Method and apparatus for manufacturing a bent product

Abstract

A bent product having a three-dimensionally bent portion intermittently or continuously in the lengthwise direction is manufactured by supporting a steel pipe at a first position A while feeding it in the lengthwise direction, locally heating the steel pipe being fed at a second position B, cooling the heated portion of the steel pipe at a third position C, and varying the position of a gripping means, which grips the steel pipe in a region D downstream of the third position C, in a three-dimensional direction including the feed direction of the steel pipe in a workspace including a space on the upstream side of the third position C in the feed direction of the steel pipe to impart a bending moment to the heated portion of the steel pipe.

Claims

1. A method of manufacturing a bent product from an elongated metal material having an axis and having a closed cross-sectional shape, the method comprising: at a first position along the axis of the metal material, supporting the metal material while the metal material is being fed in the axial direction of the metal material, the feeding of the metal material defining an upstream direction and a downstream direction; at a second position which is downstream of the first position along the axis of the metal material, heating a portion of the metal material; at a third position downstream of the second position along the axis of the metal material, cooling the heated portion of the metal material; at a fourth position downstream of the third position along the axis of the metal material, gripping the metal material using a chucking mechanism, the chucking mechanism being fixed to both the metal material and a free end of an articulated robot having six axes; and varying a location of the fourth position using the chucking mechanism and articulated robot, the fourth location varying in a three-dimensional workspace relative to at least one of the first position, the second position, and the third position in the three-dimensional workspace to impart a bending moment to the heated portion of the metal material; thereby manufacturing a bent product which has a three-dimensionally bent portion intermittently or continuously in the axial direction of the product; wherein the varying of the location of the fourth position in the three-dimensional workspace causes the axis of the three-dimensionally bent product to be not confined to a plane but to include an out-of-plane component.

2. A method of manufacturing a bent product as set forth in claim 1 wherein the bent product has at least two bent portions in the lengthwise direction of different radius of curvature.

3. A method of manufacturing a bent product as set forth in claim 1 wherein the metal material has a cross-sectional shape which is selected from a circle, a rectangle, an ellipse, an oblong, a polygon, a combination of a polygon and a circle, and a combination of a polygon and an ellipse.

4. A method of manufacturing a bent product as set forth in claim 1 wherein the chucking mechanism grips the metal material by being inserted into the leading end of the metal material.

5. A method of manufacturing a bent product as set forth in claim 1 wherein the chucking mechanism grips the metal material by contacting the outer surface of the leading end of the metal material.

6. A method of manufacturing a bent product as set forth in claim 1 wherein the metal material being fed is locally quenched by being locally heated at the second position to a temperature at which quenching is possible and being cooled at the third position.

7. A method of manufacturing a bent product as set forth in claim 1 wherein the bent product intermittently or continuously has a quenched portion in at least one of the lengthwise direction and the circumferential direction in a cross section crossing the lengthwise direction.

Description

BRIEF EXPLANATION OF THE DRAWINGS

(1) FIG. 1 is an explanatory view schematically showing in simplified form the structure of one example of a manufacturing apparatus for a bent product according to the present invention.

(2) FIG. 2 is an explanatory view schematically showing the structure of a manufacturing apparatus using an articulated robot.

(3) FIG. 3 is an explanatory view showing this articulated robot.

(4) FIG. 4 is an explanatory view schematically showing a bending apparatus according to the invention disclosed by the present applicant in Patent Document 1.

(5) FIG. 5 is an explanatory view schematically showing a bending apparatus according to the invention disclosed by the present applicant in Patent Document 1.

(6) FIG. 6 is an explanatory view schematically showing a working method disclosed in Patent Document 1.

LIST OF SYMBOLS IN THE DRAWINGS

(7) 0 bending apparatus 1 metal material 2 support means 3 feed device 4 movable roller die 4a roll pair 5 high frequency heating coil 6 water cooling device 10, 10-1 manufacturing apparatus 11 feed device 12 gripping portion 13 support device 14 high frequency heating device 15 gripping means 16 cooling device 17 body 18 first base 19 second base 20 moving mechanism

EMBODIMENTS OF THE INVENTION

(8) Below, a best mode for carrying out the present invention will be explained in detail while referring to the attached drawings.

(9) FIG. 1 is an explanatory view schematically showing in simplified form the structure of one example of a manufacturing apparatus 10 for a bent product according to the present invention.

(10) As shown in this figure, this manufacturing apparatus 10 comprises a feed device 11, a support device 13, a high frequency heating device 14, a cooling device 16, and a gripping means 15, which are individually explained below.

(11) [Feed Device 11]

(12) The feed device 11 feeds an elongated metal material 1 having a closed cross-sectional shape in its lengthwise direction.

(13) An example of the feed device 11 is of a type using an electrically powered servo cylinder. The feed device 11 need not be limited to a specific type, and any known device of this type of feed device such as a type using a ball screw or a type using a timing belt or a chain or the like can be used well.

(14) In the invention shown in FIG. 1, an example is given of the case in which the metal material 1 is a steel pipe having a circular transverse cross-sectional to shape, but the present invention is not limited to the case in which the metal material 1 is a steel pipe, and the present invention can be applied to a hollow metal material having a transverse cross-sectional shape which is rectangular, elliptical, oval, polygonal, a combination of a polygon and a circle, or a combination of a polygon and an ellipse in the same manner as for a steel pipe.

(15) The metal material 1 is held by a holding member 12 and is fed in the axial direction (lengthwise direction) at a predetermined speed by the feed device 11. The holding member 12 serves the function of holding the metal material 1 so as to carry out feeding of the metal material 1, but it may be omitted when there is a support device 13.

(16) [Support Device 13]

(17) The support device 13 supports the metal material 1 which is fed in the axial direction by the feed device 11 at a first position A while enabling the metal material 1 to move.

(18) An example of this type of support device 13 is a fixed guide, but it is not necessary to limit it to a specific type. A support device 13 can also use one or more pairs of opposing driven rolls, and any known support device of this type can be used well.

(19) The metal material 1 is fed in the axial direction while passing through the installation position A of the support device 13. The support device 13 may be replaced by the holding member 12 shown in FIG. 1.

(20) [High Frequency Heating Device 14]

(21) The high frequency heating device 14 locally heats the fed metal material 1 at a second position B which is positioned downstream from the first position A in the feed direction of the fed metal material 1.

(22) A coil which can perform high frequency induction heating of the metal material 1 can be used as the high frequency heating device 14. The high frequency heating device 14 can be any known type of high frequency heating device.

(23) By varying the distance of the heating coil of the high frequency heating device 14 from the metal material 1 in a direction parallel to the direction perpendicular to the axial direction of the metal material 1, a portion of the metal to material 1 being fed can be nonuniformly heated in its circumferential direction.

(24) By also using at least one preheating means for the metal material 1 disposed on the upstream side of the high frequency heating device 14, the metal material 1 can be heated a plurality of times.

(25) By also using at least one preheating means for the metal material 1 disposed on the upstream side of the high frequency heating device 14, it is possible to nonuniformly heat a portion of the metal material 1 being fed in the circumferential direction.

(26) The metal material 1 is locally rapidly heated by the high frequency heating device 14.

(27) [Cooling Device 16]

(28) At a third position C downstream of the second position B in the feed direction of the metal material 1, the cooling device 16 cools the portion of the metal material 1 being fed which was heated at the second position B. In the area between position B and position C, the metal material 1 is heated to a high temperature and is in a state in which its deformation resistance is greatly decreased.

(29) Any device which can provide a desired cooling rate can be used as the cooling device 16, and it is not necessary to limit it to a specific type of cooling device. As a typical example, a water cooling device which cools the metal material 1 by spraying cooling water at a predetermined position on the outer peripheral surface of the metal material 1 is used.

(30) As shown in FIG. 1, the cooling water is sprayed at an angle with respect to the direction in which the metal material 1 is being fed. The region in the axial direction in which the metal material 1 is heated can be adjusted by varying the distance of the cooling means from the metal material 1 in a direction parallel to a direction perpendicular to the axial direction of the metal material 1.

(31) The portion of the metal material 1 which was heated by the high frequency heating device 14 is locally rapidly cooled by the cooling device 16.

(32) [Gripping Means 15]

(33) The gripping means 15 is intended to impart a bending moment to the portion of the metal material 1 which was heated by the high frequency heating device 14 by moving in a three-dimensional direction including at least the feed direction of the metal material 1 within a workspace including a space on the upstream side of the third position C in the feed direction of the metal material 1 while gripping the metal material 1 being fed in a region D downstream of the third position C in the feed direction of the metal material 1. A chuck mechanism can typically be used as the gripping means.

(34) In the present invention, it is of course possible to two-dimensionally move a gripping means which can move three-dimensionally. In this manner, bending in which the bending direction varies two-dimensionally can be carried out to manufacture a bent product, such as a bent product in which the bending direction of a metal material varies two-dimensionally as in S-bending.

(35) The workspace is a three-dimensional space defined by the following Equations 1, 2, and 3.
x<0 and (y=0 or y≧0.5D) and 0≦θ<360°  (1)
x.sup.2+(y−Rmin).sup.2≧Rmin.sup.2  (2)
x.sup.2+(y+Rmin).sup.2≧Rmin.sup.2−(0.5D−Rmin).sup.2+(0.5D+Rmin).sup.2  (3)

(36) In Equations 1-3, D means the smallest outer dimension (mm) of the bent product, Rmin means the smallest radius of curvature (mm) of the bent product, and x, y, and θ are the cylindrical coordinates having its origin at the second position in which the x-direction is the instantaneous feed direction of the metal material, the y-direction is the direction perpendicular to the x-direction in a horizontal plane, and θ is the angle in the circumferential direction.

(37) The gripping means 15 carries out bending of the metal material 1 by three-dimensionally moving in this workspace to manufacture a bent product having a desired shape and intermittently or continuously having a bent portion in the lengthwise direction. The workspace is a space based on a technical idea, so when the operation of a manufacturing line or the like is fixed, a physical object which may optionally be installed may exist in this space.

(38) The gripping means 15 has a body 17 having a cylindrical outer shape and a moving mechanism 20 on which the body 17 is mounted. The moving mechanism 20 is constituted by a second base 19 which is disposed so as to be able to move in the direction perpendicular to the feed direction of the metal material 1 (in the vertical direction in FIG. 1) and a second base 19 which is disposed so as to be able to move in the feed direction.

(39) The first base 18 and the second base 19 are both moved by a ball screw and a drive motor. This moving mechanism 20 makes the body 17 movable two-dimensionally in a horizontal plane.

(40) The body 17 is constituted by a hollow member having an inner peripheral surface with a shape which matches that of the outer peripheral surface of the metal material 1. The body 17 grips the metal material 1 by intimately contacting the outer surface of the leading end of the metal material 1.

(41) In contrast to the example shown in FIG. 1, the body 17 may be constituted by a tube having an outer peripheral surface with a shape matching that of the inner peripheral surface of the metal material 1. In this case, the body 17 can grip the metal material 1 by being inserted into the leading end of the metal material 1.

(42) Instead of being supported by the moving mechanism 20 shown in FIG. 1, the body 17 can be supported using an articulated robot having a joint which can rotate about at least one axis. FIG. 2 is an explanatory view schematically showing the structure of a manufacturing apparatus 10-1 using an articulated robot 21, and FIG. 3 is an explanatory view showing this articulated robot 21.

(43) By using this articulated robot 21, the body 17 can be easily supported so as to be able to move in a three-dimensional direction including at least the feed direction of the metal material 1.

(44) Next, the manufacture using this manufacturing apparatus 10 of a bent product either intermittently or continuously having in its lengthwise direction a bent portion which is bent three-dimensionally will be explained.

(45) First, an elongated metal material 1 having a closed cross-sectional shape is supported at a first position A by the support device 13 and is fed in its lengthwise direction by the feed device 11.

(46) Next, the following steps (a) to (c) are carried out continuously in accordance with the target shape of a product: (a) locally heating the metal material 1 being fed at a second position B downstream from the first position A in the feed direction of the metal material 1 by means of the high frequency heating device 14, (b) cooling the portion of the metal material which was heated at the second position B by the cooling device 16 at a third position C downstream of the second position B in the feed direction of the metal material 1, and (c) varying the position of the gripping means 15, which grips the metal material 1 in a region D downstream from the third position C in the feed direction of the metal material 1, in a three-dimensional direction including at least the feed direction of the metal material within a workspace including a space on the upstream side of the third position C in the feed direction of the metal material 1 to impart a bending moment to the heated portion of the metal material 1.

(47) As a result, a bent product intermittently or continuously having in its lengthwise direction a bent portion which is bent three-dimensionally and which is shaped by bending produced by the above-described bending moment is continuously manufactured.

(48) At this time, by locally heating the metal material 1 at the second position B to a temperature at which quenching is possible and cooling it at a predetermined cooling rate at the third position C, the heated portion of the metal material 1 can be quenched, whereby a bent product intermittently or continuously having a quenched portion at least in the lengthwise direction and/or in the circumferential direction in a cross section crossing the lengthwise direction can be manufactured.

(49) A bent product can be continuously manufactured by disposing the manufacturing apparatus 10 either

(50) (a) in a continuous manufacturing apparatus for a bent product which is incorporated in a seam welded pipe manufacturing line constituted by an uncoiler which continuously pays out a steel strip, a forming means which forms the paid out steel strip into a pipe having a predetermined cross-sectional shape, a welding means which welds the abutting side edges of the steel strip to form a continuous pipe, and a post-treatment means which cuts off the weld bead and if necessary performs post-annealing or sizing, the apparatus 10 being disposed on the exit side of the post-treatment means, or

(51) (b) in a continuous manufacturing apparatus for a bent product which is incorporated in a roll forming line constituted by an uncoiler which continuously pays out a steel strip and a shaping means which shapes the paid out steel strip into a predetermined cross-sectional shape, the apparatus 10 being disposed on the exit side of the shaping means.

(52) According to the present invention, even when manufacturing a bent product which requires a widely varying bent shape and which has a bending direction which varies three dimensionally and even when it is necessary to perform bending of a metal material having a high strength, it is possible to efficiently and inexpensively manufacture a bent product having a high strength, good shape retention, a predetermined hardness distribution, a desired dimensional accuracy, and a bending radius of curvature which is not constant in the lengthwise direction but which has at least two bent portions of different radius of curvature in the lengthwise direction.

(53) Moreover, a metal material is subjected to bending while being gripped by a gripping means which is supported by an articulated robot or the like. Therefore, a large bending angle can be guaranteed, deterioration in the surface condition and occurrence of surface scratches can be suppressed, bending accuracy can be guaranteed, and bending with excellent operating efficiency is possible.

(54) Accordingly, the present invention can be widely employed, for example, as a bending technique for bent products to be used in automobiles, which is being developed to a higher level.