JPS6251691B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention applies a pressing force in the axial direction to a material using a movable mold to press-form the material, and increases the hydraulic pressure inside the material within the movable mold. The present invention relates to a bulge forming device for stretch forming a material.

[Technical background of the invention]

A continuous bulge forming method in which a movable mold applies axial pressing force to a material to press-form the material, and then increases hydraulic pressure in the movable mold to stretch and mold the material was developed by the applicant in Japanese Patent Publication No. 56 It has already been developed as Publication No. -25332 (Patent Registration No. 1084220).

The device applied to the bulge molding method described in the above publication is such that the first piston cylinder, the second piston cylinder, and the lower movable mold are attached to the lower fixed plate, and the first piston cylinder and the lower movable mold are attached to the upper movable plate. and an upper movable mold that constitutes a molding cavity in cooperation with the first and second pushers facing the second piston cylinder and the lower movable mold. A material is attached to the lower movable mold, and the lower movable mold is provided with a nozzle that faces into the material. Working fluid, such as water, pressurized by the first and second piston cylinders is ejected into the material from the nozzle.

The first piston cylinder has a smaller operating stroke than the second piston cylinder, so the first pusher that presses the first piston cylinder has a smaller operating stroke than the second piston cylinder. The second piston cylinder is provided with an elastic member, such as urethane rubber, for absorbing these stroke differences so that the second piston cylinder can continue to operate even if the stroke difference occurs.

Further, the lower movable type and the upper movable type are each provided with an elastic member, such as urethane rubber, so that the second piston cylinder can continue to operate in the closed state.

According to such a bulge forming apparatus, as the upper movable plate descends, the first and second pushers and the upper movable die move downward, and the upper movable die presses the material that has been attached to the lower movable die in advance. At the same time as the material hits the top surface and begins to push the material in the axial direction, the first and second pushers begin to press the first and second piston cylinders, respectively, and are pressurized by these first and second piston cylinders. The water is sprayed into the material from the nozzle. The pressurized water sprayed from the nozzle initially stirs the air inside the material to create a bubble mixture, but when the neck of the material moves away from the nozzle, it is expelled to the outside through these gaps. At this time, the internal pressure is determined by (1) the strength of the material, the deformation strength of the neck part determined by the material quality, (2) the clearance determined by the lower die, nozzle, and plate thickness;
(3) The injection water flow rate is determined by the ram speed and piston diameter, (4) It is determined by conditions such as the nozzle diameter, side surface roughness, and mold shape accuracy.

When the material is pressed by a predetermined amount in the axial direction, the first piston cylinder completes its stroke, and thereafter the second piston cylinder supplies pressurized water to the nozzle. Note that while the second piston cylinder is in operation, an elastic member such as urethane rubber provided on the first pusher is deformed to maintain the stopped state of the first piston cylinder and absorb the downward stroke of the upper movable plate. do.

Thereafter, the upper movable mold comes into contact with the lower movable mold to close the molding cavity, and stretch molding is performed so that the material follows the inner surface of the molding cavity.

In such a device, the actuation timing of the first and second pistons is adjusted so as to skillfully avoid the buckling region and the fracture region and achieve smooth bulge formation, as shown by the broken line in FIG. is set.

However, for example, when attempting to process product 2 shown in FIG. 9 from material 1 shown in FIG. 8, product ₂ shown in FIG. It was found that since the mold was sufficiently larger than the diameter d ₁ and provided with a large number of irregularities 4 in the circumferential direction, there was a region where the material protruded while the mold was closed, as shown in FIG. When such a product 2 is processed using the above-mentioned conventional device, it enters the protruding area as shown by the broken line in FIG. It may cause scratches, galling, or breakage.

In order to prevent this, settings must be made so that the bulging process is performed within a narrow forming area between the buckling area and the protruding area, as shown by the solid line in FIG. Therefore, the first and second
The operation timing of the piston is made more precise,
Moreover, more accurate internal pressure setting is required.

Furthermore, after the mold was closed, it was found that by raising the pressure to ultra-high pressure again, it was possible to form bulges in complex shapes with high precision.

[Problems with background technology]

However, in the conventional bulge forming apparatus used for the method disclosed in the above-mentioned publication, the internal pressure inside the material is as described above (1) material strength, deformation strength of the neck part determined by the material quality of the material, ( 2) Clearance determined by the lower die, nozzle and plate thickness, (3) Injection water flow rate determined by ram speed and piston diameter, (4)
It is determined by conditions such as the diameter of the nozzle, the roughness of the side surface, and the accuracy of the mold shape, and is configured such that only the maximum pressure is determined by the relief valve. For this reason, if the set pressure of the relief valve is set high, the internal pressure will become high and enter the overflow region, and if it is set low, on the other hand, ultra-high pressure will not be generated immediately after the bulge is completed, making it impossible to obtain the desired high-precision product. It was hot.

[Purpose of the invention]

The present invention was developed based on these circumstances, and its purpose is to be able to set the pressure applied inside the material at any desired timing and with high precision, and to produce products with complex shapes. The object of the present invention is to provide a bulge forming apparatus that can perform efficient and highly accurate forming through a series of continuous processing even when the bulge is formed.

[Summary of the invention]

In order to achieve the above object, the present invention provides the first piston cylinder with a first relief valve that sets the maximum pressure of the first piston cylinder, and the second piston cylinder with a first relief valve that sets the maximum pressure of the first piston cylinder. a second relief valve that sets the maximum pressure of the first piston cylinder to a maximum pressure higher than the maximum pressure of the first piston cylinder, and between the first piston cylinder and the second piston cylinder, the second piston cylinder A check valve is provided to prevent liquid from flowing backward from the cylinder side to the first piston cylinder side, and after the first piston cylinder supplies relatively low pressure liquid into the material, the second piston cylinder It is characterized by supplying high-pressure liquid into the material.

[Embodiments of the invention]

The present invention will be described in detail below based on the embodiments shown in FIGS. 1 to 7. In FIGS. 1 to 4 showing the entire apparatus, 10 indicates a lower fixing plate, which is fixed to the bed of a press machine (not shown). A manifold 11 is attached to the upper surface of the lower fixed plate 10, and the manifold 11 is provided with a first cylinder 12, a second cylinder 13, and a lower fixed mold 14.

The first cylinder 12 is connected to a water supply device (not shown) through a water supply pipe 15.
5 is provided with a first check valve 16 and a first relief valve 17 for low pressure. The first cylinder 12 and the second cylinder 13 are connected to each other by a communication passage 18 formed in the manifold 11, and the second cylinder 13 is connected to the communication passage 18.
A second check valve 19 is provided to prevent water from flowing backward from the side toward the first cylinder 12 side. Further, a pressure feeder 20 and a discharger 21 are connected to the communication path 18. The pressure feed path 20 includes a high-pressure nozzle 22 that is fixedly protruding from the upper surface of the manifold 11 and faces the lower fixed mold 14.
The discharge passage 21 is connected to a tank (not shown) via a second high-pressure relief valve 23. The opening pressure P ₂ of the second high-pressure relief valve 23 is set higher than the opening pressure P ₁ of the first low-pressure relief valve 17 (P ₂ >P ₁ ). Note that a spool valve 24 is provided in the pressure feeding path 20.

The first cylinder 12 includes a first stage piston 25 and a second stage piston 2 that can reciprocate in the vertical direction.
6 are coaxially arranged, so that the first piston cylinder forms a two-stage piston cylinder. In this case, when the first stage piston 25 is pushed and its stroke ends, the first stage piston 25 and the second stage piston 26 are continuously pushed integrally. 2nd stage piston 26
An extrusion hole 27 is provided in which the water pushed by the first stage piston 25 is extruded. On the other hand, the second cylinder 13 is provided with a second piston 28 that can reciprocate in the vertical direction.

Although not shown in detail, automatic air venting devices 28 and 29 are provided on the upper surfaces of the first piston 25 and the second piston 28, respectively.
The air inside the cylinder 12 and the second cylinder 13 is vented. In addition, each piston 25, 2
6 and 28 are designed to be raised and returned by water supply pressure.

The lower fixed mold 14 is fixed to a pedestal 30, and a vertical through hole 31 is bored in the lower fixed mold 14 at the center thereof. This through hole 3
1 has the nozzle 22 inserted therethrough. In this case, as shown in FIG. 5A, there is a gap between the inner surface of the through hole 31 and the outer surface of the nozzle 22 even though the neck portion 3 of the material 1 is fitted into the inner surface of the through hole 31. A gap is provided between the outer surfaces of 22 to ensure a passage 32. A substantially hemispherical cavity 33 that matches the shape of the lower half of the product 2 shown in FIG.
is opened. The upper end opening of the nozzle 22 extends into the cavity 33. In addition,
Although not shown, an air vent is formed in the cavity 33.

A relief chamber 34 is formed in the pedestal 30, and the relief chamber 34 is connected to the cavity 33 through the gap formed between the inner surface of the through hole 31 and the outer surface of the nozzle 22.
It is connected to the tank (not shown) through a discharge pipe.

Above the manifold 11 as described above, an upper movable plate 40 is disposed to face the manifold 11.
is arranged so as to be fixed to a ram of a press machine (not shown). Upper movable plate 40
On the lower surface of the first cylinder 12 and the second cylinder 12,
A first pusher 41, a second pusher 42, and an upper movable mold 43 are mounted opposite the lower fixed mold 14, respectively.

The first and second pushers 41 and 42 move up and down together with the upper movable plate 40, but the first
The timing at which the pusher 41 pushes the first-stage piston 25 and the second-stage piston 26 is set to be earlier than the timing at which the second pusher 42 pushes the second piston 28. That is, as the upper movable plate 40 descends, the first and second pushers 41 and 42 descend together, but first the first pusher 41
5, press this and the first stage piston 25
After completing the stroke, the first pusher 41 continues to push the second piston 26, and when the second piston 26 is pushed to a predetermined stroke, the second pusher 42 pushes the second piston 28. It is set to start pressing .

Note that these first and second pushers 41,
When the piston 42 hits the first piston 25 and the second piston 28, the air vent holes of the air vent devices 29, 29 are closed.

The upper movable mold 43 faces the lower fixed mold 14 and contacts the lower fixed mold 14 so as to be able to come into contact with and separate from the lower fixed mold 14.
A substantially hemispherical cavity 44 matching the shape of the upper half of the product 2 shown in FIG. 9 is formed on the lower surface of the upper movable mold 43.

The upper movable die 43 is held by a retainer 45, and the retainer 45 is attached to a guide holder 46 fixed to the upper movable plate 40 so as to be slidable in the vertical direction. Retainer 45
A first cushion 47 made of an elastic member such as a spring or urethane rubber is provided between the guide holder 46 and the guide holder 46, and when an upward pressure of more than a predetermined value is applied to the upper movable mold 43 from below, The lowering of the upper movable mold 43 is stopped regardless of the lowering of the upper movable plate 40. Further, the upper movable plate 40 is provided with a second cushion 48 that passes through the guide holder 46 and faces the retainer 45. This second cushion 48 also stops the lowering of the upper movable mold 43 regardless of the lowering of the upper movable plate 40 when a larger upward pressure of more than a predetermined value is applied to the upper movable mold 43 from below. Therefore, the second cushion 48
has a larger elastic force than the first cushion 47.

The operation of the bulge forming apparatus having such a structure will be explained with reference to FIGS. 5 to 7.

First, as shown in FIG.
0 to the uppermost position, and the material to be molded, eg, the material 1 of FIG. 8 made of brass, is placed in the cavity 33 of the lower fixed mold 14. In this case, the neck portion 3 of the material 1 is fitted into the vertical through hole 31 of the lower fixed mold 14, as shown in FIG.
4, and the inner surface of this neck part 3 and the nozzle 22
A gap to form a passage 32 is secured between the outer surface of the

At this time, water maintained at a constant pressure is supplied from a water supply device (not shown) through the water supply pipe 15 to the first check valve 16 and the first low pressure relief valve 17.
Water is supplied to the first cylinder 12 through the passage 18, and also to the second cylinder 13 through the communication passage 18, so that the first cylinder 12 and the second cylinder 13 are filled with water. Note that the spool valve 24 is maintained not to open under the water supply pressure sent from the water supply device through the water supply pipe 15.
Further, when the first cylinder 12 and the second cylinder 13 are filled with water, the air inside the cylinders 12 and 13 is exhausted to the outside through the air purge devices 29 and 29.

Thus, the first and second cylinders 12,1
3 is filled with water, the upper movable plate 40
is lowered from time A shown in FIG. 6, and when it reaches time B in FIG. 6, as shown in FIG. 2, the first pusher 41 hits the first stage piston 25 and the upper movable mold 43 cavities 4
The top surface of material 4 corresponds to the top surface of material 1. Note that when the first pusher 41 hits the first stage piston 25,
Air vent device 2 provided on this first stage piston 25
No. 9 air vents are closed.

Furthermore, the upper movable plate 40 is lowered, and the sixth
Between time B and time C in the figure, the first stage piston 2
5 is pushed down, the water in the first cylinder 12 is pressurized, which opens the spool valve 24 and the pressurized water is supplied from the nozzle 22 into the material 1 through the communication path 18 and the pressure feeding path 20. In this case, the water pressure is generated by the first-stage piston 25, so it is relatively low pressure, and such low-pressure water supply continues from time B to time C.

During this time, the upper movable mold 43 tries to push the top surface of the material 1, but receives an upward force due to the resistance of the material 1. This force is absorbed by the elastic deformation of the first cushion 47, and the upper movable mold 43 tries to push the top surface of the material 1. The mold 43 stops descending while touching the top surface of the material 1.

When the upper movable plate 40 reaches time C in FIG.
and the second stage piston 26 is the first pusher 41
and are pushed down together. At this stage, the pressurized area of the first cylinder 12 increases, so the amount of water supplied from the communication path 18 to the inside of the material 1 from the nozzle 22 through the pressure feed path 20 increases, and this amount of supplied water is replaced by the amount of water released through the path 32. Since the amount is sufficiently larger, the internal pressure of the material 1 increases rapidly.

At this time, the upper movable die 43 moves as shown between time C and time D in FIG. 6 due to the balance between the lowering of the upper movable plate 40 and the elastic force of the first cushion 47. It is lowered at a lower speed than the descending speed. Therefore, the upper movable die 43 pushes the top surface of the material 1, and the material 1
As shown in Figure C, the top surface is pressed downward and press molded while receiving pressure from the inside.

When the movable plate 40 reaches time D in FIG. 6, the pressure in the first cylinder 12 exceeds the opening pressure _P1 of the first relief valve 17, so the first relief valve 17 is opened and Relieve pressure greater than ₁ . In other words, even after time D in FIG.
The amount of internal pressure exceeding P ₁ is released by the first relief valve 17, so the pressure inside the material 1 is maintained at P ₁ .

At this time, the first cushion 47 has reached its maximum compression state and no longer has a cushioning effect, and the upper movable mold 43 is lowered at the same speed as the upper movable plate 40. Therefore, in this state, press molding is performed while maintaining the internal pressure of the material 1 constant.

When the upper movable plate 40 reaches time E in FIG. 6, the lower surface of the upper movable mold 43 comes into contact with the upper surface of the lower fixed mold 14, thereby closing the cavities 33 and 44 as shown in FIG. 5D. do. Therefore, the upper movable die 43 is stopped regardless of the lowering of the upper movable plate 40.

Subsequently, the upper movable plate 40 is lowered,
When time F in FIG. 6 is reached, the second pusher 42 moves the second piston 28 as shown in FIG.
corresponds to Therefore, pressurized water is supplied from the second cylinder 13 from now on. That is, before the second pusher 42 hits the second piston 28,
Since the second cylinder 13 communicates with the first cylinder 12 through the communication passage 18, it is maintained at _P1 .
When the second piston 28 hits the second pusher 42, the water in the second cylinder 13 is pressurized by the piston 28. The communication path 18 is connected from the second cylinder 13 to the first cylinder 12.
Since a check valve 19 is provided to prevent the flow toward P ₁ generated in the second cylinder 13,
The above pressure is not transmitted to the first cylinder 12 side, that is, first to the relief valve 17 side, and therefore, after the second pusher 42 hits the second piston 28, it is transmitted to the second cylinder 13. A pressure greater than P ₁ is generated. This pressure is transmitted to the inside of the material 1 through the nozzle 22, so that the internal pressure of the material 1 rises rapidly again.

Although the upper movable plate 40 continues to descend,
Since the upper movable mold 43 is in contact with the lower fixed mold 14, it is stopped, and at this time, the retainer 45 hits the second cushion 48 and the second cushion 4
The upper movable die 43 is kept stationary by the action of the cushion 8.

As a result, material 1 is closed cavity 3
3, 44, a large pressure is applied from the inside, so that a bulge is formed as shown in FIG. 5E.

Then, the pressure inside the second cylinder 13, that is, the internal pressure of the material 1 is applied to the second relief valve 23.
When the opening pressure reaches P ₂ or higher, this second relief valve 23 opens to maintain the internal pressure of the material 1 within P ₂ . This prevents the material 1 from breaking.

When the upper movable plate 40 reaches time G in FIG. 6, the upper movable plate 40 reaches the bottom dead center and reaches the fourth position.
Finish the bulge forming as shown in the figure.

After time G in FIG. 6 is exceeded, the upper movable plate 40 returns to the upward position. After the second pusher 42 is separated from the second piston 28 due to the upward return of the upper movable plate 40, when the second stage piston 26 completes its return stroke, the upper movable die 43 also begins to rise and the cavity opens. Thereafter, the upper movable plate 40 returns to the top dead center and one cycle of machining is completed.

Therefore, the product 2 remaining in the lower fixed mold 14 is taken out, and the next material 1 is inserted. During such product removal and material input, water is supplied to the first cylinder 12 from the water supply pipe 15.

Thereafter, the above operations are repeated to perform continuous processing.

According to the above bulging apparatus, as can be understood from FIG. 7, relatively low pressure water is supplied into the material 1 by the pressing action of the first stage piston 25 in the initial stage. And the first stage piston 25
When the piston 26 finishes its stroke and the second stage piston 26 starts operating, the pressure inside the first cylinder 12 rises rapidly, so the internal pressure of the material 1 rises rapidly.
Due to the balance between the internal pressure at this time and the force of the upper movable die 43 pushing the top of the material 1 downward, the material 1 is press-formed while avoiding the protruding region and without being in the buckling region.

When the pressure inside the first cylinder 12 exceeds the set pressure P ₁ of the first relief valve 17, this relief valve 17 opens to maintain the internal pressure of the material 1 at P ₁ , and from then on until the mold closes. Therefore, press forming can proceed smoothly between the protruding area and the buckling area.

When the second piston 28 starts operating, the pressure inside the material 1 rises rapidly again, and stretch molding is performed. In this case, when the pressure inside the material 1 reaches the set pressure P ₁ of the second relief valve 23 or higher, the relief valve 23 opens to prevent further pressure rise, so bulging can be performed without reaching the rupture area. It will be done.

Therefore, in the above embodiment, the pressure applied to the material is controlled by the first and second relief valves 17 and 23, and this pressure can be kept constant regardless of the movement of the upper movable plate 40, so that highly accurate bulge forming can be achieved. becomes possible.

〔Effect of the invention〕

As described above, according to the present invention, the pressure applied to the material by the first and second relief valves can be controlled with high precision, so that pressure molding and stretch molding can be performed while avoiding protruding regions, buckling regions, and fracture regions. Can be performed continuously and with high precision. Therefore, even if the product has a complicated shape, bulge molding with a good finish can be performed.

[Brief explanation of the drawing]

1 to 7 show one embodiment of the present invention, FIG. 1 is a sectional view showing the overall structure of the device, and FIG.
Figures 4 through 4 are cross-sectional views showing different operating states;
Figures 5A to 5E are process explanatory diagrams showing the molding process in sequence, Figure 6 is a flow chart showing the operation timing, Figure 7 is a characteristic diagram showing the internal pressure of the material during molding, and Figure 8 is a A perspective view of the material, and FIG. 9 is a perspective view of the product. DESCRIPTION OF SYMBOLS 1...Material, 2...Product, 10...Lower fixed plate, 11...Manifold, 12...First cylinder, 13...Second cylinder, 14...Lower fixed type, 15... Water supply pipe, 16... first check valve, 17... first relief valve, 19...
...Second check valve, 22...Nozzle, 23...
Second relief valve, 24...Spool valve, 2
5...1st stage piston, 26...2nd stage piston, 28...2nd piston, 40...upper movable plate, 41...1st pusher, 42...2nd pusher, 43... Upper movable type, 47...first cushion, 42...second cushion.

Claims (1)

[Scope of Claims] 1. A molding mechanism including first and second piston cylinders and at least one movable mold that pressurizes the material from the outside; a liquid introduction mechanism that pressurizes and molds the material in cooperation with the molding mechanism; a liquid introduction mechanism that drives a second piston cylinder to operate subsequent to the operation of the first piston cylinder; In the bulge forming apparatus, the first piston cylinder is provided with a first relief valve that sets the maximum pressure of the first piston cylinder, and the second piston cylinder is provided with a first relief valve that sets the maximum pressure of the first piston cylinder. a second relief valve that sets the maximum pressure of the second piston cylinder to a maximum pressure higher than the maximum pressure of the first piston cylinder; In between, a check valve is provided to prevent liquid from flowing back from the second piston cylinder side to the first piston cylinder side, and after the first piston cylinder has supplied relatively low pressure liquid into the material. A bulge forming apparatus characterized in that a second piston cylinder supplies relatively high pressure liquid into the material. 2. The movable mold of the molding mechanism includes a relatively weak first cushion and a relatively strong second cushion,
Claim 1, wherein the first cushion is actuated during actuation of the first piston cylinder, and the second cushion is actuated while the second piston cylinder is actuated. bulge forming equipment. 3. The first piston cylinder is a two-stage piston cylinder that includes a first-stage piston and a second-stage piston coaxially. The bulge forming device according to item 2.