WO2015182666A1 - 曲げ部材の製造方法と鋼材の熱間曲げ加工装置 - Google Patents
曲げ部材の製造方法と鋼材の熱間曲げ加工装置 Download PDFInfo
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- WO2015182666A1 WO2015182666A1 PCT/JP2015/065277 JP2015065277W WO2015182666A1 WO 2015182666 A1 WO2015182666 A1 WO 2015182666A1 JP 2015065277 W JP2015065277 W JP 2015065277W WO 2015182666 A1 WO2015182666 A1 WO 2015182666A1
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- heating
- steel pipe
- induction heating
- bending
- steel material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D7/00—Bending rods, profiles, or tubes
- B21D7/12—Bending rods, profiles, or tubes with programme control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D9/00—Bending tubes using mandrels or the like
- B21D9/04—Bending tubes using mandrels or the like the mandrel being rigid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D7/00—Bending rods, profiles, or tubes
- B21D7/16—Auxiliary equipment, e.g. for heating or cooling of bends
- B21D7/162—Heating equipment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/16—Heating or cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D7/00—Bending rods, profiles, or tubes
- B21D7/08—Bending rods, profiles, or tubes by passing between rollers or through a curved die
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D7/00—Bending rods, profiles, or tubes
- B21D7/16—Auxiliary equipment, e.g. for heating or cooling of bends
Definitions
- the present invention relates to a manufacturing method of a bending member and a hot bending apparatus for steel.
- the present application was filed on May 27, 2014 in Japanese Patent Application No. 2014-109361 filed in Japan, October 10, 2014, Japanese Patent Application No. 2014-209052 filed in Japan, and December 4, 2014. Claiming priority based on Japanese Patent Application No. 2014-245639 filed in Japan, the contents of which are incorporated herein by reference.
- a metal strength member, reinforcing member or structural member (hereinafter referred to as a bending member) having a bent shape is used in automobiles and various machines.
- the bending member is required to have high strength, light weight, and small size.
- methods such as welding of press-worked products, punching of thick plates, and forging have been used for manufacturing bent members.
- the bending member is required to have higher strength, lighter weight, and smaller size.
- Non-Patent Document 1 discloses a method of manufacturing a bending member by a tube hydroforming method in which a steel pipe is processed by applying water pressure to the inside of the steel pipe. According to the tube hydroforming method, it is possible to reduce the plate thickness of the bending member to be manufactured, improve the shape freezing property, and improve the economic efficiency related to the manufacturing of the bending member. However, there are problems such as the fact that materials that can be used for the tube hydroforming method are limited and that the bending process using the tube hydroforming method has insufficient shape flexibility.
- FIG. 12 is an explanatory view showing an outline of the hot bending apparatus 0 for steel disclosed in Patent Document 1. As shown in FIG.
- a hot bending apparatus 0 for a steel material has a steel pipe 1 supported by a support device 2 so as to be movable in the longitudinal direction from the upstream side to the downstream side, for example, a feeding device 3 using a ball screw.
- the bending member 8 is manufactured by performing a bending process downstream of the support device 2 while being fed.
- the heating part 1 a is formed in a part in the longitudinal direction of the steel pipe 1 by rapidly heating a part of the steel pipe 1 to a temperature range in which the steel pipe 1 can be quenched by the induction heating device 5 downstream of the support device 2. After the heating, the steel pipe 1 is rapidly cooled by the cooling device 6 disposed downstream of the induction heating device 5. While heating and cooling, while feeding the steel pipe 1 in the longitudinal direction, a bending moment is applied to the heating part 1a by moving the end of the steel pipe 1 in the three-dimensional direction.
- the steel pipe 1 can be quenched by controlling the heating temperature and cooling rate of the steel pipe 1. For this reason, according to the method of manufacturing the bending member 8 using the hot bending apparatus 0 for steel materials, the bending member 8 can be increased in strength, reduced in weight, and reduced in size.
- the manufacturing method of the bending member 8 using the hot-bending apparatus 0 for steel is referred to as 3DQ (abbreviation of “3 Dimensional Hot Bending and Quench”).
- FIG. 13A is a schematic diagram for explaining a case where the steel pipe 1 is gripped from the inside by a short chuck 10 supported by the drive mechanism 9.
- the cooling device 6 is omitted.
- the case of using a chuck that holds the inside of the steel pipe 1 will be described as an example, but the same applies to a chuck that holds the steel pipe 1 from the outside.
- the chuck 10 is formed of a stepped cylindrical body having a large diameter portion 10a and a small diameter portion 10b.
- the small diameter portion 10b is also referred to as a claw 10b.
- the large diameter portion 10 a has the same outer diameter as the outer diameter of the steel pipe 1.
- the small diameter portion 10b has a predetermined length in the axial direction, and is inserted into the front end portion 1b or the rear end portion 1d of the steel pipe 1.
- the small-diameter portion 10b is configured to be able to expand and contract. By expanding the small diameter portion 10b, the outer surface of the small diameter portion 10b comes into contact with the inner surface of the front end portion 1b or the rear end portion 1d of the steel pipe 1, thereby gripping the front end portion 1b or the rear end portion 1d of the steel pipe 1. .
- FIG. 13B is a schematic diagram for explaining a case where the front end 1b or the rear end 1d of the steel pipe 1 is gripped from the inside by the long chuck 11 supported by the drive mechanism 9.
- the chuck 11 is formed of a stepped cylindrical body having a large-diameter main body portion 11a and a small-diameter insertion portion 11b.
- the method of bending the steel pipe 1 is the same when the short chuck 10 is used and when the long chuck 11 is used.
- the gripping method using the chucks 10 and 11 is the same when gripping the front end 1b of the steel pipe 1 and gripping the rear end 1d.
- the present inventors have made further studies for improving the productivity and economic efficiency of the bending member 8 by 3DQ using the chuck 10 or 11, and have found the following problems.
- the case where the bending member is manufactured using the short chuck 10 will be described as an example, but the same applies to the case where the bending member is manufactured using the long chuck 11.
- the tip of the steel pipe 1 When bending is performed in the vicinity of the tip 1b of the steel pipe 1 with the chuck 10 holding the tip 1b of the steel pipe 1, the tip of the steel pipe 1 is heated when the steel pipe 1 is heated by the induction heating device 5. It is necessary to prevent the small-diameter portion 10b of the chuck 10 that holds 1b from being heated to, for example, more than 500 ° C. This is because the small-diameter portion 10b of the chuck 10 that grips the tip portion 1b of the steel pipe 1 is subject to fatigue failure when the small-diameter portion 10b of the chuck 10 that grips the tip portion 1b of the steel pipe 1 is heated to over 500 ° C. Because there is.
- induction heating by the induction heating device 5 is started at a site separated from the tip portion 1b of the steel pipe 1.
- a method is conceivable.
- induction heating by the induction heating device 5 is started at a site separated from the tip portion 1b of the steel pipe 1, the vicinity of the tip portion 1b is not heated to a temperature that can be hardened, so that it is quenched near the tip portion 1b.
- Many parts hereinafter referred to as unquenched parts are not formed.
- the strength of the unquenched part is low, it is considered as an unnecessary part in a part that requires strength and may be cut.
- productivity of a bending member falls.
- part which is not commercialized will arise in the steel pipe which is material by cutting an unnecessary site
- induction heating by the induction heating device 5 is started at a site separated from the tip portion 1b of the steel pipe 1 It is not preferable from the viewpoint of productivity and economy.
- FIG. 14A to FIG. 14D are schematic views for explaining the case where the manufacturing of the bending member is started with the chuck 10 holding the tip 1b of the steel pipe 1 using the conventional method. 14A to 14D, only one set of support means 2 is shown.
- FIG. 14A shows a state at time t 0 when the induction heating of the steel pipe 1 by the induction heating device 5 and the feeding of the steel pipe 1 by the feeding device 3 are not started.
- the distal end portion 1 b of the steel pipe 1 is located at a position where it can be heated by the induction heating device 5. Proceeding from time t 0 to t 1, feeding by the feeding device 3 of the steel tube 1 to start cooling of the steel pipe 1 by injecting a cooling medium from the heating and cooling device 6 of the steel pipe 1 by the induction heating device 5 ( Figure 14B reference).
- the heating part 1a formed in the vicinity of the tip 1b of the steel pipe 1 is brought to a desired temperature. It was found that it was not heated and bending could not be performed properly.
- the heating temperature of the heating part 1a formed in the vicinity of the tip part 1b of the steel pipe 1 is less than 900 ° C.
- an excessive load acts on the driving mechanism 9 when bending is performed by the driving mechanism 9.
- the drive mechanism 9 may be damaged.
- An example of the temperature of the heating unit 1a for appropriately performing the bending process is 900 to 1000 ° C.
- the heating unit 1a When the temperature of the heating unit 1a is 900 to 1000 ° C., the heating unit 1a can be appropriately bent, and the heating unit 1a is cooled by injecting a cooling medium from the cooling device 6 and heated. Quenching can be performed on the part 1a.
- the unquenched portion formed in the tip portion 1b of the steel pipe 1 is made as small as possible, and the small diameter portion 10b of the chuck 10 that holds the tip portion 1b of the steel pipe 1 is not heated to more than 500 ° C.
- the present invention adopts the following means in order to solve the above problems and achieve the object.
- the manufacturing method of the bending member which concerns on 1 aspect of this invention WHEREIN: The holding
- the heating amount applied when forming the heating portion at the one end portion is viewed along the feeding direction of the steel material, from an upstream adjacent portion adjacent to the upstream side of the one end portion. And the chuck is cooled by the cooling medium.
- the steel material is fed in the longitudinal direction in the feeding process, and is applied to the part in the heating process.
- the heating unit is started at the one end by starting the feeding step after a predetermined time from the start of the heating step.
- the bending member further includes a temperature measuring step of measuring temperatures at a plurality of locations in the longitudinal direction of the steel material,
- a configuration may be adopted in which the feed rate of the steel material in the longitudinal direction is determined based on the temperature measurement result obtained in the temperature measurement process.
- the heating amount applied when forming the heating portion at the other end portion in the longitudinal direction of the steel material You may employ
- the bending condition is set in the bending process in the first condition that the heating temperature of the nail of the chuck is 500 ° C. or less.
- the second condition in which the heating temperature of the heating part when applying the moment is greater than Ac3 point, and the maximum temperature reached by the steel material is equal to or lower than the temperature at which the coarsening of the steel material proceeds or lower than the temperature at which the toughness decreases.
- the heating step includes a first heating unit at a position between the one end and the other end of the steel material.
- the width of the unquenched portion when viewed along the longitudinal direction, is 0.15 times or more the heating width by the high-frequency induction heating. You may employ
- a steel material hot bending apparatus includes a chuck that grips one longitudinal end of a long steel material having an open end, and a drive mechanism that moves the chuck in a three-dimensional direction.
- a feed mechanism that feeds the steel material along the longitudinal direction with the one end as a head, an induction heating mechanism that forms a heating part by high-frequency induction heating of a portion of the steel material in the longitudinal direction, and the heating
- a cooling mechanism that injects a cooling medium onto the part and cools the chuck, the drive mechanism, the feed mechanism, the induction heating mechanism, and a control unit that controls the cooling mechanism.
- the upstream adjacent to the upstream of the one end when the control unit looks at the heating amount when forming the heating at the one end by the induction heating mechanism along the feeding direction of the steel material The size of the chuck is larger than the portion, and the cooling mechanism is controlled to cool the chuck with the cooling medium.
- control section applies heating when the heating section is formed at the other end in the longitudinal direction of the steel by the induction heating mechanism.
- the control unit performs first heating at a position between the one end portion and the other end portion of the steel material by the induction heating mechanism. Part is formed, a second heating part is formed at a position upstream of the first heating part on the steel material, and an unquenched part is provided at a position between the first heating part and the second heating part. You may employ
- a first temperature measurement mechanism that measures the temperature of the one end, and the temperature of the heating unit
- a configuration may be employed in which the control unit controls at least one of the feed mechanism and the induction heating mechanism such that at least one of the outer diameter deformation amounts falls within a predetermined range.
- a method of manufacturing a bending member and a hot bending apparatus for steel that can prevent fatigue fracture of a chuck that grips the tip of the steel and that is excellent in productivity and economy are provided. can do.
- FIG. 1A is a schematic diagram illustrating a state of a steel pipe and a hot bending apparatus for the steel pipe when bending is performed near the tip of the steel pipe according to the present invention.
- FIG. 1B is a schematic diagram illustrating a state of a steel pipe and a hot bending apparatus for the steel pipe when bending is performed near the tip of the steel pipe according to the present invention.
- FIG. 1C is a schematic diagram illustrating a state of a steel pipe and a hot bending apparatus for the steel pipe when bending is performed near the tip of the steel pipe according to the present invention.
- FIG. 1D is a schematic diagram illustrating a state of a steel pipe and a hot bending apparatus for the steel pipe when bending is performed in the vicinity of the tip of the steel pipe according to the present invention.
- FIG. 1E is a schematic view showing a state of a steel pipe and a hot bending apparatus for the steel pipe when bending is performed near the tip of the steel pipe according to the present invention.
- Fig.2 (a) is the graph which represented the heating amount given to a steel pipe with an induction heating apparatus with respect to the position on a steel pipe.
- FIG.2 (b) is the graph which represented the temperature of the steel pipe surface when the induction heating apparatus is located in A point with respect to the position on a steel pipe.
- FIG.2 (c) is the graph which represented the highest ultimate temperature with respect to the position on a steel pipe.
- FIG.2 (d) is the graph which represented hardness with respect to the position on a steel pipe.
- FIG. 3A is a graph showing the amount of high-frequency power supplied to the induction heating device of Embodiment 1-1 with respect to time.
- FIG. 3B is a graph showing the feed rate of the steel pipe in Embodiment 1-1 with respect to time.
- FIG. 4A is a schematic diagram showing a positional relationship among the steel pipe, the induction heating device, and the cooling device in Embodiment 1-1.
- FIG. 4B is a graph showing the heating amount applied to the steel pipe in Embodiment 1-1 with respect to the position on the steel pipe.
- FIG. 5A is a graph showing the amount of high-frequency power supplied to the induction heating device of Embodiment 1-2 with respect to time.
- FIG. 5B is a graph showing the steel pipe feed speed with respect to time in Embodiment 1-2.
- FIG. 6A is a graph showing the amount of high-frequency power supplied to the induction heating device of Embodiment 1-3 with respect to time.
- FIG. 6B is a graph showing the feed rate of the steel pipe in Embodiment 1-3 with respect to time.
- FIG. 7 is an explanatory view showing a configuration example of a steel material hot bending apparatus according to the present invention.
- Fig.8 (a) is a schematic diagram which shows the positional relationship of the steel pipe in Example 1, an induction heating apparatus, and a cooling device.
- FIG.8 (b) is the graph which represented the hardness of the steel pipe in Example 1 with respect to the position on a steel pipe.
- FIG. 9A is a side view of a steel pipe for explaining positions A and B.
- FIG. 9B is a graph showing the maximum temperature reached at positions A and B with respect to the position on the steel pipe.
- FIG.9 (c) is the graph which represented the hardness of the steel pipe in the position A and B with respect to the position on a steel pipe.
- FIG. 10A is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 1-1 with respect to time.
- FIG. 10B is a graph showing the feed rate of the steel pipe in Example 1-1 with respect to time.
- FIG. 10C is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 1-2 with respect to time.
- FIG. 10 (d) is a graph showing the steel pipe feed rate with respect to time in Example 1-2.
- FIG. 10E is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 1-3 with respect to time.
- FIG. 10 (f) is a graph showing the steel pipe feed rate in Example 1-3 with respect to time.
- FIG. 11A is a graph showing the amount of high-frequency power supplied to the induction heating device of Comparative Example 1-1 with respect to time.
- FIG. 11B is a graph showing the feed rate of the steel pipe in Comparative Example 1-1 with respect to time.
- FIG. 12 is a schematic diagram showing a hot bending apparatus for steel disclosed in Patent Document 1.
- FIG. 13A is a schematic view when the inside of a steel pipe is gripped by a short chuck.
- FIG. 13B is a schematic view when the inside of the steel pipe is gripped by a long chuck.
- FIG. 14A is a schematic diagram showing a steel material and a hot bending apparatus for the steel material when bending is performed in the vicinity of the tip portion of the steel pipe according to the conventional technique.
- FIG. 14B is a schematic diagram showing a steel material and a hot bending apparatus for the steel material when bending is performed in the vicinity of the distal end portion of the steel pipe according to the related art.
- FIG. 14A is a schematic diagram showing a steel material and a hot bending apparatus for the steel material when bending is performed in the vicinity of the distal end portion of the steel pipe according to the related art.
- FIG. 14C is a schematic diagram illustrating a steel material and a hot bending apparatus for the steel material when bending is performed in the vicinity of the distal end portion of the steel pipe according to the related art.
- FIG. 14D is a schematic diagram illustrating a steel material and a hot bending apparatus for the steel material when bending is performed in the vicinity of the tip portion of the steel pipe according to the conventional technique.
- FIG. 15 is a schematic diagram showing a steel pipe and a hot-bending apparatus for the steel pipe when bending is performed on the vicinity of the rear end portion of the steel pipe by 3DQ.
- Fig.16 (a) is a schematic diagram which shows the positional relationship of the steel pipe and hot bending apparatus in the rear-end part vicinity of a steel pipe.
- FIG. 16B is a graph showing the relationship between the hardness in the vicinity of the rear end portion of the steel pipe and the position on the steel pipe.
- FIG. 17A assumes that the heating amount given to the position A shown in FIG. 9A is 10% more than the heating amount given to the position B when bending is performed near the rear end of the steel pipe. It is a simulation result showing the relationship between the maximum temperature achieved and the position on the steel pipe.
- FIG. 17B assumes that when the bending process is performed in the vicinity of the rear end portion of the steel pipe, the heating amount given to the position A shown in FIG. 9A is 10% higher than the heating amount given to the position B. It is a simulation result showing the relationship between the hardness and the position on the steel pipe in the case of.
- FIG. 18 (a) to 18 (d) show the maximum temperature reached and the temperature distribution at the current time when bending is performed in the vicinity of the rear end of the steel pipe using the conventional technique with respect to the position on the steel pipe. It is a graph.
- FIG. 18 (e) is a graph showing the relationship between the hardness of the steel pipe and the position on the steel pipe after the bending shown in FIGS. 18 (a) to 18 (d).
- 19 (a) to 19 (d) are graphs showing the maximum temperature reached and the temperature distribution at the present time when the rear end of the steel pipe is bent using the present invention with respect to the position on the steel pipe. It is a graph.
- FIG. 18 (e) is a graph showing the relationship between the hardness of the steel pipe and the position on the steel pipe after the bending shown in FIGS. 18 (a) to 18 (d).
- 19 (a) to 19 (d) are graphs showing the maximum temperature reached and the temperature distribution at the present time when the rear end of the steel pipe is bent using the present invention
- FIG. 19 (e) is a graph showing the relationship between the hardness of the steel pipe and the position on the steel pipe after the bending shown in FIGS. 19 (a) to 19 (d).
- FIG. 20A is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 2-1 with respect to time.
- FIG. 20B is a graph showing the steel pipe feed rate with respect to time in Example 2-1.
- FIG. 20C is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 2-2 with respect to time.
- FIG. 20 (d) is a graph showing the steel pipe feed rate with respect to time in Example 2-2.
- FIG. 20 (e) is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 2-3 with respect to time.
- FIG. 20A is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 2-1 with respect to time.
- FIG. 20B is a graph showing the steel pipe feed rate with respect to
- FIG. 20F is a graph showing the steel pipe feed rate with respect to time in Example 2-3.
- FIG. 21A is a graph showing the amount of high-frequency power supplied to the induction heating device of Comparative Example 2-1 with respect to time.
- FIG. 21B is a graph showing the feed rate of the steel pipe in Comparative Example 2-1 with respect to time.
- FIG. 22A is a schematic diagram illustrating a state in which bending is performed in the vicinity of the rear end portion of the steel pipe using the conventional technique.
- FIG. 22B is a schematic diagram illustrating a state in which bending is performed in the vicinity of the rear end portion of the steel pipe using the conventional technique.
- FIG. 22C is a schematic diagram showing a state in which bending is performed in the vicinity of the rear end portion of the steel pipe using the conventional technique.
- FIG. 22D is a schematic diagram illustrating a state in which bending is performed in the vicinity of the rear end portion of the steel pipe using the conventional technique.
- 23 (a) to 23 (e) show the maximum temperature reached and the temperature distribution at the current time when bending is performed on a portion other than the front end and rear end of the steel pipe using the present invention. It is the graph represented with respect to position.
- FIG. 24 is a graph showing the relationship between the hardness of the steel pipe and the position on the steel pipe in Comparative Examples 3-1 to 3-4.
- FIG. 25 is a conceptual diagram for explaining an unquenched portion and a base material hardness portion.
- FIG. 26A is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 3-1 with respect to time.
- FIG. 26B is a graph showing the feed position of the steel pipe in Example 3-1 with respect to time.
- FIG. 27A is a graph showing the amount of high-frequency power supplied to the induction heating apparatus of Example 3-2 with respect to time.
- FIG. 27B is a graph showing the steel pipe feed position with respect to time in Example 3-2.
- FIG. 28A is a graph showing the amount of high-frequency power supplied to the induction heating device of Example 3-3 with respect to time.
- FIG. 28B is a graph showing the steel pipe feed position with respect to time in Example 3-3.
- 29 (a) to 29 (e) show the maximum temperature reached and the temperature distribution at the current time when bending is performed on a portion other than the tip and rear ends of the steel pipe using the conventional technology. It is the graph represented with respect to position.
- time t 1 is the time when ⁇ t seconds have elapsed from time t 0 .
- the steel pipe 1, as can be inductively heated along a longitudinal direction (right direction in FIG. 1A) of the tip 1b starting position may be heated by induction heating apparatus 5 Placed in.
- the position of the heating part 1a moves in the direction opposite to the direction in which the steel pipe 1 is sent. That is, as the steel pipe 1 is sent in the longitudinal direction, the distance between the heating part 1a and the tip part 1b increases.
- a bending moment is applied to the heating portion 1 a of the steel pipe 1 by moving the chuck 10 that holds the tip 1 b of the steel pipe 1 in a three-dimensional direction by the drive mechanism 9. As a result, the steel pipe 1 is bent.
- the drive mechanism 9 a robot arm or the like can be used.
- the heating part 1a is formed in a part adjacent to the upstream side of the tip part 1b (hereinafter referred to as upstream adjacent part) for the amount of heating given when forming the heating part 1a on the tip part 1b. Make it larger than the amount of heating given.
- the steel pipe 1 in the longitudinal direction The method of changing at least one of the feed rate at the time of feeding to the heating unit 1a from the induction heating device 5 and the feeding of the steel pipe 1 after a predetermined time has elapsed since the start of supplying high frequency power to the induction heating device 5 The method of starting is mentioned.
- the heating amount given when forming the heating part 1a in the steel pipe 1 can be changed by changing the high frequency electric power supplied to the induction heating apparatus 5.
- Example 1-1 feeding of the steel pipe 1 is started after a predetermined time has elapsed since the start of supplying high-frequency power to the induction heating device 5.
- the feeding device 3 is activated to start feeding the steel pipe 1 in the longitudinal direction.
- Examples of the feed speed in the longitudinal direction of the steel pipe 1 include 10 to 200 mm / second.
- the heating portion 1a is formed from the distal end 1b of the steel tube 1 at a distance L 1 in the longitudinal direction. That is, the pawl 10b of the chuck 10 is in contact with during the heating portion 1a from time t 0 to time t 2, the no contact with the heating portion 1a at the time after time t 2. Therefore, by setting the appropriate range the time between the time t 0 to time t 2, the can be the temperature of the pawl 10b of the chuck 10 is prevented from increasing excessively.
- the heating portion 1a is formed.
- the heating unit 1 a is heated to a predetermined temperature (for example, 800 ° C. or higher) exceeding the Ac 3 point.
- a predetermined temperature for example, 800 ° C. or higher
- the heating portion 1a formed at a distance L 2 in the longitudinal direction from the distal end 1b of the steel tube 1, together is changed to the hardness which can perform bending by the drive mechanism 9, a cooling device 6 Quenching can be performed by injecting a cooling medium from above.
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 can be set based on the result of simulation or preliminary experiment.
- a preliminary experiment for example, there is a method in which a plurality of thermocouples are attached to a plurality of locations in the longitudinal direction of the steel pipe 1 and bending is performed in a state where the temperatures of the plurality of locations can be measured, and a temperature measurement result is obtained (temperature measurement step). Can be mentioned.
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 is preferably 2 seconds or less.
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 is 2 seconds or less, so that the heating part 1a of the steel pipe 1 has a temperature at which the coarsening of the steel material proceeds or the steel material It is possible to prevent heating to a temperature exceeding toughness (for example, 1100 ° C.).
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 is more preferably 0.3 seconds or less.
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 is 0.3 seconds or less, so that the unquenched part necessary for welding and drilling of the end of the member is 30 mm or less. It is possible to secure in a range.
- the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding of the steel pipe 1 is particularly preferably 0.04 seconds or less. When the time ⁇ t from the start of induction heating to the steel pipe 1 to the start of feeding the steel pipe 1 is 0.04 seconds or less, it is possible to secure a quenching region up to the end of the member (range of 3 mm or less). It is.
- Embodiment 1-1 the state of quenching in Embodiment 1-1 will be described with reference to FIGS. 2 to 4B.
- 3DQ is actually arranged in a state where the induction heating device 5 and the cooling device 6 are fixed, and the steel pipe 1 is sent by the feeding device 3, but in the following description, in order to facilitate understanding, A position is demonstrated by the relative position with respect to the steel pipe 1.
- FIG. 1 A position is demonstrated by the relative position with respect to the steel pipe 1.
- FIG. 2A is a graph showing the heating amount (vertical axis) given to the steel pipe by the induction heating device with respect to the position on the steel pipe (horizontal axis).
- FIG. 2B is a graph showing the temperature (vertical axis) on the surface of the steel pipe when the induction heating device is located at point A with respect to the position on the steel pipe (horizontal axis).
- FIG. 2C is a graph showing the maximum temperature reached (vertical axis) with respect to the position on the steel pipe (horizontal axis).
- FIG. 2D is a graph showing the hardness (vertical axis) with respect to the position on the steel pipe (horizontal axis). 2A to 2D, the origin of the horizontal axis is the tip 1b of the steel pipe 1.
- the heating amount given to the steel pipe 1 is distributed in a bell shape around the induction heating device 5.
- the induction heating device 5 also moves relatively.
- the heating temperature of the steel pipe 1 by the induction heating device 5 is a portion (hereinafter referred to as a cooling unit) cooled by a cooling medium (arrow in FIG. 2 (b)) injected by the cooling device 6. In the cooling part, it is rapidly cooled by the injected cooling medium.
- the hardness of the steel pipe 1 changes depending on the maximum temperature shown in FIG. Specifically, the hardness shown in FIG. 2 (d) is the same hardness as that of the base metal in the portion of the steel pipe 1 where the maximum temperature reached is below the Ac1 point, and is full in the portion where the maximum temperature reached above the Ac3 point. It is the hardness of martensite, and is the hardness between the base material and full martensite at the site where the maximum temperature reaches more than Ac1 and less than Ac3.
- FIG. 3 (a) is a graph showing the amount of high-frequency power (vertical axis) supplied to the induction heating device 5 of Embodiment 1-1 with respect to time (horizontal axis).
- FIG. 3B is a graph showing the feed rate (vertical axis) of the steel pipe in Embodiment 1-1 with respect to time (horizontal axis).
- the claw 10b Before starting the feeding and induction heating of the steel pipe 1, the claw 10b is cooled by spraying a cooling medium from the cooling device 6 onto the claw 10b of the chuck 10. Note that the cooling medium may be sprayed on the entire claw 10b or a part thereof. As will be described later, in the present embodiment, the heating amount given when forming the heating portion 1a at the distal end portion 1b of the steel pipe 1 is greater than the heating amount given when forming the heating portion 1a at the upstream adjacent portion.
- the claw 10b of the chuck 10 is also formed when the heating part 1a is formed at the tip 1b of the steel pipe 1 by cooling the claw 10b of the chuck 10 before starting feeding and induction heating of the steel pipe 1. Heating to over 500 ° C. can be prevented.
- the tip 1b By making the amount of heating given when forming the heating part 1a at the tip 1b of the steel pipe 1 larger than the amount of heating given when forming the heating part 1a at the upstream adjacent portion, the tip 1b While the unquenched portion is formed, bending can be performed as close as possible to the tip portion 1b.
- the bending member manufactured according to the present embodiment When the bending member manufactured according to the present embodiment is used as an automobile part or the like, it is often joined to other members by welding.
- tip part 1b and the rear-end part 1d) of the bending member manufactured by this embodiment is not quenched. preferable. Since the unquenched portion is formed at the distal end portion 1b of the steel pipe 1 subjected to the bending process of the embodiment 1-1, it is suitable for welding with other members. Further, according to the manufacturing method of the bending member of Embodiment 1-1, the unquenched portion formed in the tip portion 1b can be reduced, and therefore, when the bending member is manufactured, an unnecessary portion of the tip portion 1b is removed. A cutting step is unnecessary. Therefore, it is possible to improve productivity and economy related to the production of the bending member.
- FIG. 5A is a graph showing the amount of high-frequency power (vertical axis) supplied to the induction heating device 5 of Embodiment 1-2 with respect to time (horizontal axis).
- FIG. 5B is a graph showing the feed rate (vertical axis) of the steel pipe 1 in Embodiment 1-2 with respect to time (horizontal axis).
- Embodiment 1-2 as shown in FIGS. 5A and 5B, the induction heating of the steel pipe 1 by the induction heating device 5 and the feeding of the steel pipe 1 by the feeding device 3 are started simultaneously.
- the induction heating device 5 is supplied with a certain amount of high-frequency power from the start of supply of high-frequency power.
- FIG. 5 (b) the feeding of the steel pipe 1 by the feeding device 3 is gradually accelerated from the start, and after reaching a predetermined feeding speed, the feeding speed is kept constant.
- the feed speed at the start of feed, the feed speed after acceleration, and the acceleration rate of the feed speed are determined so that the heating temperature of the steel pipe 1 does not become too high (for example, the steel pipe 1 is not heated above 1100 ° C.). It is preferable to do. Further, the point that it is preferable to cool the claw 10b of the chuck 10 with a cooling medium before the start of feeding and induction heating is the same as in Embodiment 1-1.
- FIG. 6A is a graph showing the amount of high-frequency power (vertical axis) supplied to the induction heating apparatus of Embodiment 1-3 with respect to time (horizontal axis).
- FIG. 6B is a graph showing the feed rate (vertical axis) of the steel pipe in Embodiment 1-3 with respect to time (horizontal axis).
- Embodiment 1-3 as shown in FIGS. 6A and 6B, induction heating of the steel pipe 1 by the induction heating device 5 and feeding of the steel pipe 1 by the feeding device 3 are started simultaneously.
- the amount of high-frequency power supplied to the induction heating device 5 at a predetermined time from the start of induction heating is constant, but is supplied to the induction heating device 5 after a predetermined time has elapsed. Reduce the amount of high frequency power that is played.
- FIG.6 (b) the feed rate of the steel pipe 1 after starting feed is constant. The point that it is preferable to cool the claw 10b of the chuck 10 with a cooling medium before the start of feeding and induction heating is the same as in Embodiment 1-1.
- the present inventors have found through prior examination that there is a difference of 10% in the amount of heating given during induction heating depending on the circumferential position of the steel pipe 1 when the conventional technique is used.
- FIG. 9B it is assumed that the heating amount given at the time of induction heating is different by 10% at positions A and B, and the maximum temperature reached (vertical axis) and the position on the steel pipe ( (Horizontal axis).
- FIG. 9B the relationship between the maximum temperature reached (vertical axis) and the position on the steel pipe 1 (horizontal axis)
- FIG. 9B the hardness (vertical axis) and the position on the steel pipe 1 (horizontal axis)
- FIG. 9 (c) when the heating amount given by induction heating is different in the circumferential direction of the steel pipe 1, the hardness increasing position is different depending on the circumferential position.
- the hardness increasing position differs depending on the circumferential position of the steel pipe 1, which is not preferable because the quality of the manufactured bending member is not uniform.
- the manufacturing method of the bending member of this embodiment it is possible to make the hardness in the circumferential direction of the steel pipe 1 more uniform than in the prior art.
- 22A to 22D are schematic views showing a state in which bending is performed in the vicinity of the rear end portion 1d of the steel pipe 1 using a conventional technique.
- Figure 22A shows a state at time t 4 when the feed of the induction heating and the feed device 3 according to the steel pipe 1 by the induction heating device 5 has been performed.
- the rear end portion 1d of the steel pipe 1 is positioned at a position spaced from the induction heating device 5 and the cooling device 6.
- the rear end portion 1d of the steel pipe 1 is close gradually to the induction heating device 5 and the cooling device 6.
- the heating portion 1 a is formed in the steel pipe 1.
- the present inventors have found that when the bending process is performed in the vicinity of the rear end portion 1d of the steel pipe 1 by the method shown in FIGS. 22A to 22D, the rear end portion 1d of the steel pipe 1 is heated to over 1100 ° C. did.
- the rear end 1d of the steel pipe 1 is heated to over 1100 ° C., the rear end 1d of the steel pipe 1 is softened, and the rear end 1d of the steel pipe 1 may be deformed by the gripping force of the chuck 10. This is not preferable.
- the induction heating by the induction heating device 5 is stopped at a position away from the rear end 1d of the steel pipe 1. A way to do this is considered. However, when the induction heating by the induction heating device 5 is stopped at a position separated from the rear end 1d of the steel pipe 1 when bending the steel pipe 1, the steel pipe 1 is formed at the rear end 1d. This is not preferable from the viewpoint of productivity and economy.
- FIG. 15 is a schematic diagram showing the steel pipe 1 and the hot bending apparatus 0 for the steel pipe when bending is performed on the vicinity of the rear end portion 1d of the steel pipe 1 by 3DQ.
- a distance E in FIG. 15 is a distance from a downstream end (hereinafter referred to as a bending end position) of a portion where bending is performed in the steel pipe 1 to a rear end portion 1d of the steel pipe 1.
- FIG. 16A is a schematic diagram showing the positional relationship between the steel pipe 1 and the hot bending apparatus 0 for the steel pipe in the vicinity of the rear end portion 1d of the steel pipe 1.
- FIG. 16A is a distance at which the claw 10 b of the chuck 10 is in contact with the inner surface of the rear end 1 d of the steel pipe 1.
- the distance G in FIG. 16 (a) is the distance from the longitudinal center of the heating part 1a (hereinafter referred to as the heating end position) to the rear end part 1d of the steel pipe 1 when induction heating for the steel pipe 1 is completed.
- FIG. 16B is a graph showing the relationship between the hardness (vertical axis) in the vicinity of the rear end 1d of the steel pipe 1 and the position (horizontal axis) on the steel pipe 1.
- a distance H in FIG. 16B is a distance from a downstream end (hereinafter referred to as a hardness reduction position) of a portion having a hardness of 500 Hv in the steel pipe 1 to a rear end portion 1 d of the steel pipe 1.
- the unquenched part formed in the rear end part 1d of the steel pipe 1 becomes large. If the unquenched part is large, a cutting process of the unquenched part may be necessary after bending, so that the productivity and economy related to the production of the bent member are lowered.
- a method of shortening the distance G is conceivable.
- the rear end portion 1d of the steel pipe 1 may be heated to over 1100 ° C. in some cases. When the rear end portion 1d of the steel pipe 1 is heated to a temperature exceeding 1100 ° C., coarsening of the metal structure occurs in the heating portion 1a, and the workability is lowered, which is not preferable.
- FIG. 17A shows that when bending is performed in the vicinity of the rear end 1d of the steel pipe 1, the heating amount given to the position A shown in FIG. 9A is 10% higher than the heating amount given to the position B. It is a simulation result showing the relationship between the highest attained temperature (vertical axis) and the position on the steel pipe 1 (horizontal axis).
- FIG. 17B shows that when bending is performed in the vicinity of the rear end 1d of the steel pipe 1, the heating amount given to the position A shown in FIG. 9A is 10% higher than the heating amount given to the position B. It is a simulation result showing the relationship between the hardness (vertical axis) and the position on the steel pipe 1 (horizontal axis) when assumed. As shown in FIG.
- FIGS. 18 (a) to 18 (d) show the maximum temperature reached and the temperature distribution (vertical axis) at the current time when bending is performed in the vicinity of the rear end 1d of the steel pipe 1 using the conventional technique. It is the graph represented with respect to the position (horizontal axis). Note that the origin of the horizontal axis in FIGS. 18A to 18D is an arbitrary position on the steel pipe 1.
- the portion of the steel pipe 1 that is induction-heated by the induction heating device 5 is represented as a heating portion, and is cooled by spraying a cooling medium from the cooling device 6.
- part of the steel pipe 1 is represented as a cooling part.
- induction heating of the steel pipe 1 by the induction heating device 5 cooling of the steel pipe 1 by injecting a cooling medium from the cooling device 6, and feeding of the steel pipe 1 by the feeding device 3 are performed.
- FIG. 18A shows the induction heating of the steel pipe 1 by the induction heating device 5, the cooling of the steel pipe 1 by injecting the cooling medium from the cooling device 6, and the feeding of the steel pipe 1 by the feeding device 3.
- the state is shown in FIG.
- FIG. 18B shows the induction heating of the steel pipe 1 by the induction heating device 5 is stopped.
- FIG. 18C shows a state where the induction heating of the steel pipe 1 by the induction heating device 5 is stopped and the steel pipe 1 is cooled and fed from the state shown in FIG. At the time shown in FIG. 18C, there is no portion having a temperature higher than the Ac1 point.
- 18D shows a state in which the steel pipe 1 is cooled by injecting the cooling medium from the cooling device 6 and the steel pipe 1 is fed by the feeding device 3 from the state shown in FIG. At the time shown in FIG. 18 (d), the bending process for the steel pipe 1 is completed.
- FIG. 18 (e) shows the relationship between the hardness (vertical axis) of the steel pipe 1 and the position (horizontal axis) on the steel pipe 1 after the bending shown in FIGS. 18 (a) to 18 (d). It is a graph.
- the origin of the horizontal axis in FIG. 18 (e) is an arbitrary position on the steel pipe 1.
- the distance J shown in FIG. 18 (e) represents the distance from the hardness decrease position to the position where the maximum temperature reached is 500 ° C. in the vicinity of the rear end portion 1d of the steel pipe 1. In order to set the heating temperature of the claw 10b of the chuck 10 holding the rear end 1d of the steel pipe 1 to 500 ° C.
- the heating temperature of the rear end 1d of the steel pipe 1 held by the claw 10b of the chuck 10 is 500. It should just be below °C.
- the hardness reduction position is close to the rear end portion 1 d of the steel pipe 1. For the above-described reason, the distance J can be shortened in order to prevent fatigue failure of the chuck 10 that holds the rear end 1d of the steel pipe 1 and to improve productivity and economy in manufacturing the bending member. preferable.
- the heating unit 1a is applied to a portion adjacent to the downstream side of the rear end portion 1d (hereinafter referred to as a downstream adjacent portion) for the amount of heating given when the heating portion 1a is formed on the rear end portion 1d.
- the amount of heating is greater than the amount of heating applied during formation.
- a method of stopping induction heating of the steel pipe 1 by stopping the supply of electric power can be mentioned. Furthermore, as another method, the induction heating, cooling, and feeding are performed at the rear end 1d of the steel pipe 1, and the amount of high-frequency power supplied to the induction heating device 5 is increased. After a predetermined time has elapsed, induction heating is performed. A method of stopping the induction heating of the steel pipe 1 by stopping the supply of high-frequency power to the device 5 can be mentioned.
- FIGS. 19 (a) to 19 (d) show the maximum temperature reached when the rear end portion 1d of the steel pipe 1 is bent according to this embodiment and the temperature distribution (vertical axis) at the current time on the steel pipe 1. It is the graph represented with respect to the position (horizontal axis). Note that the origin of the horizontal axis in FIGS. 19 (a) to 19 (d) is an arbitrary position on the steel pipe 1.
- FIG. 19A At the time shown in FIG. 19A, the induction heating of the steel pipe 1 by the induction heating device 5, the cooling of the steel pipe 1 by injecting the cooling medium from the cooling device 6, and the feeding of the steel pipe 1 by the feeding device 3 are performed.
- FIG. 19A From the state shown in FIG. 19A, the induction heating of the steel pipe 1 by the induction heating device 5, the cooling of the steel pipe 1 by injecting the cooling medium from the cooling device 6, and the feeding of the steel pipe 1 by the feeding device 3 are continuously performed.
- This state is shown in FIG.
- FIG. 19 (b) At the time shown in FIG. 19 (b), the feeding of the steel pipe 1 by the feeding device 3 is stopped, and the induction heating of the steel pipe 1 by the induction heating device 5 and the cooling of the steel pipe 1 by injecting the cooling medium from the cooling device 6 are continued. And do it.
- FIG. 19C shows a state in which the steel pipe 1 is continuously cooled by inductive heating of the steel pipe 1 by the induction heating device 5 and injection of the cooling medium from the cooling device 6 from the state shown in FIG. 19B.
- FIG. 19D shows a state in which the steel pipe 1 is cooled by injecting a cooling medium from the state shown in FIG. As shown in FIG. 19 (d), when bending is performed on the rear end portion 1d of the steel pipe 1 according to the present embodiment, the portion where the maximum temperature is higher than other portions (the maximum temperature is T 1 ).
- FIG. 19 (e) shows the relationship between the hardness (vertical axis) of the steel pipe 1 and the position on the steel pipe 1 (horizontal axis) after the bending shown in FIGS. 19 (a) to 19 (d). It is a graph.
- the origin of the horizontal axis in FIG. 19 (e) is an arbitrary position on the steel pipe 1.
- the rear of the steel pipe 1 is manufactured by the manufacturing method of the bending member of this embodiment. It can be seen that the distance J when the end portion 1d is bent is shorter. As described above, when the bending process is performed on the rear end portion 1d of the steel pipe 1 by the manufacturing method of the bending member of the present embodiment, the distance J can be shortened compared to the conventional technique. It is possible to prevent fatigue failure of the chuck 10 that grips the rear end 1d, and to improve the productivity and economy of manufacturing the bending member.
- the manufacturing method of the bending member which concerns on 3rd Embodiment forms a 1st heating part in parts other than the front-end
- an unquenched part is formed between the first heating part and the second heating part.
- the method for manufacturing a bending member according to the third embodiment when the unquenched portion of the manufactured bending member is cut in the longitudinal direction to obtain a plurality of bending members, the hardness of the unquenched portion that is a cutting site is Since it is low, the bending member can be easily cut.
- part is a hardness equivalent to a base material.
- the manufacturing method of the bending member which concerns on 3rd Embodiment, since a bending process can be performed to the vicinity of the unhardened part which is a cutting
- a plurality of bending members are obtained by cutting the bending member, when the end portions of the bending member after cutting are used as automobile parts or the like, they are often joined to other members by welding or the like.
- the end of the bending member after cutting is not quenched. Since the unquenched part is formed in the cutting part of the bending member manufactured by 3rd Embodiment, it is suitable when welding with another member.
- the steel pipe 1 is fed and induction-heated.
- the supply of the high frequency power to the induction heating device 5 may be temporarily stopped and then the supply of the high frequency power to the induction heating device 5 may be started again. Seem.
- the present inventors have found that it is difficult to form an unquenched portion having the same hardness as that of the base material and having the shortest possible width dimension by the above-described method.
- 29 (a) to 29 (e) show the maximum temperature reached and the temperature distribution at the current time when bending is performed on a portion other than the front end portion 1b and the rear end portion 1d of the steel pipe 1 using the conventional technique. It is the graph which represented (vertical axis) with respect to the position on the steel pipe 1 (horizontal axis).
- FIG. 29A shows that the first heating part is formed at a position different from the front end 1b and the rear end 1d of the steel pipe 1 by supplying high frequency power to the induction heating device 5 while feeding the steel pipe 1 in the longitudinal direction. Represents the state.
- the step of forming the first heating part is referred to as a first heating step.
- FIG.29 (b) shows the state which performed the induction heating of the steel pipe 1, cooling, and feeding from the state shown to Fig.29 (a).
- FIG. 29 (b) shows the state which performed the induction heating of the steel pipe 1, cooling, and feeding from the state shown to Fig.29 (a).
- FIG. 29 (b) shows the state which performed the induction heating of the steel pipe 1, cooling, and feeding from the state shown to Fig.29 (a).
- the process of forming an unquenched part between a 1st heating part and a 2nd heating part is called a heating stop process.
- FIG.29 (c) shows the state which cooled and sent the steel pipe 1 from the state shown in FIG.29 (b).
- the induction heating of the steel pipe 1 is resumed, and the second heating part is formed at a position upstream of the first heating part.
- the step of forming the second heating unit is referred to as a second heating step.
- FIG.29 (d) shows the state which performed the induction heating, cooling, and feeding of the steel pipe 1 from the state shown in FIG.29 (c).
- FIG.29 (e) shows the state which performed the induction heating of the steel pipe 1, cooling, and feeding from the state shown in FIG.29 (d).
- a portion having a hardness equivalent to that of the base material hereinafter referred to as a base material hardness portion
- the base material hardness part is not formed, but the portion where the maximum temperature reaches more than Ac1 point and less than Ac3 point is not quenched even after cooling. A quenching part is formed.
- the present inventors provide a base material hardness part of 1.40 times or less the heating width by the induction heating device 5 between the first heating part and the second heating part. It was found that it cannot be formed.
- the present inventors give a heating amount larger than the heating amount given to the first heating unit at the start of the second heating step between the first heating unit and the second heating unit.
- the width of the formed unquenched portion can be reduced, and the hardness of the unquenched portion formed between the first heated portion and the second heated portion can be made equal to the hardness of the base material. I found out.
- FIGS. 23 (a) to 23 (e) show the maximum temperature reached and the temperature distribution at the current time when bending is performed on a portion other than the front end 1b and the rear end 1d of the steel pipe 1 according to the present embodiment ( It is the graph which expressed the vertical axis
- FIG. 23A shows that the first heating part is formed at a position different from the front end 1b and the rear end 1d of the steel pipe 1 by supplying high-frequency power to the induction heating device 5 while feeding the steel pipe 1 in the longitudinal direction.
- FIG.23 (b) shows the state which performed the induction heating of the steel pipe 1, cooling, and feeding from the state shown to Fig.23 (a).
- FIG. 23B shows that only the induction heating of the steel pipe 1 is stopped while the steel pipe 1 is cooled and fed. Thereby, an unquenched part is formed between the 1st heating part and the 2nd heating part (heating stop process).
- FIG.23 (c) shows the state which cooled and sent the steel pipe 1 from the state shown in FIG.23 (b).
- induction heating of the steel pipe 1 is resumed, the second heating part is formed (second heating step), and the feeding of the steel pipe 1 is stopped.
- FIG.23 (d) shows the state which performed the induction heating and cooling of the steel pipe 1 from the state shown in FIG.23 (c).
- the feeding of the steel pipe 1 is resumed.
- FIG.23 (e) shows the state which performed the induction heating, cooling, and feeding of the steel pipe 1 from the state shown in FIG.23 (d).
- the amount of heating given when forming the second heating portion is set to the first heating portion. It is larger than the heating amount given at the time of forming. Therefore, as shown in FIG.23 (e), the site
- the heating amount given when forming the second heating unit is made larger than the heating amount given when forming the first heating unit, thereby making the first heating
- a base material hardness part can be formed between the part and the second heating part.
- a bending member can be cut
- the heating amount given when forming the second heating unit is made larger than the heating amount given when forming the first heating unit, so that the first heating unit and the first heating unit The width dimension of the unquenched part formed between the two heating parts can be reduced.
- the width dimension of the unquenched part formed between the first heating part and the second heating part is set to be 0.15 times or more and 1.40 times or less of the heating width by the induction heating device 5. Can do. Thereby, since an unnecessary site
- FIG. 7 is an explanatory view showing a configuration example of a steel material hot bending apparatus according to the present embodiment.
- the hot bending apparatus 0 includes a support device (support mechanism) 2, a feed device (feed mechanism) 3, an induction heating device (induction heating mechanism) 5, and a cooling device (cooling mechanism). 6, a drive device (drive mechanism) 9, a chuck 10, a first temperature measurement device (first temperature measurement mechanism) 26, a shape measurement device (shape measurement mechanism) 27, and a second temperature measurement device (second Temperature measuring mechanism) 28 and a control unit 29.
- the feeding device 3 feeds the steel pipe 1 in the longitudinal direction.
- the feeding speed may be constant or may be changed.
- the feeding of the steel pipe 1 by the feeding device 3 may be continuous or intermittent.
- the support device 22 supports the steel pipe 1 sent by the feeding device 3.
- the induction heating device 5 partially heats the steel pipe 1 by induction. In the induction heating of the steel pipe 1 by the induction heating device 5, the amount of high-frequency power supplied to the induction heating device 5 may be constant or may be changed. Moreover, the induction heating of the steel pipe 1 by the induction heating device 5 may be continuous or intermittent.
- the cooling device 6 partially cools the steel pipe 1 by injecting a cooling medium.
- a cooling medium is water.
- the drive device 9 applies a bending moment to the heating portion 1a of the steel pipe 1 by moving the chuck 10 that grips the tip portion 1b of the steel pipe 1 three-dimensionally.
- the chuck 10 holds the front end 1b and the rear end 1d of the steel pipe 1.
- the feeding device 3, the supporting device 22, the induction heating device 5, the cooling device 6 and the chuck 10 are arranged along the longitudinal direction of the steel pipe 1.
- the control unit 29 controls the feeding device 3, the induction heating mechanism 5, the cooling mechanism 6, the driving device 9, and the chuck 10.
- the control unit 29 controls the induction heating device 5 so that the heating amount at the time of forming the heating unit 1a at the tip 1b of the steel pipe 1 is larger than the heating amount at the time of forming the heating unit 1a at the upstream adjacent portion. To do.
- the control unit 29 controls the cooling unit 6 to cool the chuck 10 with a cooling medium when the induction unit 5 forms the heating unit 1 a at the tip 1 b of the steel pipe 1.
- the control part 29 is larger than the heating amount added when forming the heating part 1a in the downstream adjacent part, when the heating part 1a is formed in the rear end part 1d of the steel pipe 1 by the induction heating device 5. You may control to do.
- a first heating unit is formed between the front end 1b and the rear end 1d of the steel pipe 1 by the induction heating device 5, and a second heating unit is formed at a position upstream of the first heating unit.
- the unquenched part may be controlled to be formed at a position between the first heating part and the second heating part.
- the first temperature measuring device 26 measures the temperature of the tip portion 1 b of the steel pipe 1.
- Examples of the first temperature measuring device 26 include a thermocouple embedded in the claw 10b of the chuck 10, a thermocouple for measuring the thermoelectromotive force between the chuck 10 and the steel pipe 1, or a contact or non-contact thermometer. Can be used.
- the shape measuring device 27 measures the external deformation amount of the tip 1b of the steel pipe 1. As the shape measuring device 27, a contact-type or non-contact-type displacement meter, a detection device for the amount of movement of the claw 10b of the chuck 10, or the like can be used.
- the second temperature measuring device 28 measures the temperature of the heating unit 1 a formed on the steel pipe 1. As the second temperature measuring device 28, a non-contact type thermometer incorporated in the induction heating device 5 can be used.
- the control unit 29 uses the temperature of the tip 1b of the steel pipe 1 measured by the first temperature measuring device 26, the external deformation amount of the tip 1b of the steel pipe 1 measured by the shape measuring device 27, and the second temperature measuring device 28. You may control at least one of the feeding apparatus 3 and the induction heating apparatus 5 so that at least one of the temperatures of the heating part 1a of the steel pipe 1 to be measured may fall within a predetermined range.
- the control unit 29 uses the temperature of the tip 1b of the steel pipe 1 measured by the first temperature measuring device 26, the external deformation amount of the tip 1b of the steel pipe 1 measured by the shape measuring device 27, and the second temperature measuring device 28. After starting the feeding of the steel pipe 1 by the feeding device 3 and the induction heating of the steel pipe 1 by the induction heating device 5 so that at least one of the temperatures of the heating part 1a of the steel pipe 1 to be measured falls within a predetermined range. Further, at least one of the feeding speed of the steel pipe 1 by the feeding device 3 and the high-frequency power supplied to the induction heating device 5 may be changed.
- control part 29 is the temperature of the front-end
- the induction heating of the steel pipe 1 by the induction heating device 5 may be started first, and the feeding of the steel pipe 1 by the feeding device 3 may be started after a predetermined time has elapsed.
- Example 1 A steel pipe having an open end with an outer diameter of 31.8 mm and a wall thickness of 2.0 mm was subjected to bending by 3DQ, and an S-shaped bent portion was formed at the center in the longitudinal direction of the steel pipe.
- the hardness of the central portion in the longitudinal direction of the steel pipe after bending was 520 Hv.
- the C content was 0.22% by mass and the Mn content was 1.25% by mass.
- Example 1 is an example corresponding to the first embodiment.
- FIG. 8A is a schematic diagram showing the positional relationship between the steel pipe, the induction heating device, and the cooling device in Example 1.
- FIG. FIG.8 (b) is the graph which represented the hardness (vertical axis) of the steel pipe in Example 1 with respect to the position (horizontal axis) on a steel pipe.
- the induction heating device As the induction heating device, a 2-turn coil was used. The feed rate of the steel pipe was constant and 80 mm / second. A constant high-frequency electric energy (142 kW) was supplied to the induction heating device so that the maximum temperature reached by the steel pipe exceeded 1000 ° C.
- ⁇ shown in FIG. 8 (a) is the distance that the claw 10b of the chuck 10 is in contact with the inner surface of the steel pipe, and is 20 mm.
- ⁇ shown in FIG. 8A is the distance from the tip of the steel pipe to the longitudinal center of the heating part (hereinafter referred to as the heating start position) at the start of induction heating.
- ⁇ shown in FIG. 8A is a distance from the heating start position to the upstream end of the cooling unit, and is 27 mm.
- ⁇ shown in FIG. 8B is a distance from the tip to a position where the hardness is 500 Hv (hereinafter referred to as a hardness increase position).
- FIG. 9A is a side view of the steel pipe for explaining the positions A and B.
- FIG. 9B is a graph showing the maximum attained temperature (vertical axis) at positions A and B with respect to the position on the steel pipe (horizontal axis).
- FIG.9 (c) is the graph which represented the hardness (vertical axis) of the steel pipe in the position A and B with respect to the position (horizontal axis) on a steel pipe.
- Example 1-1 is an example corresponding to Embodiment 1-1, and the feeding of the steel pipe was started 0.15 seconds after the start of the supply of the high frequency power to the induction heating device.
- FIG. 10A shows the relationship between the amount of high-frequency power (vertical axis) and time (horizontal axis) supplied to the induction heating apparatus in Example 1-1, and the feed rate (vertical axis) in Example 1-1. The relationship with time (horizontal axis) is shown in FIG.
- Example 1-2 is an example corresponding to Form 1-2, and at the same time as the supply of high-frequency power to the induction heating apparatus is started, the feeding of the steel pipe is started at a feed rate of 26.7 mm / sec. After 06 seconds, the feed speed of the steel pipe was changed to 80 mm / second.
- FIG. 10C shows the relationship between the amount of high-frequency power (vertical axis) and time (horizontal axis) supplied to the induction heating apparatus in Example 1-2, and the feed rate (vertical axis) in Example 1-2. The relationship with time (horizontal axis) is shown in FIG.
- Example 1-3 is an example corresponding to Embodiment 1-3, and the feeding of the steel pipe was started simultaneously with the start of the supply of high-frequency power to the induction heating apparatus.
- the supply amount of the high frequency power to the induction heating device at the start of the supply of the high frequency power to the induction heating device is twice the supply amount of the high frequency power to the induction heating device in Example 1-1 and Example 1-2. It was.
- the amount of high-frequency power supplied to the induction heating device was changed 0.5 times 0.1 second after the start of supply of high-frequency power to the induction heating device and the start of feeding of the steel pipe.
- FIG. 10 (e) shows the relationship between the amount of high-frequency power (vertical axis) and time (horizontal axis) supplied to the induction heating device in Example 1-3, and the feed rate (vertical axis) in Example 1-3.
- the relationship with time (horizontal axis) is shown in FIG.
- Comparative Example 1-1 starts the supply of high-frequency power to the induction heating device after a lapse of a predetermined time from the start of feeding the steel pipe.
- the amount of high-frequency power supplied to the induction heating device and the feed speed of the steel pipe are The value was constant from the start of each.
- FIG. 11A shows the relationship between the amount of high-frequency power (vertical axis) and time (horizontal axis) supplied to the induction heating apparatus in Comparative Example 1-1, and the feed rate (vertical axis) in Comparative Example 1-1. The relationship with time (horizontal axis) is shown in FIG.
- Example 1-1 to 1-3 and Comparative Example 1-1 the maximum temperature of the chuck claw, the maximum temperature reached by the steel pipe, the distance from the tip of the steel pipe to the heating start position, and the hardness increasing position from the tip of the steel pipe Table 1 shows the distance from the tip of the steel pipe to the bending start position, and the distance between the hardness increasing position at position A and the hardness increasing position at position B.
- Comparative Example 1-1 although the heating was started from a position 21 mm from the tip of the steel pipe, the distance from the tip to the hardness increasing position was 35 mm, and the distance from the tip to the bending start position was 54 mm. Met.
- the maximum reach temperature of the chuck claw and the steel pipe is suppressed to a predetermined temperature or less, and the distance from the tip of the steel pipe to the hardness increasing position and the tip of the steel pipe are determined.
- the distance to the bending start position could be made shorter than that of Comparative Example 1-1.
- the distance from the tip of the steel pipe to the heating start position could be made longer than that in Comparative Example 1-1.
- the distance between the hardness increase position at position A and the hardness increase position at position B could be made shorter than that of Comparative Example 1-1.
- Example 2 A steel pipe having an open end with an outer diameter of 31.8 mm and a wall thickness of 2.0 mm was subjected to bending by 3DQ, and an S-shaped bent portion was formed at the center in the longitudinal direction of the steel pipe.
- the hardness of the central portion in the longitudinal direction of the steel pipe after bending was 520 Hv.
- the C content was 0.22% by mass and the Mn content was 1.25% by mass.
- Example 2 is an example corresponding to 2nd Embodiment.
- a two-turn coil was used as the induction heating device.
- the feed rate of the steel pipe was constant and 80 mm / second.
- a constant high-frequency electric energy (142 kW) was supplied to the induction heating device so that the maximum temperature reached by the steel pipe was 1000 ° C.
- the maximum reached temperature of the chuck claw that holds the rear end of the steel pipe, the highest reached temperature of the steel pipe, and the distance from the heating end position of the steel pipe to the rear end (distance G)
- the distance from the hardness reduction position of the steel pipe to the rear end (distance H), the distance from the bending end position of the steel pipe to the rear end, and the distance between the hardness reduction position at position A and the hardness reduction position at position B were determined. .
- Example 2-1 In Example 2-1, only the feeding was stopped from the state where the induction heating, cooling, and feeding of the steel pipe were performed, and the supply of high-frequency power to the induction heating device was stopped 0.15 seconds after the feeding was stopped.
- FIG. 20A shows the amount of high-frequency power (vertical axis) supplied to the induction heating apparatus of Example 2-1 with respect to time (horizontal axis).
- FIG. 20B shows the steel pipe feed speed (vertical axis) in Example 2-1 with respect to time (horizontal axis).
- Example 2-2 In Example 2-2, the feed rate is reduced to one third from the state where the induction heating, cooling and feed of the steel pipe are performed, and the high frequency power to the induction heating device is 0.06 seconds after the feed rate is reduced. The supply of was stopped.
- FIG. 20C shows the amount of high-frequency power (vertical axis) supplied to the induction heating apparatus of Example 2-2 with respect to time (horizontal axis).
- FIG. 20D shows the steel pipe feed rate (vertical axis) in Example 2-2 versus time (horizontal axis).
- Example 2-3 In Example 2-3, since the induction heating, cooling, and feeding of the steel pipe are performed, the high frequency power supplied to the induction heating device is doubled, and the increase in the supply of high frequency power to the induction heating device is 0. • After 1 second, the supply of high-frequency power to the induction heating apparatus was stopped. In Example 2-3, the steel pipe was fed at a constant feed rate.
- FIG. 20 (e) shows the amount of high-frequency power (vertical axis) supplied to the induction heating apparatus of Example 2-3 with respect to time (horizontal axis).
- FIG. 20F shows the steel pipe feed rate (vertical axis) in Example 2-3 with respect to time (horizontal axis).
- FIG. 21A shows the amount of high-frequency power (vertical axis) supplied to the induction heating apparatus of Comparative Example 2-1 with respect to time (horizontal axis).
- FIG. 21B shows the steel pipe feed speed (vertical axis) in Comparative Example 2-1 with respect to time (horizontal axis).
- Examples 2-1 to 2-3 the maximum reached temperature of the chuck claw was 500 ° C. or less, and the maximum reached temperature of the steel pipe was 1100 ° C. or less. Further, in Examples 2-1 to 2-3, compared to Comparative Example 2-1, the distance (distance H) from the hardness reduction position of the steel pipe to the rear end part and the bending end position of the steel pipe to the rear end part. The distance was shortened, and the productivity and economy in manufacturing the bending member were improved. In Examples 2-1 to 2-3, compared to Comparative Example 2-1, the distance (distance G) from the heating end position of the steel pipe to the rear end portion could be increased.
- Example 2-1 to 2-3 the distance between the hardness reduction position at position A and the hardness reduction position at position B is shorter than in Comparative Example 2-1, and the steel pipe is bent. At the time, it was found that the steel pipe was uniformly quenched in the circumferential direction.
- Example 3 A steel pipe having an open end with an outer diameter of 31.8 mm and a wall thickness of 2.6 mm was bent by 3DQ. A two-turn coil was used as the induction heating device.
- Example 3 is an example corresponding to the third embodiment.
- the first heating part is formed at a position other than the front end part and the rear end part of the steel pipe, and the second heating part is formed at a position upstream of the first heating part. Then, an unquenched portion was formed between the first heated portion and the second heated portion, and the width dimension of the unquenched portion and the formation status of the base material hardness portion were examined.
- Example 3-1 In Example 3-1, only induction heating was stopped from the state where induction heating, cooling, and feeding were performed on the steel pipe ((1) in FIG. 26B). In Examples 3-1 to 3-3, the amount of high-frequency power supplied to the induction heating apparatus was 154 kW. Further, in Example 3-1, the feeding speed when feeding the steel pipe was set to 80 mm / sec. When the steel pipe was sent 15 mm downstream after the induction heating for the steel pipe was stopped, the induction heating for the steel pipe was resumed and the feeding of the steel pipe was stopped ((3) in FIG. 26B). The steel pipe feed was resumed 0.15 seconds after the steel pipe feed was stopped ((4) in FIG. 26B).
- Example 3-2 In Example 3-2, only induction heating was stopped from the state where induction heating, cooling and feeding were performed on the steel pipe ((1) in FIG. 27B). The feed rate of the steel pipe at this time was 80 mm / second. When the steel pipe is sent 13 mm downstream after the induction heating for the steel pipe is stopped, the induction heating for the steel pipe is resumed and the feed speed of the steel pipe is reduced from 80 mm / second to 10 mm / second (FIG. 27B). (3)). 0.15 seconds after the steel pipe feed speed was reduced, the steel pipe feed speed was accelerated from 10 mm / second to 80 mm / second ((5) in FIG. 27B).
- Example 3-3 In Example 3-3, only induction heating was stopped from the state where induction heating (the amount of high-frequency power supplied to the induction heating device was 154 kW), cooling and feeding was performed on the steel pipe (FIG. 28B). (1)).
- the feed rate of the steel pipe in Example 3-3 was always 80 mm / second.
- induction heating was started with the high-frequency power supplied to the induction heating device being 308 kW ((3) in FIG. 28 (b)). . 0.15 seconds after starting the induction heating with the high frequency power supplied to the induction heating device being 308 kW, the high frequency power supplied to the induction heating device was lowered to 154 kW (((b) in FIG. 28B)). 4)).
- Comparative Examples 3-1 to 3-4 In Comparative Examples 3-1 to 3-4, only induction heating was stopped from a state where induction heating (the amount of high-frequency power supplied to the induction heating apparatus was 200 kW), cooling and feeding was performed on the steel pipe. After the induction heating for the steel pipe was stopped, the induction heating for the steel pipe was resumed when the steel pipe was sent a predetermined distance in the downstream direction. The distance that the steel pipe is sent in the downstream direction from when induction heating is stopped to when it is restarted is referred to as a heating stop section. In Comparative Examples 3-1 to 3-4, the distance of the heating stop section is different.
- Comparative Example 3-1 25 mm
- Comparative Example 3-2 10 mm
- Comparative Example 3-3 5 mm
- Comparative Example 3-4 2 mm.
- the hardness distribution in Comparative Examples 3-1 to 3-4 is shown in FIG.
- the feed rate of the steel pipe in Comparative Examples 3-1 to 3-4 was always 70 mm / second.
- Table 3 shows the width of the unquenched part and the formation state of the base material hardness part formed by the bending member manufacturing methods of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-4.
- Examples 3-1 to 3-3 compared with Comparative Examples 3-1 to 3-4, the width of the formed unquenched portion could be reduced.
- the base material hardness part could be formed, but in Comparative Examples 3-2 to 3-4, the base material hardness part could not be formed.
- a bending member manufacturing method and a steel material hot bending apparatus that are capable of preventing fatigue failure of a chuck that grips the tip of a steel material and that are excellent in productivity and economy. Can be provided.
Abstract
Description
本願は、2014年5月27日に、日本に出願された特願2014-109361号、2014年10月10日に、日本に出願された特願2014-209052号及び2014年12月4日に、日本に出願された特願2014-245639号に基づき優先権を主張し、これらの内容をここに援用する。
なお、鋼管1の先端部1bを把持する場合と後端部1dを把持する場合とで、チャック10及び11による把持の方法は同様である。
未焼入れ部は強度が低いため、強度が必要とされる部品では不要部位とされ、切断される場合がある。未焼入れ部を切断する場合には、切断工程が増えるため、曲げ部材の生産性が低下する。また、製造された曲げ部材に対して不要部位の切断を行うことにより、材料である鋼管のうち製品化されない部位が生じてしまうため、経済性が低下する。
時刻t0では、鋼管1の先端部1bは、誘導加熱装置5により加熱され得る位置に位置している。時刻t0からt1へ進むと、送り装置3による鋼管1の送り、誘導加熱装置5による鋼管1の加熱及び冷却装置6から冷却媒体を噴射することによる鋼管1の冷却を開始する(図14B参照)。
送り装置3による鋼管1の送り、誘導加熱装置5による鋼管1の加熱及び冷却装置6から冷却媒体を噴射することによる鋼管1の冷却を継続した状態で、鋼管1の先端部1bと加熱部1aの長手方向中心部との距離が所定の距離L2に達した時刻t2において、駆動機構9によりチャック10を三次元方向に移動させることにより、加熱部1aに曲げモーメントを付与する(図14C参照)。
加熱部1aへの曲げモーメントの付与により、時刻t3に鋼管1に曲がり部1cが形成される(図14D参照)。
鋼管1の先端部1bの近傍に形成された加熱部1aの加熱温度が900℃未満である場合には、駆動機構9により曲げ加工を行った際に、駆動機構9に過剰な負荷が作用し、駆動機構9の損傷を生じる可能性がある。
曲げ加工を適切に行うための加熱部1aの温度としては、900~1000℃が例として挙げられる。加熱部1aの温度が900~1000℃であれば、加熱部1aに対して曲げ加工を適切に行うことができるとともに、冷却装置6から冷却媒体を噴射することにより加熱部1aが冷却され、加熱部1aに対して焼入れを行うことができる。
以下、本発明を実施するための形態を、添付図面を参照しながら説明する。以降の説明では、断面形状が円形である鋼管に対して曲げ加工を行う場合を例にして説明するが、開口端を有し長尺な鋼管であれば、断面形状が矩形である鋼管に対しても本発明を適用することが可能である。また、同一の部材には同一の符号を付すことにより、重複する説明を適宜省略する。
第1実施形態に係る曲げ部材の製造方法は、鋼管の先端部に曲げ加工を行う際に、鋼管の先端部に形成される未焼入れ部を可能な限り小さくするとともに、鋼管の先端部を把持するチャックの小径部が500℃超に加熱されないようにすることにより、曲げ部材の製造の生産性及び経済性を向上させるとともに、鋼管の先端部を把持するチャックの小径部の疲労破壊を防ぐものである。
図1A~1Eは、本発明により鋼管1の先端部1b近傍に曲げ加工を行う場合の鋼管1及び鋼管の熱間曲げ加工装置0の状態を示す模式図である。図1A~図1Eは、それぞれ時刻t0、t1、t2、t3、t4における鋼管1及び鋼管の熱間曲げ加工装置0の状態を示している。なお、時刻t1は時刻t0からΔt秒経過した時刻である。
誘導加熱装置5により加熱されることにより、鋼管1には加熱部1aが形成される。鋼管1に形成される加熱部1aの位置は、図1B~図1Eに示されるように、誘導加熱装置5の位置を基準とするとほとんど移動しない。一方、先端部1bを基準とした場合には、加熱部1aの位置は、鋼管1が送られる方向と逆の方向へ移動する。つまり、鋼管1が長手方向に送られるに従い、加熱部1aと先端部1bとの距離は大きくなる。
なお、駆動機構9としては、ロボットアーム等を用いることができる。
先端部1bに加熱部1aを形成する際に与える加熱量を、先端部1bの上流側隣接部位に加熱部1aを形成する際に与える加熱量よりも大きくする方法としては、鋼管1を長手方向に送る際の送り速度と誘導加熱装置5から加熱部1aに与えられる加熱量との少なくとも一方を変化させる方法及び誘導加熱装置5に高周波電力を供給し始めてから所定の時間経過後に鋼管1の送りを開始する方法が挙げられる。
なお、誘導加熱装置5に供給する高周波電力量を変化させることにより、鋼管1に加熱部1aを形成する際に与える加熱量を変化させることができる。
形態例1-1では、誘導加熱装置5に高周波電力を供給し始めてから所定の時間経過後に鋼管1の送りを開始する。
鋼管1に対する誘導加熱を開始してから鋼管1の送りを開始するまでの時間Δtは、0.3秒以下であることが更に好ましい。鋼管1に対する誘導加熱を開始してから鋼管1の送りを開始するまでの時間Δtが0.3秒以下であることにより、部材端部の溶接や穴あけ加工に必要な未焼入れ部を30mm以下の範囲で確保することが可能である。
鋼管1に対する誘導加熱を開始してから鋼管1の送りを開始するまでの時間Δtは、0.04秒以下であることが特に好ましい。鋼管1に対する誘導加熱を開始してから鋼管1の送りを開始するまでの時間Δtが0.04秒以下であることにより、部材端部(3mm以下の範囲)まで焼入れ領域を確保することが可能である。
なお、図2(a)~2(d)の横軸の原点は、鋼管1の先端部1bである。
図2(b)に示すように、誘導加熱装置5による鋼管1の加熱温度は、冷却装置6により噴射された冷却媒体(図2(b)の矢印)により冷却される部位(以下、冷却部と呼称する)の近傍で最大となり、冷却部では噴射される冷却媒体によって急速に冷却される。
具体的には、図2(d)に示す硬度は、鋼管1のうち、最高到達温度がAc1点以下の部位では母材と同等の硬度であり、最高到達温度がAc3点以上の部位ではフルマルテンサイトの硬度であり、最高到達温度がAc1点超Ac3点未満の部位では母材とフルマルテンサイトとの間の硬度である。
後述するように、本実施形態では、鋼管1の先端部1bに加熱部1aを形成する際に与えられる加熱量を、上流側隣接部位に加熱部1aを形成する際に与えられる加熱量よりも大きくするが、鋼管1の送り及び誘導加熱を開始する前に、チャック10の爪10bを冷却することにより、鋼管1の先端部1bに加熱部1aを形成する際も、チャック10の爪10bが500℃超に加熱されることを防止することができる。
時刻t0からΔt秒後の時刻t1に、鋼管1の送りを開始する。これにより、鋼管1の先端部1bに加熱部1aを形成する際に与えられる加熱量を、上流側隣接部位に加熱部1aを形成する際に与えられる加熱量よりも大きくする。鋼管1の先端部1bに加熱部1aを形成する際に与えられる加熱量を、上流側隣接部位に加熱部1aを形成する際に与えられる加熱量よりも大きくすることにより、先端部1bには未焼入れ部を形成する一方、先端部1bの可能な限り近傍に対して曲げ加工を行うことができる。
また、形態例1-1の曲げ部材の製造方法によれば、先端部1bに形成される未焼入れ部を小さくすることができるため、曲げ部材を製造する際に、先端部1bの不要部位を切断する工程が不要である。そのため、曲げ部材の製造に関する生産性及び経済性を向上することが可能である。
形態例1-2では、先端部1bに加熱部1aを形成する際に与える加熱量を、上流側隣接部位に加熱部1aを形成する際に与える加熱量よりも大きくするために、鋼管1の送り速度を変化させる。
図5(a)は、形態例1-2の誘導加熱装置5に供給される高周波電力量(縦軸)を時間(横軸)に対して表したグラフである。図5(b)は、形態例1-2における鋼管1の送り速度(縦軸)を時間(横軸)に対して表したグラフである。
なお、送り開始時の送り速度、加速後の送り速度及び送り速度の加速率は、鋼管1の加熱温度が高くなりすぎないように(例えば、鋼管1が1100℃超に加熱されないように)決定することが好ましい。また、送り及び誘導加熱の開始前にチャック10の爪10bを冷却媒体で冷却することが好ましい点については、形態例1-1と同様である。
形態例1-3では、鋼管1の送り速度を一定にする一方、誘導加熱装置5に供給する高周波電力量を変化させることにより、鋼管1の先端部1bに加熱部1aを形成する際に与える加熱量を、上流側隣接部位に加熱部1aを形成する際に与える加熱量よりも大きくする。
図6(a)は、形態例1-3の誘導加熱装置に供給される高周波電力量(縦軸)を時間(横軸)に対して表したグラフである。図6(b)は、形態例1-3における鋼管の送り速度(縦軸)を時間(横軸)に対して表したグラフである。
なお、送り及び誘導加熱の開始前にチャック10の爪10bを冷却媒体で冷却することが好ましい点については、形態例1-1と同様である。
最高到達温度(縦軸)と鋼管1上の位置(横軸)との関係が図9(b)で表される場合における、硬度(縦軸)と鋼管1上の位置(横軸)との関係を図9(c)に示す。図9(c)に示すように、誘導加熱により与えられる加熱量が鋼管1の周方向に異なる場合には、周方向の位置により硬度上昇位置が異なる。
本実施形態の曲げ部材の製造方法によれば、鋼管1の周方向の硬度を従来技術に比べてより均一にすることが可能である。
第2実施形態に係る曲げ部材の製造方法は、鋼管の後端部に曲げ加工を行う際に、鋼管の後端部に形成される未焼入れ部を可能な限り小さくするとともに、鋼管の後端部を把持するチャックの小径部が500℃超に加熱されないようにすることにより、曲げ部材の製造の生産性及び経済性を向上させるとともに、鋼管の後端部を把持するチャックの小径部の疲労破壊を防ぐものである。
図22Aに示されている時刻t4から図22Bに示されている時刻t5へと進むにつれ、鋼管1の後端部1dが徐々に誘導加熱装置5及び冷却装置6に近接する。時刻t5では、鋼管1に対する誘導加熱が行われているため、鋼管1に加熱部1aが形成されている。
その後、鋼管1の送り及び冷却を行い、図22Dに示す時刻t7において、鋼管1に対する曲げ加工を終了する。
また、鋼管1の後端部1dが1100℃超に加熱された場合には、鋼管1の後端部1dを把持するチャック10の爪10bが500℃超に加熱される可能性が高くなる。チャック10の爪10bが500℃超に加熱されると、チャック10が疲労破壊する可能性が高くなるため、好ましくない。
さらに、鋼管1の後端部1dが1100℃超に加熱された場合には、鋼管1の後端部1dが軟化し、チャック10の把持力により鋼管1の後端部1dが変形する可能性があるため、好ましくない。
図16(a)は、鋼管1の後端部1d近傍における鋼管1と鋼管の熱間曲げ加工装置0との位置関係を示す模式図である。図16(a)中の距離Fは、チャック10の爪10bが鋼管1の後端部1dの内面に接触している距離である。図16(a)中の距離Gは、鋼管1に対する誘導加熱を終了した時点における加熱部1aの長手方向中心部(以下、加熱終了位置と呼称する)から鋼管1の後端部1dまでの距離である。
図16(b)は、鋼管1の後端部1d近傍における硬度(縦軸)と鋼管1上の位置(横軸)との関係を表したグラフである。図16(b)中の距離Hは、鋼管1において硬度が500Hvである部位の下流端(以下、硬度低下位置と呼称する)から鋼管1の後端部1dまでの距離である。
距離Hを短くするためには、距離Gを短くする方法が考えられるが、距離Gを短くすることにより、鋼管1の後端部1dが1100℃超に加熱される場合がある。鋼管1の後端部1dが1100℃超に加熱された場合には、加熱部1aにおいて金属組織の粗粒化が生じ、加工性が低下するため、好ましくない。
また、鋼管1の後端部1dが1100℃超に加熱された場合には、鋼管1の後端部1dを把持するチャック10の爪10bが500℃超に加熱される可能性が高くなる。チャック10の爪10bが500℃超に加熱されると、チャック10が疲労破壊する可能性が高くなるため、好ましくない。
さらに、鋼管1の後端部1dが1100℃超に加熱された場合には、鋼管1の後端部1dが軟化し、チャック10の把持力により鋼管1の後端部1dが変形する可能性があるため、好ましくない。
図17(b)に示すように、図9(a)に示した位置Aに与えられる加熱量が位置Bに与えられる加熱量よりも10%多いと想定した場合には、位置Aの硬度低下位置と位置Bの硬度低下位置とは鋼管1の長手方向に距離Iだけ離間している。曲げ部材の製造に係る生産性及び経済性を向上するためには、距離Iを可能な限り短くすることが好ましい。距離Iを短くするためには、鋼管1に与えられる加熱量を周方向で均一にすることが必要である。
なお、図18(a)~18(d)では、誘導加熱装置5により誘導加熱されている鋼管1の部位を加熱部と表し、冷却装置6から冷却媒体が噴射されることにより冷却されている鋼管1の部位を冷却部と表す。
図18(b)に示す状態から、誘導加熱装置5による鋼管1の誘導加熱を停止し、鋼管1の冷却及び送りを行った状態を図18(c)に示す。図18(c)に示す時点では、Ac1点超の温度を有する部位は存在しない。
図18(c)に示す状態から、冷却装置6から冷却媒体を噴射することによる鋼管1の冷却及び送り装置3による鋼管1の送りを行った状態を図18(d)に示す。図18(d)に示す時点で、鋼管1に対する曲げ加工を終了する。
図18(e)に示す距離Jは、鋼管1の後端部1d近傍における、硬度低下位置から最高到達温度が500℃である位置までの距離を表している。鋼管1の後端部1dを把持するチャック10の爪10bの加熱温度を500℃以下にするためには、チャック10の爪10bにより把持されている鋼管1の後端部1dの加熱温度が500℃以下であればよい。また、曲げ部材の製造に係る生産性及び経済性を向上するためには、硬度低下位置が鋼管1の後端部1dに近いことが好ましい。
上述の理由から、鋼管1の後端部1dを把持するチャック10の疲労破壊を防止すると共に、曲げ部材の製造に係る生産性及び経済性を向上するためには、距離Jを短くすることが好ましい。
後端部1dに加熱部1aを形成する際に与える加熱量を、後端部1dの下流側隣接部位に加熱部1aを形成する際に与える加熱量よりも大きくする方法としては、鋼管1の後端部1dにおいて誘導加熱、冷却及び送りを行っている状態から、送りのみを停止し、所定の時間経過後に誘導加熱装置5への高周波電力の供給を停止することにより、鋼管1の誘導加熱を停止する方法が挙げられる。
また、別の方法としては、鋼管1の後端部1dにおいて誘導加熱、冷却及び送りを行っている状態から、鋼管1の送り速度を減速し、所定の時間経過後に誘導加熱装置5への高周波電力の供給を停止することにより、鋼管1の誘導加熱を停止する方法が挙げられる。
さらに、別の方法としては、鋼管1の後端部1dにおいて誘導加熱、冷却及び送りを行っている状態から、誘導加熱装置5に供給する高周波電力量を増加し、所定の時間経過後に誘導加熱装置5への高周波電力の供給を停止することにより、鋼管1の誘導加熱を停止する方法が挙げられる。
図19(a)に示す時点では、誘導加熱装置5による鋼管1の誘導加熱、冷却装置6から冷却媒体を噴射することによる鋼管1の冷却及び送り装置3による鋼管1の送りを行っている。
図19(b)に示す状態から、誘導加熱装置5による鋼管1の誘導加熱及び冷却装置6から冷却媒体を噴射することによる鋼管1の冷却を継続して行った状態を図19(c)に示す。図19(c)に示す時点において、停止していた送り装置3による鋼管1の送りを再開すると共に、誘導加熱装置5による鋼管1の誘導加熱を停止する。なお、冷却装置6から冷却媒体を噴射することによる鋼管1の冷却は継続して行う。
上述のように、本実施形態の曲げ部材の製造方法により鋼管1の後端部1dに曲げ加工を行った場合には、従来技術に比べて距離Jを短くすることができるため、鋼管1の後端部1dを把持するチャック10の疲労破壊を防止すると共に、曲げ部材の製造に係る生産性及び経済性を向上することが可能である。
第3実施形態に係る曲げ部材の製造方法は、鋼管の先端部及び後端部以外の部分に第1加熱部を形成し、第1加熱部よりも上流側の位置に第2加熱部を形成し、第1加熱部と第2加熱部との間に未焼入れ部を形成する方法である。
第3実施形態に係る曲げ部材の製造方法によれば、製造された曲げ部材の未焼入れ部を長手方向に切断して複数の曲げ部材を得る場合に、切断部位である未焼入れ部の硬度が低いため、曲げ部材を容易に切断することができる。なお、切断部位をより容易に切断するためには、切断部位の硬度は母材と同等の硬度であることが好ましい。
また、第3実施形態に係る曲げ部材の製造方法によれば、切断部位である未焼入れ部の近傍まで曲げ加工を行うことができるので、不要部位が生じず、経済性を向上することができる。
曲げ部材を切断して複数の曲げ部材を得た場合に、切断後の曲げ部材の端部を自動車部品等として用いられる場合には、他の部材と溶接等により接合される場合が多い。切断後の曲げ部材と他の部材とを溶接する場合には、切断後の曲げ部材の端部は焼入れされていないことが好ましい。第3実施形態により製造された曲げ部材の切断部には未焼入れ部が形成されているため、他の部材と溶接する際に好適である。
しかしながら、本発明者らは、上述の方法では母材と同等の硬度を有し、可能な限り幅寸法の短い未焼入れ部を形成することが困難であることを知見した。
図29(b)は、図29(a)に示す状態から、鋼管1の誘導加熱、冷却及び送りを行った状態を示す。図29(b)に示す時点で、鋼管1の冷却及び送りは行ったまま、鋼管1の誘導加熱のみを停止する。これにより、第1加熱部と第2加熱部との間に未焼入れ部を形成する。なお、第1加熱部と第2加熱部との間に未焼入れ部を形成する工程を、加熱停止工程と呼称する。
図29(d)は、図29(c)に示す状態から、鋼管1の誘導加熱、冷却及び送りを行った状態を示す。
図29(e)に示すように、従来技術を用いた場合には、第1加熱工程、加熱停止工程及び第2加熱工程の終了後に、最高到達温度がAc1点以下である部位は存在しない。そのため、母材と同等の硬度を有する部位(以下、母材硬度部と呼称する)は形成されない。
なお、上述の通り、従来技術を用いた場合には母材硬度部が形成されないが、最高到達温度がAc1点超Ac3点未満である部位は冷却を行っても焼入れが行われないため、未焼入れ部が形成される。
図23(b)は、図23(a)に示す状態から、鋼管1の誘導加熱、冷却及び送りを行った状態を示す。図23(b)に示す時点で、鋼管1の冷却及び送りは行ったまま、鋼管1の誘導加熱のみを停止する。これにより、第1加熱部と第2加熱部との間に未焼入れ部を形成する(加熱停止工程)。
図23(d)は、図23(c)に示す状態から、鋼管1の誘導加熱及び冷却を行った状態を示す。図23(d)に示す時点で、鋼管1の送りを再開する。
図23(e)は、図23(d)に示す状態から、鋼管1の誘導加熱、冷却及び送りを行った状態を示す。
なお、第2加熱工程の開始時に、第2加熱部を形成する際に与えられる加熱量を第1加熱部を形成する際に与えられる加熱量よりも大きくする方法としては、第2加熱工程の開始時に、鋼管1の送りを停止せずに、送り速度を減速させた状態で誘導加熱を行う方法が挙げられる。また、第2加熱工程の開始時に、第2加熱部を形成する際に与えられる加熱量を第1加熱部を形成する際に与えられる加熱量よりも大きくする方法としては、第2加熱工程の開始時に、鋼管1の送り速度を変化させずに、誘導加熱装置5へ供給する高周波電力量を増加させる方法も挙げられる。
また、第2加熱工程の開始時に、第2加熱部を形成する際に与えられる加熱量を第1加熱部を形成する際に与えられる加熱量よりも大きくすることにより、第1加熱部と第2加熱部との間に形成される未焼入れ部の幅寸法を小さくすることができる。具体的には、第1加熱部と第2加熱部との間に形成される未焼入れ部の幅寸法を、誘導加熱装置5による加熱幅の0.15倍以上1.40倍以下にすることができる。これにより、曲げ部材を切断する際に不要部位が生じないため、曲げ部材の製造に係る経済性を向上することができる。
次に、本実施形態に係る鋼材の熱間曲げ加工装置について説明する。
図7は、本実施形態に係る鋼材の熱間曲げ加工装置の構成例を示す説明図である。
支持装置22は、送り装置3により送られた鋼管1を支持する。
誘導加熱装置5は、鋼管1を部分的に誘導加熱する。誘導加熱装置5による鋼管1の誘導加熱において、誘導加熱装置5に供給される高周波電力量は一定でもよいし、変化させてもよい。また、誘導加熱装置5による鋼管1の誘導加熱は、連続的でもよいし、断続的でもよい。
駆動装置9は、鋼管1の先端部1bを把持するチャック10を三次元に移動させることにより、鋼管1の加熱部1aに対して曲げモーメントを付与する。
チャック10は、鋼管1の先端部1b及び後端部1dを把持する。
制御部29は、誘導加熱装置5により鋼管1の先端部1bに加熱部1aを形成する際の加熱量を、上流側隣接部位に加熱部1aを形成する際の加熱量よりも大きくするよう制御する。また、制御部29は、誘導加熱装置5により鋼管1の先端部1bに加熱部1aを形成する際に、冷却装置6によりチャック10を冷却媒体で冷却するように制御する。
制御部29は、誘導加熱装置5により鋼管1の先端部1bと後端部1dとの間に第1加熱部が形成され、第1加熱部よりも上流側の位置に第2加熱部が形成され、第1加熱部と第2加熱部との間の位置に未焼入れ部が形成されるように制御してもよい。
形状測定装置27は、鋼管1の先端部1bの外形変形量を測定する。形状測定装置27としては、接触式あるいは非接触式の変位計又はチャック10の爪10bの移動量の検出装置等を用いることができる。
第2温度測定装置28は、鋼管1に形成された加熱部1aの温度を測定する。第2温度測定装置28としては、誘導加熱装置5に組み込んだ非接触式の温度計等を用いることができる。
また、制御部29は、第1温度測定装置26によって測定される鋼管1の先端部1bの温度、形状測定装置27によって測定される鋼管1の先端部1bの外形変形量及び第2温度測定装置28によって測定される鋼管1の加熱部1aの温度のうちの少なくとも一つが予め定めた範囲内となるように、送り装置3による鋼管1の送りと誘導加熱装置5による鋼管1の誘導加熱とのうち、誘導加熱装置5による鋼管1の誘導加熱を先に開始し、所定の時間経過後に、送り装置3による鋼管1の送りを開始してもよい。
外径31.8mm、肉厚2.0mmの開口端を有する鋼管に対して3DQによる曲げ加工を行い、鋼管の長手方向中央部にS字形状の曲り部を形成した。曲げ加工を行った後の鋼管の長手方向中央部の硬度は、520Hvであった。鋼管の代表的な化学組成としては、Cの含有量が0.22質量%,Mnの含有量が1.25質量%であった。なお、実施例1は、第1実施形態に対応する実施例である。
実施例1-1は、形態例1-1に相当する実施例であり、誘導加熱装置への高周波電力の供給開始から0.15秒後に鋼管の送りを開始した。実施例1-1における誘導加熱装置へ供給される高周波電力量(縦軸)と時間(横軸)との関係を図10(a)に、実施例1-1における送り速度(縦軸)と時間(横軸)との関係を図10(b)に示した。
実施例1-2は、形態例1-2に相当する実施例であり、誘導加熱装置への高周波電力の供給開始と同時に26.7mm/秒の送り速度で鋼管の送りを開始し、0.06秒後に鋼管の送り速度を80mm/秒に変化させた。実施例1-2における誘導加熱装置へ供給される高周波電力量(縦軸)と時間(横軸)との関係を図10(c)に、実施例1-2における送り速度(縦軸)と時間(横軸)との関係を図10(d)に示した。
実施例1-3は、形態例1-3に相当する実施例であり、誘導加熱装置への高周波電力の供給開始と同時に鋼管の送りを開始した。誘導加熱装置への高周波電力への供給開始時における誘導加熱装置への高周波電力の供給量は、実施例1-1及び実施例1-2における誘導加熱装置への高周波電力の供給量の2倍とした。次に、誘導加熱装置への高周波電力の供給開始及び鋼管の送り開始から0.1秒後に誘導加熱装置に供給する高周波電力量を0.5倍に変化させた。実施例1-3における誘導加熱装置へ供給される高周波電力量(縦軸)と時間(横軸)との関係を図10(e)に、実施例1-3における送り速度(縦軸)と時間(横軸)との関係を図10(f)に示した。
比較例1-1は、鋼管の送りを開始してから所定の時間経過後に誘導加熱装置への高周波電力の供給を開始するもので、誘導加熱装置へ供給する高周波電力量及び鋼管の送り速度は、それぞれの開始時から一定の値とした。比較例1-1における誘導加熱装置へ供給される高周波電力量(縦軸)と時間(横軸)との関係を図11(a)に、比較例1-1における送り速度(縦軸)と時間(横軸)との関係を図11(b)に示した。
これに対し、実施例1-1~1-3では、チャックの爪及び鋼管の最高到達温度を所定の温度以下に抑制し、鋼管の先端部から硬度上昇位置までの距離及び鋼管の先端部から曲げ開始位置までの距離を比較例1-1よりも短くすることができた。一方、実施例1-1~1-3では、鋼管の先端部から加熱開始位置までの距離を比較例1-1よりも長くすることができた。
また、実施例1-1~1-3では、位置Aにおける硬度上昇位置と位置Bにおける硬度上昇位置との距離を、比較例1-1よりも短くすることができた。
外径31.8mm、肉厚2.0mmの開口端を有する鋼管に対して3DQによる曲げ加工を行い、鋼管の長手方向中央部にS字形状の曲り部を形成した。曲げ加工を行った後の鋼管の長手方向中央部の硬度は、520Hvであった。鋼管の代表的な化学組成としては、Cの含有量が0.22質量%,Mnの含有量が1.25質量%であった。なお、実施例2は第2実施形態に対応する実施例である。
誘導加熱装置としては、2ターンコイルを用いた。鋼管の送り速度は一定速度とし、80mm/秒とした。鋼管の最高到達温度が1000℃となるように、誘導加熱装置へは一定の高周波電力量(142kW)を供給した。
具体的には、実施例及び比較例において、鋼管の後端部を把持するチャックの爪の最高到達温度、鋼管の最高到達温度、鋼管の加熱終了位置から後端部までの距離(距離G)、鋼管の硬度低下位置から後端部までの距離(距離H)、鋼管の曲げ終了位置から後端部までの距離及び位置Aにおける硬度低下位置と位置Bにおける硬度低下位置との距離を求めた。
実施例2-1では、鋼管の誘導加熱、冷却及び送りを行っている状態から送りのみを停止し、送りの停止から0.15秒後に誘導加熱装置への高周波電力の供給を停止した。
図20(a)に、実施例2-1の誘導加熱装置に供給される高周波電力量(縦軸)を時間(横軸)に対して表した。図20(b)に、実施例2-1における鋼管の送り速度(縦軸)を時間(横軸)に対して表した。
実施例2-2では、鋼管の誘導加熱、冷却及び送りを行っている状態から、送り速度を3分の1に減速し、送り速度の減速から0.06秒後に誘導加熱装置への高周波電力の供給を停止した。
図20(c)に、実施例2-2の誘導加熱装置に供給される高周波電力量(縦軸)を時間(横軸)に対して表した。図20(d)に、実施例2-2における鋼管の送り速度(縦軸)を時間(横軸)に対して表した。
実施例2-3では、鋼管の誘導加熱、冷却及び送りを行っている状態から、誘導加熱装置に供給される高周波電力を2倍に増やし、誘導加熱装置への高周波電力の供給の増加から0.1秒後に誘導加熱装置への高周波電力の供給を停止した。なお、実施例2-3では、鋼管の送りは一定の送り速度で行った。
図20(e)に、実施例2-3の誘導加熱装置に供給される高周波電力量(縦軸)を時間(横軸)に対して表した。図20(f)に、実施例2-3における鋼管の送り速度(縦軸)を時間(横軸)に対して表した。
比較例2-1では、鋼管の誘導加熱、冷却及び送りを行っている状態から、誘導加熱装置への高周波電力の供給を停止した。なお、比較例2-1では、鋼管の送りは一定の送り速度で行った。
図21(a)に、比較例2-1の誘導加熱装置に供給される高周波電力量(縦軸)を時間(横軸)に対して表した。図21(b)に、比較例2-1における鋼管の送り速度(縦軸)を時間(横軸)に対して表した。
さらに、実施例2-1~2-3では、比較例2-1に比べて、位置Aにおける硬度低下位置と位置Bにおける硬度低下位置との距離が短くなっており、鋼管の曲げ加工を施す際に、鋼管の周方向に均一に焼入れされていることが分かった。
外径31.8mm、肉厚2.6mmの開口端を有する鋼管に対して3DQによる曲げ加工を行った。誘導加熱装置としては、2ターンコイルを用いた。なお、実施例3は第3実施形態に対応する実施例である。
実施例3-1では、鋼管に対して誘導加熱、冷却及び送りを行っている状態から、誘導加熱のみを停止した(図26(b)の(1))。なお、実施例3-1~3-3では、誘導加熱装置に供給される高周波電力量を154kWとした。また、実施例3-1において鋼管を送る際の送り速度は80mm/秒とした。
鋼管に対する誘導加熱を停止してから鋼管が15mm下流に送られた時点で鋼管に対する誘導加熱を再開するとともに、鋼管の送りを停止した(図26(b)の(3))。鋼管の送りを停止してから0.15秒後に、鋼管の送りを再開した(図26(b)の(4))。
実施例3-2では、鋼管に対して誘導加熱、冷却及び送りを行っている状態から、誘導加熱のみを停止した(図27(b)の(1))。この時点での鋼管の送り速度は80mm/秒とした。
鋼管に対する誘導加熱を停止してから鋼管が13mm下流に送られた時点で鋼管に対する誘導加熱を再開するとともに、鋼管の送り速度を80mm/秒から10mm/秒に減速させた(図27(b)の(3))。鋼管の送り速度の減速から0.15秒後に、鋼管の送り速度を10mm/秒から80mm/秒に加速させた(図27(b)の(5))。
実施例3-3では、鋼管に対して誘導加熱(誘導加熱装置に供給される高周波電力量は154kW)、冷却及び送りを行っている状態から、誘導加熱のみを停止した(図28(b)の(1))。なお、実施例3-3での鋼管の送り速度は、常に80mm/秒とした。
鋼管に対する誘導加熱を停止してから鋼管が13mm下流に送られた時点で、誘導加熱装置に供給される高周波電力量を308kWとする誘導加熱を開始した(図28(b)の(3))。誘導加熱装置に供給される高周波電力量を308kWとする誘導加熱を開始してから0.15秒後に、誘導加熱装置に供給される高周波電力量を154kWに下げた(図28(b)の(4))。
比較例3-1~3-4では、鋼管に対して誘導加熱(誘導加熱装置に供給される高周波電力量は200kW)、冷却及び送りを行っている状態から、誘導加熱のみを停止した。鋼管に対する誘導加熱を停止してから鋼管が下流方向へ所定の距離送られた時点で、鋼管に対する誘導加熱を再開した。誘導加熱を停止してから再開するまでの間に、鋼管が下流方向へ送られる距離を加熱停止区間と呼称する。
比較例3-1~3-4では、加熱停止区間の距離が異なる。各比較例における加熱停止区間の距離は、比較例3-1:25mm、比較例3-2:10mm、比較例3-3:5mm、比較例3-4:2mmであった。比較例3-1~3-4における硬度分布を図24に示した。
なお、比較例3-1~3-4における鋼管の送り速度は、常に70mm/秒とした。
1 鋼管
1a加熱部
1b 先端部
1c 曲がり部
1d 後端部
2 支持装置(支持機構)
3 送り装置(送り機構)
4 可動ローラーダイス
4a ロール対
5 誘導加熱装置(誘導加熱機構)
6 冷却装置(冷却機構)
9 駆動装置(駆動機構)
10 チャック
10a 大径部
10b 小径部(爪)
11 チャック
11a 大径部
11b 小径部(爪)
26 第1温度測定機構
27 形状測定機構
28 第2温度測定機構
29 制御部
Claims (14)
- 開口端を有する長尺の鋼材の長手方向の一端部をチャックで把持する把持工程と;
前記把持工程後の前記鋼材を、前記一端部を先頭にして前記長手方向に沿って送る送り工程と;
前記鋼材の前記長手方向の一部分を高周波誘導加熱して加熱部を形成する加熱工程と;
前記チャックを三次元方向に移動させることで前記加熱部に曲げモーメントを付与する曲げ工程と;
前記曲げ工程後の前記加熱部に冷却媒体を噴射して冷却する冷却工程と;
を有し、
前記加熱工程の開始時に、
前記一端部に前記加熱部を形成する際に加える加熱量を、前記鋼材の送り方向に沿って見た場合に前記一端部の上流側に隣接する上流側隣接部位よりも大きくするとともに、
前記チャックを前記冷却媒体で冷却する
ことを特徴とする、曲げ部材の製造方法。 - 前記加熱工程の前記開始時に、前記送り工程における前記鋼材の前記長手方向への送り速度と、前記加熱工程で前記一部分に付与する加熱量との少なくとも一方を変更することで、
前記一端部に前記加熱部を形成する際に加える前記加熱量を、前記上流側隣接部位よりも大きくする
ことを特徴とする、請求項1に記載の曲げ部材の製造方法。 - 前記加熱工程の前記開始時から所定の時間後に前記送り工程を開始することで、
前記一端部に前記加熱部を形成する際に加える前記加熱量を、前記上流側隣接部位よりも大きくする
ことを特徴とする、請求項1又は請求項2に記載の曲げ部材の製造方法。 - 前記鋼材の前記長手方向における複数箇所で温度を測定する温度測定工程をさらに有し;
前記送り工程において、前記温度測定工程で得られた温度測定結果に基づき、前記鋼材の前記長手方向への送り速度を決定する;
ことを特徴とする、請求項1から請求項3のいずれか1項に記載の曲げ部材の製造方法。 - 前記鋼材における前記長手方向の他端部に前記加熱部を形成する際に加える加熱量を、前記鋼材の前記送り方向に沿って見た場合に前記他端部の下流側に隣接する下流側隣接部位よりも大きくする
ことを特徴とする、請求項1から請求項4のいずれか1項に記載の曲げ部材の製造方法。 - 前記加熱工程の前記高周波誘導加熱を停止する前に、前記送り工程における前記鋼材の前記長手方向への送り速度と前記加熱工程における加熱量との少なくとも一方を変更することで、
前記他端部に前記加熱部を形成する際に加える前記加熱量を、前記下流側隣接部位よりも大きくする
ことを特徴とする、請求項5に記載の曲げ部材の製造方法。 - 前記加熱工程の前記高周波誘導加熱を停止する前に、前記送り工程における前記鋼材の送りを停止することで、
前記他端部に前記加熱部を形成する際に加える前記加熱量を、前記下流側隣接部位よりも大きくする
ことを特徴とする、請求項6に記載の曲げ部材の製造方法。 - 前記チャックの爪の加熱温度が500℃以下となる第1条件と、
前記曲げ工程で前記曲げモーメントを付与する際の前記加熱部の加熱温度がAc3点超となる第2条件と、
前記鋼材の最高到達温度が前記鋼材の粗粒化が進行する温度以下又は靭性が低下する温度以下となる第3条件と、
の全てを満たすように、前記加熱工程での加熱量を制御する
ことを特徴とする、請求項1から請求項7のいずれか1項に記載の曲げ部材の製造方法。 - 前記加熱工程が、
前記鋼材の前記一端部及び他端部間の位置に第1加熱部を形成する第1加熱工程と;
前記鋼材上の前記第1加熱部よりも上流側の位置に第2加熱部を形成する第2加熱工程と;
前記第1加熱工程と前記第2加熱工程との間に、前記高周波誘導加熱を停止することにより、前記第1加熱部と前記第2加熱部との間の位置に未焼入れ部を形成する加熱停止工程と;
を有し、
前記第2加熱工程の開始時に、前記第1加熱部に与える加熱量よりも大きな加熱量を前記第2加熱部に与える
ことを特徴とする、請求項1から請求項8のいずれか1項に記載の曲げ部材の製造方法。 - 前記長手方向に沿って見た場合に、前記未焼入れ部の幅寸法を、前記高周波誘導加熱による加熱幅の0.15倍以上1.40倍以下とする
ことを特徴とする、請求項9に記載の曲げ部材の製造方法。 - 開口端を有する長尺の鋼材の長手方向の一端部を把持するチャックと;
前記チャックを三次元方向に移動させる駆動機構と;
前記鋼材を、前記一端部を先頭にして前記長手方向に沿って送る送り機構と;
前記鋼材の前記長手方向の一部分を高周波誘導加熱して加熱部を形成する誘導加熱機構と;
前記加熱部に冷却媒体を噴射して冷却する冷却機構と;
前記チャック、前記駆動機構、前記送り機構、前記誘導加熱機構、及び前記冷却機構を制御する制御部と;
を備え、
前記制御部が、
前記誘導加熱機構により前記一端部に前記加熱部を形成する際の加熱量を、前記鋼材の送り方向に沿って見た場合に前記一端部の上流側に隣接する上流側隣接部位よりも大きくするとともに、
前記冷却機構により前記チャックを前記冷却媒体で冷却するように制御する
ことを特徴とする、鋼材の熱間曲げ加工装置。 - 前記制御部が、
前記誘導加熱機構により前記鋼材における前記長手方向の他端部に前記加熱部を形成する際に加える加熱量を、前記送り方向に沿って見た場合に前記他端部の下流側に隣接する下流側隣接部位よりも大きくするように制御する
ことを特徴とする、請求項11に記載の鋼材の熱間曲げ加工装置。 - 前記制御部が、
前記誘導加熱機構により前記鋼材の前記一端部及び他端部間の位置に第1加熱部が形成され、前記鋼材上の前記第1加熱部よりも上流側の位置に第2加熱部が形成され、前記第1加熱部と前記第2加熱部との間の位置に未焼入れ部が形成されるように制御する
ことを特徴とする、請求項11又は請求項12に記載の鋼材の熱間曲げ加工装置。 - 前記一端部の温度を測定する第1温度測定機構と、前記加熱部の温度を測定する第2温度測定機構と、前記一端部の外形変形量を測定する形状測定機構とのうちの少なくとも一つを更に備え、
前記一端部の前記温度と前記加熱部の前記温度と前記一端部の前記外形変形量とのうちの少なくとも一つが予め定めた範囲内となるように、
前記制御部が、前記送り機構及び前記誘導加熱機構の少なくとも一方を制御する
ことを特徴とする、請求項11から請求項13のいずれか1項に記載の鋼材の熱間曲げ加工装置。
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CN106413934B (zh) | 2018-10-12 |
CN106413934A (zh) | 2017-02-15 |
KR20160146903A (ko) | 2016-12-21 |
RU2661978C2 (ru) | 2018-07-23 |
EP3150296A1 (en) | 2017-04-05 |
EP3150296A4 (en) | 2018-02-07 |
RU2016146105A (ru) | 2018-06-27 |
US20170197237A1 (en) | 2017-07-13 |
US10543519B2 (en) | 2020-01-28 |
KR101950563B1 (ko) | 2019-02-20 |
RU2016146105A3 (ja) | 2018-06-27 |
JP6245358B2 (ja) | 2017-12-13 |
JPWO2015182666A1 (ja) | 2017-04-20 |
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