JPS61132232A - Bulge forming apparatus - Google Patents

Abstract

PURPOSE:To increase dimensional accuracy of finishing by setting a max. pressure in the 2nd piston cylinder higher than that in the 1st piston cylinder through a relief valve and installing a check valve on a line between the two cylinders. CONSTITUTION:The 1st cylinder 12, the 2nd cylinder 13, and a fixed lower die 14 are set on a manifold 11. Relief valves 17 and 23 are set on the cylinders 12 and 13, respectively. A pressure of the valve 23 is set higher than that of the valve 17. The check valve 19 is installed on a line between the cylinders 12 and 13 to stop reverse flow from the cylinder 13. A top moving plate 40 is moved down to press a material 1 by a set pressure in the 1st cylinder 12 from the inside before pressing the material 1 by a set pressure in the 2nd cylinder 13. Therefore, pressing forces are controlled to be constant and pressing and bulging are continuously performed to increase dimensional accuracy of the finishing.

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 the movable mold increases hydraulic pressure to stretch and mold the material was developed by the present applicant in Japanese Patent Publication No. 56 -25332 Publication <Patent Registration No. 108422
No. 0) has already been developed.

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 a second movable mold which cooperates with the first and second bushers facing the second piston cylinder and the lower movable mold to form a molding cavity. A material is attached to the lower movable mold, and the lower movable mold is provided with a nozzle that faces into the material. 1st and 2nd above
Working fluid, such as water, pressurized by the piston cylinder is ejected into the material from the nozzle.

The first piston cylinder is set to have a smaller operating stroke than the second piston cylinder, and therefore the first piston cylinder has a smaller operating stroke than the second piston cylinder. In order to allow the second piston cylinder to continue operating even after the stroke is finished, an elastic member such as urethane rubber is provided to absorb these stroke differences.

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 bushings and the upper movable mold descend, and the upper movable mold molds the material that has been attached to the lower movable mold in advance. At the same time as they hit the top surface and begin to push the material in the axial direction, the first and second bushings begin to push the first and second piston cylinders, respectively;
Water pressurized by these first and second piston cylinders is injected 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) material strength and deformation strength of the neck part determined by the material quality, (2) clearance determined by the lower die, nozzle, and plate thickness, (3) jet water flow rate determined by ram speed and piston diameter. , (4) Determined by conditions such as the diameter of the nozzle, the roughness of the side surface, and the precision of the mold shape.

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. In addition,
While the second piston cylinder is in operation, an elastic member such as urethane rubber provided on the first bushing is deformed to maintain the stopped state of the first piston cylinder and absorb the downward stroke of the upper movable plate.

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 processing the product 2 shown in FIG. 9 from the material 1 shown in FIG. 8, the outer diameter d2 of the product 2 shown in FIG. It was found that since the mold was sufficiently larger than d1 and had a large number of irregularities 4 in the circumferential direction, there was an area where the material protruded while the mold was closed, as shown in FIG. When trying to process such a product 2 using the above-mentioned conventional equipment, the seventh
As shown by the broken line in the figure, the material may enter the protruding area and be caught between the lower movable mold and the lower movable mold, causing damage to the outer surface, galling, and breakage.

To prevent this, as shown by the solid line in Figure 7,
The setting must be such that bulge processing is performed within a narrow forming area between the buckling area and the protruding area. Therefore, it is required to make the actuation timing of the first and second pistons more accurate and to set the internal pressure more accurately.

It was also found that, after the mold is closed, if the pressure is increased to ultra-high pressure again, it is possible to process 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: The clearance is determined by the lower die, the nozzle, and the plate thickness, (3) the jet water flow rate determined by the ram speed and piston diameter, (4) the nozzle diameter, side surface roughness, and mold shape accuracy9, etc. Moreover, 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 rise and enter the overflow region, and conversely, if it is set low, the extremely high pressure immediately after the bulge is completed will occur. This has the disadvantage that a product with the desired high precision cannot be obtained.

[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.
! The purpose of the present invention is to provide a bulge forming apparatus that can efficiently form even products with rough shapes with high precision through a series of continuous processes.

[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, reference numeral 10 indicates a lower fixing plate, which is fixed to the bed of a breath 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, and the water supply pipe 15 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 electrically connected to each other by a communication passage 18 formed in the manifold 11. A second check valve 19 is provided to prevent water from flowing back. Further, the communication path 18 includes a pressure feeding path 20 and a discharge path 2.
1 is connected.

The pressure feed path 20 is a high □ pressure nozzle 2 that is fixedly protruding from the upper surface of the manifold 11 and faces the lower fixed mold 14.
2, and the discharge passage 21 is connected to the high pressure second
It is communicated with a tank (not shown) via a relief valve 23 . The opening pressure P2 of the second high-pressure relief valve 23 is set higher than the opening pressure PL of the first low-pressure relief valve 17 (P2 > Pl). Note that a spool valve 24 is provided in the pressure feeding path 20.

The first cylinder 12 is coaxially provided with a first-stage piston 25 and a second-stage piston 26 that can reciprocate in the vertical direction.
It forms a stepped 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 subsequently 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 has a second piston 2 that can reciprocate in the vertical direction.
8 is provided.

Although not shown in detail, automatic air vent devices 29, 29 are provided on the upper surfaces of the first piston 25 and the second piston 28, respectively.
are provided to bleed air from the first cylinder 12 and the second cylinder 13, respectively. Further, each piston 25, 26, 28 is adapted to be raised and returned to its original position by the water supply pressure.

The lower fixed mold 14 has a receiver fixed to a stand 30, and the lower fixed mold 14 has a vertical through hole 31 located in the center.
is drilled. The nozzle 22 is inserted into this through hole 31.
is penetrated. In this case, as shown in FIG. 5(A), 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 nozzle 22 and the outer surface of the nozzle 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. 9 is formed on the upper surface of the lower fixed mold 14.
The vertical through hole 31 is opened at the center lower surface of. The upper end opening of the nozzle 22 extends into the cavity 33. Note that the cavity 33 is provided with an air channel (not shown).

A relief chamber 34 is formed in the stand 30, and this relief chamber 34
communicates with the cavity 33 through a gap formed between the inner surface of the through hole 31 and the outer surface of the nozzle 22, and is opened to a 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 and to be fixed to a ram of a press wire machine (not shown). On the lower surface of the upper movable plate 40, the first cylinder 12 and the second cylinder 13 are arranged opposite to the lower fixed mold 14, and a first pusher v41, a second pusher 42, and an upper movable mold 43 are arranged on the lower surface of the upper movable plate 40. is installed.

The first bushing 41 and the second bushing 41 and 42 move up and down together with the upper movable plate 40, but the first bushing 41 and the second bushing 41 and 42 move up and down together with the upper movable plate 40.
The timing at which the second button 42 presses the second piston 28 is set to be earlier than the timing at which the second button 42 presses the second piston 28. That is, as the upper movable plate 40 descends, the first and second bushings 41 and 42 descend together, but first the first bushing 41 touches the first stage piston 25.
When the 250 strokes of the first stage piston are completed, this first bushing 41 continues to push the second stage piston 2G, and when the second stage piston 26 is pushed to a predetermined stroke, the second stage piston 26 is finally pressed. Butsusha 4
2 is set to begin pushing the second piston 28.

Note that these first and second buttons 41 and 42 are 1
When it hits the stage piston 25 and the second piston 28, the atmosphere release hole of the air vent device 29, 29 is closed.

The upper movable mold 43 faces the lower fixed mold 14 and is in contact with the lower fixed mold 14 so as to be able to come into contact with and separate from it. A substantially hemispherical cavity 44 matching the shape is formed.

The upper movable mold 43 is held by a retainer 45,
This 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. A first cushion 47 made of an elastic member such as a spring or urethane rubber is provided between the retainer 45 and the guide holder 46, and an upward pressure of more than a predetermined value is applied to the upper movable mold 43 from below. In this case, the lowering of the upper movable die 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 from below to the upper movable mold 43. Therefore, the second cushion 48 has a larger elastic force than the first cushion 47.

Regarding the operation of such a groove bottom bulge forming device, see the fifth section.
This will be explained with reference to FIGS. 7 to 7.

First, as shown in FIG. 1, the upper movable plate 40 is brought 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 part 3 of the material 1 is fitted into the vertical through hole 31 of the lower fixed mold 14, as shown in FIG. A gap serving as a passage 32 is secured between the inner surface of the nozzle 22 and the outer surface of the nozzle 22.

At this time, water maintained at a constant pressure from a water supply device (not shown) is supplied from the water supply pipe 15 to the first cylinder 12 through the first check valve 16 and the relief valve 17 of the low pressure foil 1, and Water is also supplied to the second cylinders 13 via 18, and these first cylinders 12
and the second cylinder 13 is 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. Also,
When filling the first cylinder 12 and the second cylinder 13 with water, the air in the cylinder 12.13 is expelled to the outside through the air bleed device 29.29.

Thus, when the first and second cylinders 12.13 are filled with water, the upper movable plate 40 is lowered from time A shown in FIG. 6, and when this reaches 8 hours in FIG. As shown in the figure, the first bushing 41 hits the first stage piston 25, and the upper surface of the cavity 44 of the upper movable mold 43 hits the top surface of the material 1. Note that when the first bushing 41 hits the first stage piston 25, the atmosphere opening hole of the air vent device 29 provided in the first stage piston 25 is closed.

The upper movable plate 40 is further lowered, and the first stage piston 25 is pushed down between hours 8 and C in FIG. 6, pressurizing the water in the first cylinder 12, which opens the spool valve 24 Pressure water for the lever is supplied into the material 1 from the nozzle 22 through the communication path 18 and the pressure feeding path 20. The water pressure in this case is relatively low because it is generated by the first stage piston 25, and such low pressure water supply continues for a period from 8 hours to C time.

During this time, the upper movable die 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 die 43 tries to push the top surface of the material 1. The mold 43 stops descending while hitting the top surface of the material 1.

When the upper movable plate 40 reaches time C in FIG.
When the operating stroke of the first stage piston 25 ends, the first stage piston 25 starts pushing the second stage piston 26, so the first stage piston 25 and the second stage piston 26 are pushed together by the first bushing 41. will be lowered to At this stage, the pressurized area of the first cylinder 12 increases, so the amount of water supplied from the nozzle 22 to the inside of the material 1 from the communication passage 18 through the pressure passage 20 increases, and this amount of supplied water is released through the passage 32. Since the amount is much larger than the amount of water, the internal pressure of the material 1 rises rapidly.

At this time, the upper movable mold 43 moves the upper movable plate 4
Due to the balance between the lowering speed of 0 and the elastic force of the first cushion 47, the upper movable plate 40 is lowered at a lower speed than the lowering speed of the upper movable plate 40, as shown between time C and time 0 in FIG. Therefore, the upper movable mold 43 pushes the top surface of the material 1,
As shown in FIG. 5(C), the material 1 is press-molded while the top surface is pressed downward and receives the pressure from the inside.

When the upper movable plate 40 reaches time 0 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 Pl is increased. I miss the pressure to pursue it.

That is, even after time 0 in FIG. 6, the pressure inside the material 1 that exceeds Pl is released by the first relief valve 17, so that the pressure inside the material 1 is maintained at Pl.

At this time, the first cushion 47 reaches the maximum compression state,
No longer acting as a cushion, 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,
As a result, as shown in FIG. 5(D), the cavity 33
and block 44. Therefore, the upper movable mold 43 is stopped regardless of the lowering of the upper movable plate 40.

When the upper movable plate 40 continues to be lowered and reaches time F in FIG. 6, the second bushing 42 hits the second piston 28, as shown in FIG. For this reason,
Thereafter, pressurized water is supplied from the second cylinder 13. That is, before the second bushing 42 hits the second piston 28, the second cylinder 13 is maintained at Pl because it communicates with the first cylinder 12 through the communication passage 18, and the second bushing 42 is kept at Pl. 42 hits the second piston 28, the piston 28 pressurizes the water in the second cylinder 13.

The communication passage 18 is provided with a check valve 19 that prevents the flow from the second cylinder 13 toward the first cylinder 12.
1 or more pressure is not transmitted to the first cylinder 12 side, that is, first to the relief valve 17 side, so after the second bushing 42 hits the second piston 28, no pressure is transmitted to the second cylinder 13. A pressure of 21 or more 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.

The upper movable plate 40 continues to descend, but since the upper movable mold 43 is in contact with the lower fixed mold 14, it is stopped.
At this time, the retainer 45 hits the second cushion 48 and the cushioning action of the second cushion 48 keeps the upper movable mold 43 stationary.

As a result, a large pressure is applied to the material 1 from within the closed cavity 33.44, as shown in Fig. 5 (E).
) is bulge molded as shown.

Then, the pressure inside the second cylinder 13, that is, the material 1
When the internal pressure reaches the opening pressure 22 of the second relief valve 23 or higher, the second relief valve 23 opens,
Maintain the internal pressure of material 1 within 92°C. As a result, material 1
to prevent breakage.

When the upper movable plate 40 reaches time 0 as shown in FIG. 6, the upper movable plate 40 reaches the bottom dead center and completes the bulge forming as shown in FIG.

When time 0 in FIG. 6 is exceeded, the upper movable plate 40 returns to the upward position. Due to the return of the upper movable plate 40,
After the second bushing 42 separates from the second piston 28 and the second-stage piston 26 completes its return stroke, the upper movable mold 43 also begins to rise, opening the gear and tee. From then on,
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, the first cylinder 12 is
replenish water.

Thereafter, the above operation is reversed to perform continuous processing.

According to the above-mentioned bulge processing apparatus, relatively low pressure water is supplied into the material 1 by the pressing action of the first stage piston 25 in the initial stage, as shown in FIG. 7. When the first-stage piston 25 finishes its stroke and the second-stage piston 26 starts operating, the pressure inside the first cylinder 12 rises rapidly, causing the internal pressure of the material 1 to rise rapidly. Due to the balance between the pressure 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.

The pressure in the first cylinder 12 is reduced to the first relief valve 1
When the set pressure P1 of No. 7 is exceeded, this relief valve 17 opens to maintain the internal pressure of the material 1 at Pl, and this pressure is maintained until the mold is closed, so that press forming is not performed between the protruding region and the buckling region. It will proceed smoothly.

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 rope material 1 reaches the set pressure P1 or higher of the second relief valve 23, the relief valve 23 opens and prevents any further increase in pressure. will be held.

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 controlled to be constant regardless of the movement of the upper movable plate 40, making it possible to perform bulge forming with high precision. become.

〔Effect of the invention〕

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

[Brief explanation of the drawing]

1 to 7 show one embodiment of the present invention, FIG. 1 is a sectional view showing the groove bottom of the entire device, FIGS. 2 to 4 are sectional views showing different operating states, and FIG. 5 (A) to fifth
Figure (E) is a process explanatory diagram showing the molding process sequentially, Figure 6 is a flowchart showing the operation timing, Figure 7 is a characteristic diagram showing the internal pressure of the material during molding, Figure 8 is a perspective view of the material,
FIG. 9 is a perspective view of the product. DESCRIPTION OF SYMBOLS 1...Material, 2...Product, 10...Lower movement fixing plate, 11...Manifold, 12...First cylinder, 13...Second cylinder, 14...Bottom Side 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, 25... First stage Piston, 26... Second stage piston, 28... Second piston, 40... Upper movable plate, 41... First button, 42... Second button, 43...
Upper movable type, 47... first cushion, 42...
Second cushion. Applicant's agent Patent attorney Takehiko Suzue Figure 7 Unexamined Patent Publication - Figure 8 Figure 9

Claims (3)

[Claims] (1) A molding mechanism including first and second piston cylinders and at least one movable mold that pressurizes the material from the outside, and a molding mechanism that supplies liquid pressurized by each of the piston cylinders into the material. a liquid introduction mechanism that cooperates with the molding mechanism to pressurize and mold the material; and a liquid introduction mechanism that drives a second piston cylinder to operate subsequent to the operation of the first piston cylinder, and operates the movable mold on the material. 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 is provided for setting the maximum pressure of the piston cylinder to a maximum pressure higher than the maximum pressure of the first piston cylinder, and a second relief valve is provided between the first piston cylinder and the second piston cylinder. A check valve is provided to prevent liquid from flowing backward from the second piston 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 A bulge forming device characterized by a cylinder supplying 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, the first cushion being actuated during operation of the first piston cylinder, and the second cushion being actuated during operation of the first piston cylinder. 2. The bulge forming apparatus according to claim 1, wherein the cushion is actuated during operation of the second piston cylinder. (3) The first piston cylinder is a two-stage piston cylinder that includes a first-stage piston and a second-stage piston coaxially. Or the bulge forming device according to item 2.