JP4086216B2 - Hydroforming method of pipe material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydroforming method suitable for the manufacture of a product that uses a pipe material as a raw material and at least partially has a modified cross-sectional shape having a dimension smaller than the diameter of the pipe material.
[0002]
[Prior art]
For example, a part represented by an undercarriage frame of an automobile has a U-shaped or L-shaped planar shape and a closed cross-sectional structure, and is also partially polygonal or oval for installation and connection of other parts. Etc. have a partially different cross-sectional shape.
In the case of obtaining such a product, conventionally, a method has been employed in which an upper body and a lower body having a panel shape are formed by pressing, and the flanges of the upper body and the lower body are overlapped and spot-welded. However, since this method has a flange, the weight increases accordingly, the size increases, the arrangement space efficiency decreases, the strength decreases due to spot welding, and the cost is high because the process is complicated. There were problems such as becoming.
[0003]
In order to improve such a problem, a pipe material is used as a raw material, and a method of forming this using a hydroforming technique is known. There are roughly two types of hydroforming methods.
The first type is shown in FIG. 1, and as shown in (a), a pipe having a circular cross section is bent into a required plane shape, for example, a U shape, and the width is narrower than the pipe diameter of the bent product. The product part is crushed (preform) into a cross-sectional shape in which the width dimension is reduced from the material diameter as shown in (b) by a press or a dedicated machine, and the crushed product is made up and down as shown in (c). After the upper and lower molds are clamped as shown in (d), a liquid is injected into the crushed product as shown in (e) to create an internal pressure of high pressure (eg, about 22000 psi). Thus, the material is plastically deformed so as to conform to the mold surface, and is formed into a cross-sectional shape as shown in (f).
[0004]
The second type is shown in FIG. 2, and a circular pipe is bent into a required plane shape, for example, a U-shape as shown in FIG. 2 (a), and the bent product is again pressed or by a dedicated machine (b). Crush the cross-sectional shape with a reduced width dimension as shown in Fig. 6 and load the crushed product into the upper and lower mold cavities as shown in (c), and press the low pressure inside the crushed product before clamping as shown in (d). (For example, about 1000 psi) is created and pre-press-molded, then clamped as shown in (e), and the pre-press-molded product is as high as 6000-7000 psi so as to have a cross-sectional shape as shown in (f) In this method, the material is plastically deformed so as to conform to the mold surface with internal pressure.
[0005]
The second type performs pre-pressure molding at a low pressure as a first stage at the time of hydraulic molding, so that the power can be divided, so that the press can be downsized compared to the first type. Because of the low pressure pre-press forming, the reduction of wall thickness due to abrupt material change is reduced, cracking is suppressed, and the working tact can be greatly shortened compared to the first type. It has the advantage that it can.
[0006]
However, the second type also requires a preliminary processing step of crushing the bent pipe into a cross-sectional shape with a reduced width dimension as shown in FIG. In addition, a two-step pressurization process is required in which liquid is injected into the pre-processed product before mold clamping, low pressure is applied to perform pre-press molding, and then the mold is clamped to increase the internal pressure.
For this reason, combined with the large number of processes, the production efficiency is still low, and it cannot be denied that the production cost is insufficient. Moreover, since the mold is clamped by the force of the press itself, there is a problem that a large press is required.
[0007]
[Problems to be solved by the invention]
The present invention was devised to solve the above-mentioned problems, and the object of the present invention is to produce a closed cross-section product including a deformed portion from a pipe material with a simple process, a simple small equipment, and a short tact. An object of the present invention is to provide a hydroforming method that can be manufactured with high accuracy and can significantly reduce the manufacturing cost.
[0008]
In order to achieve the above object, the present invention provides a pipe material bent into a desired planar shape in order to obtain a product having a cross-sectional area with a width narrower than the diameter of the pipe material from at least a part of the entire length of the pipe material bent in a plane. The processed bent product is loaded between the slide blocks of the lower die provided with a pair of slide blocks movable in the left-right direction in the outer die, and the bent product is filled with liquid and pressurized. By operating the upper mold having the upper molding surface, the pair of slide blocks are moved in the approaching direction, and the bent product is clamped while continuously deforming the slide block and the upper molding surface, and the upper mold is lowered. While being locked to the mold, the inner pressure of the bent product is continuously raised to perform pressure molding until a desired cross-sectional shape is obtained.
[0009]
The mold used for the method preferably has the following configuration.
It has a fixed side wall on both sides, a base part having a mold surface for molding the bottom on the cross section of the product between them and a deep groove on both sides of the base part, and a recess is formed in the middle region of the fixed side wall The first die,
A pair of left and right slide blocks disposed on the platform and having a mold surface on the opposing surface and a tapered surface on the upper outer side;
It has a pair of projecting walls having a distance corresponding to the inner dimension of the fixed side wall and a length capable of entering the deep groove at the end of the descent, and the projecting walls are in contact with the tapered surface of the slide block at the tip and slide. A second die having a tapered surface for moving the block, having a concave portion corresponding to the concave portion on the outer surface, and a mold surface for forming a top portion on the cross section of the product between the protruding walls;
A lock mechanism including a lock piece disposed on a fixed side wall of the first die and capable of being fitted into a recess when the protruding wall enters, and an actuator for driving the lock piece.
The second die preferably has a tapered surface in contact with the tapered surface of the slide block in the base region of the protruding wall.
Further, the second die preferably has a base portion that fits inside the upper portion of the slide block.
[0010]
Of course, the hydroforming method according to the present invention includes forming the whole into a shape having a cross-sectional area with a width narrower than the diameter of the pipe material. In addition to forming into a shape having a cross-sectional area with a width narrower than the diameter of the pipe material, other parts include a case of forming into a non-circular cross-sectional shape in a direction different from the cross-sectional area (for example, the lateral direction). In this part, the mold does not have a slide block but has a fixed cavity.
[0011]
[Action]
In the hydroforming method according to the present invention, since a pair of left and right slide blocks is used as the inner mold, when a product having a cross-sectional area with a width smaller than the diameter of the pipe material is pressure-formed, the pipe material is formed into a desired planar shape. The bent product after bending can be put into a mold as it is and pressure-formed to the product shape. Therefore, a separate process for crushing the bent product and equipment therefor are not required.
Then, if the second die is operated with internal pressure applied between a pair of left and right slide blocks, the protruding wall functions as a slide cam, and the slide block automatically moves to form the product side wall. Therefore, it is possible to rapidly and continuously plastically deform the product shape into a product shape by continuing the movement of the second die and increasing the internal pressure of the bent product.
And since the 1st die | dye has the actuator of a lock mechanism, by operating this, a lock piece fits into a protruding wall, and the sealed cavity and the mold clamping state are maintained. Accordingly, the pressing force for clamping and holding the mold can be reduced, and a product with good shape accuracy can be pressure-molded with a small capacity equipment.
If the mold according to the invention is used, the method can be carried out with a relatively simple structure.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 3 shows an example of a product to which the hydroforming method for a pipe material according to the present invention is applied and changes in the material. A pipe material A having a circular cross section is cut to a required length as shown in FIG. The pipe material a is bent into a desired planar shape such as a U-shape by a pipe bender to obtain a bent product b as shown in FIG. Then, the bent product b is formed to obtain a product C partially having a vertically long cross-sectional area (rectangular shape in this example) c as shown in (c) and (d).
The vertically long cross-sectional area c is not limited to a rectangle, but may be an arbitrary polygon such as a pentagon or an oval, and the lateral dimension w is smaller than the lateral dimension W of the bent product b as a pressure molding material.
The product C has laterally long cross-sectional shape regions d and d in a portion different from the longitudinally long cross-sectional shape region c. The laterally long cross-sectional shape regions d and d are bent products b as pressure forming materials. Therefore, the molding is easy.
[0013]
In the manufacture of such a product C, the present invention uses a mold having a special structure at the portion corresponding to the vertically long cross-sectional area c, and the width of the bent product b as in the conventional method is measured by a press or a dedicated machine. The process of crushing into a reduced ellipse or oval shape is omitted, and hydroforming into a product C having a longitudinally long cross-sectional area c continuously from a bent product b whose cross section perpendicular to the axis is circular. is there.
[0014]
4 to 9 show the mold and the process of the present invention, and FIG. 10 shows a hydraulic pressure introduction system for forming.
First, the mold will be described. 1 is a disk-shaped lower mold arranged on the bed side, 2 is a first die fixed to the lower mold 1, and 3 is a movable 1 arranged in the first die 2. A pair of slide blocks that perform the function of the mold. Reference numeral 1 ′ denotes an upper die that is raised and lowered by a ram (not shown), 5 denotes a second die fixed to the lower side of the upper die 4, and 4 denotes a lock mechanism.
[0015]
The first die has fixed side walls 6, 6 on the left and right sides, and a base part 7 is provided between the fixed side walls 6, 6. A mold piece 8 having a shaped mold surface is fixed. A pair of deep grooves 9 and 9 for entering the second die, which will be described later, are provided between both ends in the width direction of the platform 7 and the inner roots of the fixed side walls 6 and 6. And the recessed part 60,60 opened to an inner surface is formed in the height direction intermediate part of the said fixed side walls 6,6.
The pair of slide blocks 3 and 3 are slidably disposed in the region of the base portion 7, and the inner surfaces facing each other have mold surfaces 10 and 10 that immediately correspond to the side surface shape of the cross section to be molded. And the taper surfaces 11 and 11 which incline outward at a required angle are provided in a pair of slide blocks 3 and 3 upper part outer side.
The slide blocks 3 and 3 are biased so as to be separated in a normal state. The means may be arbitrary, and an elastic body such as a tension spring may be connected to the slide blocks 3 and 3 from the fixed side walls 6 and 6 and forcibly expanded. A body such as a push spring 3a is interposed, and the slide blocks 3 and 3 are expanded by the reaction force of the spring.
FIG. 5 shows a specific example thereof. A T-groove 70 is formed in the base 7, and the lower overhangs 30, 30 of the slide blocks 3, 3 are fitted into the T-groove 70 between the slide blocks 3, 3. An arbitrary number of elastic bodies, such as push springs 3a, are interposed.
[0016]
The second die 5 has a pair of projecting walls 12, 12 that can enter along the inner surfaces of the fixed side walls 6, 6. Tapered surfaces 13, 13 that can come into contact with the tapered surfaces 11, 11 of the blocks 3, 3 are provided, and a central portion of the bottom portion following these tapered surfaces 13, 13 has a die surface having an upper surface shape of a cross section to be formed. The mold piece 14 is fixed.
The projecting walls 12 and 12 have such a length that they can enter the pair of deep grooves 9 and 9 at the end of the descent, and the slide blocks 3 and 3 are moved inside the lower end so as to correspond to the tapered surfaces 11 and 11. The moving taper surfaces 15 and 15 are provided. Further, the outer surfaces of the projecting walls 12 and 12 are formed with recesses 120 and 120 that coincide with the recesses 60 and 60 of the fixed side walls 6 and 6 when entering the deep grooves 9 and 9.
In this embodiment, the mold piece 14 is provided on the pedestal 16, and the stepped portions 17 and 17 for fitting with the pedestal 16 at the time of mold clamping are provided inside the upper ends of the pair of slide blocks 3 and 3. Is formed.
When the pair of slide blocks 3 and 3 are pulled and expanded by the elastic body from the fixed side walls 6 and 6 side, the projecting walls 12 and 12 are provided with cut grooves for dosing the elastic body from the lower end to the required height. It is done.
[0017]
The lock mechanism 4 is means for integrating the second die 5 and the first die 2 in order to reduce the clamping force, and is a locking piece fitted in the recesses 60, 60 of the fixed side walls 6, 6. 40 and an actuator 41 for fitting the locking piece 40 into the recesses 120 and 120 of the slide blocks 3 and 3 when the mold is clamped. The actuator 41 is a hydraulic cylinder in this example.
[0018]
As shown in FIG. 10, the forming fluid pressure introduction system for forming supplies a fluid pressure into the bent product b through the seal head 19 that is removably fitted to the end of the bent product b. Means. The seal head 19 has a flange 190 and a piston rod 191 on the rear side, and the piston rod 191 is moved back and forth by supplying hydraulic pressure to a piston located in the hydraulic cylinder 20.
The piston rod 191 has a forming fluid pressure introduction hole 192 from the front end of the seal head 19 to the rear end of the rod, and the introduction hole 192 is supplied with pressurized liquid via a supply pressure control valve 21 by a flexible conduit. A source (pump or the like) 22 is connected. The liquid may be any one that is corrosion resistant, such as a mixture of water and rust preventive oil.
[0019]
In obtaining the product C according to the present invention, the upper die 1 ′ is positioned at a level such that the second die 5 is sufficiently separated from the first die 2 as shown in FIG. At this time, the pair of slide blocks 3, 3 are in a positional relationship in which they are separated and expanded, and the lock pieces 40, 40 of the lock mechanisms 4, 4 are fitted in the recesses 60, 60 of the fixed side walls 6, 6.
In this state, a bent product b made of a pipe material is set on the base 7 between the slide blocks 3 and 3 as shown in FIG. Since the pair of slide blocks 3 and 3 are expanded by the pressing force of the elastic body 3a, it is easy to set the bent product b.
Next, as shown in FIG. 9 (a), the upper die 1 'is lowered by the damper actuator (not shown) with the pipe fixing block 18 provided on the upper die 1', and is bent out of the die. The end of the product b is firmly fixed to the lower mold side. Next, the hydraulic cylinder 20 is actuated as shown in (b), whereby the seal head 19 is pressed into the end of the fixed bent product b by the hydraulic cylinder 20 and the end of the bent product b is sealed. The
[0020]
In this state, the upper die 1 'is lowered, but the low pressure P controlled by the supply pressure control valve 21 from the pressurized liquid supply source 22 is bent into the bent product b just before or at the start of the lowering. The internal pressure is started.
When the upper die 1 ′ is operated as described above, the outer surfaces of the pair of projecting walls 12 and 12 of the second die 5 are in contact with the inner surfaces of the fixed side walls 6 and 6, and the pair of moving taper surfaces 15 and 15 at the tip are paired. The slide blocks 3 and 3 come into contact with the tapered surfaces 11 and 11, whereby the inner mold surfaces 10 and 10 of the pair of slide blocks 3 and 3 come into contact with the side surfaces of the bent product b. This is the state of FIG.
Then, since the slide blocks 3 and 3 are pressed and moved further inward as the pair of protruding walls 12 and 12 continue to descend, the bent product b is pinched from both sides. Since the supply pressure from the pressurized liquid supply source 22 is continuously and gradually increased along with the movement of the slide blocks 3 and 3, the bent product b is continuously formed into a vertically elongated cross-sectional shape. .
[0021]
When the lowering of the second die 5 continues, the outer surfaces of the pair of projecting walls 12 and 12 continue to descend along the inner surfaces of the fixed side walls 6 and 6, and at this stage, the slide blocks 3 and 3 reach the limit of movement. As shown in FIG. 7, when the mold piece 14 of the second die 5 comes into contact with the upper part of the bent product b and the base portion 16 starts to be fitted into the step portions 17 and 17 of the slide blocks 3 and 3, the slide block 3. , 3 is in the stage of completion of movement, and the slide blocks 3, 3 are prevented from moving backward by the protruding walls 12, 12, and the movement of the slide block 3, 3 is advanced due to the fitting of the base portion 16 and the step portions 17, 17. Therefore, the bent product b is plastically deformed so as to be almost adapted to the mold surfaces 8, 14, 10, and 10 due to the increase of the internal pressure, and becomes a preform state.
[0022]
Then, when the second die 5 descends to the end, and the distal ends of the pair of projecting walls 12 and 12 enter the deep grooves 9 and 9, the tapered surfaces inside the pair of projecting walls 12 and 12 as shown in FIG. 13 and 13 are in close contact with the tapered surfaces 11 and 11 of the slide blocks 3 and 3, and the recesses 120 and 120 on the outer surface of the projecting walls 12 and 12 are aligned with the recesses 60 and 60 on the inner surfaces of the fixed side walls 6 and 6.
Therefore, when the actuators 41 and 41 are operated, the lock pieces 40 and 40 are moved forward to a position across the recesses 120 and 120 and the recesses 60 and 60, whereby the second die 5 is locked with the first die 2.
This completes the mold clamping, and the slide blocks 3 and 3 and the first and second dies 2 and 5 create a sealed cavity that immediately corresponds to the product cross-sectional shape. By this state, the hydraulic pressure applied to the bent product b has been increased to the maximum pressure Pmax, and the process proceeds to the main molding. In this case, the internal pressure of the bent product b is high, so that the material Is further plastically deformed to be completely deformed along the mold surfaces 8, 14, 10, and 10, and is maintained in a state where the internal pressure is high for a short time, so that it is accurately formed into the intended cross-sectional shape.
[0023]
Although a strong reaction force is generated at the time of molding, since the lock pieces 41 and 41 are fitted in the recesses 120 and 120 and the recesses 60 and 60, the second die does not come out upward, and a high pressure of 7000 psi or more is required. It can withstand the pressure, and therefore the clamping force can be reduced. As the press, it is sufficient to have an output that is equal to or reasonably better than the internal pressure, and at the same time, the molding accuracy can be improved.
In the case where there is an expanded portion, the hydraulic cylinder 20 is operated at the time of molding, and the bent product b is pressed in the axial direction by the flange 190 of the seal head 19 so that the material is a mold. Since it is forced to flow inward, a decrease in thickness can be further suppressed.
At the time of the main molding, if necessary, a punch may be plunged into the material from a mold portion corresponding to a proper position of the product, and in this way, the hole is simultaneously processed.
[0024]
After the pressurization and holding are completed as described above and the target cross-sectional shape is formed, the hydraulic pressure in the product C is released, and the actuators 41 and 41 are operated in the backward direction to fix the lock pieces 40 and 40 again. It returns to the recessed parts 60 and 60 of the inner surface of the side walls 6 and 6, and then raises upper mold | type 1 'like FIG.
In this way, the pair of projecting walls 12 and 12 come out along the inner surfaces of the fixed side walls 6 and 6, the force applied to the slide blocks 3 and 3 in the inner direction is released, and the slide is caused by the reaction force of the elastic body 3 a. Blocks 3 and 3 expand left and right. Therefore, the product C may be taken out, and the unnecessary portion at the end may be cut off.
[0025]
In the present invention, as described above, since the internal pressure is applied from the stage of the bent product b having a circular cross section and the internal pressure is continuously increased steplessly toward the target product shape, a series of pressure forming is performed. Abrupt changes in shape due to the difference in shape between the crushed shape and the finished shape can be eliminated, so that buckling and reduction in plate thickness do not occur, the range of applicable materials can be expanded, and molding accuracy It is possible to improve.
[0026]
FIG. 11 to FIG. 17 show an example in which a product having an elliptical deformed portion partially in the horizontal direction and the vertical direction is manufactured by the method of the present invention.
11A and 11B show examples of products and changes in materials. FIG. 11A shows a pipe material a obtained by cutting a pipe material having a circular cross section into a required length, and FIG. 11B shows this pipe material a by vip bender. Shows a bent product b which is bent by. Then, the bent product b is formed, and as shown in (c) to (f), the longitudinally long cross-sectional areas c and c and the laterally long cross-sectional areas d and d are directed outward. The product C having the irregular cross-sectional shape regions e and e of the concavity is obtained.
In the manufacture of such a product C, the present invention uses the mold shown in FIGS. 12 to 15, and continuously and continuously from the bent product b having a circular cross section perpendicular to the axis line. Hydroforming products with d and e.
[0027]
12, 13, and 14, reference numeral 1 denotes a lower mold, and 1 ′ denotes an upper mold, which is guided up and down by guide posts 25 at four corners. Reference numeral 2 denotes a first die mounted on the lower mold 1 and has an inner mold 2 ′ made of sintered metal having a substantially U-shaped groove on the plane.
The inner mold 2 'made of sintered metal has mold surfaces 23, 23 enlarged on both sides so as to correspond to the half section of the horizontally long cross-sectional area d as shown in FIG. As described above, the mold surfaces 24 and 24 are enlarged only on the outer side so as to quickly correspond to the half cross section of the deformed cross sectional shape region e. In addition, groove-like cavities 25 and 25 having a required width are not provided in portions corresponding to the longitudinally long cross-sectional areas c and c so as to intersect the axis, and are shown in FIGS. 3 to 7. Special mold is incorporated.
The same applies to the upper die 1 ′, and the second die 5 has an inner die 5 ′ made of sintered metal having a substantially U-shaped flat surface, and a half cross section of the horizontally long cross-sectional shape regions d and d. The mold surfaces 23 'and 23' are enlarged on both sides so as to respond quickly, and the mold surface 24 'is expanded only on the outside so as to respond quickly to the half cross section of the deformed cross-sectional area e as shown in FIG. , 24 '. And the special metal mold | die shown in FIG. 3 thru | or FIG. 8 is integrated in the part corresponded to the said longitudinally long cross-sectional area | regions c and c.
The mold surfaces 24 and 24 'have slightly different cross-sectional shapes, and the mold surface 24 of the first die 2 has an appropriate gradient toward the outside.
[0028]
The first die 2 is provided with external hydraulic pressure supply units 26 and 26 at several locations. These external hydraulic pressure supply parts communicate with the inner mold 2 'made of sintered metal by a passage. The external hydraulic pressure supply units 26 and 26 are connected to a pressurized liquid supply source 28 via pressure control valves 27 and 27, and are lubricated at the time of forming by using the porous characteristics of the inner mold 2 'made of sintered metal. External pressure is applied so as to balance the internal pressure of the pipe to ensure the property.
In the upper mold 1 ′, pipe fixing blocks 18 and 18 that can be moved up and down by a damper are arranged at portions corresponding to the cylinders 20 and 20 installed in the lower mold 1, and the hydraulic pressure in the pipe at the time of forming is set. Yoke-like seal head stoppers 18 'and 18' for preventing the seal head 19 from retreating when it is raised are provided so as to synchronize with the pipe fixing block.
[0029]
The molds corresponding to the vertically long cross-sectional areas c and c are substantially the same as those shown in FIGS. 3 to 8, and are fixed to the left and right sides of the first die 2 as shown in FIGS. It has side wall parts 6, 6, and a base part 7 is provided between the fixed side wall parts 6, 6. The center of the base part 7 is on the lower surface of the cross section to be molded of the bent product b. A mold piece 8 having a suitable mold surface is fixed. A pair of deep grooves 9 and 9 are provided between the widthwise ends of the platform 7 and the inner roots of the fixed side wall portions 6 and 6, and are provided at intermediate positions in the height direction of the fixed side wall portions 6 and 6. Are formed with recesses 60, 60.
The pair of slide blocks 3 and 3 are made of a mold material, not a sintered material, and are slidably disposed on the base portion 7, and the opposite inner surfaces are mold surfaces 10 and 10 that immediately correspond to the cross-sectional side surfaces to be molded. have. In this example, a connecting mold surface portion is provided so as to smoothly connect to a circular cross section at both end portions in the length direction of the product. Note that a mechanism for urging the pair of slide blocks 3 and 3 toward the expansion side in a normal state is not shown.
And the taper surface 11 which inclines outward at a required angle is provided in the upper-end part outer side of a pair of slide blocks 3 and 3, respectively.
[0030]
The second die 5 has a pair of projecting walls 12, 12 that can enter along the inner surfaces of the fixed side wall parts 6, 6. Tapered surfaces 13, 13 that can come into contact with the tapered surfaces 11, 11 of the slide blocks 3, 3 are provided, and a die surface having an upper surface shape of a cross section to be molded is formed at the central portion of the bottom portion following these tapered surfaces 13, 13. The mold piece 14 is fixed. The projecting walls 12 and 12 have such a length that they can enter the pair of deep grooves 9 and 9 at the end of the descent, and are moved at an angle corresponding to the tapered surfaces 11 and 11 of the slide blocks 3 and 3 on the lower end inside. Tapered surfaces 15 and 15 are provided.
Further, the outer surfaces of the projecting walls 12 and 12 are formed with recesses 120 and 120 that coincide with the recesses 60 and 60 of the fixed side walls 6 and 6 when entering the deep grooves 9 and 9. The lock piece 40 of the lock mechanism 4 is movably disposed in the recesses 60, 60, 120, 120, and the lock piece 40 is fitted into the recess 120 of the slide block 3 by the actuator 41 when the mold is clamped. .
[0031]
In forming with such an apparatus, the bent product b made of a pipe material is loaded into the inner die 2 ′ of the first die 2 as shown in FIG. 12 with the upper die 1 ′ raised. At this time, since the slide blocks 3 and 3 are open as in the left half of FIG. 14, the setting is easy. Moreover, since the mold surfaces 23 and 24 are larger than the diameter of the bent product b, there is no problem in loading and setting.
Next, when the upper mold 1 ′ is lowered, first, the pipe fixing blocks 18 and 18 are fixed at the ends of the bent product b. The seal heads 19 and 19 are press-fitted by the cylinders 20 and 20 into the ends of the bent product b thus fixed.
In this state, the upper mold 1 ′ is lowered. In parallel with this, the liquid is injected at a low pressure from the pressurized fluid supply source 22 immediately before the lowering starts, and the internal pressure is increased continuously and steplessly at the start of mold clamping. go.
[0032]
When the upper die 1 ′ is operated as described above, the outer surfaces of the pair of projecting walls 12 and 12 of the second die 5 are in contact with the inner surfaces of the fixed side walls 6 and 6, and the pair of moving taper surfaces 15 and 15 at the tip are paired. Since the slide blocks 3 and 3 are pressed and moved further inward as the pair of projecting walls 12 and 12 continue to descend, the bent product b is on both sides. It is pinched from. Along with the movement of the slide blocks 3 and 3, the supply pressure from the pressurized liquid supply source 22 is gradually and gradually increased.
[0033]
When the second die 5 continues to descend, the outer surfaces of the pair of projecting walls 12 and 12 continue to descend along the inner surfaces of the fixed side walls 6 and 6, and when the first mold clamping is completed, the slide blocks 3 and 3 Is prevented from moving backward by the projecting walls 12, 12, and is prevented from moving forward by fitting the mold piece 14 and the material. It is plastically deformed so as to be generally adapted to 14, 10, and 10 and is in a preform state.
[0034]
Then, when the second die 5 descends to the end, and the front ends of the pair of projecting walls 12 and 12 enter the deep grooves 9 and 9, the inner sides of the pair of projecting walls 12 as shown in the right half of FIG. When the taper surface 13 is in close contact with the taper surface 11 of the slide block 3, the concave portion 120 on the outer surface of the projecting wall 12 and the concave portion 60 on the inner surface of the fixed side walls 6, 6 are aligned, and the actuator 41 is operated. Is advanced to a position across the recess 120 and the recess 60, and the second die 5 is locked with the first die 2.
With this, the mold clamping is completed, and the slide block 3, 3 and the first and second dies 2, 5 create a sealed cavity that immediately responds to the cross-sectional shape of the product, and if the internal pressure of the bent product b is increased to the maximum pressure, Since the internal pressure of the bent product b becomes high, the material is further plastically deformed and plastically deformed so as to be completely adapted to the mold surfaces 8, 14, 10, and 10, and the high internal pressure is maintained for a short time. Molded accurately to the desired cross-sectional shape.
[0035]
On the other hand, in other mold parts, a required part of the bent product b is formed into a horizontally long cross-sectional shape as shown in FIG. 14 due to the close contact of the mold surfaces 23 and 23 ′ and the pipe internal pressure. Further, another required portion of the bent product b is formed into a horizontally elongated cross-sectional shape e as shown in FIG. 15 due to the close contact between the mold surfaces 24 and 24 ′ and the pipe internal pressure.
[0036]
In addition, at the time of the forming process, the laterally long irregular cross-sectional shape e is a pipe expansion process in which the circumference increases. Therefore, in order to reduce the reduction in the thickness of the stretched portion, the cylinder 20 is operated while pressurizing the bent product b, and the material is drawn by the inner molds 2 ′ and 5 ′ from the axial direction by the flange of the seal head. Push into the resulting cavity. At this time, since the internal pressure is applied to the bent product b, the outer surface of the bent product b is pressed against the inner molds 2 'and 5' by the pressure applied to the outside due to this, and the lubricity is deteriorated. It becomes impossible to follow the increase in internal pressure and cracks are likely to occur.
Therefore, the inner molds 2 ′ and 5 ′ made of sintered metal are used, and external hydraulic pressure is applied from the pressurized liquid supply source 28 to the inner molds 2 ′ and 5 ′ via the external hydraulic pressure supply units 26 and 26. The pressurized liquid passes through the pores of the inner molds 2 ′ and 5 ′, and a hydraulic surface is created on the outer surface, that is, the sliding surface of the bent product b. For this reason, good lubricity is obtained, and the molding proceeds in a state where the external hydraulic pressure is filled in the space around the bent product b, particularly the outer corner side, on the mold surfaces 24 and 24 ′. While maintaining the balance between the hydraulic pressure and the internal pressure as the molding progresses, the pressure can be gradually reduced to fit the mold surfaces 24 and 24 ′ so as to be molded into an accurate shape with little reduction in plate thickness.
[0037]
FIG. 13 shows a state where the molding is completed after holding the pressure, and then the hydraulic pressure in the product C is released, the seal head 19 is extracted, the actuator 41 is operated in the backward direction, and the lock piece 40 is again fixed to the fixed side wall portion 6. 6 is returned to the recesses 60, 60 on the inner surface, the upper mold 1 ′ is raised, the product C between the expanded slide blocks 3, 3 is taken out, and then the unnecessary portion at the end is cut off. .
In the above process, a product C partially having a vertically long cross-sectional shape region c, c, a horizontally long cross-sectional shape region d, d, and a deformed cross-sectional shape region e, e tapered toward the outside, Continuous and stepless molding can be performed directly from the bent product b without a complicated crushing process.
[0038]
Next, specific examples of the present invention will be described.
As a material, use a material SAPH45, a round pipe material with a diameter of 60 mm, cut this to 2500 mm in length, and make a U shape as shown in FIG. Bending products b each having a length of 850 mm were produced.
As shown in FIG. 11 (c), the product has longitudinally elongated sectional regions c and c, laterally elongated sectional regions d and d, and irregularly shaped sectional regions e and e that are tapered outward. The longitudinal cross-sectional shape regions c and c are 35 mm wide and 64 mm high, the horizontal cross-sectional shape regions d and d are 64 mm wide and 35 mm high, and the irregular cross-sectional shape regions e and e are 75 mm wide and 40 mm high with a gradient of 10 °. This is the specification.
The bent product b was loaded into a mold shown in FIGS. 12 to 16 and molded. As a result, it was possible to mold into an accurate shape as specified. For comparison, the conventional first type and second type were also molded. FIG. 17 shows the relationship between the internal pressure (psi) required for molding at this time and the tact time.
As is apparent from FIG. 17, when the present invention is adopted, the pressure is about 1/3 that of the first type of 22000 psi, and about the same as the tact time of 26 sec. It turns out that it can shape | mold with the precision of a grade. Further, it can be seen that the second type can be molded with the same degree of accuracy in a short time of about 2/3 with respect to the tact time of 22 sec, although the pressure is about the same. And since it has a lock mechanism, it was possible to use a 500-ton press much smaller than the 1000-ton press required for the second type.
[0039]
【The invention's effect】
According to the present invention as described above, when manufacturing a closed cross-section product including a deformed portion having a width narrower than the diameter of the material, a separate crushing process can be completely omitted, and a bent product is introduced to form the product shape. Since the process is continuously steplessly molded, the molding accuracy is high, the processing speed is high, and the clamping mechanism that can withstand the internal pressure can be maintained by the lock mechanism, which means that simple and compact equipment is sufficient, greatly reducing manufacturing costs. The excellent effect that it can be obtained. In addition, because there are no instability factors due to the large difference in shape from the product shape, such as buckling due to the crushing process, the applicable range of materials is widened and the required strength is satisfied even if the material is reduced. The effect that it can be made to correspond, or it becomes possible to correspond to a high-tensile material is also acquired.
[Brief description of the drawings]
FIGS. 1A to 1F are explanatory views showing an outline of a first type of a conventional pipe material hydroforming method.
FIGS. 2A to 2F are explanatory views showing an outline of a second type of conventional hydroforming method for pipe materials.
FIGS. 3A to 3D are explanatory views showing a product example according to the present invention and the shape change of a pipe material in stages.
FIG. 4 is a cross-sectional view showing an example of a mold used in the hydroforming method of the present invention and a molding first stage (at the time of setting) using the mold.
FIG. 5A is a cross-sectional view of the main part of the mold, and FIG.
FIG. 6 is a cross-sectional view showing a second stage of the present invention.
FIG. 7 is a cross-sectional view showing a third stage of the present invention.
FIG. 8 is a cross-sectional view showing a fourth stage (clamping completion) of the present invention.
FIG. 9 is a cross-sectional view showing a mold released state.
FIG. 10A is a partially cutaway plan view showing a pipe material end seal and a hydraulic pressure introduction diameter in the present invention, and FIG.
FIGS. 11A to 11E are explanatory views showing a shape change up to a product according to the present invention. FIGS.
12 is a transverse cross-sectional view showing a state where a mold for forming the product of FIG. 11 is loaded with a bent product. FIG.
FIG. 13 is a cross-sectional view showing a completed state of molding.
FIG. 14 is a cross-sectional view showing a mold structure of a longitudinally long cross-sectional shape portion, half before the start of molding, and in a molding state.
FIG. 15 is a cross-sectional view showing a mold structure and a molding state of a horizontally long cross-sectional shape portion.
FIG. 16 is a cross-sectional view showing a mold structure and a molding state of a deformed cross-sectional shape portion.
FIG. 17 is a diagram showing the relationship between the molding time and internal pressure of the method of the present invention and the conventional first and second types.
[Explanation of symbols]
1 Lower mold
1 'Upper mold
2 1st die
3 Slide block
4 Locking mechanism
5 Second die
6 Fixed side wall
8, 10, 14 mold surface
9 Deep groove
11 Tapered surface
12 Projection wall
13 Tapered surface
15 Tapered surface
40 lock pieces
41 Actuator
60,120 recess

Claims (2)

In order to obtain a product having a cross-sectional area narrower than the diameter of the pipe material in at least a part of the overall length from the pipe material bent in a plane, a bent product obtained by bending the pipe material into a desired planar shape is placed in the outer mold. Is loaded between the slide blocks of the lower mold provided with a pair of slide blocks movable in the left and right directions, and the upper mold having the upper molding surface is operated in a state where the bent product is filled with liquid and pressurized. By moving the pair of slide blocks in the approaching direction, the bent product is clamped while being continuously deformed between the slide block and the upper molding surface, and the upper die is bent with the lower die locked. A method of hydroforming a pipe material, characterized in that the internal pressure of a processed product is continuously increased to perform pressure molding until a desired cross-sectional shape is obtained. The pipe material hydroforming method according to claim 1, wherein the mold has the following configuration.
It has a fixed side wall on both sides, a base part having a mold surface for molding the bottom on the cross section of the product between them and a deep groove on both sides of the base part, and a recess is formed in the middle region of the fixed side wall The first die,
A pair of left and right slide blocks disposed on the platform and having a mold surface on the opposing surface and a tapered surface on the upper outer side;
It has a pair of projecting walls having a distance corresponding to the inner dimension of the fixed side wall and a length capable of entering the deep groove at the end of the descent, and the projecting walls are in contact with the tapered surface of the slide block at the tip and slide. A second die having a tapered surface for moving the block, having a concave portion corresponding to the concave portion on the outer surface, and a mold surface for forming a top portion on the cross section of the product between the protruding walls;
A lock mechanism including a lock piece disposed on a fixed side wall of the first die and capable of being fitted into a recess when the protruding wall enters, and an actuator for driving the lock piece.

Images