JP2011020149A - Method for manufacturing formed body having closed section shape including dissimilar u-shaped part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily bend a closed section with excellent accuracy when forming the closed section by bending an end of a dissimilar U-shaped part, and to manufacture a formed body having the closed section as one component out of one material. <P>SOLUTION: The method for manufacturing a formed body includes: a preparing step of preparing a formed body having a dissimilar U-shaped part with its bottom surface showing a recessed curved surface which is bend in an inwardly recessed manner along its longitudinal direction; an end bending step of forming a bent end by bending an end of a side surface part by using a core device 7; and a joining step of forming a closed section shape by joining bent ends with each other. The core device 7 has a core body 71 having an edge part 715 on a boundary corner part between side abutting surfaces 712, 713 and an end abutting surface 717, and a side surface part expansion-supporting mechanism part 73 for expanding a pair of right and left side face parts in the separating direction from each other after forming the bent ends. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has a modified U-shaped portion having a concave curved surface that is bent so that the bottom surface portion is recessed inward along the longitudinal direction, and has a closed cross-sectional shape including the deformed U-shaped portion. The present invention relates to a method for manufacturing a body.

  For example, a frame component incorporated in a seat back of a vehicle seat has a rectangular cross section, and two surfaces corresponding to the long side portion (hereinafter, referred to as a long side surface as appropriate) are substantially flat. Although there is a surface, there is a component having a shape in which a surface corresponding to the short side portion (hereinafter, referred to as a short side surface as appropriate) is curved along the shape of the seat back. One short side surface is curved to be convex outward along the longitudinal direction, and the other short side surface is convex inward along the longitudinal direction (indented inward) It is curved.

  Such a specially shaped member is formed by molding two parts with the short side surfaces standing upright from the curved side ends of the substantially flat long side surface, and welding these short side surfaces together. It was manufactured by making the cross section rectangular. In addition, as a shaping | molding method so far, such as a flange product etc. which has a curved ridgeline, there exist a thing of patent documents 1-3.

Japanese Patent Publication No. 6-61581 JP 2002-1445 A Japanese Patent No. 2855492

In the method of manufacturing a molded body having a special shape by making two parts and then joining them, the number of manufacturing steps is large and the material yield is not good. Furthermore, since the welding is performed at two locations in the finished product, it is disadvantageous in strength, and it is difficult to reduce the weight by increasing the weight of the welded portion.
In order to solve such a problem, it is necessary to find a method that can be manufactured with one component from one material to the end and that can reduce the number of parts to be welded.

  In order to establish a method of manufacturing from a single material, a molded body having a U-shaped cross section with the short side surface as the bottom surface is prepared, and then a U-shaped opening end portion (a pair of left and right side surfaces) It is necessary to form a closed end portion by bending the end portions on the opposite side of the bottom surface portion of the portion in a direction approaching each other to form a bent end portion and joining them.

  In order to perform the bending process of the bent end portion with high accuracy, it is effective to perform the bending process along with the cored bar applied thereto. However, as described above, when the bottom surface of the U-shaped portion is curved inward, the cored bar cannot be pulled out from the opening of the closed cross section after the bending process if the cored bar conforming to the shape is used. . Therefore, a method using a simple mandrel cannot be adopted.

  The present invention has been made in view of such a conventional problem, and has a closed cross-section by bending an end portion of a deformed U-shaped portion having a concave curved surface whose bottom surface is bent inward along the longitudinal direction. It is an object of the present invention to provide a method that can be easily and accurately bent when forming a molded body having a closed cross section and can be manufactured from a single material at a high yield as a single component.

The present invention presents a U-shaped cross section having a bottom surface portion and a pair of left and right side portions erected from both sides of the bottom surface portion, and a concave curved surface in which the bottom surface portion is bent inward along the longitudinal direction. A preparation step for preparing a molded body having a deformed U-shaped portion formed by
An end bending step of forming a bent end portion by bending the end portions on the opposite side of the bottom surface portion in the pair of left and right side portions using a mandrel device,
Joining the bent ends together to form a closed cross-sectional shape,
The cored bar device used in the end bending step contacts the bottom contact surface that contacts the bottom surface portion of the molded body, the pair of left and right side surface contact surfaces that contact the side surface portion, and the bent end portion. A cored bar body having an edge contact surface and a edge portion at a boundary corner between the side contact surface and the end contact surface;
A side surface portion expansion assist mechanism for expanding the pair of left and right side surface portions in a direction away from each other after forming the bent end portion;
The side surface portion expansion assist mechanism portion includes a pair of left and right rollers provided so as to be able to protrude and retract from the pair of left and right side surface contact surfaces of the metal core body, and rotatably supporting the rollers. A roller support portion that urges to protrude away from the side contact surface;
In the end bending step, the cored bar device is inserted into the deformed U-shaped part, the bottom contact surface is brought into contact with the bottom surface part,
Next, a pressing force is applied to the pair of left and right side portions from the outside, the side portions are pressed against the side surface contact surface of the core metal device, and the roller is immersed in the side surface contact surface,
Next, the end portions of the side surface portions are bent along the edge portions to form a pair of left and right bent ends,
Next, by releasing the pressing force to the side surface portion, the side surface portion is expanded in a direction away from each other by the urging force of the roller support portion, and a gap is provided between the pair of bent end portions,
Next, the cored bar device and the molded body are moved relative to each other while the roller is rotated, and the cored bar apparatus is extracted from the gap. (Claim 1).

In this invention, it has the preparatory process which prepares the molded object which has the said odd-shaped U-shaped part, the said edge part bending process, and the said joining process. The point to be noted here is that the core metal device used in the end bending step has the special configuration described above.
That is, the cored bar device has the cored bar body and a side surface part expansion assisting mechanism unit incorporated therein. The side surface portion expansion assist mechanism portion includes a pair of left and right rollers and a roller support portion that rotatably supports and urges these rollers.

  In the end bending step, the cored bar device is inserted into the deformed U-shaped portion, and the bottom contact surface is brought into contact with the bottom surface portion. Thereby, the edge part of the core metal body is arranged at a position corresponding to the bending start point of the bent end part. At this time, the pair of left and right side portions of the odd-shaped U-shaped portion is expanded in a direction away from each other by the roller of the cored bar device.

  Next, a pressing force is applied to the pair of left and right side portions from the outside. The application of the pressing force can be easily performed by pressing a pressing jig or the like with an actuator such as a hydraulic pressure. Then, by applying the pressing force, the side surface portion is pressed against the side surface contact surface of the core metal device, and the roller is immersed in the side surface contact surface.

Next, while applying a pressing force to the side surface portion, the end portion of the side surface portion is bent along the edge portion to form a pair of left and right bent ends. The bending process can be easily performed by pressing a bending jig against the side surface portion.
Next, the pressing force to the side surface portion is released. As a result, the roller protrudes from the core metal body by the urging force of the roller support portion, and the side portions are expanded in a direction away from each other. A gap is provided between the pair of bent ends. Thereby, the path | route which passes through between the said bending | flexion edge parts from the inside of a molded object, and is extracted is ensured.

Next, the cored bar device and the molded body are relatively moved while rotating the roller, and the cored bar apparatus is extracted from the gap. At this time, since the roller can rotate, the relative movement between the two is assisted, and a smooth extraction operation can be performed.
After extracting the cored bar device, the side surface portion of the molded body returns to its original position, so that the joining process can be easily performed, and a molded body having a closed cross-sectional shape including a deformed U-shaped portion. Can be completed.

  Thus, in the present invention, by using a special cored bar device in which the roller and the roller support part are incorporated in the cored bar body, when bending the end of the odd-shaped U-shaped part to form a closed cross section, Bending can be easily and accurately performed, and a molded body having the above-described closed cross section can be manufactured from a single material with a high yield with one component.

The top view which shows the blank material in Example 1. FIG. In Example 1, (a) a state in which the blank material is disposed between the preliminary processing die and the preliminary processing punch, and (b) immediately after the blank material is sandwiched between the preliminary processing die and the preliminary processing punch and bent. Explanatory drawing which shows the state of. 2 is a perspective view of intermediate molding in Example 1. FIG. Explanatory drawing which shows the structure of the metal mold | die provided with the punch, cushion, and die in Example 1. FIG. In Example 1, (a) The state which pinched | interposed the blank material between the punch and the cushion, (b) The explanatory view which shows the state which made the whole bottom face part and only a part of side part pass between die blade parts. The perspective view which shows the preforming body in the state which stood up the odd-shaped U-shaped part in Example 1. FIG. The perspective view which shows the preforming body in the state which laid the deformed U-shaped part in Example 1. FIG. Sectional drawing of the preform in Example 1 (AA arrow directional cross-sectional view of FIG. 6). FIG. 3 is an explanatory diagram illustrating a configuration of a cored bar device according to the first embodiment. Explanatory drawing which shows the side part expansion assistance mechanism part of the metal core apparatus in Example 1. FIG. Explanatory drawing which shows the state which inserted the metal core apparatus in Example 1 in the odd-shaped U-shaped part, and bent-shaped the bending end part. FIG. 3 is an explanatory diagram illustrating a state in which a side surface portion is expanded by a biasing force of a roller support portion and a gap is provided between bent end portions in the first embodiment. FIG. 3 is an explanatory diagram illustrating an initial stage in which the cored bar device and the molded body are relatively moved while rotating the roller in the first embodiment. Explanatory drawing which shows the state in which the bending edge part front-end | tip is located in the recessed part of a roller during the relative movement of the metal core apparatus and a molded object in Example 1. FIG. Explanatory drawing which shows the state in which the front-end | tip of a bending end got over a roller during the relative movement of the metal core apparatus and a molded object in Example 1. FIG. Explanatory drawing which shows the state in which the core metal apparatus fell out from the inside of the closed cross section of the molded object in Example 1. FIG. FIG. 3 is a perspective view showing a molded body in Example 1. Sectional drawing of the molded object in Example 1 (BB sectional view taken on the line in FIG. 17). Explanatory drawing which shows the structure of the metal core apparatus in the reference example 1. FIG. Explanatory drawing which shows the state which is implementing the edge part bending process in the reference example 1. FIG. Explanatory drawing which shows the bending process which bends the side part of a molded object in the reference example 1 in the state which becomes a substantially right angle with a bottom face part.

In the manufacturing method of the present invention, the roller in the side surface portion expansion assist mechanism portion has a tooth profile shape in which a concave portion and a convex portion are provided on an outer peripheral surface thereof, and the core metal after the bent end portion is formed. It is preferable that the roller is configured to rotate in a state where the tip of the bent end portion is positioned in the concave portion of the roller during relative movement between the apparatus and the molded body.
In this case, since the tip of the bent end enters the concave portion of the roller, the width of the gap necessary for exiting the gap can be minimized, and the core metal apparatus can be more easily pulled out. It can be smooth.

  The roller may be rotated as long as it can freely rotate, but may be driven actively.

Further, the roller support part in the side surface part expansion assist mechanism part has a pipe-like outer shaft part and an inner shaft part arranged coaxially inside the outer shaft part and fixes one end of both of them. And a torsion bar
A first arm fixed to the other end of the outer shaft portion and rotatably supporting one of the rollers;
A second arm fixed to the other end of the inner shaft portion and rotatably supporting the other roller;
A line connecting a first fulcrum, which is the rotation center of the roller provided on the first arm, and a second fulcrum, which is the rotation center of the roller provided on the second arm, with the shaft center of the torsion bar, respectively. It is configured so that the torsional force of the torsion bar acts when changing the internal angle,
The torsional force of the torsion bar expands the side surface portions in a direction away from each other via the roller when the pressing force to the side surface portion is released after the bent end portion is formed in the end portion bending step. It is preferable that the gap between the pair of bent end portions obtained as described above is adjusted to a force that can be larger than the distance between the pair of edge portions of the core metal body.
In this case, by using the torsion bar, it is possible to easily apply a biasing force to the roller without providing a separate spring or the like. In addition, by adopting the torsion bar, the entire side surface portion expansion assist mechanism portion becomes compact, and it is easy to incorporate it into the core metal body.

Moreover, it is preferable that two or more sets of the side surface portion expansion assist mechanism portions are built in the core metal body.
In this case, it is possible to perform the side surface portion expanding operation stably by the plurality of side surface portion expansion assist mechanism portions.

Moreover, it is preferable that the longitudinal direction both ends of the said metal core main body are provided with the slide block for positioning so as to face the both ends in the longitudinal direction, when it inserts in the inside of the said odd-shaped U-shaped part ( Claim 5).
In this case, due to the presence of the slide block, the drawing operation can be performed while stably maintaining the relative positional relationship between the cored bar device and the molded body.

Moreover, it is preferable that the angle formed by the side surface contact surface and the end surface contact surface sandwiching the edge portion is less than 90 ° (Claim 6).
That is, after the bent end portion is bent, the bending angle can be reduced to about 90 ° by a so-called springback. Specifically, although it depends on the material of the molded body, for example, in the case of a so-called 100 kg class high-tensile material, the angle of the spring back is assumed to be 6 ° to 10 °, and the edge portion in the core metal body is sandwiched. The angle formed between the side contact surface and the end contact surface is preferably in the range of 80 ° to 94 °.

Further, in producing a molded body having the odd-shaped U-shaped portion prepared in the preparation step,
Prepare a flat blank,
The blank material is bent starting from a linear boundary line between the bottom surface portion and the side surface portion, and the bottom surface portion is a flat surface and the angle formed between the side surface portions on both sides thereof is Both form an intermediate molded body that is obtuse,
Corresponding to the punch having a concave clamping surface corresponding to the desired inner surface shape of the concave curved surface in the bottom surface portion, the cushion having the convex clamping surface corresponding to the outer surface shape of the concave curved surface, and the outer width dimension of the bottom surface portion Using a die having a die having a die blade portion arranged at an interval of the punch, the concave sandwiching surface of the punch disposed inside the intermediate molded body and the cushion disposed opposite thereto The bottom surface portion is sandwiched by the convex sandwiching surface to deform the bottom surface portion into the concave curved surface,
Then, while maintaining the clamping state between the punch and the cushion, the entire bottom surface portion is inserted between the die blade portions, and when only a part of the side surface portion passes through the die blade portion, By stopping the relative movement between the bottom surface portion and the die, a part of the side surface portion that does not pass between the die blade portions becomes a bulging portion that bulges outward, and its periphery is It is preferable that the deformed U-shaped portion is formed so as to be a planar side surface portion erected substantially perpendicular to the bottom surface portion.

  In this case, as described above, the intermediate molded body is once formed using a flat blank material. Since this intermediate molded body has a shape in which the bottom surface portion is a flat surface and the angle between the side surface portions on both sides thereof is an obtuse angle, it can be easily obtained by simple bending.

  Next, the intermediate molded body is processed by the mold. First, the bottom surface portion is sandwiched by the concave sandwiching surface of the punch and the convex sandwiching surface of the cushion to deform the bottom surface portion into the concave curved surface. When the deformation of the bottom surface portion is executed, a stronger tensile stress is applied to the side surface portions on both sides of the bottom surface portion as the distance from the bottom surface portion increases. Therefore, it deform | transforms so that it may open between side parts, and a part of side part will swell and will be in the state which is not flat. In addition, since the deformation | transformation at this time also has the ratio of elastic deformation, if the clamping state of the said punch and the said cushion is cancelled | released, it will approximate the shape of the original intermediate molded object. Therefore, the next step is performed while maintaining the sandwiched state between the punch and the cushion.

Specifically, it is inserted between the die blades with the entire bottom surface being at the top while maintaining the clamping state between the punch and the cushion. That is, the boundary line portion between the bottom surface portion and the side surface portion is all passed between the die blade portions. Thereby, the corner | angular part between the said bottom face part and the said side part becomes a substantially right angle.
And the relative advance with respect to the die | dye of the said intermediate molded object is stopped when only a part of said side part passes the said die blade part after the said whole bottom face part passed the die blade part. And it avoids that the whole side part passes a die blade part. As a result, the bottom surface portion and the pair of left and right side surfaces standing from both sides thereof have a U-shaped cross section, and the bottom surface portion exhibits a concave curved surface that is bent inward along the longitudinal direction. A molded body having a deformed U-shaped portion can be obtained.

  The odd-shaped U-shaped part of the molded body thus obtained is inevitably the bulging part partially bulging outward, not the entire side part. Due to the presence of the bulging portion, the rigidity of the side surface portion can be increased. On the other hand, the above manufacturing method cannot be applied to products in which the shape of the bulging portion is not allowed.

In addition, the bulging portion formed on the side surface portion is formed with a very smooth natural shape change in the surrounding flat side surface portion, and the appearance characteristics such as unnecessary wrinkles are reduced. Does not occur. Rather, it can be regarded as a shape in which the above-mentioned bulging portion is positively provided, and an excellent appearance characteristic that brings out even a novel design can be obtained.
On the other hand, when the intermediate formed body is passed between the die blade portions, when the entire side surface portion is passed, the so-called springback phenomenon occurs after the entire shape becomes substantially flat and is taken out between the dies. As a result, a phenomenon occurs in which the distance between both side surfaces increases as the distance from the bottom surface increases. Furthermore, wrinkle-like appearance defects remain on the side portions, making it difficult to produce a product.

  Thus, by producing a molded body having the above-mentioned deformed U-shaped portion by the above method, the deformed shape formed as a concave curved surface curved so that the bottom surface portion is recessed inward along the longitudinal direction as described above. A molded body having a letter-shaped portion can be easily manufactured in a state excellent in appearance characteristics, and can be manufactured at a high yield as a single component from a single material. And since the obtained odd-shaped U-shaped portion is obtained by integrally connecting the bottom surface portion and the side surface portions on both sides thereof, at least the bottom surface portion does not need to be joined by welding. Therefore, the weight can be reduced accordingly. Furthermore, the plate | board thickness of raw material itself can also be reduced by the strength improvement effect by the rigidity improvement of the said side part, and the necessity of a welding part, and the weight reduction effect by this can also be acquired.

Moreover, it is preferable that the said die blade part of the said die | dye is provided on two parallel straight lines. In this case, the side surface portion in the vicinity of both ends in the longitudinal direction of the curved bottom portion passes through the die blade portion to a relatively deep position, and the vicinity of the central portion is formed to pass the die blade portion only to a relatively shallow position. can do. Thereby, it becomes possible to set the formation position of the said bulging part from the center.
It is also possible to adjust the position and shape of the bulging portion by providing the die blade portion of the die in a curved shape.

  The intermediate molded body preferably has an angle formed by the bottom surface portion and the side surface portion in a range of 135 ° ± 10 °. In this case, it is possible to facilitate deformation when the bottom portion of the intermediate molded body is sandwiched between the punch and the cushion. On the other hand, when the angle formed between the bottom surface portion and the side surface portion is less than 125 ° or exceeding 145 °, subsequent molding is possible, but the deformation at the time of clamping may not be stabilized.

  Further, the bending process for forming the intermediate molded body corresponds to a pre-processed die having a valley-shaped molding surface corresponding to the bent shape of the bottom surface part and the side surface part of the intermediate molded body, and the bent shape. It is preferable to carry out by sandwiching the blank material between them using a pre-processed punch having a mountain-shaped forming surface. In this case, it is possible to easily form the intermediate molded body simply by sandwiching the blank material with the preliminary processing die and the preliminary processing punch.

  Moreover, it is preferable that the said molded object is a frame component incorporated in the seat back of a vehicle seat. The molded body can be increased in strength and weight, and is optimal as a frame component incorporated in a seat back of a vehicle seat.

Example 1
The manufacturing method of the molded object which has a closed cross-sectional shape containing the odd-shaped U-shaped part concerning the Example of this invention is demonstrated using figures.
As shown in FIG. 17, the molded body 1 manufactured in this example has a U-shaped cross section having a bottom surface portion 21 and a pair of left and right side surface portions 22 and 23 erected from both sides of the bottom surface portion 21. The bottom surface portion 21 has a deformed U-shaped portion 20 having a concave curved surface bent so as to be recessed inward along the longitudinal direction. Further, the molded body 1 is formed by joining the bent end portions 227 and 237 obtained by bending the end portions on the opposite side of the bottom surface portion 21 of the pair of left and right side surface portions 22 and 23 to each other. A closed cross-sectional shape including the character-shaped portion 20 is formed.
As shown in FIGS. 17 and 18, the side surface portions 22 and 23 of the molded body 1 have bulging portions 225 and 235 that bulge outward, and the bulging portions 225 and 235 have the bottom surface around the bulging portions 225 and 235. It has planar side portions 226 and 236 that are erected substantially perpendicular to the portion 21.

In manufacturing the molded body 1, a preparation step for preparing a molded body having the deformed U-shaped portion 20 (this state is appropriately referred to as a preformed body 16) and the bent end portions 227 and 237 are formed. An end bending step and a joining step of joining the bent end portions 227 and 237 together to form a closed cross-sectional shape including the deformed U-shaped portion 20.
These steps will be described in order.

In carrying out the preparation step, first, as shown in FIG. 1, a blank 10 made of a flat steel plate is prepared. In this example, the width dimension of the blank material 10 is changed to correspond to the width dimension of the side surface portions 22 and 23, and a substantially trapezoidal shape is obtained. Further, the blank 10 was provided with a plurality of through holes 19 for weight reduction in advance.
Next, as shown in FIGS. 2 and 3, an intermediate molded body 15 is formed using the blank material 10.

  In this example, as shown in FIG. 2, bending is performed using a pair of preforming dies 4. The preforming die 4 includes a preforming die 41 having a valley-shaped molding surface 410 corresponding to the bent shape of the bottom surface portion 21 and the side surface portions 22 and 23 of the intermediate molded body 15 (FIG. 3) to be obtained, It comprises a pre-processed punch 42 having a mountain-shaped forming surface 420 corresponding to the bent shape.

  More specifically, the preliminary processing die 41 has the above-described valley-shaped molding surface 410 that is recessed downward from the flat upper surface 411, and the valley-shaped molding surface 410 has a cushion portion 413 having a flat receiving surface 412 on the upper surface. And a pair of tapered die surfaces 414 that are inclined so that a spatial distance between the two becomes wider toward the upper side. The cushion portion 413 is disposed so as to be retractable in accordance with the pressing force from the preliminary machining punch 42.

  The mountain-shaped forming surface 420 of the pre-processed punch 42 has a pair of tapered punch surfaces 424 that are inclined to the left and right of the flat front end surface 421 so that the thickness dimension between the two becomes wider as it approaches the upper side. The pair of corners 425 between the tip surface 421 and the taper punch surface 424 are the boundary line a between the bottom surface portion 21 and the side surface portions 22 and 23 of the intermediate molded body 15 and the molded body 1 to be obtained. 1 and FIG. 3). Further, the taper die surface 414 and the taper punch surface 424 of the preliminary machining die 41 are inclined according to the formation angle of the side surface portions 21 and 22 of the intermediate molded body 15 to be obtained. In this example, the inclination angle α is 45 ° with respect to the relative movement direction of the preliminary machining punch 42, that is, the angle between the bottom surface portion 21 and the side surface portions 22, 23 (inclination angle α). The angle was set to 135 °.

  Using such a preforming die 4, first, as shown in FIG. 2A, the blank material 10 is placed on the upper surface 411 of the preforming die 41. At this time, the position that becomes the boundary line a (FIGS. 1 and 3) between the bottom surface portion 21 and the side surface portions 22 and 23 is matched with the position facing the corner portion 425 of the preliminary machining punch 42.

  Next, as shown in FIG. 2 (b), the preliminary processing punch 42 is relatively advanced toward the preliminary processing die 41, and the mountain-shaped forming surface 420 is inserted into the valley-shaped forming surface 410. Thereby, the blank material 10 is bent with the linear boundary line a between the bottom surface portion 21 and the side surface portions 22 and 23 as a starting point. As shown in FIG. 3, an intermediate molded body 15 is obtained in which the bottom surface portion 21 is a flat surface and the angle β between the side surface portions 22 and 23 on both sides thereof is an obtuse angle of approximately 135 °. .

  Next, as shown in FIG. 4, a punch 51 having a concave sandwiching surface 510 corresponding to the desired inner surface shape of the concave curved surface in the bottom surface portion 21 and a convex sandwiching surface 520 corresponding to the outer surface shape of the concave curved surface. Processing is performed using the mold 5 including the cushion 52 having the die 52 and the die 53 having the die blade portion 530 arranged at an interval corresponding to the outer width dimension of the bottom surface portion 21.

  The punch 51 has an insertion part 511 having a thickness corresponding to the inner dimension of the side parts 21 and 22 of the molded body 1 to be obtained, and the concave sandwiching surface 510 is provided at the tip thereof. The angle γ formed between the side surface 512 of the insertion portion 511 and the concave sandwiching surface 510 is a right angle (90 °).

The cushion 52 has the convex sandwiching surface 520 on the upper end surface facing the concave sandwiching surface 510 of the insertion portion 511 of the punch 51.
The die 53 includes a pair of left and right die blade portions 530, and the cushion 52 is disposed therebetween. The die blade portion 530 is set so that the cross-sectional shape thereof is an arc shape. In addition, by making the upper surface 531 of the die 53 a flat surface, the shape along the longitudinal direction of the die blade portion 530 was provided on two parallel straight lines.
The cushion 52 is arranged so that it can be raised and lowered in a state in which the convex clamping surface 520 protrudes above the die 53 in the initial state.

As shown in FIG. 5 (a), using the mold 5, the concave sandwiching surface 510 of the punch 51 disposed inside the intermediate molded body 15 and the convex sandwiching surface 520 of the cushion 52 disposed opposite thereto are used. The bottom surface portion 21 is sandwiched to deform the bottom surface portion 21 into a concave curved surface.
When the deformation of the bottom surface portion 21 is executed, a stronger tensile stress is applied to the side surface portions 22 and 23 on both sides in the longitudinal direction as the distance from the bottom surface portion 21 increases. Therefore, as shown in the figure, the side surface portions 22 and 23 are deformed so as to be opened, and a part (b portion) of the side surface portions 22 and 23 swells and is not flat. In addition, since the deformation | transformation at this time also has the ratio of elastic deformation, if the clamping state of the said punch 51 and the cushion 52 is cancelled | released, the shape of the original intermediate molded object 15 will be approached. Therefore, the next step is performed while maintaining the sandwiched state between the punch 51 and the cushion 52.

  That is, as shown in FIG. 5 (b), the entire bottom surface 21 is inserted between the die blades 530 while maintaining the clamping state between the punch 51 and the cushion 52. And the part of the boundary line a (FIG. 3) between the bottom face part 21 and the side face parts 22 and 23 passes between the die blade parts 530. Thereby, the corner | angular part between the bottom face part 21 and the side part 22 and 23 becomes a substantially right angle.

  Further, as shown in the figure, relative advancement of the intermediate molded body 15 with respect to the die 53 is such that after the entire bottom surface portion 21 passes through the die blade portion 530, only a part of the side surface portions 22 and 23 is the die blade portion 530. Is stopped at the time of passing, so that the entire side portions 22 and 23 do not pass the die blade portion 530. Thereby, as shown in FIGS. 6 to 8, the bottom surface portion 21 and the pair of left and right side surface portions 22 and 23 erected from both sides thereof have a U-shaped cross section, and the bottom surface portion 21 extends along the longitudinal direction. Thus, a preform 16 having a deformed U-shaped portion 20 having a concave curved surface bent so as to be recessed inward is obtained. The deformed U-shaped portion 20 of the obtained preform 16 is inevitably not the flat side surfaces 22 and 23 as a whole, but the bulged portions 225 and 235 partially bulged outward. It becomes. Due to the presence of the bulging portions 225 and 235, the rigidity of the side surface portions 22 and 23 can be increased as compared with the case where the entire side surface portion is flat.

  Further, the bulging portions 225 and 235 formed on the side surface portions 22 and 23 are formed by a very smooth natural shape change in the surrounding planar side surface portions 226 and 236, and unnecessary wrinkles and the like are formed. Features that reduce appearance characteristics do not occur. Rather, it can be regarded as a shape in which the bulging portions 225 and 235 are actively provided, and an excellent appearance characteristic having a novel design can be obtained. Further, the presence of the through hole 19 provided in the blank 10 in advance does not cause any problem in molding, and does not deteriorate the above-described excellent appearance characteristics.

Next, an end bending process is performed.
In the end bending process, a special mandrel apparatus 7 is used as shown in FIGS. The core metal device 7 includes a core metal main body 71 and a side surface portion expansion assisting mechanism portion 73 incorporated therein.
As shown in FIG. 9, the metal core body 71 includes a bottom contact surface 711 that contacts the bottom surface portion 21 of the molded body 1 (preliminary molded body 16) and a pair of left and right side surface contact surfaces that contact the side surface portions 22 and 23. 712 and 713 and end contact surfaces 717 that contact the bent ends 227 and 237. Further, the core metal main body 71 has an edge portion 715 at a boundary corner portion between the side surface contact surfaces 712 and 713 and the end portion contact surface 717. Further, the angle formed between the side contact surface 712 and the end contact surface 717 sandwiching the edge portion 715 is set to 82 ° in consideration of 8 ° for the spring back. The cored bar main body 71 is provided with through holes 718 at two locations, and two sets of side surface part expansion assisting mechanism parts 73 are incorporated.
In addition, slide blocks 719 are provided at both ends in the longitudinal direction of the cored bar 71 for positioning so as to face both ends in the longitudinal direction when inserted into the deformed U-shaped portion 20.

  As shown in FIG. 10, the side surface portion expansion assist mechanism portion 73 includes a pair of left and right rollers 741 and 742 that are provided so as to be able to protrude and retract from the pair of left and right side surface contact surfaces 712 and 713 of the metal core body 71, 741 and 742 are rotatably supported, and the rollers 741 and 742 are separated from each other and are urged so as to protrude from the side contact surfaces 712 and 713.

The rollers 741 and 742 in the side surface portion expansion assist mechanism portion 73 have a tooth profile shape in which a concave portion 751 and a convex portion 752 are provided on the outer peripheral surface thereof.
The roller support portion 76 includes a pipe-like outer shaft portion 761 and an inner shaft portion 762 that is coaxially disposed inside the outer shaft portion 761 and has a torsion bar 760 that is fixed at one end thereof. ing. A first arm 763 that rotatably supports one roller 741 is fixed to the other end of the outer shaft portion 761. A second arm 764 that supports the other roller 742 rotatably is fixed to the other end of the inner shaft portion 762.

The torsion bar 76 has a first fulcrum P1 that is the rotation center of the roller 741 provided on the first arm 763 and a second fulcrum P2 that is the rotation center of the roller 742 provided on the second arm 764, respectively. When the internal angle θ (see FIG. 12) of the line connected to the axis C is changed, the torsional force of the torsion bar 76 acts.
A fixed block 769 is provided on one end side of the torsion bar 76. By embedding the fixing block 769 in the core metal body 71, the entire side surface portion expansion assisting mechanism 73 can be firmly fixed to the core metal body 71.

  As described later, the torsional force of the torsion bar 760 causes the side surface portions 22 and 23 to pass through the rollers 741 and 742 when the pressing force F applied to the side surface portions 22 and 23 is released after the bent ends 227 and 237 are formed. The gap D (FIG. 12) between the pair of bent end portions 227 and 237 obtained by expanding in a direction away from each other is adjusted to a force that can be larger than the interval between the pair of edge portions 715 of the core metal body 71. Has been.

  Using such a metal core device 7, first, it is inserted into the inside of the deformed U-shaped portion 20 of the preform 16. At this time, the cored bar device 7 stably guides the relative positional relationship between the cored bar apparatus 7 and the preformed body 16 by guiding the slide blocks 719 at both ends thereof to face both ends of the preformed body 16. It can be inserted while being held in place. Then, the bottom contact surface 711 of the core metal main body 71 is brought into contact with the bottom surface portion 21. Thereby, the edge part 715 of the metal core main body 71 is arrange | positioned in the position corresponding to the bending start point of the bending end parts 227 and 237. At this time, the pair of left and right side portions 22 and 23 of the odd-shaped U-shaped portion 20 are initially arranged in a substantially parallel state, but are expanded in a direction away from each other by the rollers 741 and 742 of the core metal device 7. Open (not shown).

  Next, as shown in FIG. 11, a pressing force F is applied to the pair of left and right side portions 22 and 23 from the outside. The application of the pressing force is performed by pressing a pressing jig (not shown) with a hydraulic actuator. By applying the pressing force F, the side surface portions 22 and 23 are pressed against the side surface contact surfaces 712 and 713 of the core metal main body 71 and the rollers 741 and 742 are immersed in the side surface contact surfaces 712 and 713.

  Next, as shown in the figure, a pair of left and right bent end portions 227, 237 are formed by bending the end portions of the side surface portions 22, 23 along the edge portion 715 while applying the pressing force to the side surface portions 22, 23. Form. The bending process can be easily performed by pressing a bending jig (not shown) against the side surfaces 22 and 23.

  Next, as shown in FIG. 12, the pressing force F applied to the side surface portions 22, 23 is released. As a result, the rollers 741 and 742 protrude from the core metal main body 71 by the urging force of the roller support portion 76, and the side surface portions 22 and 23 are expanded in a direction away from each other. A gap D is provided between the pair of bent end portions 227 and 237. Thereby, the path | route which passes the space | interval between the bending edge parts 227 and 237 from the inside of the molded object 1 is ensured.

  Next, as shown in FIGS. 13 to 16, the cored bar device 7 and the molded body 1 are relatively moved while rotating the rollers 741 and 742, and the cored bar apparatus 7 is extracted from the gap D. At this time, since the rollers 741 and 742 are rotatable, the relative movement between the rollers 741 and 742 is assisted, and a smooth extraction operation can be performed.

  In particular, as described above, the rollers 741 and 742 have a tooth profile shape in which a concave portion 751 and a convex portion 752 are provided on the outer peripheral surface thereof. Therefore, while the core metal device 7 and the molded body 1 are moved relative to each other, the ends of the bent end portions 227 and 237 enter the concave portion 751 as shown in FIG. Therefore, the interval between the bent end portions 227 and 237 can be made smaller than the position of the maximum outer diameter of the rollers 741 and 742, and a smoother relative movement can be realized.

  Further, since the slide blocks 719 at both ends of the core metal device 7 face and guide both ends of the molded body 1, the extraction operation is performed while stably maintaining the relative positional relationship between the core metal device 7 and the molded body 1. Can be implemented.

As shown in FIG. 16, after the mandrel apparatus 7 is extracted from the inside, the pair of left and right side surfaces 22 and 23 try to return to the original substantially parallel state.
And as shown in FIG. 17, while the side parts 22 and 23 become substantially parallel, the front-end | tip of the bending edge parts 227 and 237 will be in the overlapping state. Note that the ends of the bent end portions 227 and 237 may remain flat without the pair of left and right side portions 22 and 23 returning to a substantially parallel state. In this case, the side surfaces 22 and 23 can be easily returned to a substantially parallel state by pressing.

Thereafter, in this example, the overlapping bent ends 227 and 237 are joined by welding.
As a result, as shown in the figure, it has a U-shaped cross section having a bottom surface portion 21 and a pair of left and right side surface portions 22 and 23 erected from both sides of the bottom surface portion 21, and the bottom surface portion 21 extends in the longitudinal direction. And a bent end portion 227, 237 on the opposite side to the bottom surface portion 21 in the pair of left and right side surface portions 22, 23, having a deformed U-shaped portion 20 having a concave curved surface bent so as to be recessed inwardly along. By joining together, the molded object 1 which has the substantially rectangular closed cross-sectional shape containing the said odd-shaped U-shaped part 20 is obtained.

  Thus, if the manufacturing method of this example is used, the molded object 1 of the closed cross-sectional shape containing the odd-shaped U-shaped part 20 can be easily manufactured in the state excellent in the external appearance characteristic. In particular, by using a special cored bar device in which the rollers 741 and 742 and the roller support part 76 are incorporated in the cored bar body 7, it is easy to bend the end of the deformed U-shaped part 20 to form a closed section. Moreover, the bending process can be performed with high accuracy, and the molded body 1 having the above-described closed cross section can be manufactured from a single material with a high yield as a single component.

  In addition, the deformed U-shaped portion 20 of the obtained molded body 1 is obtained by integrally connecting the bottom surface portion 21 and the side surface portions 22 and 23 on both sides thereof, so that at least the bottom surface portion 21 side is welded. There is no need to join. Therefore, the weight can be reduced accordingly. Furthermore, the plate | board thickness of raw material itself can also be reduced by the strength improvement effect by the rigidity improvement of the said side parts 22 and 23, and the necessity of a welding part, and the weight reduction effect by this can also be acquired.

  Further, in this example, the prepared preform 16 has bulged portions 225 and 235 on the side surface portions 22 and 23, and the bulged portions 225 and 235 are also formed in the final molded body 1 having a closed cross-sectional shape. Remains. Due to the presence of the bulging portions 225 and 235, the molded body 1 has excellent rigidity and excellent strength of the side surface portions 22 and 23, and has excellent appearance characteristics and a novel design.

(Reference Example 1)
A reference example for solving the same problem as that of the present invention will be described.
This example is an example in which the molded body (preliminary molded body) 16 having the deformed U-shaped portion 20 in Example 1 described above is used, and the subsequent end bending process is performed by a method different from that in Example 1.

  That is, in this example, as shown in FIG. 19, the cored bar device 8 including the cored bar body 81 not provided with the side surface part expansion assisting mechanism part 73 in Example 1 is used. The core metal body 81 is the same as the above-described core metal body 71 except that the side surface portion expansion assist mechanism portion 73 is not provided, and includes an edge portion 715 and the like.

  As shown in FIG. 20A, the molded body 16 is formed into an open shape in which the side surface portions 22 and 23 are widened away from the bottom surface portion 21 before the end bending process. The spread interval is set to a dimension in which the interval is larger than the thickness dimension of the cored bar body 81 in the state where the bent end portions 227 and 237 to be formed later exist.

Then, as shown in FIGS. 20A and 20B, the core metal body 81 is positioned inside the molded body 16, and the side surface portions 22 and 23 are pressed by pressing means (not shown) to be brought into close contact with the core metal body 81. Next, as shown in FIG. 20 (c), bending is performed along the edge portion 715 to form the bent end portions 227 and 237.
Next, as shown in FIG. 20 (d), by releasing the pressing force on the side surfaces 22 and 23, the side surfaces 22 and 23 return to the original open shape. Thereby, the space | interval of the bending edge parts 227 and 237 spreads more than the thickness dimension of the metal core main body 81. FIG. Therefore, the cored bar body 81 can be easily extracted from the obtained molded body 1.

Then, as shown in FIG. 21, before performing the joining step, by pressing the base of the side portions 22 and 23 of the molded body 1 inward with the punch 85 without inserting the cored bar device. Bending is performed so that the angle between the side surface portions 22 and 23 and the bottom surface portion 21 is substantially a right angle. Then, the same joining process as Example 1 is performed.
Thus, in this reference example, the end bending process using the simple cored bar device 8 can be performed on the assumption that the bending process is performed.

DESCRIPTION OF SYMBOLS 1 Molded body 16 Preliminary molded body 20 Profile-shaped U-shaped part 21 Bottom surface part 22, 23 Side surface part 225, 235 Swelling part 226, 236 Planar side surface part 227, 237 Bending edge part 4 Preliminary mold 5 Mold 51 Punch 52 Cushion 53 Dies 7 Core Bar Device 71 Core Bar Main Body 73 Side Surface Expansion Support Mechanism Unit 741, 742 Roller 751 Concave 752 Convex Portion 76 Roller Support Unit 760 Torsion Bar

Claims (8)

It has a U-shaped cross section having a bottom surface portion and a pair of left and right side portions erected from both sides of the bottom surface portion, and has a concave curved surface that is curved so as to be recessed inward along the longitudinal direction. A preparation step of preparing a molded body having an irregular U-shaped portion;
An end bending step of forming a bent end portion by bending the end portions on the opposite side of the bottom surface portion in the pair of left and right side portions using a mandrel device,
Joining the bent ends together to form a closed cross-sectional shape,
The cored bar device used in the end bending step contacts the bottom contact surface that contacts the bottom surface portion of the molded body, the pair of left and right side surface contact surfaces that contact the side surface portion, and the bent end portion. A cored bar body having an edge contact surface and a edge portion at a boundary corner between the side contact surface and the end contact surface;
A side surface portion expansion assist mechanism for expanding the pair of left and right side surface portions in a direction away from each other after forming the bent end portion;
The side surface portion expansion assist mechanism portion includes a pair of left and right rollers provided so as to be able to protrude and retract from the pair of left and right side surface contact surfaces of the metal core body, and rotatably supporting the rollers. A roller support portion that urges to protrude away from the side contact surface;
In the end bending step, the cored bar device is inserted into the deformed U-shaped part, the bottom contact surface is brought into contact with the bottom surface part,
Next, a pressing force is applied to the pair of left and right side portions from the outside, the side portions are pressed against the side surface contact surface of the core metal device, and the roller is immersed in the side surface contact surface,
Next, the end portions of the side surface portions are bent along the edge portions to form a pair of left and right bent ends,
Next, by releasing the pressing force to the side surface portion, the side surface portion is expanded in a direction away from each other by the urging force of the roller support portion, and a gap is provided between the pair of bent end portions,
Next, the cored bar device and the molded body are moved relative to each other while the roller is rotated, and the cored bar apparatus is extracted from the gap. Manufacturing method.   In Claim 1, the said roller in the said side part expansion assistance mechanism part has the tooth profile shape which provided the recessed part and the convex part in the outer peripheral surface, The said cored bar apparatus after the said bending end part formation, and the said In the relative movement with the molded body, the roller is configured to rotate in a state where the tip of the bent end is positioned in the recess of the roller. The manufacturing method of the molded object which has a cross-sectional shape. 3. The roller support portion in the side surface portion expansion assist mechanism portion according to claim 1, wherein the roller support portion includes a pipe-shaped outer shaft portion and an inner shaft portion that is coaxially arranged inside the outer shaft portion. A torsion bar with one end fixed,
A first arm fixed to the other end of the outer shaft portion and rotatably supporting one of the rollers;
A second arm fixed to the other end of the inner shaft portion and rotatably supporting the other roller;
A line connecting a first fulcrum, which is the rotation center of the roller provided on the first arm, and a second fulcrum, which is the rotation center of the roller provided on the second arm, with the shaft center of the torsion bar, respectively. It is configured so that the torsional force of the torsion bar acts when changing the internal angle,
The torsional force of the torsion bar expands the side surface portions in a direction away from each other via the roller when the pressing force to the side surface portion is released after the bent end portion is formed in the end portion bending step. A deformed U-shaped portion characterized in that the gap between the pair of bent end portions obtained by the adjustment is adjusted to a force that can be larger than the interval between the pair of edge portions of the core metal body. A method for producing a molded body having a closed cross-sectional shape.   4. The method of manufacturing a molded body having a closed cross-sectional shape including a deformed U-shaped portion according to claim 3, wherein two or more sets of the side surface portion expansion assist mechanism portions are built in the metal core body. .   5. The slide for positioning according to any one of claims 1 to 4, wherein both ends in the longitudinal direction of the metal core body are opposed to both ends in the longitudinal direction when inserted into the deformed U-shaped portion. The manufacturing method of the molded object which has the closed cross-sectional shape containing the odd-shaped U-shaped part provided with the block.   6. The deformed U-shaped portion according to claim 1, wherein an angle formed by the side surface contact surface and the end surface contact surface sandwiching the edge portion is less than 90 °. A method for producing a molded body having a closed cross-sectional shape. In any one of Claims 1-6, in producing the molded object which has the said deformed U-shaped part prepared in the said preparation process,
Prepare a flat blank,
The blank material is bent starting from a linear boundary line between the bottom surface portion and the side surface portion, and the bottom surface portion is a flat surface and the angle formed between the side surface portions on both sides thereof is Both form an intermediate molded body that is obtuse,
Corresponding to the punch having a concave clamping surface corresponding to the desired inner surface shape of the concave curved surface in the bottom surface portion, the cushion having the convex clamping surface corresponding to the outer surface shape of the concave curved surface, and the outer width dimension of the bottom surface portion Using a die having a die having a die blade portion arranged at an interval of the punch, the concave sandwiching surface of the punch disposed inside the intermediate molded body and the cushion disposed opposite thereto The bottom surface portion is sandwiched by the convex sandwiching surface to deform the bottom surface portion into the concave curved surface,
Then, while maintaining the clamping state between the punch and the cushion, the entire bottom surface portion is inserted between the die blade portions, and when only a part of the side surface portion passes through the die blade portion, By stopping the relative movement between the bottom surface portion and the die, a part of the side surface portion that does not pass between the die blade portions becomes a bulging portion that bulges outward, and its periphery is Producing a molded body having a closed cross-sectional shape including a deformed U-shaped part, wherein the deformed U-shaped part is formed so as to be a planar side surface erected substantially perpendicular to the bottom surface part. Method.   8. The molding having a closed cross-sectional shape including a deformed U-shaped portion according to claim 1, wherein the molded body is a frame component built in a seat back of a vehicle seat. Body manufacturing method.

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