JP2012218059A - Pressure control system for press molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to quickly change the pressing force of hydraulic cylinders in an upper mold according to the movement of a press molding apparatus, and to thin piping from the hydraulic cylinders to secure lay-out property.SOLUTION: This pressure control system 50 includes a supply side hydraulic path 30 for supplying an operating fluid to the hydraulic cylinders 4 arranged in an upper mold 2 of the press molding apparatus 51, and a return side hydraulic path 20 for discharging the operating fluid from the hydraulic cylinders 4. The return side hydraulic path 20 has a pressure damping container 13 connected to the hydraulic cylinders 4 through a return side on-off control valve 26, and the passage cross section of a first passage 21 from the hydraulic cylinders 4 to the pressure damping container 13 is larger than that of a second passage 24 downstream of the pressure damping container 13.

Description

  The present invention relates to a pressure control system for a press molding apparatus, and more specifically, the pressure of a hydraulic cylinder in a press mold can be quickly switched in accordance with the movement of the press molding apparatus, and the pipe from the hydraulic cylinder is made narrower. It is related with the pressure control system of the press molding apparatus which can ensure handling property.

Conventionally, there has been proposed a press forming method capable of performing draw processing and trim processing or trim bend processing in one behavior (see Patent Document 1).
That is, in such a press molding method, first, the upper mold is lowered toward the lower mold on which the workpiece is placed, and the molding pad suspended from the upper mold via the hydraulic cylinder is used as the hydraulic pressure of the hydraulic cylinder. The workpiece is drawn by maintaining pressure at a high pressure and pressing it against the lower die. Thereafter, the hydraulic pressure of the hydraulic cylinder is rapidly lowered to a low pressure that maintains the work pressing state of the work to the lower mold by the molding pad.
Thereafter, the upper die is further lowered, and the workpiece is trimmed or trimmed with a trim blade provided on the upper die.

JP 2003-103313 A

  Here, the press forming apparatus for performing the press forming method described in Patent Document 1 is a method in which a pressing force of a hydraulic cylinder in which a forming pad is suspended from an upper die is pressed against the lower die. Therefore, it is necessary to rapidly lower at the timing of the end of the drawing process from the high pressure maintained for the drawing process to the low pressure for maintaining the pressing state of the work to the lower mold by the molding pad.

As shown in FIG. 4 (schematic diagram showing a pressure control system of a conventional press molding apparatus), a hydraulic cylinder provided on an upper mold 102 of a press molding apparatus 151 and having a molding pad 103 suspended from the upper mold 102 The hydraulic system for operating 104 includes a supply-side hydraulic passage 131 connected from the hydraulic pump 115 to the hydraulic cylinder 104 via a supply-side open / close valve 136, and a return-side open / close control valve from the hydraulic cylinder 104 to the hydraulic oil tank 116. 126 and a return-side hydraulic passage 121 connected through 126.
The supply side hydraulic passage 131 and the return side hydraulic passage 121 include a flexible pipe 135 and a flexible pipe 125, respectively, in order to absorb the movement F of the upper mold 102 that moves up and down.

Here, in order to rapidly lower the working oil pressure in the hydraulic cylinder 104, it is necessary to cause the working oil to flow through the return side hydraulic passage 121 rapidly. For that purpose, it is necessary to make the return side hydraulic passage 121 (and the flexible pipe 125) sufficiently thick (the flow passage area is large) (see FIG. 4).
However, increasing the return-side hydraulic passage 121 (and the flexible pipe 125) (increasing the flow path area) increases the diameter of the pipe connecting the upper mold 102 and the base 152 of the press molding apparatus 151, and handling the pipe. Worsens sex.

  The present invention has been made in view of such a situation, and the pressing force of the hydraulic cylinder in the press mold can be quickly switched in accordance with the movement of the press molding apparatus, and the piping from the hydraulic cylinder is made thinner. It is an object of the present invention to provide a pressure control system for a press molding apparatus that can ensure handling.

(1) a lower mold (for example, a lower mold 1 described later) on which a plate-shaped workpiece (for example, a workpiece W described later) is placed;
An upper mold (for example, an upper mold 2 described later) arranged to be movable up and down with respect to the lower mold;
A molding pad (for example, a molding pad 3 to be described later) suspended from the upper mold via a hydraulic cylinder (for example, a hydraulic cylinder 4 to be described later);
A cutting tool (for example, a trim blade 5 described later) provided in the upper mold;
A supply-side hydraulic system path (for example, a later-described supply-side hydraulic system path 30) that supplies hydraulic oil (for example, a later-described hydraulic oil L) connected to the hydraulic cylinder and the hydraulic oil from the hydraulic cylinder. A return side hydraulic system path (for example, a return side hydraulic system path 20 described later),
When the upper mold descends toward the lower mold, the working pressure of the hydraulic cylinder is maintained at a high pressure, and the molding pad is pressed against the lower mold to perform the first machining, The hydraulic pressure of the hydraulic cylinder is lowered to a low pressure so that the molding pad is brought close to the upper die while maintaining the pressing state of the workpiece against the lower die by the molding pad, and the workpiece is secondly applied to the workpiece by the cutting tool. A pressure control system (for example, a pressure control system 50 described later) of a press molding apparatus that performs the processing of
The return side hydraulic system path includes a pressure damping container (for example, a pressure damping container 13 described later) connected to the hydraulic cylinder via an opening / closing control valve (for example, a return side opening / closing control valve 26 described later), A flow passage cross-sectional area of a first passage (for example, a first passage 21 described later) from a hydraulic cylinder to the pressure damping container is a second passage (for example, a second passage described later) downstream from the pressure damping container. A pressure control system for a press forming apparatus, characterized in that it is larger than the flow path cross-sectional area of the passage 25).

  According to the invention of (1), the upper die is first lowered to press the molding pad against the workpiece placed on the lower die, and the workpiece is subjected to the first machining (for example, draw machining). At this time, the hydraulic pressure of the hydraulic cylinder for suspending the forming pad is maintained at a high pressure so that the workpiece is pressed against the lower mold and the workpiece is subjected to the first machining. Subsequently, the upper die is further lowered to cut the cutting tool provided on the upper die into the workpiece to perform the second processing (for example, trim processing, piercing processing). At this time, the hydraulic pressure of the hydraulic cylinder is set to a low pressure for holding the work on the lower mold by the molding pad. Thereby, the 1st processing (for example, draw processing) and the 2nd processing (for example, trim processing, piercing processing) are performed by one descent of the upper mold.

Here, between the completion of the first machining and the start of the second machining, by lowering the hydraulic pressure of the hydraulic cylinder for suspending the molding pad from high pressure to low pressure, Since the pressing force of the workpiece by the forming pad has already been sufficiently reduced, there is no force in the direction to prevent the upper die from descending from the forming pad, and the first processing (for example, without overloading the apparatus) , Draw processing) and second processing (for example, trim processing, piercing processing) can be performed in one behavior.
The hydraulic pressure of the hydraulic cylinder for suspending the molding pad is controlled by operating the supply side hydraulic system path for supplying the hydraulic oil to the hydraulic cylinder and the return side hydraulic system path for discharging the hydraulic oil from the hydraulic cylinder. Is called.

The return side hydraulic system path includes a pressure damping container connected to the hydraulic cylinder via an open / close control valve. The pressure damping container can temporarily store high-pressure hydraulic fluid that flows out of the hydraulic cylinder when the open / close control valve is opened.
The flow passage cross-sectional area of the first passage from the hydraulic cylinder to the pressure damping container is configured to be larger than the flow passage cross-sectional area of the second passage downstream from the pressure damping container. The flow resistance to the container is small, the high-speed flow of hydraulic oil from the hydraulic cylinder to the pressure damping container is not hindered, and the hydraulic pressure of the hydraulic cylinder can be reliably lowered rapidly to a low pressure.
The hydraulic oil once stored in the pressure damping container is then discharged through the second passage. At this time, even if the flow passage cross-sectional area of the second passage is small and the flow resistance is large, the working oil pressure in the hydraulic cylinder has already been switched to a low pressure. The switch from high pressure to low pressure is not disturbed.

  Therefore, according to the invention of (1), in the pressure control system of the press molding apparatus, the pressing force of the hydraulic cylinder in the press mold can be quickly switched in accordance with the movement of the press molding apparatus, It is possible to secure the manageability by making the piping thin.

  (2) The pressure control system for a press forming apparatus according to claim 1, wherein the pressure damping container, the open / close control valve, and the first passage are all arranged in the upper mold. .

  According to the invention of (2), the pressure damping container, the open / close control valve, and the first passage whose passage cross-sectional area is larger than the flow passage cross-sectional area of the second passage downstream from the pressure damping container are the upper mold Therefore, the upper die and the fixed side of the press molding apparatus are connected to each other only by the second passage having a small passage cross-sectional area as the return side hydraulic system passage. Therefore, in the pressure control system of the press molding apparatus, it is possible to reliably ensure the manageability of piping from the hydraulic cylinder.

  According to the present invention, the pressurizing force of the hydraulic cylinder in the press mold can be quickly switched in accordance with the movement of the press molding apparatus, and the piping from the hydraulic cylinder can be narrowed to ensure the handling performance. A pressure control system for a press forming apparatus can be provided.

It is a figure which shows the pressure control system of the press molding apparatus of one Embodiment of this invention, (a) is explanatory vertical sectional drawing, (b) is a schematic diagram. It is explanatory vertical section which shows the action | operation of the press molding apparatus of one Embodiment of this invention. It is a diagram which shows the relationship between raising / lowering of an upper mold | type, and the working hydraulic pressure of a hydraulic cylinder. It is a schematic diagram which shows the pressure control system of the conventional press molding apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a pressure control system of a press molding apparatus according to an embodiment of the present invention, in which (a) is an explanatory longitudinal sectional view and (b) is a schematic diagram. FIG. 2 is an explanatory longitudinal sectional view showing the operation of the press molding apparatus according to one embodiment of the present invention, and FIGS. 2 (a), (b) and (c) show the transition of the lowering of the upper die. FIG. 3 is a diagram showing the relationship between the upper mold position and the hydraulic pressure of the hydraulic cylinder.

As shown in FIG. 1A and FIGS. 2A to 2C, the press forming apparatus 51 on which the pressure control system 50 is mounted includes a lower mold 1 on which a workpiece W is placed, and an upper side of the lower mold 1. The upper mold 2 is moved up and down by a lifting device (not shown).
The upper mold 2 includes a molding pad 3 corresponding to the shape of the workpiece W that is drawn. The molding pad 3 is suspended through a plurality of hydraulic cylinders 4 provided on the upper mold 2.
Further, the upper die 2 includes a trim blade 5 corresponding to the trimming shape of the workpiece W, and further includes a presser frame 6 that presses a non-molded portion of the workpiece W. The trim blade 5 may be provided with a bend processing wall for bend processing on its inner peripheral wall.

As shown in FIG. 1A and FIGS. 2A to 2C, the lower mold 1 includes a drawing surface 8 corresponding to the molding pad 3 and a trim groove 9 corresponding to the trim blade 5. ing. A pressing member 10 is provided on the outer side of the lower mold 1 so as to face the pressing frame 6 of the upper mold 2 and hold the workpiece between the pressing frame 6 and the pressing frame 10. The pressing member 10 is connected and supported by a rod 11 biased by a biasing means (not shown).
The trim groove 9 may have a bend processing surface corresponding to the bend processing wall of the trim blade 5 along the inner wall on the draw processing surface 8 side.

  The pressure control system 50 is a system that controls the relative position of the molding pad 3 with respect to the upper mold 2, and as shown in FIG. 1 (b), a plurality of hydraulic cylinders 4 (only one is shown, but others are also shown). All are the same), and includes a hydraulic control device 53, and a supply side hydraulic system path 30 and a return side hydraulic system path 20 that connect them. The hydraulic control device 53 is disposed in the base 52 of the press molding device 51 and includes a hydraulic pump 15 that pumps the hydraulic oil L at a high pressure, a hydraulic oil tank 16, and a supply-side on-off valve 36. The hydraulic control device 53 controls the raising and lowering of the hydraulic pressure of each hydraulic cylinder 4 at a predetermined timing.

The supply-side hydraulic system path 30 includes a supply-side on-off valve 36 for adjusting the amount of hydraulic oil L supplied from the hydraulic pump 15 to the hydraulic chamber 4 a of the hydraulic cylinder 4, and the hydraulic pump 15 and the supply-side on-off valve 36. And a supply-side hydraulic passage 31 that connects the supply-side on-off valve 36 and the hydraulic cylinder 4 to each other.
The return side hydraulic system path 20 is connected to the hydraulic cylinder 4 via the return side opening / closing control valve 26 for adjusting the discharge amount of the hydraulic oil L from the hydraulic chamber 4 a of the hydraulic cylinder 4 and the return side opening / closing control valve 26. The pressure damping container 13, the first passage 21 communicating between the hydraulic cylinder 4 and the return side on-off valve 26, and the return side on-off valve 26 and the pressure damping container 13, respectively, And a second passage 24 communicating with the hydraulic oil tank 16.

  The supply side opening / closing valve 36 and the return side opening / closing control valve 26 may be electromagnetic valves. The supply-side on / off valve 36 and the return-side on / off control valve 26 may be on / off valves, but it is preferable that the opening degree can be adjusted in multiple stages or continuously.

  The pressure damping container 13 is a “container that increases its volume when the pressure of the internal liquid increases”, and is a substantially cylindrical cylinder having a piston 13a slidable therein, and a pressure applied to the back surface of the piston 13a. A gas chamber 13c for application may be provided. The piston 13a slides due to the pressure difference between the liquid chamber 13b and the gas chamber 13c, changes the volume of the liquid chamber 13b, and balances the pressure between the liquid chamber 13b and the gas chamber 13c. The piston 13a is hermetically sealed so that the liquid in the liquid chamber 13b does not pass through the gas chamber 13c, and conversely, the gas in the gas chamber 13c does not pass through the liquid chamber 13b.

The liquid chamber 13 b of the pressure damping container 13 is filled with the hydraulic oil L, connected to the first passage 21 that communicates with the return side opening / closing control valve 26, and is connected to the second passage 24 that communicates with the hydraulic oil tank 16. Connected.
On the other hand, the gas chamber 13c may be filled with a high-pressure gas having a predetermined pressure, and the pressure is adjusted by the high-pressure gas supply means 13d. The high pressure gas may be high pressure air.
According to this configuration, when the hydraulic pressure of the hydraulic oil L in the liquid chamber 13b of the pressure damping container 13 becomes higher than the high-pressure gas pressure in the gas chamber 13c, the piston 13a slides toward the gas chamber 13c and the volume of the liquid chamber 13b. The hydraulic oil L in the first passage 21 flows into the liquid chamber 13b.
Conversely, when the hydraulic pressure of the hydraulic oil L in the liquid chamber 13b of the pressure damping container 13 decreases, the piston 13a slides toward the liquid chamber 13b to reduce the volume of the liquid chamber 13b, and the hydraulic oil L is reduced to the liquid chamber 13b. It flows out from the inside to the first passage 21 and the second passage 24.

  The pressure damping container 13 adjusts the position of the piston 13a that balances with the hydraulic pressure of the high-pressure hydraulic oil L that flows in by temporarily changing the pressure of the gas chamber 13c by the high-pressure gas supply means 13d. It is possible to adjust the amount of hydraulic oil L stored in the tank.

  The pressure damping container 13 may have a shape other than the substantially cylindrical shape. Further, as a means for applying a pressing force in the direction of the liquid chamber 13b to the piston 13a, a spring member may be used instead of the high-pressure gas.

  The flow passage cross-sectional area of the first passage 21 that connects the hydraulic cylinder 4 and the pressure damping container 13 via the return side opening / closing control valve 26 is the first that connects the pressure damping container 13 and the hydraulic oil tank. 2 is larger than the cross-sectional area of the passage 24.

  The supply-side hydraulic passage 31 may be directly connected to the hydraulic cylinder 4, but may be connected to the first passage 21 in the vicinity of the hydraulic cylinder 4 as shown in FIG.

The combination of the return-side opening / closing control valve 26, the pressure damping container 13, the first passage 21, and the second passage 24 constituting the return-side hydraulic system passage 20 is used to precisely control the position of the molding pad 3. It is preferably provided for each of the plurality of hydraulic cylinders 4. However, a plurality of hydraulic cylinders 4 may be grouped, and one set of these may be provided for each group.
Similarly, the combination of the supply-side on-off valve 36 and the supply-side hydraulic passage 31 constituting the supply-side hydraulic system path 30 is preferably provided for each of the plurality of hydraulic cylinders 4. However, similarly, a plurality of hydraulic cylinders 4 may be grouped, and one set of these may be provided for each group.
The supply-side hydraulic passage 31 may branch between the hydraulic pump 15 and the supply-side on / off valve 36 so as to correspond to the plurality of supply-side on / off valves 36.

The supply side hydraulic path 30 is provided with a flexible pipe 35 in the middle in order to flexibly absorb the relative movement between the upper mold 2 that repeats the vertical movement F and the fixed side 52 of the press molding apparatus 51.
Similarly, the return side hydraulic path 20 is provided with a flexible pipe 25 in the middle in order to flexibly absorb the relative movement between the upper mold 2 that repeats the vertical movement F and the fixed side 52 of the press molding apparatus 51. ing.

  The hydraulic control pump 15, the supply side on / off valve 36, the return side on / off control valve 26, and the high pressure gas supply means 13 d of each set are supplied to the press forming device 51 by applying control forces of a plurality of hydraulic cylinders 4 by control means (not shown). Control is performed in association with the lift position of the mold 2. The pressurizing forces of the plurality of hydraulic cylinders 4 may not all be the same, and the pressurizing force and the timing for increasing or decreasing the pressurizing force are determined according to the shape of the molding pad 3 and the shape of the workpiece to be processed. You may change it.

  Next, the operation of the pressure control system 50 together with the operation of the press molding apparatus 51 will be described.

Hereinafter, the operation of the press forming apparatus 51 will be described.
First, as shown in the upper mold operation curve h of FIGS. 2A and 3, when the upper mold 2 is in the raised position (near the top dead center), the workpiece W is put on the lower mold 1. At this time, the hydraulic pressure of the hydraulic cylinder 4 is locked at a high pressure as shown by the hydraulic pressure curve p in FIG. The working oil pressure at high pressure may be about 25 MPa.

  Next, as shown in FIG. 2B, the upper die 2 is lowered, and draw processing is performed at points D1 to D2 on the upper die operation curve h in FIG. 3 (first machining). First, as shown in FIG. 2B, the work W is sandwiched between the presser frame 6 and the presser member 10. At this time, since the hydraulic pressure of the hydraulic cylinder 4 is in a locked state, the workpiece W is pressed against the lower mold 1 by the molding pad 3 and the drawing process is performed.

  When the drawing process on the workpiece W is completed and the upper die 2 is further lowered toward the bottom dead center, the trim blade 5 hits the workpiece W, and trimming is performed at the point T in the upper die operation curve h in FIG. Be started.

  Subsequently, the upper die 2 is further lowered, and as shown in FIG. 2C, the workpiece W is bent by the bend processing wall of the trim blade 5 and the bend processing surface of the lower die 1. That is, referring to FIG. 3, when trim processing is performed at point T on the upper mold operating curve h, bend machining on the workpiece W is subsequently started at point B1, and the upper mold 2 is further lowered to move the upper mold. Bend processing is completed at point B2 where 2 reaches bottom dead center (second processing).

  On the other hand, the operating hydraulic pressure of the hydraulic cylinder 4 is released from the high-pressure locked state until the trim processing is started after the draw processing is completed, and rapidly decreases to a low pressure as shown by the operating hydraulic pressure curve p in FIG. Is done. The operating hydraulic pressure at the low pressure is a pressure that can hold the state in which the molding pad 3 presses the workpiece W against the lower mold 1, and may be, for example, about 2 MPa.

  Then, when the upper mold 2 reaches the bottom dead center and the bending process is completed at the point B2, the upper mold 2 starts to rise. At this time, the operating hydraulic pressure of the front hydraulic cylinder 4 is rapidly increased to an intermediate pressure (for example, about 10 MPa) by the point S at which the trim blade 5 rises and completely comes out of the trim groove 9. As a result, the molding pad 3 is relatively separated from the rising upper mold 2, and the workpiece W is held by the lower mold 1 by the molding pad 3 until the trim blade 5 is separated from the workpiece W. It is possible to prevent the trimming blade 5 from biting the workpiece W.

Thereafter, after the upper die 2 is further raised and the trim blade 5 is completely removed from the trim groove 9, the hydraulic pressure of the hydraulic cylinder 4 is increased to a high pressure until the upper die 2 reaches the top dead center. Then, the molding pad 3 is separated above the workpiece W and the workpiece W is taken out.

Next, the operation of the pressure control system 50 will be described.
When the press molding apparatus 51 is operated, the hydraulic pressure of the hydraulic cylinder 4 changes in the following cycle as described above.
(1) While the workpiece W is loaded and the drawing process is being performed, the pressure is locked at a high pressure. (2) During the period from the completion of the drawing process to the start of the trim process, the lower mold 2 is rapidly lowered to the low pressure. When it rises again, the trim blade 5 rises and completely rises from the trim groove 9 to rapidly increase the pressure to the intermediate pressure. (4) The pressure is gradually increased while the upper die 2 goes to the top dead center, and the pressure is increased again. Return to (1)

  Of these, the hydraulic pressure of the hydraulic cylinder 4 relating to (1), (3) and (4) is controlled by operating the supply-side on-off valve 36 and the return-side on-off control valve 26. The opening degree of the side opening / closing valve 36 is increased, and the opening degree of the return side opening / closing control valve 26 is lowered to change to a high pressure. Conversely, the opening degree of the supply side opening / closing valve 36 is lowered, and the return side opening / closing control valve 26 is changed. This is performed by increasing the valve opening degree to a low pressure.

The pressure control system 50 performs the following operation regarding the rapid drop in the hydraulic pressure of the hydraulic cylinder 4 in (2).
The pressure control system 50 rapidly lowers the opening degree of the supply-side on-off valve 36 and opens the return-side on-off control valve 26 at the timing when the drawing process is completed based on an instruction from a control unit (not shown). As a result, the high-pressure hydraulic oil L in the hydraulic chamber 4a of the hydraulic cylinder 4 flows through the first passage 21 toward the pressure damping container 13, and the high-pressure hydraulic oil L toward the pressure damping container 13 is pressure-damped. The piston 13a of the container 13 is pushed to increase the volume of the liquid chamber 13b, and flows into the liquid chamber 13b. Accordingly, when the return side opening / closing control valve 26 is opened, the high-pressure hydraulic oil L flowing out from the hydraulic cylinder 4 can be temporarily stored in the pressure damping container 13.
Here, since the flow passage cross-sectional area of the first passage 21 from the hydraulic cylinder 4 to the pressure damping container 13 is larger than the flow passage cross-sectional area of the second passage 24 downstream from the pressure damping container 13, the pressure from the hydraulic cylinder 4 is increased. The flow resistance to the damping container 13 is small, and the operating hydraulic pressure of the hydraulic cylinder 4 can be reliably lowered rapidly to a low pressure.

The hydraulic oil L temporarily stored in the liquid chamber 13b of the pressure damping container 13 is then gradually discharged from the liquid chamber 13b, passes through the second passage 21, and is discharged to the hydraulic oil tank 16. Even if the flow passage cross-sectional area of the second passage 24 is small and its flow resistance is large, the working oil pressure in the hydraulic cylinder 4 has already been switched to a low pressure. The function of quickly switching from high pressure to low pressure according to the elevation position of the upper mold 2 of the device 51 is not hindered.
Therefore, the pressure applied to the hydraulic cylinder 4 in the upper die 2 can be quickly switched in accordance with the movement of the press molding device 51, and the piping from the hydraulic cylinder 4 can be made thin to ensure handling. .

  Moreover, it is preferable that the pressure damping container 13, the return side opening / closing control valve 26, and the first passage 21 are all disposed in the upper mold 2. If arranged in this way, the upper die 2 and the fixed side 52 of the press molding apparatus 51 are connected only by the second passage 24 having a small passage cross-sectional area as the return side hydraulic system passage 20. The property can be further secured.

  In addition, this invention is not limited to the above-mentioned embodiment, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.

1 Lower mold 2 Upper mold 3 Molding pad 4 Hydraulic cylinder 5 Trim blade (cutting tool)
13 Pressure Damping Container 20 Return Side Hydraulic Path 21 First Passage 24 Second Passage 26 Return Side Open / Close Control Valve (Open / Close Control Valve)
30 Supply side hydraulic path 50 Pressure control system 51 Press molding machine L Hydraulic oil W Workpiece

Claims (2)

A lower mold on which a plate-shaped workpiece is placed;
An upper mold arranged to be movable up and down with respect to the lower mold;
A molding pad suspended from the upper mold via a hydraulic cylinder;
A cutting tool provided in the upper mold;
A supply side hydraulic system path connected to the hydraulic cylinder for supplying hydraulic oil to the hydraulic cylinder and a return side hydraulic system path for discharging hydraulic oil from the hydraulic cylinder;
When the upper mold descends toward the lower mold, the working pressure of the hydraulic cylinder is maintained at a high pressure, and the molding pad is pressed against the lower mold to perform the first machining, The hydraulic pressure of the hydraulic cylinder is lowered to a low pressure so that the molding pad is brought close to the upper die while maintaining the pressing state of the workpiece against the lower die by the molding pad, and the workpiece is secondly applied to the workpiece by the cutting tool. A pressure control system for a press forming apparatus that performs the following processing:
The return-side hydraulic system path includes a pressure damping container connected to the hydraulic cylinder via an open / close control valve, and a flow path cross-sectional area of a first passage from the hydraulic cylinder to the pressure damping container is the pressure A pressure control system for a press molding apparatus, wherein the pressure control system is larger than a flow path cross-sectional area of a second passage downstream from a damping container.   2. The pressure control system for a press apparatus according to claim 1, wherein the pressure damping container, the open / close control valve, and the first passage are all disposed in the upper mold.

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