JP2000079439A - Method and apparatus for controlling forging die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a die by preventing the die from being damaged even through an upper die abuts on a lower die when a forging stock is not yet loaded in a cavity. SOLUTION: A hydraulic controller 10 is provided with a pressure sensor 121 which detects the pressure of pressurized fluid filled in a pressure chamber and a pressure reducing and relieving valve 133 which detects whether or not the oil pressure of pressurized oil filled in the pressure chamber 58 composing a buffer mechanism reaches an initial setting pressure in a forming initial stage based on detecting signals outputted from the pressure sensor 121 and which guides out the pressurized oil filled in the pressure chamber 58 to a tank 110 via a relief valve 104 on the assumption that the forging stock is not yet loaded when the oil pressure of the pressurized oil filled in the pressure chamber 58 does not yet reach the initial setting pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a forging die in which a cavity is filled with a forging material and which can be forged under the action of a punch.

[0002]

2. Description of the Related Art Conventionally, a material for forging is inserted into a cavity formed in an upper die and a lower die joined to each other, and a pressing force is applied to the material for forging via a punch. A forging die for forging a sheet into a predetermined shape is known.

Incidentally, the present applicant has proposed a forging die apparatus provided with a buffer mechanism for absorbing a surplus displacement amount until the punch abuts on the lower die and reaches the bottom dead center. Japanese Patent Application No. 9-335923.

This cushioning mechanism has a piston which is displaceable along a pressure chamber filled with a pressure fluid (pressure oil), and a punch abuts on a lower die under the action of displacement of the piston. It functions to appropriately absorb the surplus displacement amount until the bottom dead center is reached by the pressure fluid (pressure oil) filled in the pressure chamber.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in connection with the above-mentioned proposal, and when a forging material is not loaded in a cavity, even if an upper die and a lower die come into contact with each other, the die is formed on the die. An object of the present invention is to provide a method and an apparatus for controlling a forging die that can prevent damage and improve the durability of the die.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a method for controlling the displacement of a surplus from when a first mold member abuts a second mold member to when a bottom dead center is reached. A method for controlling a forging die provided with a buffer mechanism for absorbing an amount, wherein the first mold member and the second mold member are relatively displaced and the first mold member and the second mold member are displaced. Before the contact, it is detected whether or not the pressure of the pressure fluid filled in the pressure chamber constituting the buffer mechanism has reached the initial set pressure in the initial stage of molding, and the pressure of the pressure fluid is set to the initial set pressure. If not reached, the forging material is not loaded and the pressure fluid filled in the pressure chamber is forcibly led out.

[0007] In this case, the pressure fluid filled in the pressure chamber is composed of pressure oil, and the pressure fluid is discharged to the outside by urging the solenoid valve to release the relief pressure of the relief valve.

Further, the pressure of the pressure fluid filled in the pressure chamber is detected, and when the pressure of the pressure fluid is out of a predetermined filling pressure range, the relative displacement between the first mold member and the second mold member is detected. Is stopped.

Further, the abutment load when the first mold member and the second mold member are relatively displaced and come into contact with each other is detected,
When the first and second mold members are not in contact with each other, the relative displacement between the first and second mold members is stopped.

Further, the relief pressure of the pressurized fluid in the pressure chamber between the time when the first mold member and the second mold member abut and the time when the bottom mold reaches the bottom dead center is detected. If it is outside the predetermined range, the relative displacement between the first mold member and the second mold member is stopped.

The air mixed into the pressure fluid in the pressure chamber is removed to the outside together with the pressure fluid leaking from the pressure chamber under the action of the air release circuit.

Further, the present invention provides a forging material by displacing a first mold member and a second mold member relative to each other and applying a pressing force to a forging material loaded in a cavity. A control device for a forging die for forging,
The first mold member and the second mold member are relatively displaced, and by the action of the pressure fluid filled in the pressure chamber, the first mold member and the second mold member come into contact with each other and reach a bottom dead center. A buffer mechanism that absorbs a surplus displacement amount until the pressure reaches the pressure chamber, a pressure detection unit that detects a pressure of the pressure fluid filled in the pressure chamber, and a detection signal output from the pressure detection unit. When the pressure of the pressure fluid filled in the pressure chamber constituting the buffer mechanism has not reached the initial set pressure in the initial stage of molding, the pressure fluid filled in the pressure chamber is determined to be unloaded with the forging material. And pressure fluid control means leading out to the outside.

In this case, the pressure fluid control means is connected to a relief valve having an inlet port communicating with the pressure chamber and a relief port of the relief valve, and releases the relief pressure of the relief valve under a switching action. And a solenoid valve.

The pressure detecting means comprises a pressure sensor,
A load sensor is provided separately from the pressure sensor for detecting whether the first mold member and the second mold member are in contact with each other.

An air bleeding circuit is provided for removing air mixed in the pressure fluid consisting of the pressure oil in the pressure chamber, and the air mixed in the pressure fluid is removed under the urging action of the air bleeding circuit. It is preferable that the pressure fluid leaks out of the pressure chamber and is led out to the outside. It is preferable to provide a pressure control valve for controlling the pressure of the pressure fluid supplied to the relief chamber of the relief valve.

According to the present invention, when the pressure of the pressure fluid filled in the pressure chamber has not reached the initial set pressure in the initial stage of molding via the pressure fluid control means, the forging material is not loaded. If there is, the pressure fluid filled in the pressure chamber is led out. Therefore, even if the upper die and the lower die are in contact with each other when the forging material is not loaded in the cavity, the die is not damaged and the durability of the die is improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for controlling a forging die according to the present invention will be described in detail below with reference to the accompanying drawings. .

FIG. 1 shows a forging die 11 in which a hydraulic control device 10 according to the present embodiment is incorporated.

This forging die 11 is provided with a first die holder 14 having a plurality of guide means 12a to 12d standing upright at four corners, and laminated at the center of the first die holder 14. And a second die holder 16 and a third die holder 18.

On the second die holder 16, a thick press-fit ring 20 integrally formed is fixed via a fastening means 22, and a thin-walled sleeve is formed in a hole of the press-fit ring 20. The upper dice 26 and the lower dice 28 are integrally joined via 24.

An annular recess 30 formed on the upper side of the press-fit ring 20 has a first ring body 34 having a hole 32 formed therein, and a second ring body externally fitted to the first ring body 34. 36, and a fastening ring 38 for holding the first ring body 34 and the second ring body 36 are provided. The first ring body 34 and the second ring body 36 are formed on the upper side of the press-fit ring 20 and are press-fitted with good concentricity into a hole 37 concentrically formed with a cavity 46 described later. In this case, the first ring body 34 and the second ring body 36 may be integrally formed as ring bodies instead of being formed separately.

A first plate 44 for restricting the amount of displacement of the punch 40 is provided on the upper surface of the upper die 26 and the sleeve 24 by contacting a second plate 42 which is displaced integrally with the punch 40 described later. Provided. The upper die 26 and the lower die 28 including the first plate 44 function as a first mold member.

As shown in FIG. 4, the first plate 44 has a load sensor 45 for detecting whether or not the forming load by the punch 40 is reliably applied to the forging material.
Is arranged. In this case, the load sensor 45 detects that the second plate 42 displaced integrally with the punch 40 abuts on the first plate 44 and introduces a detection signal output from the load sensor 45 to a controller (not shown). Accordingly, the controller determines whether or not the first plate 44 and the second plate 42 are in contact with each other and the displacement of the punch 40 is regulated, and the forging material is forged into a predetermined thickness.

The first ring body 34 is made of, for example, a super hard material and subjected to shrink fitting.
6 is strongly tightened toward the center. Further, the first ring body 34 and the second ring body 3
6 is press-fitted into a hole 37 concentrically machined with the cavity 46 and tightened by a tapered portion of a fastening ring 38 which is screwed into a screw hole of the press-fit ring 20, so that the concentricity with the cavity 46 is good. It is integrally joined to the recess 30 of the ring 20.

In this case, a cavity 46 is formed by the upper die 26 and the lower die 28, and a knockout pin 48 for extruding a forged product is formed in the second die holder 16 and the third die holder 18 below the cavity 46. Along the formed hole 50 so as to be able to advance and retreat. The cavity 46 is loaded with a secondary molded product 52 as shown in FIG. 8 as a forging material.

Above a predetermined distance from the press-fit ring 20, there is provided an elevating part 54 connected to a ram of a mechanical press (not shown) and displaced vertically with the ram under the driving action of the mechanical press. Can be

The elevating section 54 starts the forging by the punch 40 abutting on the forging material, and forging the forging material by the upper mold and the lower mold abutting before reaching the bottom dead center. After that, there is provided a buffer mechanism 56 for absorbing a surplus displacement amount until the bottom dead center is reached.

The cushioning mechanism 56 has a bottomed cylindrical block body 62 having a pressure chamber 58 formed therein and having a piston 60 provided to be vertically displaceable along the pressure chamber 58; A pair of connecting blocks 66a and 66b, which are connected to the body 62 in a liquid-tight manner and have a passage 64 communicating with the pressure chamber 58, are formed. The block body 6
A ring-shaped stopper 68 for preventing the piston 60 from descending is fixed to the bottom surface of the second member 2.

A ring-shaped high-pressure packing 72, a low-pressure packing 74, and a wear plate 76 are mounted on the outer peripheral portion of the piston 60 through annular grooves, respectively. A punch plate 78 is fixed to the bottom surface of the piston 60, and the punch 40 is fixed to the punch plate 78 via a holder 80 surrounding a part of the outer peripheral surface. A guide sleeve 82 made of a cylindrical metal material is fitted around the outer periphery of the holder 80, and a second plate 42 is fixed to the bottom surface of the holder 80.

The guide sleeve 82 is made of, for example, S
It is preferable that the first ring body 34 be formed of a material harder than the guide sleeve 82, such as a metal material such as KD11, FC25, or FC30.

The holder 80 including the punch 40, the guide sleeve 82, the second plate 42 and the like function as a second mold member. The punch 40 is the first
A plurality of guide means 12 a to 12 e to erect on the die holder 14.
Under the guide action of 12d, it is provided so as to be displaceable in the vertical direction integrally with the elevating unit 54.

As shown in FIG. 1, a hydraulic control device 10 according to the present embodiment is fixed to one connecting block 66a via a seal member 100. The hydraulic control device 10 includes a tube or the like. The hydraulic pressure source 102 is connected via a pipeline.

As shown in FIG. 3, the hydraulic control device 10 includes a relief valve 104,
An inlet port 106 communicating with the pressure chamber 58 in which the piston 60 is housed via the passage 64; an outlet port 112 communicating with the tank 110 of the hydraulic power source 102 via a discharge passage 108; 1
And a relief port 116 for supplying a relief pressure to a relief chamber (not shown) via the port 14.

In the middle of the passage 64, the tank 1 of the hydraulic power source 102 is connected through a check valve 117 for pilot operation.
A supply passage 118 for supplying the pressure oil stored in the pressure chamber 10 to the pressure chamber 58 is connected, and a pressure sensor (pressure detection means) for detecting the oil pressure of the pressure oil in the pressure chamber 58 via a passage 119. 121 are connected. Note that a set of pressure sensors (not shown) is used instead of the pressure sensor 121, and the detection signals output from the set of pressure sensors are introduced into a controller (not shown), and the AND of the set of detection signals is obtained. Alternatively, it may be detected.

The relief valve 104 is provided with an inlet port 106 and an outlet port 112 when the oil pressure of the pressure oil filled in the pressure chamber 58 exceeds the oil pressure of the pressure oil filled in the relief chamber, and a valve body (not shown) is displaced. When the oil pressure of the pressure oil filled in the pressure chamber 58 is lower than the oil pressure of the pressure oil charged in the relief chamber,
It is configured such that the communication between the inlet port 106 and the outlet port 112 is shut off and the valve is in a closed state.

A check valve 1 for pilot operation is provided in a passage 120 branched from the relief pressure supply passage 114.
A high pressure accumulator 124 is connected via 22
A low-pressure accumulator 128 is connected to a passage 126 branched from the discharge passage 108. Also,
The low-pressure accumulator 128 is connected to a supply passage 118 via a check valve 123 for pilot operation. The low-pressure accumulator 128 is a large-capacity piston type, and the high-pressure accumulator 1
24 is preferably a balloon type.

The check valve 122 is normally in an open state. The check valve 122 is in a closed state under the action of supplying a pilot pressure to maintain the internal pressure of the high-pressure accumulator 124, thereby protecting the high-pressure accumulator 124. Has functions.

The pressure chamber 58 is connected via a passage 125 to an input side of an air release circuit 127 for removing air mixed in the pressure oil filled in the pressure chamber 58. The output side is connected to the discharge passage 108 via the passage 129.

The air bleeding circuit 127 has an air bleed valve 131 composed of a normally open type solenoid valve.
By opening the air vent valve 131, a function of discharging a small amount of pressure oil leaking from the pressure chamber 58 and air mixed in the pressure oil to the tank 110 via the discharge passage 108 is performed. . As a result, the air in the pressure oil filled in the pressure chamber 58 is removed.

In the relief pressure supply passage 114,
Under the switching action of the relief pressure release valve 133 formed of an electromagnetic valve, the pressure oil stored in the relief chamber of the relief valve 104 is led out to the discharge passage 108 to make the relief set pressure of the relief valve 104 zero. A relief pressure release circuit 135 is provided. A passage 137 communicating with the relief pressure supply passage 114 is connected to the input side of the relief pressure release valve 133, while the discharge passage 1 is connected to the output side.
08 is connected to the passage 139. Reference numeral 141 indicates a check valve.

In this case, the relief valve 104, the relief pressure release valve 133, and the controller (not shown) function as pressure fluid control means.

The hydraulic pressure source 102 is connected to a tank 110 in which pressure oil is stored and a supply passage 11 under the action of a motor 130.
A first hydraulic pump 132 for supplying pressurized oil via the hydraulic motor 8 and a relief pressure supply passage 1 under the driving action of the electric motor 130.
And a second hydraulic pump 134 for supplying pressurized oil to the relief chamber of the relief valve 104 via.

The relief valve 10 is provided between the second hydraulic pump 134 and the relief valve 104 based on a relief pressure control signal introduced from a controller (not shown).
4, a pressure control valve 136 for controlling the relief pressure is provided.

The hydraulic control device 1 according to the embodiment of the present invention
0 is incorporated in the forging die 11 basically as described above.
1 will be described. The following describes an example in which an outer cup forming a constant velocity joint is forged as a forged product.

A cylindrical billet 8 as shown in FIG.
By performing the first forging on the mold 4 by a mold device (not shown), as shown in FIG. 6, the first molded products 86 having different diameters through the intermediate step are obtained. Subsequently, after performing the preliminary molding on the primary molded product 86 (see FIG. 7), the secondary forging is performed by another mold device (not shown), as shown in FIG. A second portion including the cup portion 88 and the shaft portion 90
The next molded product 52 is obtained. The forging die 11 uses the second
Third forging is further performed using the next molded product 52 as a forging material.

First, as a preparation work, the first ring body 34
When the guide sleeve 82 is inserted into the hole 32 of the upper die 26, the lower die 28, the sleeve 24
The punch 40 is positioned with respect to the cavity 46 formed in the upper die 26 and the lower die 28 by integrally assembling the press-fit ring 20 and the like.

The first hydraulic pump 1 is provided in the pressure chamber 58.
Under the driving action of 32, pressure oil having a predetermined oil pressure is filled through the supply passage 118 and the passage 64. Also,
A relief pressure supply passage 1 is driven by a second hydraulic pump 134 in a relief chamber (not shown) of the relief valve 104.
Pressure oil is supplied via the pump 14 and is set to a predetermined relief pressure. The relief set pressure is controlled by a pressure control valve 136 based on a relief pressure control signal introduced from a controller (not shown).

Further, when a protection circuit (overload mechanism) (not shown) is activated when an overload occurs, it takes time to return to a normal operation state, and forging cannot be performed continuously. Is set to be equal to or greater than the forming load for the forging material and equal to or less than the overload working load, and the forming load for the forging material is
It is provided so as to be supported by the pressure oil filled in the pressure chamber 58.

Next, in a state where the punch 40 is arranged at a raised position (initial position) not shown, the cavity 4
6 is loaded with a second molded product 52 as a forging material. Then, the punch 40 descends integrally with the elevating part 54 connected to the ram under the driving action of a mechanical press (not shown),
When the state shown in (1) is reached, forging is started.

When the punch 40 descends integrally with the lifting / lowering portion 54, a plurality of guide means 12a to 12d provided between the lifting / lowering portion 54 and the first die holder 14 preferably apply a lateral biased load. Is absorbed by the guide sleeve 8
The punch 40 can be smoothly pressed into the center of the hole 32 of the first and second ring bodies 34 and 36 disposed coaxially with the cavity 46 via the second hole 2.

When forging is started, the guide sleeve 82 which is fitted to a part of the outer peripheral surface of the punch 40 is provided with an annular groove (not shown) formed at the upper end of the hole 32 of the first ring body 34. When the punch 40 enters under the guiding action and the punch 40 descends, the punch 40, the holder 80 and the guide sleeve 82 are integrally displaced while being pressed into the hole 32 of the first ring body 34.

Here, the displacement amount of the punch 40 and the pressure chamber 58
FIG. 9 shows the relationship with the pressurized oil filled in the. In FIG. 9, a curve A shown by a solid line is a displacement amount of the punch 40 which is displaced integrally with the ram under a driving action of a mechanical press (not shown), and a curve B shown by a two-dot chain line is filled in the pressure chamber 58. Pressure (oil pressure) of compressed oil, curve C indicated by a dashed line
Is the separation distance D between the second plate 42 provided on the displacement side and the first plate 44 provided on the fixed side (see FIG. 1).
Are respectively shown.

The ram of the mechanical press (not shown) is displaced downward from a predetermined raised position, and the punch 40 and the second plate 42 are integrally lowered with the ram, whereby the fixed-side ram is moved. The distance D between the first plate 44 and the second plate 42 on the displacement side gradually decreases. The piston 60 is held by the stopper 68 and is prevented from being displaced downward.
After the start of molding, the hydraulic pressure of the pressure oil
Gradually increases with an increase in the load applied to the substrate.

Immediately before the punch 40 further descends from the state shown in FIG. 1 to reach the bottom dead center, the second plate 42
By contacting the plate 44, that is, by setting the separation distance D between the first plate 44 and the second plate 42 to 0, the displacement of the punch 40 on the lower side is regulated, and the thickness of the forging material is regulated accurately. Thus, forging is completed.

Further, when the punch 40 descends by a very small distance and the hydraulic pressure in the pressure chamber 58 reaches the relief set pressure, the relief valve 104 is opened and the pressure chamber 5 is opened.
8 is discharged to the outside to reach the state shown in FIG.

As described above, the size of the bottom thickness T (see FIG. 10) of the cup portion 94 of the outer cup obtained as the forged product 92 is provided on the second plate 42 provided on the punch 40 side and the press-fit ring 20 side. This is determined by the contact of the first plate 44 with the first plate 44. Therefore, the size of the bottom thickness T of the cup portion 94 of the outer cup obtained as the forged product 92 does not vary, and the bottom thickness T of the cup portion 94 does not vary.
Dimensional accuracy is maintained with high accuracy.

In this manner, the punch 40 is lowered, and FIG.
2 from the forming start position shown in FIG. 2 to the forming end position shown in FIG. 2, forging is performed on the forging material through the punch 40, the lower die 28 and the upper die 26, and the forging is performed. The material plastically flows along the shape of the cavity 46.

After the forging is completed, the punch 40 is moved up to the initial position integrally with the elevating portion 54 connected to the ram under the driving action of the mechanical press.
0, the holder 80 and the guide sleeve 82 are separated from the hole 32 of the first ring body 34, and are in a standby state for the next step. Then, the forged product 92 (see FIG. 10) is taken out under the displacement action of the knockout pin 48.

Next, the operation and effect of the hydraulic control device 10 including the air release circuit 127 and the relief pressure release circuit 135 will be described with reference to the flowchart shown in FIG.

It is assumed that the pressure chamber 58 is previously filled with a pressure oil having a predetermined oil pressure via the supply passage 118 and the passage 64 under the driving action of the first hydraulic pump 132 (step). S1).

The air release valve 1 of the air release circuit 127
31 is extinguished and the valve is opened in advance. Therefore,
The air mixed in the pressure oil filled in the pressure chamber 58 is discharged to the tank 110 via the passage 125, the passage 129 and the discharge passage 108 together with a small amount of the pressure oil leaking from the pressure chamber 58. Air in the pressure oil filled in the chamber 58 is reliably removed.

After the completion of the preparatory work, a controller (not shown) urges the solenoid valve to close the air release valve 131 (step S2).

When the air vent valve 131 is closed, the pressure sensor 121 detects the filling pressure of the pressure oil filled in the pressure chamber 58 (see FIG. 12), and derives the detection signal to a controller (not shown). I do. The controller determines whether or not the filling pressure of the pressure oil in the pressure chamber 58 is equal to or higher than a set pressure based on the detection signal (step S3). Deriving a stop signal. As a result, the operation of the mechanical press stops immediately, so that the punch 40 is kept stopped at the top dead center (step S4). If the filling pressure of the pressure oil in the pressure chamber 58 is equal to or higher than the set pressure, the process proceeds to the next step S5.

In step S5, the punch 40 is lowered by the driving action of the mechanical press, and the forming of the forging material is started, so that the oil pressure of the pressure oil in the pressure chamber 58 is increased. In this case, the pressure sensor 121 detects the oil pressure of the pressure oil in the pressure chamber 58 at the initial stage of molding (FIG. 12).
), And derives the detection signal to a controller (not shown). The controller determines whether or not the oil pressure of the pressure oil in the pressure chamber 58 at the initial stage of molding has increased from the detection signal to an initially set oil pressure (step S6).
If the hydraulic pressure of the pressure oil in the pressure chamber 58 has not risen to the initially set hydraulic pressure, it is determined that the forging material has not been loaded into the cavity 46, and an urging signal is derived to the relief pressure release valve 133, and the relief pressure is released. By turning on the drain valve 133, the relief control pressure of the relief valve 104 is opened (step S7).

That is, the valve position of the relief pressure relief valve 133 is switched, and the pressure oil stored in the relief chamber of the relief valve 104 passes through the passage 137 and the relief pressure relief valve 13.
3 and through the passage 139 to the tank 110 via the discharge passage 108. Therefore, the relief control pressure is rapidly reduced to zero, and the relief valve 104 is opened. The pilot pressure is supplied to the check valve 122 by switching the valve position of the relief pressure release valve 133, the check valve 122 is closed, and the internal pressure of the high-pressure accumulator is maintained at a predetermined pressure.

When the relief valve 104 is opened, the inlet port 106 and the outlet port 11 are opened.
2 communicates with each other, and a large amount of pressure oil filled in the pressure chamber 58 is sucked into the low-pressure accumulator 128 under the driving action of the low-pressure accumulator 128. As a result,
Reducing the flow path resistance when the large-capacity pressure oil filled in the pressure chamber 58 flows out along the discharge passage 108;
Generation of a surge pressure (see FIG. 9) can be prevented.

In this case, the forging material is not loaded and the pressure oil supporting load of the piston 60 acts on the contact portion between the first plate 44 and the second plate 42, but the relief valve 104 is opened. In this state, the relief pressure of the relief valve 104 becomes zero, so that the pressure oil supporting load applied to the contact portion between the first plate 44 and the second plate 42 becomes zero, and the upper die and the lower die are separated. There is no impact or damage to it. At this time, the controller (not shown) regards the loading of the forging material as abnormal, raises the punch 40 under the driving action of the mechanical press, and stops when the top dead center is reached (step S8).

Next, when the hydraulic pressure of the pressure oil in the pressure chamber 58 has risen to the initially set hydraulic pressure in the initial stage, it is determined whether or not a predetermined forming load has been applied to the forging material by the punch 40. It is detected by the load sensor 45 (step S9).

That is, it is detected by the load sensor 45 that the first plate 44 and the second plate 42 have reliably contacted, and the load sensor 45 derives a detection signal to a controller (not shown). The controller, based on the detection signal, the first plate 44 and the second plate 4
2 for a predetermined load or more, and it is determined whether or not the forging material has been forged into a predetermined thickness.

For example, as shown by the solid line in FIG. 13, when the output of the load sensor 45 changes to a chevron in response to a change in the oil pressure of the pressure oil in the pressure chamber 58, the controller:
The first plate 44 and the second plate 42 abut against each other with a predetermined load or more, and it is determined that the thickness of the forging material has been regulated to the predetermined thickness by the contact of the mold.

On the other hand, the forming load on the forging material is higher than the pressure oil supporting load, and the output of the load sensor 45 corresponding to the change in the oil pressure of the pressure in the pressure chamber 58 is indicated by the broken line in FIG. In the case of a flat linear shape, the controller determines that the pressure oil is relieved without the first plate 44 and the second plate 42 abutting, and that the thickness dimension of the forging material is not regulated by the contact of the mold. to decide.

A controller (not shown) feedback-controls the relief pressure based on the detection signal output from the load sensor 45, so that the thickness dimension of the forging material can be made even more precise. That is, the controller derives a relief pressure control signal corresponding to the detection signal output from the load sensor 45 to the pressure control valve 136, and controls the relief pressure in accordance with the abutting load, thereby reducing the forging material. The thickness can be regulated with high precision.

When the contact of the mold is not detected by the detection signal output from the load sensor 45, the controller determines that the contact of the mold is abnormal and outputs a drive stop signal to a mechanical press (not shown). After the punch 40 moves up, it stops at the top dead center (step S10). If a predetermined forming load is applied, the next step S
Proceed to 11.

Next, a molding load is applied to the forging material by the punch 40, and before the punch 40 reaches the bottom dead center, the pressure sensor 121 detects the relief set pressure in the pressure chamber 58 ( The detection signal is derived to a controller (not shown). A controller (not shown) determines whether or not the relief set pressure is within a predetermined range based on the detection signal (step S11).

If the set relief pressure is not within the predetermined range, a drive stop signal is output to a mechanical press (not shown), and the punch 40 is lifted and stopped at the top dead center (step S12). When it is determined that the relief set pressure is within the predetermined range, the process proceeds to the next step S13.

In the next step S13, the pressure oil in the pressure chamber 58 is relieved by the displacement action of the piston 60, and the punch 40 reaches the bottom dead center, and then rises toward the top dead center.
In addition, while the punch 40 rises after reaching the bottom dead center and reaches the top dead center, the pressure chamber 58 is supplied through the supply passage 118.
Is filled again with the pressure oil, the piston 60 returns to the initial position, and the solenoid valve is deactivated by the controller (not shown), and the air vent valve 131 is opened (steps S14 to S17). .

By continuously performing such steps, forging can be continuously performed on the forging material.

In this embodiment, it is detected that the forging material is not loaded in the cavity 46 at the stage of the initial rise of the hydraulic pressure, and the valve position of the relief pressure release valve 133 is switched to make the pressure oil supporting load zero. This prevents the mold from being overloaded when the first plate 44 and the second plate 42 abut. As a result, in the present embodiment, the occurrence of stress in the mold can be avoided, the damage to the mold can be prevented, and the durability of the mold can be improved.

In the present embodiment, the variation due to the extension of a frame, a connecting rod, etc. of a mechanical press (not shown), which usually causes a variation in the thickness of the forging material, is reduced by the piston 6.
It is absorbed as a change in the stroke amount of zero, and the thickness of the material is determined by the contact between the upper die and the lower die, so that it is not affected by the extension of the frame or the like.

In the present embodiment, the outer cup constituting the constant velocity joint is used as a material for forging. However, the present invention is not limited to this. It is needless to say that the present invention can be applied to various forged products that require dimensional accuracy in the thickness direction of components.

In addition, in the present embodiment, the buffer mechanism 56
Is provided in the lift side 54 on the displacement side, but is not limited to this, and the upper die 26 and the lower die 28
The buffer mechanism 56 may be provided on the fixed side such as.

[0082]

According to the present invention, the following effects can be obtained.

That is, when the forging material is not loaded in the cavity, it is possible to prevent the die from being damaged even when the upper die and the lower die come into contact with each other, thereby improving the durability of the die.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a forging die into which a hydraulic control device according to an embodiment of the present invention is incorporated.

FIG. 2 is an operation explanatory view showing a state where a punch descends from a forging start position shown in FIG. 1 and forging is completed.

FIG. 3 is a schematic configuration diagram of a hydraulic control device according to an embodiment of the present invention.

FIG. 4 is a partially enlarged sectional view of the forging die shown in FIG.

FIG. 5 is an explanatory diagram showing a manufacturing process of an outer cup constituting the constant velocity joint.

FIG. 6 is an explanatory view showing a manufacturing process of an outer cup constituting the constant velocity joint.

FIG. 7 is an explanatory diagram showing a manufacturing process of an outer cup constituting the constant velocity joint.

FIG. 8 is an explanatory diagram showing a manufacturing process of an outer cup constituting the constant velocity joint.

FIG. 9 is an explanatory diagram showing a relationship between a displacement amount of a punch and a pressure value of pressure oil.

FIG. 10 is an explanatory diagram showing a bottom thickness of a cup of an outer cup obtained as a forged product.

FIG. 11 is a flowchart illustrating an operation of the hydraulic control device according to the present embodiment.

FIG. 12 is an explanatory diagram showing a relationship between oil pressure of pressure oil filled in a pressure chamber and time.

FIG. 13 is an explanatory diagram showing an output of a load sensor corresponding to a change in oil pressure in a pressure chamber when a first plate and a second plate are in contact with each other and when they are not in contact with each other.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Hydraulic control device 11 ... Forging die 12a-12d ... Guide means 14, 16, 18 ...
Die holder 20 ... Press-fit rings 26,28 ... Dies 34,36 ... Ring body 40 ... Punch 42,44 ... Plate 45 ... Load sensor 46 ... Cavity 54 ... Elevating part 56 ... Buffer mechanism 58 ... Pressure chamber 60 ... Piston 62 ... Block body 64, 119, 120, 125, 126, 129, 13
7, 139 passage 102 hydraulic pressure source 104 relief valve 106 inlet port 108 discharge passage 110 tank 112 outlet port 114 relief pressure supply passage 116 relief port 118 supply passage 121 pressure sensor 127 ... air release circuit 131 ... air release valve 133 ... relief pressure release valve 135 ... relief pressure release circuit 136 ... pressure control valve

Claims (13)

[Claims] 1. A method for controlling a forging die provided with a buffer mechanism for absorbing a surplus displacement amount from when the first mold member and the second mold member come into contact with each other until the bottom mold reaches the bottom dead center. The pressure charged in the pressure chamber forming the buffer mechanism before the first mold member and the second mold member are relatively displaced and the first mold member and the second mold member come into contact with each other. It detects whether the pressure of the fluid has reached the initial set pressure in the initial stage of molding, and if the pressure of the pressure fluid has not reached the initial set pressure, it is determined that the forging material is not loaded and the pressure is determined. A method for controlling a forging die, wherein a pressure fluid filled in a chamber is forcibly led to the outside. 2. The method according to claim 1, wherein the pressure fluid filled in the pressure chamber is discharged to the outside by urging a solenoid valve to release the relief pressure of the relief valve. Control method of the forging die. 3. The method for controlling a forging die according to claim 1, wherein the pressurized fluid comprises pressurized oil. 4. The method according to claim 1, wherein the pressure of the pressure fluid filled in the pressure chamber is detected, and when the pressure of the pressure fluid is out of a predetermined filling pressure range, the first pressure is detected.
A method for controlling a forging die, comprising: stopping relative displacement between a mold member and a second mold member. 5. The method according to claim 1, wherein a contact load is detected when the first mold member and the second mold member are relatively displaced and come into contact with each other. A method for controlling a forging die, comprising: stopping relative displacement between a first mold member and a second mold member when the first mold member and the second mold member are not in contact with each other. 6. The method according to claim 1, wherein the pressure chamber inside the pressure chamber from when the first mold member abuts on the second mold member until the bottom dead center is reached is reached. Detecting a relief pressure of the pressurized fluid, and if the relief pressure is outside a predetermined range, the first
A method for controlling a forging die, comprising: stopping relative displacement between a mold member and a second mold member. 7. The method according to claim 1, wherein the air mixed in the pressure fluid in the pressure chamber is removed to the outside together with the pressure fluid leaking from the pressure chamber. Characteristic forging die control method. 8. A forging for forging the forging material by relatively displacing the first mold member and the second mold member and applying a pressing force to the forging material loaded in the cavity. A control device for a mold, wherein the first mold member and the second mold member are relatively displaced, and the first mold member and the second mold member are actuated by the action of a pressure fluid filled in a pressure chamber. And a buffer mechanism that absorbs a surplus amount of displacement from when it comes into contact to when it reaches the bottom dead center; a pressure detection unit that detects the pressure of the pressure fluid filled in the pressure chamber; and the pressure detection unit. Based on the detection signal output from the, if the pressure of the pressure fluid filled in the pressure chamber constituting the buffer mechanism has not reached the initial set pressure in the initial stage of molding, it is determined that the forging material is not loaded Externally pressurized fluid filled in the pressure chamber Deriving forging die of the control apparatus characterized by comprising: a pressure fluid control means, the for. 9. The pressure fluid control means according to claim 8, wherein said pressure fluid control means is connected to a relief valve having an inlet port communicating with said pressure chamber, and to a relief port of said relief valve, said relief valve being operated under a switching action. A control device for a forging die, comprising: a solenoid valve for releasing a relief pressure of the valve. 10. The control device according to claim 8, wherein the pressurized fluid is made of pressurized oil. 11. The apparatus according to claim 8, wherein said pressure detecting means comprises a pressure sensor, and said first and second mold members are provided separately from said pressure sensor. A control device for a forging die, comprising a load sensor for detecting whether or not the contact has occurred. 12. The apparatus according to claim 8, further comprising an air bleeding circuit for removing air mixed in the pressure fluid in the pressure chamber, and a biasing action of the air bleeding circuit. A control device for a die for forging, characterized in that air mixed into the pressure fluid is led out together with the pressure fluid leaking from the pressure chamber. 13. The forging die control device according to claim 9, further comprising a pressure control valve for controlling a pressure of a pressure fluid supplied to a relief chamber of the relief valve.