JPS6145930Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a hydraulic press, particularly a hydraulically driven press brake, and more particularly to a control device for controlling the operation of a movable apron (ram) in a press brake.

There are two types of hydraulic press brakes: one with a fixed apron (bed) on the bottom and a movable apron on the top, and another with a fixed apron on the top.
There is a model with a movable apron on the bottom.
In conventional hydraulic press brakes, the movable apron generally approaches the stationary apron rapidly, approaches at a low speed just before or at the same time as processing of the workpiece begins, and then bends the workpiece. After that, the movable apron moves away from the fixed apron. In such a hydraulic press brake, while the movable apron approaches the fixed apron,
Because there was no function to temporarily stop the approaching operation of the movable apron and hold it in that stopped state, it was sometimes dangerous when attaching and removing the molds and when fitting the molds together. In addition, for press brakes with a movable apron installed on the lower side, the movable apron must stop rising when the pressure in the hydraulic cylinder for raising the movable apron and the weight of the movable apron are balanced. However, in this case, since the pressure oil is supplied to the hydraulic cylinder by adjusting the amount of depression of the foot lever with one foot, the worker must stand on one foot, causing an unstable posture. It is what it is.

This idea was created in view of the conventional problems mentioned above.
Examples will be described in detail.

FIGS. 1 and 2 schematically show a hydraulic press brake according to this invention. A fixed apron (bed) 3 is fixed to the upper part of a frame 1 of the press brake, and a movable apron (ram) 5 is mounted to the lower part of the frame 1 so as to be movable up and down. That is, the movable apron 5 performs the lifting and lowering operations (approaching and separating operations with respect to the fixed apron 3) by the main cylinder 7 and pressurizing cylinder 9 attached to the frame 1, and normally the main cylinder 7 is supplied with pressurized oil. By doing this, the movable apron 5 is raised rapidly, and at the start of pressurization,
It supplies pressure oil to the pressurizing cylinder 9.

In this type of press brake, by adjusting the amount of depression of a foot lever 11 pivotally connected to the frame 1, the movable apron 5 can be raised rapidly, slowly raised, stopped, lowered, etc. That is, by adjusting the amount by which the foot lever 11 is depressed, the control valve 13 is operated appropriately, and the main circuit 15 from the hydraulic pump P (see FIG. 3) to the main cylinder 7, pressurizing cylinder 9, etc. is connected to the tank T. This is done by adjusting the opening degree of the communicating hole. For example, when the foot lever 11 is fully depressed to reduce the opening degree of the control valve 13 to zero, all the pressure oil from the hydraulic pump P is supplied to the main cylinder 7, so the movable apron 5 will rise rapidly. Next, when the amount of depression of the foot lever 11 is gradually reduced and the opening degree of the control valve 13 is gradually increased, the pressure oil discharged from the hydraulic pump P to the tank T gradually increases, so that the movable apron 5 gradually rises. When the pressure in the main cylinder 7 and the weight of the movable apron 5 become balanced, the ascent stops. If the opening degree of the control valve 13 is then further increased, the amount of pressurized oil discharged into the tank T will further increase, so that the movable apron 5 will gradually descend due to its own weight.

Next, a hydraulic circuit for controlling the operation of the movable apron 5 in the press brake described above will be explained using FIG. 3.

A 4-port, 3-position first solenoid valve 17 equipped with solenoids SOL ₁ a and SOL ₁ b is arranged between the hydraulic pump P and the main circuit 15 . This first solenoid valve 17 connects the hydraulic pump P and the main circuit 15 when the solenoid SOL ₁ a is excited, and the solenoid
When SOL ₁ b is energized, it connects the main circuit 15 to the tank T. A first branch oil passage 19 branched from the main circuit 15 is connected in series with a flow rate control valve 21 and a 4-port 2-position second solenoid valve 23 equipped with a solenoid SOL ₂ . This second solenoid valve 23 communicates the first branch oil passage 19 with the tank T when the solenoid SOL ₂ is excited.
Under normal conditions, communication is cut off.

Further, a second branch oil passage 25 is branched from the main circuit 15, and an on-off control valve 27 and the control valve 13 are connected in series to the second branch oil passage 25. The opening/closing control valve 27 is a solenoid SOL ₃
When the solenoid SOL ₃ is excited, communication with the second branch oil passage 25 is cut off, and the solenoid
When SOL ₃ is in a de-energized state, the second branch oil path 2
5 in a communicating state. Note that a relief valve 31 is connected to the second branch oil passage 25 in a branched manner.

The main circuit 15 is connected to the small diameter portion 7a of the main cylinder 7, and a third branch oil passage 33a branched from the main circuit 15 is connected to the pressurizing cylinder 9 and the main cylinder through a connecting oil passage 33b. It is connected to the large diameter portion 7b of the cylinder 7, and a check valve 35, a sequence valve 37, and a throttle valve 39 are connected in parallel between the third branch oil passage 33a and the connecting oil passage 33b. be. This sequence valve 37 is in a cutoff state in a normal state, and is switched to a communication state when the pressure in the main circuit 15 increases. The connecting oil passage 33b is connected to the tank T via the check valve 41, and the pressure switch 43 is connected to the tank T via the check valve 41.
is connected.

Furthermore, a restriction valve 45 is branched and connected to the main circuit 15. This restriction valve 45 is
It is attached to the movable apron 5 so that its position can be adjusted as appropriate, and is normally in a closed state. When the movable apron 5 approaches the stationary apron 3 and comes closest to it, it comes into contact with an actuator 47, such as a dog, provided on the frame 1 or the like, and becomes open.

Next, FIG. 4 shows a control device (control circuit) that controls the operation of the movable apron 5 by appropriately controlling the first solenoid valve 17, the second solenoid valve 23, the third solenoid valve 29, etc. I will explain using

The control device (control circuit) controls the approaching operation (in this embodiment, the raising operation) of the movable apron 5.
Start control device (start control circuit) that controls the start of
49, an operation control device (operation control circuit) 51 that controls the operation of the movable apron 5, such as a temporary stop of the approach operation of the movable apron 5, and a control device (operation control circuit) 51 for controlling the operation of the movable apron 5, such as temporarily stopping the approach operation of the movable apron 5, and a control device (operation control circuit) 51 for bringing the movable apron 5 closest to the fixed apron 3 and performing pattern matching, etc. Controlling mold matching control device (mold matching control circuit) 5
3, a selection control device (selection control circuit) 55 that selectively controls the operation of the movable apron 5 such as single action, inching, etc.; an operation control circuit) 57, a separation operation control device (separation operation control circuit) 59 that controls the separation operation (lowering operation) of the movable apron 5, and a discharge control device that controls the stoppage of the discharge of pressure oil from the hydraulic pump P to the tank T. A stop control device (discharge stop control circuit) 61, a separation stop control device (separation stop control circuit) 63 that controls the stop of the separation operation of the movable apron 5, and a deceleration control device that controls the deceleration of the approach operation of the movable apron 5. (Deceleration control circuit)
65, and a solenoid control device (solenoid control circuit) 67 for controlling the excitation of each solenoid such as the electromagnetic valves 17, 23, 29, etc.

The starting control device 49 is formed by connecting a first foot switch FS ₁ for lifting and a relay R ₁₀ in series.

The operation control device 51 includes a temporary stop circuit 69
, a temporary stop holding circuit 71, a restart circuit 73, and the like. Temporary stop circuit 69
are the temporary stop changeover switch SS ₂ , the first sensing device LS ₁ , and the relay in the selection control device 55.
The a contact (make contact) of _R18 , the a contact of the relay _R10 , and the relay _R11 are connected in series,
The a contact of relay _R14 in the mold matching control device ₅₃ is connected in parallel to the a contact of relay R10. The first sensing device LS ₁ is composed of a limit switch, a proximity switch, etc., and is attached to the frame 1 (or the movable apron 5) so that its position can be adjusted, although the attached state is not shown in the drawings. It is turned on when activated by a dog (not shown) or the like appropriately attached to the apron 5 (or frame 1).

The temporary stop holding circuit 71 is connected to the a of the relay _R11 .
The contact and relay 12 are connected in series, and the a contact of relay R ₁₁ is connected in series with the a contact of relay R ₁₂ and the b contact (break contact) of relay R ₂₁ in separation operation control device 59. The circuits are connected in parallel.

_The restart circuit 73 includes the relay R ₁₄ and the relay _{R 13 which} is energized under the conditions of the de-energization of the relay R ₁₀ and the energization of the relay R ₁₂ . It becomes a self-holding state depending on the excitation conditions. Additionally, the relay
_R13 is excited when the push button switch PB is turned on (closed).

The mold matching control device 53 includes a changeover switch SS ₃
It consists of a relay _R14 that is energized depending on the ON operation condition of the relay R14.

The selection control device 55 includes a plurality of relays R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ that are individually excited according to selection conditions of a selection switch SS ₁ having a plurality of terminals.
It consists of etc.

The approach operation control device 57 is composed of a relay R _20, etc., and this relay R ₂₀ includes (a) a relay;
Conditions for excitation of R ₁₅ ; (b) Relay R ₁₀ or relay R ₁₄
Conditions for energizing relay R ₁₆ or relay R ₁₇ and de-energizing relays R ₁₅ and R ₂₁ ; (c) Relay R ₁₀
Or, it is energized under the following conditions: relay R ₁₄ and relay R ₁₈ are energized, relay R ₁₂ is de-energized, relay R ₁₃ is energized, and relays R ₁₅ and R ₂₁ are de-energized. It should be noted that when both relay R ₂₀ in approach operation control device 57 and relay R ₂₃ in discharge stop control device 61 (described later) are in an excited state, movable apron 5 performs approach operation (raising).

The separation operation control device 59 is composed of a relay R ₂₁ and the like, and this relay R ₂₁ is a relay
Under the de-energized condition of R ₁₄ , R ₁₅ , R ₂₀ , R ₂₄ ,
The second foot switch FS ₂ is turned on and is energized by energizing either relay R ₁₇ or relay R ₁₈ as appropriate, and becomes self-holding when one relay R ₁₈ is energized. When the relay _R16 is in the energized state under the above conditions, it is always in the energized state regardless of whether the second foot switch _FS2 is ON or OF (opening/closing).
Note that the relay in this separation operation control device 59
When R ₂₀ is excited, the movable apron 5 moves away (lowers).

The discharge stop control device 61 includes a timer R ₂₂ , a relay R ₂₃ , and the like. timer
R ₂₂ , excited by the excitation conditions of relay R ₁₀ ,
The contact is opened after an appropriate amount of time has elapsed.
The relay R ₂₃ is configured to (a) de-energize relays R ₁₅ and R ₂₁ ;
Under the conditions of excitation of relay R ₁₈ , relay R ₁₀ ,
When one of R ₁₄ and R ₂₃ is the excitation condition; (b)
Relay R ₁₅ de-energized, relay R ₁₇ energized, timer
When the contact of R ₂₂ is closed or the relay R ₂₄ is de-energized and one of the relays R ₁₀ , R ₁₄ and R ₂₃ is energized as appropriate; (c) the relay R ₁₅ is de-energized and the relays R ₁₆ and R ₂₀ are energized; Conditions for excitation or excitation of relays R ₁₇ and R ₁₄ ;

The separation stop control device 63 is a second sensing device.
Relay R ₂₄ energized by the condition of closing operation of LS ₂
It is more than that. The second sensing device LS ₂ is operated to close when the movable apron 5 appropriately separates from the fixed apron 3 (usually when it is lowered to its lowest point).

The deceleration control device 65 is composed of a relay R ₂₅ and the like, and this relay R ₂₅ controls the closing of the pressure switch 43, the deceleration changeover switch SS ₄ , the closing of the third sensing device LS _3, and the non-operation of the relay R ₂₁ . It is excited under excitation conditions. The third sensing device LS ₃ is attached to the movable apron 5 (or the frame 1) as appropriate, such as in a freely adjustable position, although the state in which it is attached is not shown in the drawings.
(or the movable apron 5) by means of a dog (not shown), etc., which is appropriately attached to the movable apron 5, during the approach operation of the movable apron 5.

The solenoid control device 67 is a circuit that excites the solenoid SOL ₃ of the third solenoid valve 29 according to the excitation condition of the relay R ₂₂ , and a circuit that excites the solenoid SOL ₁ a of the first solenoid valve 17 according to the excitation condition of the relay R ₂₀ . A circuit to excite, a circuit to excite the solenoid SOL ₁ b of the first solenoid valve 17 according to the excitation conditions of the relay R ₂₁ , a circuit to excite the solenoid SOL ₂ of the second solenoid valve 23 according to the excitation conditions of the relay R ₂₅ , etc. It is more than that.

In the above configuration, selection switch SS ₁
When relay R ₁₅ is energized by selection of , relay R ₂₀
is in an energized state, and relays R ₂₁ and R ₂₃ are in a de-energized state. By energizing the relay R ₂₀ , the solenoid SOL ₁ a of the first electromagnetic valve 17 is energized. Therefore, the pressure oil from the hydraulic pump P is transferred to the first solenoid valve 1.
7, it will be recirculated to the tank T via the main circuit 15, the second branch oil path 25, the opening/closing control valve 27, and the control valve 13. In this state, by depressing the foot lever 11 and controlling the control valve 13, the movable apron 5 is raised and lowered (approaching and separating from the fixed apron 3), as described above.
can be controlled.

By the way, when the foot lever 11 is depressed to close the opening of the control valve 13, the pressure oil from the hydraulic pump P flows into the small diameter portion 7a of the main cylinder 7, so the movable apron 5 rapidly approaches (raises). . In this case, oil is drawn into the pressurized cylinder 9 from the tank T via the check valve 41. As mentioned above, the movable apron 5 operates rapidly,
Before bending of the workpiece is started by the molds attached to the movable apron 5 and the fixed apron 3, the third sensing device LS ₃ in the deceleration control device 65
When is operated to close (changeover switch SS ₄ is in the closed state), relay R ₂₅ is energized. Therefore, the second
The solenoid SOL ₂ of the electromagnetic valve 23 becomes energized. Therefore, a part of the pressure oil in the main circuit 15 is discharged to the tank T via the first branch oil passage 19, and the approach operation of the movable apron 5 becomes slow.

As described above, after the movable apron 5 approaches at a low speed, the movable apron 5 further approaches, and the molds attached to the movable apron 5 and the fixed apron 3 start bending the workpiece. The pressure in the main circuit 15 increases and the sequence valve 37 is switched from the state shown in FIG. Therefore, the pressure oil from the hydraulic pump P will be supplied to the large diameter portion 7b of the main cylinder 7 and the pressurizing cylinder 9, and a large thrust will act on the movable apron 5. As described above, when the sequence valve 37 is switched and the pressure in the connecting oil passage 33b increases, the pressure switch 43 is opened and the relay _R25 returns to the de-energized state. Therefore, the solenoid SOL ₂ of the second electromagnetic valve 23 becomes de-energized, and the first branch oil passage 19 becomes cut off. Therefore, the workpiece is bent even with the full pressure from the hydraulic pump P.

That is, when the changeover switch SS ₄ in the deceleration control device 65 is in the closed state, the movable apron 5 appropriately approaches the fixed apron 3 and closes the third sensing device LS ₃ to close the hydraulic pump P.
A part of the pressure oil from the oil passage is discharged, resulting in a low-speed approach operation, and the bending process is started, and the pressure increase in the oil passage causes the pressure switch 4 to be activated.
3 is activated, the discharge of a portion of the pressure oil is stopped, and the bending process of the workpiece is performed even with the full pressure from the hydraulic pump P.
Note that the changeover switch in the deceleration control device 65
Under the condition that SS ₄ is closed, selection switch SS ₁ also switches relay R ₁₆ as described below.
Alternatively, when relay R ₁₇ or relay R ₁₈ is selectively energized to perform various operations of movable apron 5, movable apron 5 is connected to the third sensing device.
After LS ₃ is activated, it will be a low-speed approach operation. Therefore, when bending is performed with the changeover switch _SS4 held in the closed state, the workpiece does not jump up rapidly due to the bending.

As mentioned above, when the movable apron 5 approaches at a low speed to start bending the workpiece, and the restriction valve 45 comes into contact with the actuator 47 and is activated, the pressure oil in the main circuit 15 is released. Discharge into tank T.

After bending the workpiece, turn foot lever 1
1, the pressurized oil from the hydraulic pump P and the oil in the main cylinder 7 and pressurized cylinder 9 will be discharged to the tank T, and the movable apron 5 will be lowered by its own weight (separation operation). That will happen.

That is, when the relay R ₁₅ is energized, the first foot switch FS ₁ in the starting control device 49 is activated.
By appropriately adjusting the amount of depression of the foot lever 11, the operation of the movable apron 5 can be appropriately controlled, regardless of whether the foot lever 11 is opened or closed.

Next, the relay is activated by selecting selection switch SS ₁ .
When R ₁₆ is energized, the a contact of relay R ₁₆ is closed. Note that here, the mold matching control device 53
When the changeover switch SS ₃ is closed and the relay R ₁₄ is in the energized state, the a of the relay R ₁₄ is
Since the contact is closed and the B contact is open, the relay
R ₂₀ is energized, relay R ₂₁ is de-energized, solenoid SOL ₁ a in first electromagnetic valve 17 is always energized, and solenoid SOL ₁ b is de-energized. Also, by energizing relay R ₂₀ , relay R ₂₃
is excited, and the solenoid of the third solenoid valve 29
SOL ₃ becomes energized. Therefore, the movable apron 5 is moved closer (raised), and the molds attached to the fixed apron 3 and the movable apron 5 are held in an engaged state, that is, in a state in which the molds are aligned. Therefore, the changeover switch SS ₃ in the mold matching control device 53 is held in the open state in the normal state, and when the movable apron 5 approaches the fixed apron 3, the changeover switch SS ₃ is operated to close by manual operation or the like. It is something. That is, the mold matching control device 53 closes the changeover switch SS ₃ only when performing mold matching between the molds attached to the fixed apron 3 and the movable apron 5.

Note that even when relays R ₁₇ and R ₁₈ (to be described later) are energized, the above-described pattern matching state can be maintained by keeping the changeover switch SS ₃ in the closed state. Therefore, the mold matching control device 5
By holding the changeover switch SS ₃ in the closed state, the molds can be attached to and removed from the fixed apron 3 and the movable apron 5 while maintaining the mold matching state.

In the following explanation of the operation, it will be assumed that the changeover switch _SS3 in the mold matching control device 53 is held in the open state.

Now, as described above, when the relay _R16 is energized by selection of the selection switch _SS1 , the a contact of the relay _R16 is closed. In this state, relay R ₂₀ is still in the de-energized state, so relay R ₂₁ should be in the energized state, but the movable apron 5 is in the lowered position and the second sensing device LS ₂ is closed. , so relay R ₂₄ is in the energized state. Therefore, both relays R ₂₀ and R ₂₁ are in a de-energized state.

As described above, when the first foot switch FS ₁ in the starting control device 49 is depressed and closed while the relay R ₁₆ is energized, the relay R ₁₀ is energized. Therefore, relay R ₂₀ is energized, and solenoid SOL ₁ a in first electromagnetic valve 17 is energized. Furthermore, due to the energization of the relay R ₂₀ , the relay R ₂₁ is kept in a de-energized state, and the relay R ₂₃ is energized, so that the solenoid SOL ₃ of the third solenoid valve 29 is energized.
is excited. Therefore, the movable apron 5 starts rising (approaching operation). When the movable apron 5 starts to rise, the second sensing device LS ₂ becomes open and the relay R ₂₄ becomes de-energized.

Next, when the first foot switch FS ₁ is released from the depression and opened, the relay R ₁₀ becomes de-energized. Therefore, the relays R ₂₀ and R ₂₃ are sequentially de-energized, and the solenoids SOL ₁ a and SOL ₃ are de-energized. On the other hand, since the relay R ₂₁ becomes energized and energizes the solenoid SOL ₁ b of the first solenoid valve 17, the pressure oil from the hydraulic pump P and the oil in the main circuit 15 are discharged to the tank T. The movable apron 5 will descend under its own weight. Then, at the lower end of the movable apron 5, the second sensing device
LS ₂ is closed, relay R ₂₄ is energized, and relay R ₂₁ is de-energized.

That is, when the selection switch SS ₁ is selected to energize the relay R ₁₆ , the movable apron 5 is raised by the closing operation of the first foot switch FS ₁ , and the opening operation of the first foot switch FS ₁ is performed. As a result, the movable apron 5 is lowered, and the movable apron 5 can be controlled in a single motion.

Next, when the selection switch SS ₁ is selected to energize the relay R ₁₇ , the energization of the relay R ₁₇ causes each a contact of the relay R ₁₇ to be in a closed state. In this state, when the first foot switch FS ₁ is closed, relay R ₁₀ is energized, so the relay
R ₂₀ , R ₂₃ and timer R ₂₂ are energized and the relay
The energization of R ₂₀ causes relay R ₂₁ to become de-energized.
Therefore, the movable apron 5 begins to rise. Note that the contacts of the timer R ₂₂ are operated to open after an appropriate period of time has elapsed, but the relay R ₂₄ becomes de-energized at the same time as the movable apron 5 rises. Therefore, relay R ₂₃ will maintain itself even if relay R ₁₀ is de-energized.

As mentioned above, after the movable apron 5 starts to rise, when the first foot switch FS ₁ is opened and the relay R ₁₀ is de-energized, the relay R ₂₀ is de-energized (relay R ₂₃ is self-energized). (in the holding state), the movable apron 5 stops rising. Note that since the relay R ₂₁ is also in a non-energized state, the movable apron 5 stops without rising or falling.

As mentioned above, when the movable apron 5 is in a stopped state and the second foot switch FS ₂ is closed, the relay R ₂₁ becomes energized, so the movable apron 5 will be lowered by its own weight. . Then, by opening the second foot switch _FS2 , the relay _R21 becomes de-energized, and the lowering of the movable apron 5 is stopped.

In other words, the selection switch SS ₁ also triggers the relay.
When R ₁₇ is energized, the movable apron 5 is raised by depressing the first foot switch FS ₁ (closing operation), and the movable apron 5 is raised by depressing the first foot switch FS ₁ (opening operation). can be stopped and the second foot switch
Movable apron 5 by pressing FS ₂ (closing operation)
is lowered, and the movable apron 5 can be stopped from lowering by releasing the depression (opening operation) of the second foot switch _FS2 . In other words, by keeping the relay _R17 in an excited state, the inching of the movable apron 5 can be controlled.

Furthermore, when relay R ₁₈ is then held in the energized state by selection of selection switch SS ₁ , relay R ₁₈
Each a contact of is in a closed state. In this state, when the first foot switch FS ₁ is closed, the relay
R ₁₀ is energized, and the energization of relay R ₁₀ causes the relay to
R ₂₀ and R ₂₃ are excited. Then, relay _R23 enters a self-holding state. Therefore, when the first foot switch FS ₁ is closed, the movable apron 5 starts to rise. After the movable apron 5 starts to rise, when the first foot switch FS ₁ is released and opened, the relay R ₁₀ becomes de-energized.
Relay R ₂₀ becomes de-energized and the movement of movable apron 5 is stopped.

As described above, when the second foot switch FS ₂ is depressed and operated to close after the movable apron 5 has stopped rising, the relay R ₂₁ is energized, and the relay R ₂₁ enters the self-holding state. Further, by energizing relay R ₂₁ , the self-holding of relay R ₂₃ is released. Therefore, the movable apron 5 is connected to the second foot switch.
After closing FS ₂ , the second foot switch FS ₂
Regardless of whether it is opened or closed, it will descend due to its own weight.

As mentioned above, when the first foot switch FS ₁ is closed and the movable apron 5 is raised, the movable apron 5 is appropriately raised, and the first sensing device LS ₁ in the temporary stop circuit 69 is closed (the changeover switch SS ₂ under the condition of closed state), relay
R ₁₁ is energized. By energizing this relay R ₁₁ ,
Relay R ₁₂ in temporary stop holding circuit 71 is energized, and under the condition that relay R ₂₁ is de-energized, relay R ₁₂ enters a self-holding state. Due to the excitation of the relay _R12 , the a contact of the relay _R12 is closed,
The b contact becomes open. Therefore, relay R ₂₀
becomes de-energized, and the movable apron 5 stops rising. That is, when the first sensing device LS ₁ is closed by the movable apron 5, the movement of the movable apron 5 is temporarily stopped even if the first foot switch FS ₁ is kept depressed and held in the closed state. It is something.

As described above, when the second foot switch FS ₂ is closed after the movable apron 5 has temporarily stopped rising, the movable apron 5 is lowered in the same manner as described above.

As mentioned above, after the movable apron 5 has temporarily stopped rising, the first foot switch FS ₁ is opened and the relay R ₁₀ is de-energized _.
The b contact of is in the closed state. Therefore, relay _R13 in restart circuit 73 is energized. This energization of relay R ₁₃ brings the a contact of relay R ₁₃ into a closed state, and relay R ₁₃ enters a self-holding state under the condition that relay R ₂₁ is de-energized. In this way, when the first foot switch FS ₁ is depressed again while relay R ₁₃ is in the self-holding state, the relay
_R20 becomes energized, the movable apron 5 starts to rise further from the temporary stop position, and stops when the first foot switch _FS1 is opened. Note that, as mentioned above, the movable apron 5 is lowered by the second foot switch FS ₂ .
This is done by closing the .

By the way, when the changeover switch SS ₃ in the mold matching control device 53 is closed, the relay R ₁₄ is energized, so the movable apron 5 starts to rise regardless of whether the first foot switch FS ₁ is opened or closed. 1 When the sensing device LS ₁ is closed, the movement of the movable apron 5 is temporarily stopped. After this temporary stop, the push button switch of the restart circuit 73 is activated.
By pressing PB, the movable apron 5 starts to rise again from the temporary stop position, and after starting to rise again, the relay R ₁₃ is in a self-holding state and remains in the raised state regardless of whether the push button switch PB is opened or closed. be.

As mentioned above, the changeover switch SS ₃ in the mold matching device 53 is held in the closed state, and the movable apron 5 is
When changeover switch SS ₃ is opened after the switch SS 3 is held in the raised state, relay R ₁₄ becomes de-energized and relay R ₂₀ becomes de-energized, but relay R ₂₁ becomes de-energized.
Since the first electromagnetic valve 17 is also in a de-energized state, the first electromagnetic valve 17 becomes neutral, and the movable apron 5 is maintained at the raised position without being lowered. Note that the lowering of the movable apron 5 is performed using the changeover switch as described above.
After opening SS ₃ , switch the second foot switch.
This is done by closing FS ₂ and energizing relay R ₂₁ .

Therefore, when keeping relay R ₁₈ energized by selection of selection switch SS ₁ ,
The movement of the movable apron 5 can be temporarily stopped even at the position where the first sensing device LS ₁ is activated.
In other words, it is possible to perform temporary stop control.

As can be understood from the above description of the embodiments, the gist of the present invention is as stated in the claims for utility model registration. The main circuit connecting the main cylinder and hydraulic pump for moving the apron up and down is equipped with a 3-position first solenoid valve for controlling the raising, lowering, and stopping of the movable apron. A branch oil passage equipped with a control valve that adjusts the opening degree of the communication hole to the tank by stepping on the main circuit is branched from the main circuit. The valve is provided with a control circuit for controlling the first electromagnetic valve and the opening/closing control valve. Therefore, by controlling the communication cutoff of the opening/closing control valve, the control valve can be enabled or disabled, and the raising, lowering, stopping, etc. of the movable apron can be controlled separately from the control of the control valve. In other words, according to the present invention, the movable apron can be held in a temporarily stopped state even when the foot lever for controlling the vertical movement of the movable apron is taken off. , which can be easily performed in a comfortable position other than standing on one leg.
In addition, when the temporary stop position of the movable apron is adjusted to a position where the molds attached to the movable apron and the fixed apron are engaged (mold matching position), the movable apron can be moved while the molds are engaged. Since the apron can be stopped, the mold can be easily and reliably attached to and removed from the movable apron and the fixed apron.

Note that this invention is not limited to the above-mentioned embodiments, but can be implemented in modes other than the above-mentioned embodiments by making appropriate design changes, and is movable. It can also be easily implemented in hydraulic presses of the type where the apron is on the top and the fixed apron is on the bottom.

[Brief explanation of the drawing]

Figures 1 and 2 are side and front views schematically showing a hydraulic press, and Figures 3 and 4 are hydraulic circuits and control circuits for controlling the operation of the movable apron. It is. Explanation of the symbols representing the main parts of the drawing, 1...
Frame, 3... Fixed apron, 5... Movable apron, 57... Approach action control device, 59... Departure action control device, 69... Temporary stop circuit.

Claims (1)

[Scope of utility model registration request] A movable apron that can approach and leave the fixed apron fixed to the frame of the hydraulic press is installed on the frame so as to be vertically movable, and a main cylinder 7 for vertically moving the movable apron 5 is connected to a hydraulic pump P. A movable apron 5 is attached to the main circuit 15.
A three-position first solenoid valve 17 for controlling the raising, lowering, and stopping of the tank T is arranged and provided in a branch oil line 25 branched from the main circuit 15 and connected to the tank T.
The control valve 13 whose opening degree of the communication hole to the tank T is adjusted by depressing a foot lever 11 provided on the hydraulic press and the branch oil passage 25 are automatically cut off. An opening control valve 27 for controlling validity/invalidity is connected in series, and a control device for controlling switching operations of the first electromagnetic valve 17 and the opening/closing control valve 27 is provided. Hydraulic press control device.