JPH0228406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method and apparatus for forming lipskin or similar products.

[Conventional technology and its problems]

The lipskin of a jet engine nacelle is different from a simple cylindrical body; it has an outer circumferential flange 30 and a parabolic or curved outer wall 31 as shown in FIG.
, the rounded part 32 at the tip of this outer wall, and the rounded part 3
It has a complex shape similar to a fedora hat, and has a parabolic or curved inner wall 33 that goes backward in a hairpin shape from the two ends.

For this reason, it is difficult to form such products all at once using the press processing method, and conventionally, rectangular blank plates are formed into unit parts with the above-mentioned cross-sectional shape, and these are joined together in the circumferential direction using complex individual rivets. It was formed in multiple steps using methods such as matching or the drop hammer method.

However, all of these methods are inefficient and cannot be said to be accurate enough. In particular, in the latter case, it is impossible to avoid the shock line and reduction in plate thickness that occur in each process, and in the former case, various measures must be taken to prevent peeling and gaps caused by joints. There was a problem.

[Means for solving problems]

The present invention was created after repeated research in light of the above-mentioned circumstances, and its purpose is to efficiently and precisely form lipskin and similar products with a folded hat-like cross-section in one press stroke. The goal is to provide a way to do so.

Another object of the present invention is to provide a molding device that is suitable for carrying out the above method and has a relatively simple structure.

In order to achieve this objective, the inventors of the present invention have conducted extensive research and have considered a combined forming method of drawing (shrinkage) and stretch flanges. However, when a circular blank is used as the base plate in this method, the restriction of the material on the stretch flange side is large, so the forming limit becomes low, and a large forming height cannot be obtained.

As a countermeasure to this problem, if a doughnut-shaped base plate is used, the restriction of the material will be reduced and the forming limit will be improved. However, since wrinkle suppression is performed only on the drawing flange side, the elongation of the material on the stretch flange side cannot be controlled, and the forming limit is determined by the elongation limit of the material on the stretch flange side. Also,
Since the material on the stretch flange side cannot be restrained, the problem of wrinkles occurring on the stretch flange side molding surface of the molded product shape cannot be avoided.

Therefore, the present invention uses a doughnut-shaped blank and controls the wrinkle pressing force against this material on the outer ring side (drawing flange side) and the inner ring side (stretch flange side) during molding. However, the wrinkle-pressing force against the donut-shaped blank sheet is made independent between the outer ring side and the inner ring side, and the wrinkle-pressing force on the inner ring side is first made larger than the wrinkle holding force on the outer ring side, and with the material on the inner ring side locked, the wrinkle holding force on the outer ring side is Only the material is slipped in and drawn with an annular punch, and then the wrinkle pressing force on the inner ring side and the outer ring side is equalized, and the annular punch is continued to be pushed in to form a flange by stretching to the desired height.

The above-mentioned molding may be performed using a conventional mold, or a method using opposing hydraulic pressure may be employed. The latter involves opposed hydraulic molding with pre-charging.

The apparatus of the present invention is also characterized by a die having a pillar part in the center and a ring-shaped die hole on its outer periphery, an annular punch that is inserted into and removed from the ring-shaped die hole, and a die that faces the upper surface of the outer ring of the ring-shaped die hole. A donut-shaped blank holder, a restraint plate facing the top surface of the column, a ram that separately operates the blank holder and the restraint plate, and a control unit that controls the magnitude of the pressing force between the blank holder and the restraint plate. The reason is that we have prepared the following.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figures 1 to 3 show an example (first embodiment) in which the present invention is applied to conventional molding or opposed hydraulic molding, and Figures 4 and 5 show an embodiment in which the present invention is applied to opposed hydraulic molding with pre-charge. An example (second example) will be shown.

In FIG. 1, numeral 1 is a die, which has a pillar part 5 at the center of the same height as the top surface of the die, and
A ring-shaped die hole 6 is formed on the outer periphery of this. Reference numeral 2 denotes an annular punch that is inserted into and removed from the ring-shaped die hole 6, 3 a donut-shaped blank holder facing the upper surface 7 of the die, and 4 a restraining plate facing the upper surface 8 of the column portion. 9 is a blank plate with a hole 1 in the center.
0 is formed and has a flat donut shape.

In the first embodiment, the blank 9 is installed with the hole 10 in the same shape as the column 5, and in this state, the blank holder 3 and the restraint plate 4 are lowered, and the blank 9 is attached to the die upper surface 8 and the column. It is held between the upper surface 8 and the upper surface 8.

When the annular punch 2 is lowered next in this state, the annular punch 2 bends the blank plate 9 at the die shoulder and simultaneously starts inserting it into the ring-shaped die hole 6. As shown in Fig. 2, the pressing force of the restraining plate 4 is different from the wrinkle pressing force FA of the blank holder 3 until the molding is performed at a height of approximately 1/3 to 1/2 of the molding height.
Increase FB.

As a result, the flow of the material 100 on the stretch flange side, that is, the inner ring side is locked, and the hole expansion is suppressed, while the material 101 on the drawing flange side, that is, the outer ring side is not locked, so that the annular punch 2
Due to the pushing force, the material 101 on the outer ring side flows into the ring-shaped die hole 6 so as to contract in the circumferential direction, and a predetermined molding height is obtained.

As shown in Fig. 3, the pressing force FB of the restraint plate 4 is applied from the middle stage of molding to the final stage of molding when the desired height is reached.
While weakening the pressure, press the annular punch 2 further. Since the material 100 on the inner ring side is now unrestricted, stretch flange forming is performed to widen the hole 10, and the forming is performed to the desired height. At this time, it is preferable that the pressing force FB of the restraining plate 4 is controlled to a required attenuation rate until it reaches a force comparable to the wrinkle pressing force FA of the blank holder 3.

In addition, in order to perform opposed hydraulic forming in the first embodiment,
A hydraulic circuit 60 having a pump 61 and a relief valve 62 is connected to the ring-shaped die hole 6, and this circuit fills the ring-shaped die hole 6 with liquid such as oil, which is created by pushing the annular pump 2. Since the blank plate 9 is wound around the annular punch 2 by the opposing hydraulic pressure, the forming height and accuracy are improved.

Next, in the second embodiment, the ring-shaped die hole 6 is filled with liquid by the hydraulic circuit 11 shown in FIG. Restraint plate 4 in state
The pressing force FB is the wrinkle pressing force FA of blank holder 3.
The liquid is further pumped from the pump 61, and a counter hydraulic pressure Pc is applied from the back surface of the blank plate 9.

Since the material 100 on the inner ring side is locked,
The material 101 on the outer ring side flows toward the center of the ring-shaped die hole by the opposing hydraulic pressure FC, and the blank 9 is expanded in the opposite direction to the molding direction, thereby increasing the surface area.

Next, the annular punch 2 is lowered and the expanded blank 9 is pushed toward the ring-shaped die hole 6, but from the time when this pushing starts until the end of the molding, the pressing force of the restraint plate 4 increases as shown in FIG.
This weakens the FB, which causes material 1 on the inner ring side to
00 flows into the ring-shaped die hole 6 and shifts to stretch flange forming, and by controlling the forces of FA and FB in a well-balanced manner and adjusting the opposing hydraulic pressure Pc,
Deep lipskin is formed in one step.

6 to 8 show an embodiment of the molding apparatus according to the present invention, in which 1 is a die, 2 is an annular punch, 3 is a doughnut-shaped blank holder, 4 is a restraint plate, 5 is a column part, and 6 is a It is a ring-shaped die hole.

FIG. 6 shows an example applied to a single-acting press, in which the die 1 is installed on a bolster 11 and fixed to a bed (not shown), and the annular punch 2 is mounted on a slide 12 that is raised and lowered by a main ram 13.
is fixed to the bottom of the

The blank holder 3 is connected to wrinkle presser rams 14, 14 arranged at equal intervals on the circumference, and piston portions 140, 14 of each wrinkle presser ram 14, 14.
0 is inserted into wrinkle presser cylinders 15, 15 built into the slide 12. Further, a restraint ram 16 is connected to the restraint plate 4 at its lower end,
A piston portion 160 of this is inserted into a restraining cylinder 17 built into the slide 12.

Each of the wrinkle presser cylinders 15, 15 is connected to the wrinkle presser force control unit 1 through a guide path 19.
8, and the restraining cylinder 17 is also led by a conduit 20 to a restraining force control unit 21.

As mentioned above, the wrinkle pressing force control unit 18 and the restraining force control unit 21 control the wrinkle pressing force FA and the restraining force FB at the initial stage of molding.
＞FA relationship, FA≒ in the middle to final stage of molding
Pumps 22 and 23 are connected to conduits 19 and 20 via check valves, and corresponding cylinders are connected to branch passages 190 and 200 from conduits 19 and 20. relief valves 24 and 25 for setting and controlling desired wrinkle pressing force or restraining force, respectively.

In the case of the embodiment shown in FIG. 6, the relief valve 2
The blank holder 3 and the restraint plate 4 are brought into contact with the blank plate 9 by setting wrinkle pressing force and restraint force in the blank plate 9 and supplying hydraulic pressure by the pumps 22 and 23, and lowering the slide 12 by the main ram 13. In this state, the annular punch 2 is lowered by still operating the main ram 13.

On the other hand, the wrinkle presser rams 14, 14 and the restraint ram 16
are respectively retreated to the wrinkle presser cylinders 15, 15 and the restraint cylinder 17, but since relief pressures of different magnitudes are set in these cylinders by the relief valves 24, 25 of the control units 18, 21, the restraint cylinder 17-Restraint ram 16
- The material on the inner ring side of the blank plate 9 is locked from movement by the restraint plate 4, and the material on the outer ring side of the blank plate 9 is allowed to flow toward the center by the wrinkle presser cylinder 15 - wrinkle presser rams 14, 14 - blank holder 3 .
As a result, the molding shown in FIGS. 2 and 4 is realized.

If the set pressure of the relief valve 25 of the restraint force control unit 21 is decreased as the pushing depth of the annular punch 2 increases, the restraint cylinder 17
3 and 5 is realized because the internal pressure of the plate 4 is reduced and the pressing force of the restraint plate 4 is weakened.

FIG. 7 shows an example applied to a double-acting press, in which the annular punch 2 is fixed to an inner slide 120 that is raised and lowered by an inner ram 130, a restraint cylinder 17 is built into this inner slide 120, and restraints extending from the restraint cylinder 17 are shown. A restraint plate 4 is fixed to the ram 16.

Further, the blank holder 3 is fixed to an outer slide 121 surrounding an inner ram 130, and is adapted to be raised and lowered by a plurality of outer rams 131, 131 that are in an independent relationship with the inner ram 130.

The restraining cylinder 17 is connected to a restraining force control unit 21 via a conduit 20. The configuration of this control unit is similar to that in FIG. However, in the case of FIG. 7, the blank holder 3 is given a wrinkle pressing force by the outer rams 131, 131, so the pressure of the relief valve 25 of the restraining force control unit 21 is set in correlation with the output of the outer rams 131, 131. .

In this embodiment, the outer ram 131,1
31 and the outer slide 121 apply wrinkle pressing force to the outer ring portion of the blank plate, and in this state, the inner slide 120 is lowered by the inner ram 130, and the restraint plate 4, the restraint cylinder 17, and the restraint force control unit 21 apply wrinkle pressing force to the inner ring portion of the blank plate. The annular punch 2 is pushed into the ring-shaped die hole 3 while applying a stronger pressing force than the outer ring portion of the raw plate, and initial molding is performed. Next, the set pressure of the restraining force control unit 21 is lowered, and the inner ram 130 continues to operate, so that the flanging process smoothly stretches to the target height and progresses.

FIG. 8 shows an example in which the present invention is applied to an inverted press, in which the annular punch 2 has its rear end fixed to a bolster 11 on the bed side, and the die 1 is fixed to a slide 12 that is raised and lowered by a main ram 13. Ru.

The blank holder 3 is supported on a support plate 26 via lift pins 260, 260 passing through the bolster 11, and the support plate 26 is supported on a ram 27 extending from a dicing cylinder 28.

The restraint plate 4 is fixed to a restraint ram 16 from a restraint cylinder 17 installed in the bolster 11,
The restraining cylinder 17 is connected to a restraining force control unit 21 equipped with a relief valve 25 that applies a pressing force greater than the output of the dictation cylinder 28 at the initial stage of molding.

In this embodiment, the blank plate 9 is attached to the blank holder 3 and the restraining plate 4, and is lifted to a higher level than the annular punch 2 by the hydraulic pressure introduced into the dictation cylinder 28 and the restraining cylinder 17, and in this state it is slid. By lowering the die 1 fixed to the die 12, molding is performed while applying a restraining force and a wrinkle suppressing force.

In addition, in FIGS. 6 and 7, by providing the die 1 with a hydraulic circuit as shown in FIG. 1, it becomes a natural pressure increasing type or opposed hydraulic molding device with pre-charge.

Next, specific examples of the present invention will be described.

Material A2024-0 as base plate, plate thickness 1.6mm, diameter
Lipskin was molded using a hole diameter of 1150 mmφ and a hole diameter of 590 mmφ.

The die is a ring-shaped die hole inner diameter (=column diameter)
D ₁ 736.8mmφ, ring die hole outer diameter D ₂ 953.2mm
φ, depth 270 mm, die shoulder radius 10 mm, and the annular punch has a parabolic cross section with an outer diameter of 950 mmφ and an inner diameter of 740 mmφ.

The molding apparatus shown in FIG. 6 was used, and the molding method was adopted by natural pressure-increasing opposed hydraulic molding. The wrinkle pressing force of the blank holder was set to 150 tons using the relief valve of the wrinkle pressing force control unit, the pressing force of the restraining plate was set to 63 tons using the relief valve of the restraining force control unit, and the annular punch was lowered with a pushing force of 400 tons using the main ram.

At the stage when the molding height was 55 mm, the restraint force was lowered to 30 tons using the restraint force control unit, and the annular punch was subsequently lowered with a pushing pressure of 400 tons. As a result,
Inner diameter Da736.8mmφ, outer diameter Db953.2mmφ, height H110
A lip skin element with no wrinkles on the body and flange was molded in one process using mm, and the product was made by cutting at a predetermined position.

The relationship between the punch stroke and opposing hydraulic pressure during this molding is shown in FIG. 10, and the cross-sectional shape and thickness distribution of the molded product are shown in FIG. 11. The plate thickness was measured by looking at the average value at three cross-sectional locations (0°, 45°, and 90° in the roll direction) at 20 mm intervals on the blank plate. It can be seen from FIG. 11 that the decrease in plate thickness is small and good shape and size accuracy can be obtained.

〔Effect of the invention〕

According to the first aspect of the present invention as described above, an excellent effect can be obtained in that a lip skin or a similar product can be molded with a large molding height and good precision in one press stroke.

Further, according to the second aspect of the present invention, an excellent effect can be obtained in that it is possible to provide a device which is suitable for carrying out the first aspect, has a simple structure, and is inexpensive.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views showing step-by-step an example of the lip skin molding method according to the present invention, and Figures 4 and 5 are cross-sectional views showing step-by-step another embodiment of the lip skin molding method according to the present invention. , FIGS. 6 to 8 are cross-sectional views showing an embodiment of a lip skin molding apparatus according to the present invention, FIG. 9 is a partially cutaway side view showing an example of a molded product according to the present invention, and FIG. 10 is a cross-sectional view showing an example of a molded product according to the present invention. The opposing hydraulic pressure-forming stroke diagram in the example, FIG. 11 is an explanatory diagram showing the measurement results of the shape and plate thickness distribution of the molded product. 1...Dice, 2...Annular punch, 3...Blank holder, 4...Restriction plate, 5...Column part,
6...Ring-shaped die hole, 9...Main plate, 10...
Hole, 18...Wrinkle pressing force control unit,
21...Restraint force control unit.

Claims (1)

[Scope of Claims] 1. To obtain lipskin or similar products, a donut-shaped blank is used, and the wrinkle-pressing force applied thereto is divided between the outer ring side and the inner ring side. First, the wrinkle-pressing force on the inner ring side is equal to that on the outer ring side. Lipskins that are made larger and drawn by sliding the material on the outer ring side, and then stretching to the desired height and forming a flange by applying the same wrinkle pressing force on the inner ring side and the outer ring side and pushing in with a punch. molding method. 2 Claim 1 in which the molding is a mold molding method
Method for forming lip skins as described in section. 3. The method for molding lipskins according to claim 1, wherein the molding is a opposed hydraulic molding method. 4. A die having a pillar part in the center and a ring-shaped die hole on its outer periphery, an annular punch inserted into and removed from the ring-shaped die hole, a donut-shaped blank holder facing the upper surface of the outer ring of the ring-shaped die hole, and a pillar. a restraint plate facing the upper surface of the part; a ram that separately operates the blank holder and the restraint plate;
A lip skin molding device characterized by being equipped with a control unit that controls the magnitude of the pressing force of the blank holder and the restraining plate. 5. Lipskins according to claim 4, wherein the die is fixed to a bolster, the annular punch is fixed to a slide that is moved up and down by a main ram, and the slide includes a blank holder and a lifting ram for the restraint plate. molding equipment. 6 The die is fixed to the bolster, the annular punch is fixed to the inner slide that is raised and lowered by the main ram, the inner slide has a built-in cylinder that raises and lowers the restraining plate, and the blank holder is mounted to the outer slide that is raised and lowered by the outer ram. An apparatus for forming lipskins according to claim 4. 7 The die is fixed to a slide that is raised and lowered by the main ram, the annular punch is fixed to the bolster, the bolster has a built-in cylinder that raises and lowers the restraint plate, and the restraint plate is connected to the downward die-cut mechanism through a lift pin that passes through the ring-shaped bolster. An apparatus for forming lipskins according to claim 4, which is supported by: 8. The lip skin molding apparatus according to claim 4, wherein the ring-shaped die hole is a hydraulic pressure chamber and is connected to an external hydraulic pressure supply circuit.