JP2548624B2 - Sequence valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sequence valve provided between a switching valve and two actuators to perform a continuous sequence operation, and more specifically, to a holding pressure for one actuator. The present invention relates to a valve that switches a flow path when the state is released and the operation of the next actuator is started.

<< Prior Art >> A sequence operation of releasing a pressure holding state of an actuator and then moving to the next actuator is required, for example, in a drive device of a plasticizing screw (hereinafter, simply referred to as a screw) of an injection molding machine. It

For example, a pre-plastic injection molding machine shown in FIG.
No. 236647), a screw 30 is provided with a hydraulic motor 4 for rotating the screw 30 and a hydraulic cylinder 4 for advancing the screw 30 in the axial direction. When the resin is plasticized by the rotation of the screw 30, the screw 30
Is slightly retracted by the pressure of the molten resin to open a resin passage (hereinafter, simply referred to as “passage”) 35, sends the molten resin 31 to the injection chamber 32, and retracts the plunger 36 to accumulate (measure) the resin in the injection chamber 32. ) Will be done. When it is injected by the plunger 36, the rotation of the hydraulic motor 5 is stopped, pressure oil is supplied to the back pressure side 33 of the piston 29 of the hydraulic cylinder 4, and the screw 30 is moved forward, and the tip of the screw is moved.
34a is pressed against the valve seat surface 34b of the passage 35,
Close 35. Then, the injection operation is performed by the plunger 36 while the back pressure of the piston 29 is maintained, and the molten resin 31 in the injection chamber 32 is supplied to the mold cavity (not shown).

When the resin is plasticized again, the screw 30 rotates again to plasticize the resin for the next injection operation, but when the screw 30 starts to rotate, the piston 29 held until then is If the back pressure is not released, the screw 30 cannot be retracted, and the tip 34a of the screw rotates while being pressed by the valve seat surface 34b, causing abnormal wear. This is because the retreating operation of the screw 30 is retreated by the melting pressure (reaction force) of the molten resin 31 as described above, and the passage 35 is opened by the retreating of the screw 30, and the molten resin 31
Is to flow into the injection chamber 32 and be measured.

That is, when the screw 30 is rotating to melt the resin, the back pressure is also released in the piston 29 and the piston (not shown) behind the plunger 36. When the molten resin 31 in the injection chamber 32 is injected by the plunger 36,
This is when the back pressure is applied to the piston 29 so that the screw 30 closes the passage 35 and the back pressure is applied to the piston behind the plunger 36.

As a circuit to perform such sequence operation,
As shown in FIG. 4, the switching valve 3 and the pilot check valve 37
A circuit using is conceivable. In the circuit of FIG. 4, when the switching valve 3 is switched from the state in which the back pressure of the piston 29 is held by the check action of the pilot check valve 37, the pilot check valve 37 is operated by the pressure increase of the circuit 38 on the hydraulic motor 5 side. Is released and the back pressure of the piston 29 is released. However, in the structure of FIG. 4, when the load of the hydraulic motor 5 is small, the hydraulic motor 5 starts rotating before the pressure of the circuit 38 on the hydraulic motor side reaches the cracking pressure of the pilot check valve 37, and the hydraulic motor 5 starts to rotate. The sequence operation in which the back pressure of the piston 29 has to be released before the rotation starts is not realized.

Therefore, in order to avoid such a situation, as shown in FIG. 3, the pilot pipe 39 of the circuit 38 on the hydraulic motor 5 side is provided.
If a pressure control valve 40 is provided between the hydraulic motor 5 and the hydraulic motor 5 and the hydraulic motor 5 is not loaded, the pressure in the pilot pipe 39 becomes equal to or higher than a predetermined pressure and the back pressure of the piston 29 is not released. A circuit configuration is adopted in which hydraulic pressure is not supplied to the hydraulic motor 5 side.

<< Problems to be Solved by the Invention >> As described above, when it is attempted to realize the sequence operation required in the drive system of the screw of the pre-plastic injection molding machine by the conventional control valve, the switching valve 3 for circuit switching is used.
Besides, a pilot check valve 37 and a pressure control valve 40 are required, and since the pilot check valve 37 and the pressure control valve 40 operate independently, for example, before the pilot check valve 37 opens for some reason, If the pressure control valve 40 opens, the desired sequence operation may not be realized.

Furthermore, even if the hydraulic motor load for plasticization is small, the cracking pressure is required as a minimum as the discharge pressure of the hydraulic pump, and energy loss cannot be avoided.

The present invention reliably performs a sequence operation such as rotation of a screw in an injection unit that proceeds to the next step after releasing the pressure holding state of an actuator without using a pressure control valve, and stop of the rotation and closing of a passage, and An object of the present invention is to provide a control valve that can be operated with a simpler circuit configuration.

<< Means for Solving the Problem >> The present invention made in view of the above-mentioned circumstances is the two input ports (7, 8) connected to the switching valve (3) and the first and second actuators (4, 5). There are two output ports (9, 10) for supplying pressure to the first input port (7) and the first output port (9), and the first primary chamber (22) and the first flow path ( 26) and communicates with the second input port (8) and the second
The output port (10) is the second primary chamber (23) and the second flow path (1
8) is communicated with via. Then, the first flow path (2
Between the first primary chamber (22) and 6) the coil spring (16)
A check valve (11) having a valve body (13) contacting the valve seat (12) is provided so as to block the flow from the first flow path (26) toward the first primary chamber (22), A circular hole-shaped opening (19) is formed between the second flow path (18) and the second primary chamber (23).

Further, the first and second primary chambers (22, 23) constitute one cylinder (24) communicating with each other through a hole, and the cylinder (24) has the valve element (13) of the check valve (11). ) Having a push rod (27) opposed to () and a valve rod (28) capable of moving in and out of the opening (19) on the first flow path (26) side and the second flow path (18) side. Is fitted. The balance spool (25) closes the opening (19) when moving to the second flow path (18) side, and closes the check valve (11) when moving to the first flow path (26) side. After opening, the opening (19) of the second flow path (18) is opened.

<< Operation >> As shown in FIG. 1, the first and second input ports (7, 8) of the present invention are connected to the hydraulic pump and the tank via the switching valve (3), and the first output port (9) is connected. To a first actuator (hydraulic cylinder shown) (4),
The second output port (10) is connected to a second actuator (hydraulic motor shown) (5). In the illustrated state, pressure oil is being supplied to the first actuator (4), and the hydraulic pressure supplied to the first actuator (4) is held by the check valve (11). When the switching valve (3) is switched in that state, hydraulic pressure is supplied to the second input port (8),
Since the opening (19) of the second flow path (18) is closed,
The pressure in the second primary chamber (23) rises and moves the balance spool (25) to the first flow path (26) side. And the first
The balance spool (25) moved to the flow path (26) side is opened by opening the check valve (11) to release the holding pressure of the first actuator (4) and then opening the opening (19). The actuator (5) starts operation.

Further, when the switching valve (3) is switched from the operating state of the second actuator (5), the second primary chamber (23)
When the pressure in the first primary chamber (22) rises and the pressure in the first primary chamber (22) rises, the balance spool (25) moves to the side of the second flow path (16) and closes the opening (19) to operate the second actuator (5). Stop. The oil supplied to the first primary chamber (22) passes through the check valve (11) due to the pressure, and operates the first actuator (4). Then, after the supply of hydraulic pressure to the first primary chamber (22) is stopped, the check valve (1
1) is closed and the hydraulic pressure supplied to the first actuator (4) is held.

The reference numerals in parentheses described above are for the purpose of contrast with the drawings, but do not limit the configuration of the present invention in any way.

<< Embodiment >> An embodiment of the sequence valve according to the present invention will be described below.
This will be described with reference to the drawings.

In the figure, 1 is a sequence valve of the present invention, 3 is a switching valve, 4
Is a first actuator (hydraulic cylinder), 5 is a second actuator (hydraulic motor), P is a pump port of the switching valve 3, and T is a tank port. An example in which the first output port 9 is connected to the hydraulic cylinder 4 and the second output port 10 is connected to the hydraulic motor 5 in FIG. 2 is shown together with the symbol of the hydraulic device.

Reference numeral 6 denotes a valve case, which has a first input port 7 and a second input port 8 and a first output port 9 on the other side.
And the second output port 10 is open. Reference numeral 11 is a check valve formed by a valve seat 12 and a valve body 13. The valve seat 12 is fixed to the valve case 6, and the valve body 13 is slidable in the left-right direction in the figure and screwed to the valve case 6. It is pressed against the valve seat 12 by a coil spring 16 that is interposed between the left cap 15 and the left cap 15.
Reference numeral 17 is a ring fixed to the valve case, and an opening 19 is formed in the middle of the second flow path 18 by this ring. Reference numeral 20 is a stopper integrated with the right cap 21 screwed to the valve case 6. 22 is a first primary chamber formed between the check valve 11 and the first input port 7, 23 is a second primary chamber formed between the opening 19 and the second input port 8, and the first primary chamber Room 22 and second primary room
Cylinder 24 is configured by communicating with 23,
A balance spool 25 is fitted in the cylinder.
The balance spool 25 has a push rod 27 on the first flow path 26 side.
However, the valve rods 28 are integrally formed on the second flow path 18 side, and the valve rods 28 are fitted to the ring 17 to close the opening 19.

Next, to explain the operation, when the switching valve 3 is in the state shown in FIG. 1, the oil pressure is supplied to the first primary chamber 22 and the pressure of the second primary chamber 23 is open to the atmosphere. Therefore, the balance spool 25 moves to the right in FIG. 1 until it comes into contact with the stopper 20, and when the hydraulic pressure in the first primary chamber 22 becomes equal to or higher than the cracking pressure of the check valve 11, the check valve 11 opens. , The hydraulic pressure passes through the first flow path 26 to the first actuator 4
Is supplied to. The hydraulic pressure supplied to the first actuator 4 is retained by the action of the check valve 11 even after the hydraulic pressure supply to the first primary chamber 22 is stopped.

When the switching valve 3 is switched from this state and the hydraulic pressure is supplied to the second primary chamber 23, and the first primary chamber 22 is opened to the atmosphere, the balance spool 25 is pushed to the hydraulic pressure of the second primary chamber 23. Then, it moves to the left in FIG. Then, the push rod 27 comes into contact with the valve body 13 of the check valve and moves it to the left to open the check valve 11. By this operation, the holding pressure of the first actuator 4 is released, and the piston 29 of FIG. 1 (FIG. 2) can be retracted. After the check valve 11 is opened by the push rod 27, the valve rod 28 comes out of the ring 17 and opens the opening 19. By this operation, the hydraulic pressure in the second primary chamber 23 is supplied to the second actuator 5, and the second actuator 5 is operated. Therefore, when the operation of the second actuator 5 is started, the holding pressure of the first actuator 4 is surely released.

Needless to say, a known decompression mechanism can be incorporated in the check valve 11.

<Effects of the Invention> The sequence valve having the above-described configuration changes from the screw back pressure holding state to the rotating operation in the drive for rotating the screw of the injection molding machine as shown in FIG. 2 to plasticize the resin. Of the sequence valve can be reliably and smoothly controlled by the cracking pressure in the cylinder of the present sequence valve. Therefore, the pressure control valve individually required in the past is not required, and the circuit configuration can be controlled by one circuit. Rationalization can be achieved because two sequence operations can be performed.

Further, the pressure of the hydraulic pump when driving the second actuator can be further lowered, and further, since the pressure retention releasing mechanism of the first actuator and the driving mechanism of the second actuator are interlocked with each other, a malfunction is caused. There is no fear.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention and symbols of hydraulic equipment connected thereto, and FIG. 2 is a sectional view showing an injection unit as an example of a device controlled by a sequence valve of the present invention. FIG. 3 is a diagram showing an example of a circuit for driving the device of FIG. 2, and FIG. 4 is a diagram showing a circuit as a premise of FIG. 1: Sequence valve 3: (Pressure) switching valve 4: First actuator (hydraulic cylinder) 5: Second actuator (hydraulic motor) 7: First input port 8: Second input port 9: First output port 10: No. 2 Output ports 11: Check valve 12: Valve seat 13: Valve body 16: Coil spring 17: Ring 18: Second flow path 19: Opening 22: First primary chamber 23: Second primary chamber 24: Cylinder 25: Balance spool 26: First flow path 27: Push rod 28: Valve rod 29: Piston 30: (Plasticized) screw 36: (Injection) plunger

Claims (1)

(57) [Claims] 1. A first primary chamber (22) and a first flow path (26) from a first input port (7) to a first output port (9),
A second primary chamber (23) and a second flow passage (18) extending from the second input port (8) to the second output port (10) are provided, and the first primary chamber (22) and the first flow passage (18) are provided. ) Is provided with a check valve (11), and an opening (19) is provided between the second primary chamber (23) and the second flow path (18). The first primary chamber (22) on the input port side of 11) and the second primary chamber (23) on the input port side of the opening (19) communicate with each other to form a cylinder (24), and to the cylinder. A balance spool (25) is fitted and provided, and the balance spool has a push rod (27) that opens the check valve (11) at both ends in the moving direction, and a valve rod (28) that can move in and out of the opening (19). And the balance spool (25) has a second flow path (18).
When it moves to the side, the opening (19) is closed, and the first flow path (2
2nd after opening the check valve (11) when moving to the 6) side
A sequence valve characterized by opening the opening (19) of the flow path.