JP5722069B2 - Hot processing equipment for metal tubes - Google Patents

Description

  The present invention relates to a hot processing apparatus for a metal tube for bending the metal tube into a desired shape while being heated by a high-frequency heating coil.

  A metal tube delivery device for delivering a metal tube in its longitudinal direction, a bending fulcrum member for guiding and supporting the delivered metal tube, a high-frequency heating coil for locally heating the metal tube, and a heated portion of the metal tube A hot working apparatus for a metal tube including a cooling device for cooling and a bending device for gripping the metal tube and applying a bending moment to a heated portion is known from Patent Document 1 or Patent Document 2 below.

JP 2007-83304 A WO2010 / 050460

  By the way, when a front pillar, a roof side rail, and a rear pillar of an automobile are formed by bending a single metal tube, the metal tube is not a circular cross section but an irregular cross section having irregularities, and is heated by a high frequency heating coil. At this time, it is difficult to uniformly heat each part, and it is inevitable that temperature unevenness occurs. If there is temperature unevenness in the metal tube, the degree of softening of each part is different, which causes a problem that the dimensional accuracy is lowered when it is bent into a desired shape.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable uniform heating of a metal tube by a high-frequency heating coil in a hot processing apparatus for a metal tube.

In order to achieve the above object, according to the first aspect of the present invention, a metal tube delivery device for delivering a metal tube along a longitudinal direction, and an outer periphery of the metal tube delivered from the metal tube delivery device. A high-frequency heating coil that heats the metal tube surrounding the metal tube, a bending device that applies a bending moment to the metal tube heated by the high-frequency heating coil, and an upstream side of the high-frequency heating coil in the feeding direction of the metal tube An apparatus for hot-working a metal tube comprising an electric heater that is disposed and preheats the metal tube, wherein the metal tube is manufactured by roll forming a steel plate, with respect to the inner peripheral surface of the high-frequency heating coil A linear member having a constant cross-section in the longitudinal direction having a portion recessed inward and a portion sandwiched between both ends where the current of the high-frequency heating coil flows in the opposite direction, A guide hole having the same shape as the cross-sectional shape of the metal tube is formed in a bending fulcrum member provided at an outlet portion of the installation, and the metal tube passes through the inner peripheral surface of the guide hole while sliding, and the bending fulcrum member The electric heater is embedded inside the guide hole so as to spirally surround the inner peripheral surface of the guide hole, the electric heater generates heat by an electric current to increase the temperature of the bending fulcrum member, A hot working apparatus for a metal tube is proposed, which is preheated to 600 ° C. while passing through the bending fulcrum member and is heated to 800 ° C. while passing through the high frequency heating coil .

According to the invention described in claim 2 , in addition to the configuration of claim 1, the high-frequency heating coil has a shield member that blocks passage of magnetic flux at least on a surface upstream of the metal tube in the delivery direction. A hot working apparatus for a metal tube is provided, which is characterized by comprising the following.

According to the invention described in claim 3 , in addition to the structure of claim 2 , there is proposed a hot working apparatus for a metal tube, wherein the shield member is a silicon steel plate or a pure iron plate. The

The first shielding member 27 of the implementation of embodiment corresponds to the shield member of the present invention.

  According to the configuration of the first aspect, the metal tube delivered from the metal tube delivery device is induction-heated through the high-frequency heating coil, and is bent by applying a bending moment by the bending device. Preheating means for preheating the metal tube is provided upstream of the high frequency heating coil in the metal tube delivery direction, so that the metal tube can be preheated to a predetermined temperature before being heated by the high frequency heating coil. Thus, when the bending by the high-frequency heating coil is completed, the temperature difference of each part of the metal tube can be minimized to increase the bending processing accuracy.

In particular, a metal tube manufactured by roll forming a steel plate is sandwiched between a portion recessed inward with respect to the inner peripheral surface of the high-frequency heating coil and both ends where the current of the high-frequency heating coil flows in the opposite direction. This is a linear member with a certain irregular cross section in the longitudinal direction having a portion, so that a temperature difference is likely to occur during heating by a high-frequency heating coil. However, the provision of a preheating means effectively generates the temperature difference. Can be suppressed.

In addition, a guide hole having the same shape as the cross-sectional shape of the metal tube is formed in the bending fulcrum member provided at the outlet of the metal tube delivery device, and the metal tube passes while sliding on the inner peripheral surface of the guide hole. An electric heater is embedded in the inside of the guide hole so as to spirally surround the inner peripheral surface of the guide hole, so that the bending moment by the bending device does not act on the metal pipe passing through the inside of the bending fulcrum member, and in the preheating stage It is possible to prevent the metal tube from bending.

Moreover, the metal tube is preheated to 600 ° C. while passing through the bending fulcrum member, and is heated to 800 ° C. while passing through the high frequency heating coil, so that the temperature rise by the high frequency heating coil is only 200 ° C. The temperature unevenness of each part of the metal tube generated by the main heating by the high-frequency heating coil can be further reduced.

According to the second aspect of the present invention, since the shield member that blocks the passage of the magnetic flux is provided on the upstream surface of the metal tube of the high-frequency heating coil in the delivery direction, the magnetic flux from the high-frequency heating coil is blocked by the shield member. Thus, it is possible to prevent the bending fulcrum member from being heated and the magnetic flux of the high frequency heating coil from interfering with the magnetic flux of the second high frequency heating coil. As a result, the bending fulcrum member and the second high-frequency heating coil are brought close to the high-frequency heating coil, and the bending moment applied to the metal pipe at the position of the bending fulcrum member and the second high-frequency heating coil is reduced by the bending device. It is possible to prevent the metal tube from bending other than the position of the heating coil.

According to the third aspect of the present invention, since the shield member is made of a silicon steel plate or a pure iron plate, the magnetic flux from the high frequency heating coil can be reliably blocked and the high frequency heating coil can be protected.

The figure which shows the whole structure of the hot processing apparatus of a metal tube. (First embodiment) FIG. 2 is a two-direction enlarged arrow view of FIG. 1. (First embodiment) FIG. 3 is a view taken along line 3-3 in FIG. 2. (First embodiment) FIG. 4 is a four-direction arrow view of FIG. 3. (First embodiment) FIG. 5 is a sectional view taken along line 5-5 in FIG. (First embodiment) Explanatory drawing of the temperature change of the metal pipe at the time of a heating. (First embodiment) The figure corresponding to the said FIG. ( Reference example ) The figure corresponding to the said FIG. (Second Embodiment) Explanatory drawing of the temperature change of the metal pipe at the time of a heating. (Conventional example)

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a metal tube W that is a workpiece of the present embodiment is a member that integrally constitutes a front pillar, a roof side rail, and a rear pillar of an automobile, for example, and is manufactured by roll forming a steel plate. The A hot working apparatus that heats and bends a metal tube W into a predetermined shape includes a metal tube delivery device 11 that feeds the metal tube W in the longitudinal direction thereof, and a bending fulcrum member provided at an outlet of the metal tube delivery device 11. 12, a high-frequency heating coil 13 provided on the downstream side of the bending fulcrum member 12, a cooling device 14 provided on the downstream side of the high-frequency heating coil 13, and a robot provided on the downstream side of the cooling device 14. Device 15. The metal tube W is a linear member having a constant cross section in the longitudinal direction. The metal tube W is heated by the high frequency heating coil 13 and then bent by a bending device 15 to be bent into a predetermined shape, and then cooled. Quenching is performed by quenching with cooling water ejected from the device 14.

  As is clear from FIG. 2, the bending fulcrum member 12 is provided at the outlet of the metal tube delivery device 11, and a guide hole 12a having the same shape as the cross-sectional shape of the metal tube W is formed at the center thereof. The metal tube W delivered from the metal tube delivery device 11 passes through the inner peripheral surface of the guide hole 12a of the bending fulcrum member 12 while sliding. An electric heater 16 as a preheating means is accommodated in the bending fulcrum member 12. The electric heater 16 is embedded so as to spirally surround the inner peripheral surface of the guide hole 12a. The electric heater 16 generates heat by current and raises the temperature of the bending fulcrum member 12, thereby preheating the metal tube W passing therethrough. To do.

  As is apparent from FIGS. 2 to 4, the high-frequency heating coil 13 is disposed at a position spaced a predetermined distance from the bending fulcrum member 12 on the downstream side in the feeding direction of the metal tube W, and an opening 17 a is formed at the center. The plate-shaped mount 17 is supported. The gantry 17 close to the high-frequency heating coil 13 is made of heat-resistant bakelite, glass epoxy, hard plastic or the like so as not to be damaged by being heated by the magnetic flux from the high-frequency heating coil 13.

  The high-frequency heating coil 13 is composed of a two-turn coil, and the gantry 17 is interposed via two mounting stays 19 and 19 so that a substantially constant gap is formed between the inner periphery thereof and the outer periphery of the metal tube W. Fixed to. Two cables 22 and 22 for supplying electric power to both ends of the high-frequency heating coil 13 are connected. The high frequency heating coil 13 has a water jacket formed therein, and two hoses 23 and 23 for supplying cooling water are connected to both ends of the water jacket.

  The cooling device 14 includes an annular cooling water tank 24 surrounding the outer periphery of the metal pipe W, four cooling water supply pipes 25 connected to the outer peripheral surface of the cooling water tank 24, and an inner peripheral surface of the cooling water tank 24. Are formed with a plurality of cooling water ejection holes 24a.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  The metal tube W delivered from the metal tube delivery device 11 is gripped by a clamp arm of a bending device 15 made of a robot at a position that has passed through the bending fulcrum member 12, the high-frequency heating coil 13, and the cooling device 14. When the electric heater 16 inside the bending fulcrum member 12 is energized to generate heat, the metal tube W passing therethrough is preheated and the temperature rises. Further, when a high-frequency current is supplied to the high-frequency heating coil 13 via the cables 22, 22, an eddy current is generated inside the metal tube W due to the magnetic field formed around the high-frequency heating coil 13, and the metal tube W becomes a joule. It is heated by heat.

  The high-frequency heating coil 13 itself generates heat and becomes high temperature due to energization. By supplying cooling water to the inside through the hoses 23 and 23, the high-frequency heating coil 13 can be prevented from being overheated.

  By the way, as shown in FIG. 3, the metal tube W that integrally constitutes the front pillar, roof side rail, and rear pillar of the automobile is a member having an irregular cross section having complicated irregularities, and the high frequency heating coil 13 that surrounds the metal pipe W. The gaps between them are considered to be as uniform as possible, but it is difficult to heat each part of the metal tube W evenly.

  For example, the a portion of the metal tube W that is bent thinly is sufficiently heated and the temperature tends to be higher than the target temperature. Further, the flat portion d of the metal tube W is heated appropriately and easily reaches the target temperature. Further, the c portion recessed inward of the metal tube W increases the gap with the high-frequency heating coil 13, so that the heating is insufficient and the temperature tends to be lower than the target temperature. In addition, since the portion b of the metal tube W is sandwiched between both ends of the high-frequency heating coil 13 in which currents flow in opposite directions, eddy currents are hardly generated effectively, and the temperature becomes lower than the target temperature. easy.

  FIG. 9 shows the operation of a conventional example in which preheating is not performed. For the reasons described above, even if each part a, b, c, d of the metal tube W is heated simultaneously by the high-frequency heating coil 13, the temperature of each part does not rise evenly, and the temperature of the metal tube W at the time of performing the bending process. Therefore, there is a problem that a large variation ΔT is generated and the processing accuracy of the bending process is lowered.

  Therefore, in the present embodiment, as shown in FIG. 6, preheating is performed to a predetermined temperature (for example, 600 ° C.) by the electric heater 16 while the metal tube W passes through the bending fulcrum member 12. As a result of the preliminary heating by the electric heater 16, some temperature unevenness occurs in each part of the metal tube W, but the temperature unevenness is caused by heat transfer until the heated part reaches the position of the high-frequency heating coil 13. Is eliminated, and the temperature of the metal tube W becomes uniform in each part.

  Subsequently, the metal tube W is heated to the processing temperature (for example, 800 ° C.) by the high-frequency heating coil 13, but the temperature of the pre-heated metal tube W has already increased to 600 ° C. The temperature rise by the high frequency heating coil 13 is only 200 ° C. As a result, the temperature unevenness ΔT of each part of the metal tube W generated by the main heating by the high-frequency heating coil 13 becomes smaller than that of the conventional example described with reference to FIG. 9, and the bending device 15 displaces the metal tube W in the bending direction and bends it. The processing accuracy when processing can be increased. The metal tube W bent in this way is quenched and quenched by cooling water ejected from the cooling water ejection holes 24a of the cooling water tank 24 of the cooling device 14, thereby bending the metal tube W. And quenching can be performed continuously.

  As shown in FIG. 5, the bending moment acting on the metal tube W by the bending device 15 is zero at the position of the bending device 15 and increases linearly toward the bending fulcrum member 12 from there. It becomes maximum at the outlet and becomes zero inside the bending fulcrum member 12. On the other hand, since the strength of the metal tube W with respect to the bending moment is inversely proportional to the temperature, the strength of the metal tube W gradually decreases while preheated by the electric heater 16, and after leaving the electric heater 16, the high frequency heating coil 13 is applied. It will be constant until it reaches. And the intensity | strength of the metal pipe W falls rapidly by main heating with the high frequency heating coil 13, Then, it cools with the cooling device 14, and returns to the state before a heating.

  Since the bending moment acting on the metal tube W exceeds the strength of the metal tube W after the metal tube W is heated by the high-frequency heating coil 13 until it is cooled by the cooling device 14, Bending is performed. In addition, since the bending moment by the bending device 15 does not act on the metal tube W inside the bending fulcrum member 12, by providing the electric heater 16 inside the bending fulcrum member 12, the metal tube W is bent at the stage of preheating. Can be prevented.

Next, a reference example will be described based on FIG.

In the first embodiment, the electric heater 16 is disposed inside the bending fulcrum member 12 as preheating means, but in the reference example , the bending fulcrum member 12 and the high frequency heating coil 13 are used as preheating means. A second high-frequency heating coil 26 is disposed.

With this reference example, a predetermined temperature (e.g., 600 ° C) while the metal tube W passes through the second high frequency heating coils 26 by performing preheated to the processing temperature of the metal tube W by the high frequency heating coil 13 It is possible to suppress the temperature rise during the main heating up to (for example, 800 ° C.) and to reduce the temperature unevenness of each part of the metal tube W generated by the main heating, thereby increasing the bending processing accuracy.

  By the way, in the first embodiment shown in FIG. 5, the bending moment may temporarily exceed the strength of the metal tube W at the position where the metal tube W exits the bending fulcrum member 12, and the metal tube is at that portion. Undesirable bending may occur in W. In order to prevent this, the exit of the bending fulcrum member 12 is brought close to the high-frequency heating coil 13 so that the bending moment at the position where the metal tube W exits the bending fulcrum member 12 does not exceed the strength of the metal tube W. It ’s fine.

Similarly, in the reference example shown in FIG. 7, there is a possibility that the bending moment temporarily exceeds the strength of the metal tube W at the position where the metal tube W is heated by the second high-frequency heating coil 26. Undesirable bending may occur in the tube W. In order to prevent this, the second high-frequency heating coil 26 is brought close to the high-frequency heating coil 13, and the bending moment at the position where the metal tube W is preheated by the second high-frequency heating coil 26 increases the strength of the metal tube W. Should not be exceeded.

  However, when the bending fulcrum member 12 is brought close to the high-frequency heating coil 13, the magnetic flux generated by the high-frequency heating coil 13 acts on the bending fulcrum member 12, and the bending fulcrum member 12 is deformed by excessively rising temperature. There is a problem that durability is lowered. Further, when the second high-frequency heating coil 26 is brought close to the high-frequency heating coil 13, there is a problem that the magnetic fluxes of both interfere with each other and it becomes difficult to control the heating temperature, or power is wasted.

Therefore, as shown in FIG. 8, in the second embodiment improved from the first embodiment, the surface of the high-frequency heating coil 13 facing the bending fulcrum member 12 and the surface facing the cooling device 14 are First and second shield members 27 and 28 made of a silicon steel plate or a pure iron plate that effectively suppress the transmission of magnetic flux generated by the high-frequency heating coil 13 are attached.

  According to the present embodiment, since the surface of the high-frequency heating coil 13 on the side of the bending fulcrum member 12 is covered with the first shield member 27, the magnetic flux generated by the high-frequency heating coil 13 is shielded by the first shield member 27. Therefore, even if the bending fulcrum member 12 is brought close to the high-frequency heating coil 13, the bending fulcrum member 12 is prevented from excessively rising in temperature, and the bending fulcrum member 12 can be deformed and durable. The decrease can be prevented in advance.

  As a result, the metal tube W can be bent in the vicinity of the position where the bending moment is maximized, the bending load generated by the bending device 15 made of a robot can be reduced, and the small bending device 15 can be reduced. Not only can the cost be reduced by adopting it, but also the position control accuracy of the bending device 15 can be increased to increase the bending accuracy of the metal tube W, and the bending processing speed can be increased.

Further, the magnetic flux generated by the high-frequency heating coil 13 tends to leak to the cooling device 14 side, but since the magnetic flux is shielded by the second shield member 28, the temperature rise of the cooling device 14 is suppressed and the cooling effect is enhanced. be able to. In addition, since both surfaces of the high-frequency heating coil 13 are covered and protected by the first and second shield members 27 and 28, it is possible to prevent the low-strength copper high-frequency heating coil 13 from colliding with other articles and being damaged. Can do .

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the metal pipe W is not limited to a member that integrally constitutes a front pillar, a roof side rail, and a rear pillar of an automobile, but may be any other member, and its manufacturing method is not limited to roll forming and is extruded. Molding or pultrusion molding may be used.

  In the embodiment, the high-frequency heating coil 13 includes the first shield member 27 and the second shield member 28, but the second shield member 28 can be omitted.

W Metal tube 11 Metal tube delivery device 12 Bending fulcrum member
12a the guide hole 13 high-frequency heating coil 15 bending apparatus 16 electric heater motor 27 first shield member (shield member)
b The part sandwiched between both ends of the high-frequency heating coil of the metal tube
c Indented part of metal tube

Claims (3)

A metal tube delivery device (11) for delivering the metal tube (W) along the longitudinal direction, and surrounding the outer periphery of the metal tube (W) delivered from the metal tube delivery device (11) From a high-frequency heating coil (13) for heating W), a bending device (15) for applying a bending moment to the metal tube (W) heated by the high-frequency heating coil (13), and the high-frequency heating coil (13) And a metal tube hot working apparatus provided with an electric heater (16) preliminarily heated to the metal tube (W) disposed upstream in the delivery direction of the metal tube (W) ,
The metal tube (W) is manufactured by roll forming a steel plate, and a portion (c) recessed inward with respect to the inner peripheral surface of the high-frequency heating coil (13), and the high-frequency heating coil (13) A linear member having a constant cross section in the longitudinal direction having a portion (b) sandwiched between both ends where the current flows in the opposite direction;
A guide hole (12a) having the same shape as the cross-sectional shape of the metal tube (W) is formed in the bending fulcrum member (12) provided at the outlet of the metal tube delivery device (11), and the metal tube (W) It passes through the inner peripheral surface of the guide hole (12a) while sliding, and the electric heater (16) spirals the inner peripheral surface of the guide hole (12a) inside the bending fulcrum member (12). Embedded in a surrounding, the electric heater (16) is heated by the current to raise the temperature of the bending fulcrum member (12),
The metal tube (W) is preheated to 600 ° C. while passing through the bending fulcrum member (12), and is heated to 800 ° C. while passing through the high frequency heating coil (13). A hot working device for metal tubes . Before Symbol frequency heating coil (13), the surface of the delivery upstream side of at least the metallic tube (W), characterized in that it comprises a shield member (27) for blocking the passage of magnetic flux, according to claim 1 Hot processing equipment for metal pipes. The hot working apparatus for a metal tube according to claim 2 , wherein the shield member (27) is a silicon steel plate or a pure iron plate.

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