Modified example of cooling device]
When the hollow material Pm is viewed in a cross section perpendicular to its longitudinal direction and cooling water is sprayed from all sides thereof, the configurations shown in FIGS. 6(a) to 6(d) can be considered.
First, in FIG. 6(a), the direction of cooling water injected from each nozzle on the left inner wall 14a1 and the right inner wall 14a2 is directed diagonally from the bottom to the top, which is opposite to FIG. 2(b). Also in this embodiment, the cooling water is injected so that the respective injection center lines c obliquely intersect with the right side and left side surfaces of the hollow material Pm. On the other hand, similarly to the form of FIG. 2(b), nozzle holes of conventional structure are employed for the upper inner wall 14a3 and the lower inner wall 14a4.
The following FIG. 6(b) has the same configuration as FIG. 2(b). That is, the direction of the cooling water injected from each nozzle of the left inner wall 14a1 and the right inner wall 14a2 is directed diagonally from top to bottom. Thereby, the cooling water is injected to the right side surface and the left side surface of the hollow material Pm so that each injection center line c diagonally intersects with the right side surface and the left side surface. On the other hand, nozzle holes of conventional structure are employed for the upper inner wall 14a3 and the lower inner wall 14a4.

In the subsequent FIG. 6(c), the direction of the cooling water injected from each nozzle hole in the left inner wall 14a1 is upward from below, while the direction of the cooling water injected from each nozzle hole in the right inner wall 14a2 is downward from above. . That is, the injection direction of the cooling water is reversed between the left inner wall 14a1 and the right inner wall 14a2. Further, the direction of the cooling water injected from each nozzle hole in the upper inner wall 14a3 is from the right in the drawing to the left in the drawing, while the direction of the cooling water injected from each nozzle hole in the lower inner wall 14a4 is from the left in the drawing to the right in the drawing. Therefore, the cooling water is sprayed counterclockwise in the drawing over the entire outer peripheral surface of the hollow material Pm. As a result, in FIG. 6(c), the cooling water is injected so that each injection center line c obliquely intersects the entire outer peripheral surface of the hollow material Pm.

In the subsequent FIG. 6(d), the direction of the cooling water injected from each nozzle of the left inner wall 14a1 and the right inner wall 14a2 is directed diagonally from top to bottom as in FIG. 6(b). Thereby, the cooling water is injected to the right side surface and the left side surface of the hollow material Pm so that each injection center line c diagonally intersects with the right side surface and the left side surface. On the other hand, regarding the upper inner wall 14a3 and the lower inner wall 14a4, the direction of the cooling water injected from each nozzle hole of the upper inner wall 14a3 is from the right to the left in the paper, and each of the lower inner walls 14a4 is The direction of the cooling water injected from the nozzle holes is from the left to the right in the paper. Thereby, the cooling water is injected so that each injection center line c obliquely intersects the upper surface and the lower surface of the hollow material Pm.

In addition, in FIGS. 6(a) to 6(d), the case where the hollow material Pm having a rectangular cross section is subjected to shear bending processing is explained, but this is not limited to this form. The cooling water injection nozzle 14a may be applied to the hollow material Pm having the following properties. FIG. 6(e) shows a case where the same cooling water injection nozzle 14a as in FIG. 6(b) is applied. Note that FIG. 6F shows an example in which a hollow material Pm having a circular cross section is similarly cooled by a cooling device having a conventional structure. As shown in the figure, each jetting center line c is sprayed at right angles to the outer circumferential surface of the hollow material Pm without being inclined. More specifically, the nozzle holes similar to the jet center line cc explained in FIG. 4 are arranged at equal angular intervals around the hollow material Pm. The above-mentioned effects obtained by tilting cannot be obtained. This also applies to the hollow material Pm having a rectangular cross section shown in FIG. 6(g). In this conventional example shown in FIG. 6(g), when the hollow material Pm is viewed in a cross section perpendicular to its longitudinal direction, the cooling water is sprayed perpendicularly to the outer peripheral surface of the hollow material Pm. However, this configuration also does not provide the above-mentioned effects obtained by tilting the injection center line c.
In contrast to these conventional examples, in the embodiments shown in FIGS. 6A to 6E, it is possible to obtain the effects described using FIG. 4, and the interference between the cooling water injection nozzle 14a and the hollow material Pm is reduced. is definitely avoidable.

Furthermore, in the above embodiment and the modified example of FIG. 6, the case where the center line of the cooling water injection nozzle 14a is fixed to coincide with the center axis CL of the hollow material Pm at the third position D has been described. It is not limited to only. For example, as shown in FIG. 7, the center line of the cooling water injection nozzle 14a may be tilted so as to intersect with the center axis CL of the hollow material Pm at the third position D in a plan view or a side view. This tilting angle may be controlled by the control device 16 as described above. In this case, in the straight pipe hardening shown in FIG. 7(a), a heated portion H that is inclined with respect to the central axis CL is formed. Similarly, during the shear bending process shown in FIG. 7(b), the heated portion H can be formed to be inclined according to the bent portion.

[Method for manufacturing hollow bending member]
Next, a method of manufacturing a hollow bending member Pp from a hollow material Pm using the manufacturing apparatus 10 will be described below with reference to FIG. 1 and the like again. Note that the cooling method of this embodiment is included as one step of the manufacturing method.

First, a hollow material Pm, which is a straight hollow tube made of metal, is set in the manufacturing apparatus 10. That is, the hollow material Pm is supported by the support device 12 at the first position A, the rear end side of the hollow material Pm is set on the feeding device 11, and the leading end side of the hollow material Pm is gripped by the gripping means 15a, 15b. .
At this time, the heating coil 13a of the heating device 13 is placed at a second position B downstream from the first position A, and the cooling water injection nozzle of the cooling device 14 is placed at a third position C downstream from the second position B. 14a is placed. Moreover, the heating coil 13a and the cooling water injection nozzle 14a are each arranged in a state perpendicular to the central axis CL in both a side view and a plan view.
Under the above settings, heating of the hollow material Pm by the heating device 13 is started.

That is, while supporting the hollow material Pm at the first position A and feeding it in the feeding direction F which is the longitudinal direction of the hollow material Pm (feeding process), the hollow material Pm is partially heated at the second position B. A heated portion H is formed (heating step), and a part of the hollow material Pm located downstream of the heated portion H is cooled at the third position C (cooling step). At this time, the gripping means 15a, 15b move in the feeding direction F in synchronization with the feeding speed of the hollow material Pm. Therefore, the hollow material Pm is quenched as a straight pipe while being sent in the feeding direction F without being subjected to shear bending or normal bending.

Subsequently, when the hollow material Pm reaches the position where the shear bending process is performed, the gripping positions of the gripping means 15a and 15b are moved in two-dimensional or three-dimensional directions to perform the shear bending process, and the hollow material Pm is bent. (bending process). Specifically, when looking at the gripping position in a cross section including the central axis CL of the hollow material Pm, the feeding direction F along the longitudinal direction of the hollow material Pm and the direction perpendicular to the longitudinal direction of the hollow material Pm Move it in the direction of inclination between the two. At this time, the shear bending process location is cooled with cooling water from the cooling water injection nozzle 14a, so that quenching is also performed at the same time.

When performing this cooling process, in the cooling method of this embodiment, in the cross section perpendicular to the longitudinal direction (FIG. 3(a)) at the third position C, the injection center line c of each nozzle hole in the right inner wall 14a2 is The cooling water is injected so as to obliquely intersect with the right side surface of the outer peripheral surface of the hollow material Pm. The cooling water injected from the nozzle hole whose injection center line c is inclined in this way is sprayed obliquely against the right side of the hollow material Pm, and after cooling the right side, it flows back upstream and The cooling water is discharged downward without interfering with the cooling water injected from other nozzle holes. In this way, the right side surface of the hollow material Pm, which is the outer side of the bend, is cooled. At the same time, the left side surface of the hollow material Pm, which is the inside of the bend, is also cooled in the same way as the right side surface. In addition, among the surfaces of the hollow material Pm, the upper and lower surfaces, which are not in the bending direction, are less prone to interference problems, and therefore are cooled in the conventional manner as shown in FIG. 2(b).

After the shear bending process is completed, the gripping means 15a and 15b are moved in the feeding direction F while holding the hollow material Pm and synchronizing their positions with the feeding operation of the feeding device 11. As a result, the area of the hollow material Pm upstream of the location where the shear bending process has been applied is hardened.
When the quenching of the hollow material Pm is completed to the end, the heating by the heating coil 13a is stopped, and the processed hollow bent part Pp is removed from the manufacturing apparatus 10 and thrown away.
As described above, the hollow bent part Pp is manufactured through a series of steps including a feeding step, a heating step, a cooling step, and a bending step.

[Technical effects of cooling device and cooling method]
The cooling device 14 of this embodiment and the cooling method using this cooling device 14 have been described above. Next, for better understanding, the problems of the conventional cooling device will first be explained using FIGS. 8 and 9, and then the technical effects of the cooling device 14 and the cooling method of this embodiment will be summarized again.

The conventional technology shown in FIGS. 8(a) and 8(b) has a configuration including a primary cooling device 14A and a secondary cooling device 14B as cooling devices.
The hollow material Pm sent by a feeding device (not shown) is first rapidly heated by a heating coil 13a provided in the heating device 13, immediately thereafter cooled by a primary cooling device 14A, and further cooled by a subsequent secondary cooling device 14B. Ru. Here, the heating width of the heated portion H is determined by the temperature distribution along the longitudinal direction of the hollow material Pm, which is formed by heating by the heating coil 13a and cooling by the primary cooling device 14A. Note that the primary cooling is to cool the heated portion of the hollow material Pm immediately after heating, and the end position of the deformation region is determined by the spraying position of the cooling water on the outer peripheral surface of the hollow material Pm. On the other hand, secondary cooling further lowers the material temperature lowered by primary cooling, prevents the wall temperature of the hollow material P from rising again (recuperation), and is a process necessary for heat treatment such as quenching. Since the nozzle of the secondary cooling device 14B faces the outer peripheral surface of the hollow material Pm that has already been cooled by the primary cooling, the radiant heat received from the outer peripheral surface is small. On the other hand, the nozzle of the primary cooling device 14A receives a large amount of radiant heat from the outer circumferential surface because it faces a relatively high temperature outer circumferential surface. Therefore, in the primary cooling device 14A, special consideration must be given to the influence of radiant heat received by the nozzle. Note that if the mass (heat capacity) of the hollow material Pm is small or the production rate (feeding speed of the hollow material Pm) is low, the secondary cooling device 14B may be omitted.
In this conventional example shown in FIG. 8(b), when the hollow material Pm is viewed in a cross section perpendicular to its longitudinal direction, cooling water is sprayed perpendicularly to the outer peripheral surface of the hollow material Pm. However, with this configuration, in order to be able to respond to a wide range of product types and increase production speed, it was necessary to solve the above-mentioned problems such as consideration of radiant heat.

Furthermore, another conventional cooling device 14C is shown in FIG. FIG. 9A shows this primary cooling device 14C viewed from the downstream side, and a plurality of nozzle holes are formed so as to be lined up around the hollow material Pm. Then, as shown in FIGS. 9(b) and 9(c), the cooling water is injected at an incident angle θ with respect to the feeding direction F.
As shown in FIGS. 9(b) and 9(c), the cooling water injected from the first injection hole of the nozzle provided in the cooling device 14C flows toward the downstream side along the feeding direction of the hollow material Pm. The cooling water in contact with the outer circumferential surface of the heated portion H of the hollow material Pm lowers the surface temperature of the outer circumferential surface, but the temperature shifts from nucleate boiling to film boiling, and its cooling capacity rapidly decreases. In order to perform efficient cooling, the cooling water injected from the second injection hole adjacent to the first injection hole must break the boiling film formed by the cooling water injected from the first injection hole. , must be in direct contact with the outer peripheral surface of the hollow material Pm.

Therefore, the cooling water injected from the second injection hole needs to have enough pressure to break through the boiling thickness of the cooling water that is injected from the first injection hole and flows downstream on the outer peripheral surface. Although not shown, the same situation applies to the cooling water injected from each of the third injection hole, the fourth injection hole, and so on. Therefore, the further downstream the water film that flows downstream along the outer peripheral surface becomes thicker. The cooling water injected from each injection hole must cool the hollow material Pm by breaking through this thick water film and reaching the outer peripheral surface. Therefore, a large amount of high-pressure cooling water is required. This problem is the same whether normal bending or shear bending is performed.

In the conventional cooling method, when the incident angle θ of the cooling water is increased, the collision pressure is increased and a high cooling capacity can be obtained. However, when the incident angle θ of the cooling water is increased, the cooling water hitting the outer peripheral surface tends to flow in a direction opposite to the traveling direction of the hollow material Pm. When such a backflow occurs, the temperature distribution near the landing position of the cooling water becomes inconsistent in the circumferential direction or the longitudinal direction of the hollow material Pm. In this case, the mechanical properties of the obtained hollow bent part Pp become non-uniform or the shape becomes non-uniform, so it is necessary to avoid backflow of cooling water.

On the other hand, in the conventional cooling method, it is effective to reduce the heating width in order to obtain a wrinkle-free hollow bent part Pp. Also, in shear bending, it is effective to reduce the heating width in order to ensure uniform shaping. That is, in the conventional method, it is necessary to make the distance L1 in FIG. 9(b) as small as possible. However, in order to reduce the distance L1, it is necessary to reduce the distance L0 and distance L2 shown in the figure. However, it is not easy to reduce the distance L0 due to processing and structural limitations of the cooling water injection holes in the cooling device. Further, there are restrictions on increasing the angle θ from the viewpoint of suppressing backflow. On the other hand, if the distance L2 between the outer circumferential surface of the hollow material Pm and the nozzle is made small, there is a possibility that the bent inner circumferential surface of the hollow material Pm may interfere with the nozzle during bending deformation.

As explained above, in the conventional cooling device, interference with the hollow material Pm, heat countermeasures against radiant heat from the heated portion H of the hollow material Pm, prevention of wrinkles when bending the hollow material Pm, etc. Various issues arose. In contrast, the cooling device 14 of this embodiment can solve the problem by adopting the following configuration.
(1) That is, the cooling device 14 of the present embodiment includes a feeding device (feeding mechanism) 11 that feeds a hollow metal material Pm while supporting it at a first position A along its longitudinal direction; A heating coil 13a heats the hollow material Pm at a second position B downstream from A, and a cooling water (cooling medium) is injected to the hollow material Pm at a third position C downstream from the second position B. The cooling device 14 equipped with a cooling water injection nozzle 14a having a plurality of nozzle holes and the hollow material Pm are gripped at a fourth position D downstream from the third position C, and the gripping position is set in a two-dimensional direction or a three-dimensional direction. It is used in an apparatus 10 for manufacturing a hollow bent part, which includes a shearing force applying device (bending processing section) 15 that moves in the original direction to form a bent part in the hollow material Pm. The cooling device 14 is configured such that, in a cross section perpendicular to the longitudinal direction at the third position C, at least one jet center line c of each nozzle hole is inclined with respect to the outer circumferential surface of the hollow material Pm. intersects with.

According to the cooling device 14 described in (1) above, the cooling water injected from the nozzle hole whose injection center line c is inclined is sprayed obliquely onto the outer circumferential surface of the hollow material Pm. Here, this nozzle hole is defined as the first injection hole, the nozzle hole whose spraying position with respect to the outer peripheral surface is downstream than the first injection hole is defined as the second injection hole, and the third position C is orthogonal to the longitudinal direction. The case when viewed in cross section will be explained. In this configuration, the injection center line c of the first injection hole intersects with the outer circumferential surface of the hollow material Pm so as to be inclined. That is, when the angle of this inclination is φ, the angle φ is made smaller than 90 degrees so that the injection center line c of the first injection hole lies close to the outer circumferential surface. Thereby, the cooling water injected from the first injection hole can avoid interference with the cooling water injected from the second injection hole and furthermore, the other cooling water sprayed downstream from other injection holes. . Since interference between the cooling waters can be avoided in this way, the cooling water jetted from the first injection holes is less likely to flow back upstream in the feeding direction. Therefore, when viewed in a cross section including the central axis CL of the hollow material Pm at the third position C, the angle θ formed by the injection center line of the first injection hole with respect to the outer peripheral surface of the hollow material Pm is set to be large. The injection center line c can be made to stand up without having to lie down as in the conventional case. By setting a large angle θ in this way, even if the first injection hole is located away from the outer circumferential surface of the hollow material Pm, the cooling water spraying position injected from the first injection hole can be adjusted upstream in the feeding direction. It can be moved to the side and brought closer to the heated part H. As a result, it is possible to shorten the dimension of the heated portion H along the feeding direction to prevent wrinkles from occurring at the bent portion, and it is also possible to prevent the cooling device 14 from interfering with the hollow material Pm.

(2) Furthermore, in the cooling device 14 described in (1) above, the injection center line may obliquely intersect with the bent inner surface of the bent portion, which is the outer peripheral surface.
In the case of the cooling device 14 described in (2) above, the cooling water sprayed onto the bent inner surface hits the bent inner surface while heading generally in the width direction of the hollow material Pm, cools it, and then leaves immediately. It is discharged in the substantially width direction. Here, in the conventional structure, the bent inner surface is likely to interfere with the cooling device. However, in the present cooling device 14, for the reason mentioned above, it is possible to secure a larger clearance between the bent inner surface and the nozzle hole than in the conventional structure, so that interference between them can be reliably avoided.

(3) In the cooling device 14 described in (2) above, the injection center line c may obliquely intersect with the bent inner surface of the bent portion formed by shear bending.
In the case of the cooling device 14 described in (3) above, the cooling water sprayed onto the bent inner surface formed by the shear bending process hits the bent inner surface while heading in the approximate width direction of the hollow material Pm to cool it. After that, it is immediately separated and discharged in the substantially width direction. Here, in the case of shear bending, since the hollow material Pm is bent at a steeper angle than in the case of normal bending, interference with the nozzle hole is likely to occur. However, in the present cooling device 14, interference between the bent inner surface and the cooling device 14 can be reliably avoided even during shear bending for the reasons described above.

(4) As illustrated in FIG. 10(a) described below, in the cooling device 14 described in (2) or (3) above, the bent inner surface is one of the pair of outer surfaces of the hollow material Pm. On the other hand, when the hollow material Pm is viewed in the cross section at the third position C, the injection center line c may be configured to intersect the one outer surface diagonally downward.
In the case of the cooling device 14 described in (4) above, the cooling water sprayed against the outer surface, which is the bent inner surface, hits the outer surface and cools it, and then immediately separates and is discharged downward. . At this time, the cooling water is subjected to a downward force due to gravity, so that it can be discharged more reliably.

(5) As illustrated in FIG. 10(c) described below, in the cooling device 14 described in (2) or (3) above, the bent inner surface is the upper surface of the hollow material, and the hollow material Pm When viewed in the cross section at the third position C, the injection center line c may be configured to intersect diagonally with the upper surface.
In the case of the cooling device 14 described in (5) above, the cooling water sprayed against the upper surface, which is the bent inner surface, hits the upper surface and cools it, and then immediately leaves to the side of the upper surface and then downwards due to gravity. is ejected towards. Therefore, also in this form, the cooling water can be discharged more reliably.

(6) The cooling method of the present embodiment includes a feeding process in which a hollow metal material Pm is fed while being supported at a first position A along its longitudinal direction, and a second process downstream from the first position A. a heating step of heating the hollow material Pm at position B; a cooling step of injecting cooling water from a plurality of nozzle holes toward the hollow material Pm at a third position C downstream from the second position B; a bending step of gripping the hollow material Pm at a fourth position D downstream from the position C of the hollow material Pm, and moving the gripping position in a two-dimensional direction or three-dimensional direction to form a bent part in the hollow material Pm. It is used in the cooling step in the method for manufacturing bent parts. In this cooling method, in the cross section perpendicular to the longitudinal direction at the third position C, at least one injection center line c of each nozzle hole intersects with the outer circumferential surface of the hollow material Pm at an angle. Inject cooling water.
According to the cooling method described in (6) above, the same effects as the cooling device 14 described in (1) above can be obtained.

(7) In the cooling method described in (6) above, the cooling water may be injected to the bending inner surface of the bent portion, which is the outer circumferential surface, so that the injection center line c intersects at an angle. .
According to the cooling method described in (7) above, the same effects as the cooling device 14 described in (2) above can be obtained.

(8) In the cooling method described in (7) above, the cooling medium c is injected so that the injection center line c obliquely intersects the bent inner surface of the bent part formed by shear bending. You may.
According to the cooling method described in (8) above, the same effect as the cooling device 14 described in (3) above can be obtained.

(9) As illustrated in FIG. 10(a), in the cooling method described in (7) or (8) above, the bent inner surface is one of the pair of outer surfaces of the hollow material Pm. When the hollow material Pm is viewed in the cross section at the third position C, cooling water may be injected onto the one outer surface so that the injection center line c intersects diagonally downward.
According to the cooling method described in (9) above, the same effects as the cooling device 14 described in (4) above can be obtained.

(10) As illustrated in FIG. 10(c), in the cooling method described in (7) or (8) above, the bent inner surface is the upper surface of the hollow material Pm, and the hollow material Pm is The cooling water may be injected so as to diagonally intersect the injection center line c with respect to the upper surface when viewed in the cross section at position C.
According to the cooling method described in (10) above, the same effects as the cooling device 14 described in (5) above can be obtained.

[First example]
The shear bending apparatus 10 shown in FIG. 1 was equipped with a secondary cooling device, and shear bending hardening was performed at ψ=45 degrees. A hollow material Pm made of 0.2% carbon steel and having a height of 30 mm, a width of 50 mm, and a plate thickness of 1.0 mm was prepared, and a hollow bent part Pp having a total length of 1200 mm after shear bending was manufactured. During this manufacturing, cooling water nozzles having the structure of the present invention and those having the conventional structure were used and compared. The maximum heating temperature was set to 950°C, and the amount of cooling water that would give the same hardness was investigated. Here, the amount of cooling water is the total amount of water including primary cooling and secondary cooling, and Table 1 shows the ratio with respect to the conventional method. In addition, a thermocouple is attached to the inner surface of the hollow material Pm to measure its temperature, and from the time-temperature chart and the feed rate of the hollow material Pm, the length in the longitudinal direction of the area where the temperature is 800°C or more is calculated as the heating width. did.

Invention examples 1 and 2 in Table 1, with the bending direction being rightward, the structure of the present invention is applied to the cooling water nozzle on the right side corresponding to the inner circumferential side of the bend, and the conventional nozzle structure is applied to the other upper and lower surfaces and the left side. did.
In Invention Example 3, with the bending direction being upward, the structure of the present invention was applied to the cooling water nozzle on the upper surface corresponding to the inner peripheral side of the bend, and the conventional nozzle structure was applied to the left and right surfaces and the lower surface.
Further, in Invention Example 4, the structure of the present invention was applied to the cooling water nozzle on the lower surface corresponding to the inner circumferential side of the bend, with the bending direction being downward, and the conventional nozzle structure was applied to the left and right surfaces and the upper surface.
Further, in Invention Example 5, the bending direction is the left-right direction, and the structure of the present invention is applied to the cooling water nozzle on the left and right surfaces corresponding to the inner circumferential side of the bend, and the conventional nozzle structure is applied to the upper and lower surfaces.
Regarding Comparative Example 1, the conventional nozzle structure was applied to the upper, lower, left, and right surfaces.
Shear bending was performed for each of the above configurations.

In Comparative Example 1, contact between the hollow material Pm and the cooling device occurred in all bending directions, and the bending process was interrupted. On the other hand, for Invention Examples 1 to 5, the gap between the inner circumferential surface of the primary cooling device and the outer circumferential surface of the hollow material Pm (distance L2 shown in FIG. 9(b)) is approximately 2.5 times that of the conventional structure. I was able to set it to . Therefore, under all manufacturing conditions, contact between the hollow material Pm and the cooling water nozzle did not occur, and a good hollow bent part Pp was obtained. Moreover, by increasing the gap (distance L2 shown in FIG. 9(b)), the influence of radiant heat from the hollow material Pm can be significantly reduced, and the durability of the cooling water nozzle is also increased.
Furthermore, in Invention Examples 1 to 5, it is possible to reduce the gap (distance L2 shown in FIG. 9(b)) in the conventional nozzle located in a direction other than the bending direction where there is no risk of contact, and the heating width is also compared. It was possible to reduce it compared to the example.

Comparing Invention Examples 1 and 2, the cooling water injected to the right side of the hollow material Pm flows downward in Invention Example 1 and is discharged, so the cooling water discharge efficiency is high, compared to Invention Example 2. The decrease in the amount of cooling water was somewhat large.
Similarly, when comparing Invention Examples 3 and 4, in Invention Example 3, the cooling water flows downward and is discharged, so the cooling water discharge efficiency is higher, and the amount of cooling water is reduced compared to Invention Example 4. The decrease was somewhat large.
In all invention examples 1 to 3, the amount of cooling water could be significantly reduced. Furthermore, in Inventive Example 5 in which left and right bending is performed, the structure of the present invention is arranged on the left and right sides, so that the efficiency of discharge is further increased and the amount of cooling water is further reduced.

[Second example]
Hardening was performed using the hot bending apparatus 100 shown in FIG. A hollow material Pm made of 0.2% carbon steel and having a height of 20 mm, a width of 20 mm, and a plate thickness of 1.2 mm was prepared, and a hollow bent part Pp having a total length of 800 mm after bending was manufactured. During this manufacturing, cooling water nozzles having the structure of the present invention and those having the conventional structure were used and compared. The evaluation method is the same as in the first example. The results are shown in Table 2 below.

In invention examples 6 and 7, the structure of the present invention was applied to cooling water nozzles on four sides, top, bottom, left and right. The bending directions are four directions: an up-down direction and a left-right direction. For Comparative Example 2, nozzles with a conventional structure were applied to the four cooling water nozzles on the upper, lower, left, and right sides, and bending was performed in the bending direction corresponding to the invention example.
In invention examples 6 and 7, the gap between the inner circumferential surface of the primary cooling device and the outer circumferential surface of the hollow material Pm (distance L2 shown in FIG. 9(b)) is set at all four cooling water nozzles on the upper, lower, left, and right sides. It was possible to set the structure to about 2.5 times that of the conventional structure. Therefore, the heating width in the hollow material Pm was also significantly reduced compared to Comparative Example 2. Furthermore, by increasing the distance L2, the influence of radiant heat on the cooling water nozzle can be significantly reduced, and the durability of the cooling water nozzle is also increased. Furthermore, in Inventive Examples 6 and 7, the cooling water did not flow in the downstream direction, which is the feeding direction, but was discharged in the vertical and horizontal directions, and the cooling water discharge efficiency was significantly increased. As a result, in Inventive Examples 6 and 7, compared to Comparative Example 2, a significant decrease in the amount of cooling water required for cooling was observed.

[Third example]
Using the shear bending apparatus 10 shown in FIG. 1, shear bend hardening at ψ=35 degrees was performed. A hollow material Pm, which is a circular tube made of 0.2% carbon steel and having an outer diameter of 25.4 mm and a plate thickness of 1.2 mm, was prepared, and a hollow bent part Pp having a total length of 1200 mm after shear bending was manufactured. At that time, a left-right bending test was conducted while performing the cooling method shown in Table 3 below. The evaluation method is the same as in the first example. The results are shown in Table 3 below.

In Comparative Example 3, a cooling water nozzle with a conventional structure shown in FIG. 6(f) was used. That is, the cooling pattern of Comparative Example 3 was axially symmetrical in the circumferential direction, and the incident angle θ in the longitudinal direction was 40 degrees, and the incident angle φ in the width direction was 90 degrees.
In Invention Example 8, a cooling water nozzle having the structure of the present invention shown in FIG. 6(e) was used. That is, the longitudinal incident angle θ and the widthwise incident angle φ on the upper and lower surfaces and the left and right surfaces were given as shown in Table 3, respectively. The cooling water flowed from the top to the bottom through the cooling water nozzles on the left and right sides, and was allowed to leave the product as it was.
In Comparative Example 3, contact occurred between the hollow material Pm and the cooling water nozzle, so processing was interrupted. On the other hand, in invention example 8, the gap between the inner peripheral surface of the primary cooling device and the outer peripheral surface of the hollow material Pm (distance L2 shown in FIG. 9(b)) could be set to about twice that of the conventional structure. . Therefore, contact between the hollow material Pm and the cooling water nozzle did not occur, and a good product was obtained. Furthermore, by increasing the distance L2, the influence of radiant heat on the cooling water nozzle can be significantly reduced, and the durability of the cooling water nozzle is also increased. In addition, in Inventive Example 8, compared to Comparative Example 3, a decrease in the amount of cooling water required for cooling was observed.

[Fourth example]
The present inventors have commercialized a high-strength product that has a bent portion with a bending radius that is 1 to 2 times the diameter of the metal tube (the length of the side in the bending direction in the case of a rectangular cross section) or less. A cooling device applicable to possible shear bending processing was proposed in International Publication No. 2021/172242. A primary cooling device in which the contents are actually combined with the structure of the present invention is shown in FIG. In this device configuration, by applying the structure of the present invention, it was possible to downsize the primary cooling device and avoid contact with the product. Specifically, using the shear bending apparatus 10 shown in FIG. 1 as this primary cooling device, shear bending hardening was performed at ψ=90 degrees.
A hollow material Pm, which is a circular tube made of 0.2% carbon steel and having an outer diameter of 25.4 mm and a plate thickness of 1.2 mm, was prepared, and a hollow bent part Pp having a total length of 700 mm after shear bending was manufactured. At that time, the test was conducted while performing the cooling method shown in Table 4 below. The evaluation method is the same as in the first example. The results are shown in Table 4 below.

In Comparative Example 4, processing was interrupted because interference occurred between the hollow material Pm and the cooling water nozzle in all bending directions.
On the other hand, in Inventive Examples 9 and 10, no such interference occurred and good results were obtained.

The hollow bending member Pp manufactured by the manufacturing method according to the present invention is applicable to, for example, the following uses (i) to (vii).
(i) Structural members of the automobile body, such as front side members, cross members, side members, suspension members, roof members, A-pillar reinforcements, B-pillar reinforcements, bumper reinforcements, etc. (ii) For example, seats Automobile strength members and reinforcing members such as frames and seat cross members (iii) Exhaust system parts such as automobile exhaust pipes (iv) Frames and cranks for bicycles and motorcycles (v) Reinforcing members and trolley parts for vehicles such as trains (Bolly frame, various beams, etc.)
(vi) Frame parts such as hulls, reinforcing members (vii) Strength members, reinforcing members or structural members of home appliances

10 Shear bending equipment (manufacturing equipment)
11 Feeding device (feeding mechanism)
13a Heating coil 14 Cooling device 15 Shearing force applying device (bending part)
A First position B Second position C Third position c Injection center line D Fourth position Pm Hollow bending part

Claims (10)

a feeding mechanism that feeds a metal hollow material while supporting it at a first position along its longitudinal direction;
a heating coil that heats the hollow material at a second position downstream of the first position;
a cooling device having a plurality of nozzle holes that inject a cooling medium into the hollow material at a third position downstream from the second position;
a bending section that grips the hollow material at a fourth position downstream from the third position and moves the gripping position in a two-dimensional direction or three-dimensional direction to form a bent part in the hollow material;
The cooling device used in a hollow bending component manufacturing device comprising:
In a cross section perpendicular to the longitudinal direction at the third position, at least one jet center line of each nozzle hole intersects with the outer circumferential surface of the hollow material so as to be inclined. Cooling device. The cooling device according to claim 1, wherein the injection center line obliquely intersects with the bent inner surface of the bent portion, which is the outer peripheral surface. 3. The cooling device according to claim 2, wherein the injection center line obliquely intersects the bent inner surface of the bent portion formed by shear bending. the bent inner surface is one of a pair of outer surfaces of the hollow material;
When the hollow material is viewed in the cross section at the third position, the jet center line intersects the one outer surface diagonally downward;
The cooling device according to claim 2 or 3, characterized in that: the bent inner surface is the upper surface of the hollow material;
When the hollow material is viewed in the cross section at the third position, the jetting center line obliquely intersects the upper surface;
The cooling device according to claim 2 or 3, characterized in that: a feeding step of feeding the metal hollow material while supporting it at a first position along its longitudinal direction;
a heating step of heating the hollow material at a second position downstream from the first position;
a cooling step of injecting a cooling medium from a plurality of nozzle holes toward the hollow material at a third position downstream from the second position;
a bending step of gripping the hollow material at a fourth position downstream from the third position and moving the gripping position in a two-dimensional direction or three-dimensional direction to form a bent part in the hollow material;
A cooling method used in the cooling step in a method for manufacturing a hollow bent part, comprising:
In a cross section perpendicular to the longitudinal direction at the third position, the cooling medium is supplied so that at least one jetting center line of each nozzle hole intersects the outer circumferential surface of the hollow material at an angle. A cooling method characterized by jetting. 7. The cooling method according to claim 6, wherein the cooling medium is injected so that the injection center line obliquely intersects the bent inner surface of the bent portion, which is the outer circumferential surface. The cooling method according to claim 7, characterized in that the cooling medium is injected to the bent inner surface of the bent portion formed by shear bending so that the injection center line intersects at an angle. . the bent inner surface is one of a pair of outer surfaces of the hollow material;
When the hollow material is viewed in the cross section at the third position, the cooling medium is injected onto the one outer surface so that the injection center line intersects diagonally downward;
The cooling method according to claim 7 or 8, characterized in that. the bent inner surface is the upper surface of the hollow material;
Injecting the cooling medium so that the injection center line obliquely intersects the upper surface when the hollow material is viewed in the cross section at the third position;
The cooling method according to claim 7 or 8, characterized in that.

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