JPS6317574B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a fluid pressure relief mechanism.

Conventionally, the forward end positioning of a hydraulic feed unit used in a special-purpose machine tool has been carried out by applying a movable part of the unit (for example, a table on which a tool or a workpiece is mounted) to a stopper. By the way, when machining the engine cylinder head, when boring the seat surface of the valve hole and gun reaming the valve guide hole, move the feed unit to the forward end regulated by the stopper and bore the seat surface. After this, in order to ensure surface roughness and extend tool life, the forward end position of the feed unit should be adjusted by 0.5 mm.
After relieving the valve guide hole, the valve guide hole is reamed.

FIGS. 5 and 6 are sectional views of the tip of the head of a dedicated machine tool for explaining this type of machining. In the figure, reference numeral 31 denotes a boring head body, and the boring head body 31 is mounted on a hydraulic feed unit (not shown) and is fed and driven in the left and right directions in the figure. A hollow boring main shaft 32 is pivotally supported within this boring head main body 31, and a similarly hollow holder 33 is fixed to the tip of the boring main shaft 32.
A boring tip 34 is attached to the. In addition, a guide bush 3 is provided inside the boring spindle 32.
5 is fixed, and a mounting shaft 36 is supported inside the guide bush 35 so as to be slidable in the axial direction, and a gun reamer 37 is mounted on the tip of this mounting shaft 36. The boring spindle 32 is the mounting shaft 3
The mounting shaft 36 and the mounting shaft 36 are rotated by a drive motor (not shown), while the mounting shaft 36 is driven in the axial direction with respect to the boring main shaft 32 by a hydraulic cylinder (not shown).

In such a dedicated machine tool, first, as shown in FIG. 5, with the gun reamer 37 retracted into the holder 33, the cylinder head is moved by advancing the feed unit to its forward end while rotating the boring spindle 32. 38, the valve seat surface 40 of the seat ring 39 is bored with the boring tip 3.
Perform boring in Step 4. After the boring process is completed, in order to ensure surface roughness and extend tool life, the feed unit is moved back by a relief amount l = 0.5 mm, as shown in Fig. 6, and the boring tip 3 is
4 escapes from the machined valve seat surface 40. Next, with the feed unit stopped, attach the mounting shaft 36.
The gun reamer 37 is made to protrude from the holder 33 by moving only the valve guide 41 forward.

Conventionally, in the feed unit as described above, relief has been achieved by shifting the position of the stopper using a wedge mechanism or the like. However, if the model of the workpiece is changed and the machining depth of the valve seat surface is different, the front end position of the feed unit changes accordingly, and a predetermined amount of relief (for example, about 0.5 mm) is applied based on the changed front end position. However, conventional wedge-based relief mechanisms were unable to respond to these changes. In other words, the conventional wedge mechanism did not have a function for multiple models and multiple cycles.

The present invention was made in view of the above technical situation, and its purpose is to provide a fluid pressure relief mechanism that can perform a predetermined amount of relief (backward movement) from any stop position. It's about doing.

A fluid pressure relief mechanism according to the present invention for achieving the above object connects first and second pressure fluid paths connected to the pressure fluid supply and discharge side to two pressure fluid supply ports of a double-acting fluid pressure actuator, respectively. One pressure fluid supply port of a fluid pressure cylinder having a cylinder chamber volume corresponding to a predetermined operating amount of the fluid pressure actuator is connected to this first pressure fluid path, and the pressure fluid supply/discharge side is connected from this connection part. A pilot operated check valve is provided in the first pressure fluid path, with the pressure fluid supply and discharge side as an inlet side and the fluid pressure actuator side as an outlet side, Connecting the other pressure fluid supply port of the fluid pressure cylinder to the first pressure fluid path,
A pilot port of the pilot operated check valve is connected to the second pressure fluid path via a switching valve that connects and disconnects the flow.

Therefore, in the present invention, the hydraulic actuator is operated in one direction by supplying the working fluid to the hydraulic actuator through the first pressure fluid path and discharging the working fluid through the second pressure fluid path. Next, when the supply of working fluid from the first pressure fluid path to the hydraulic actuator is cut off and the working fluid is supplied to the fluid pressure actuator from the second pressure fluid path, the discharge of the working fluid through the first pressure fluid path is stopped by the pilot. Since it is blocked by the operation check valve, the working fluid discharged from the hydraulic actuator flows into the hydraulic cylinder, and the flow of fluid is stopped when an amount corresponding to the cylinder chamber volume has flowed in. As a result, the hydraulic actuator is retracted by a predetermined amount. On the other hand, when working fluid is supplied to the hydraulic actuator through the second pressure fluid path, when the switching valve supplies the working fluid to the pilot port of the pilot operated check valve, the pilot operated check valve opens and the flow from the hydraulic actuator is Actuating fluid is discharged through the first pressure fluid path and the hydraulic actuator operates in the opposite direction as described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fluid pressure relief mechanism according to the present invention will be described in detail based on an embodiment shown in the drawings.

The embodiments shown in Figs. 1 to 4 use hydraulic pressure as fluid pressure, and Fig. 1 shows the hydraulic circuit, and the embodiments shown in Figs.
Figure 4 shows its operating state. Reference numeral 1 designates a hydraulic cylinder as a fluid pressure actuator, and a rod 3 connected to a piston 2 of the hydraulic cylinder 1 has a movable part of a feed unit (for example, a table on which a tool or a workpiece is mounted) attached. The hydraulic cylinder 1 is a double-acting type, and the oil supply port on the head side has an oil passage 4.
The oil passage 4, which is the first pressure fluid passage, has a pilot operation check for preventing the hydraulic cylinder from moving backward, with the hydraulic cylinder 1 side being the outlet side and the pressure oil supply and discharge side being the inlet side. The valve 5 is connected to an electromagnetic switching valve 7 for forward and backward movement of the hydraulic cylinder via a variable throttle valve 6 with a check valve for rapid movement of the hydraulic cylinder. An oil passage 8, which is a second pressure fluid passage, is connected to the oil supply port on the rod side of the hydraulic cylinder 1, and this oil passage 8 has a flow regulating valve 9 with a shut-off for retarding the advance of the hydraulic cylinder, and a hydraulic It is equipped with a pilot operated check valve 10 for preventing the advance of the hydraulic cylinder, with the cylinder 1 side as the outlet side and the pressure oil supply/discharge side as the inlet side. It is connected to the electromagnetic switching valve 7 for forward and backward movement. The electromagnetic switching valve 7 is a switching valve with 4 ports and 3 positions, and has an oil path (pressure port) 11 connected to the hydraulic pump and an oil tank 12.
The oil passage (return port) 13 connected to the oil passage 4, 8
It is designed to cut off or switch connection. A pilot oil passage 14 connects the oil passage 4 and the pilot port of the pilot operated check valve 10 in the oil passage 8 between the variable throttle valve with check valve 6 and the pilot operated check valve 5. 15
1 is a hydraulic cylinder for an accumulator having a cylinder chamber volume corresponding to a predetermined operating amount of the hydraulic cylinder 1, 16 is its piston, and 17 is a rod. An oil passage 18 that branches between the pilot operation check valve 5 of the oil passage 4 and the hydraulic cylinder 1 is connected to the oil supply port on the rod side of the accumulator cylinder 15, and is connected to the oil supply port on the head side. is an oil passage 19 connected between the variable throttle valve with check valve 6 of the oil passage 4 and the pilot operated check valve 5;
are connected. On the other hand, a pilot oil passage 21 connected to an oil tank 20 is provided with an electromagnetic switching valve 22 for assisting hydraulic cylinder reversing in the middle thereof, and is connected to a pilot port of the pilot operation check valve 5. An oil passage 23 is connected to the pressure port of the electromagnetic switching valve 22, which branches between the variable throttle valve 6 with a check valve of the oil passage 8 and the pilot operated check valve 10. The electromagnetic switching valve 22 is a 4-port, 2-position switching valve that connects and disconnects the oil passage 23 and the pilot oil passage 21, and when connected, connects the oil passage 8 to the pilot operation check valve 5 via the oil passage 23 and the pilot oil passage 21. communicates with the pilot port. In addition, 24 is a flow rate adjustment valve 9 with a shut-off valve and the pilot oil passage 21.
An oil passage connecting between the electromagnetic switching valve 22 and the oil tank 20;
An oil passage 26 connects the pilot operating valve 5 and the oil passage 25.

Next, the operation of the relief mechanism having the above configuration will be explained.

To advance the movable part attached to the rod 3 of the hydraulic cylinder 1, as shown in Fig. 2,
The solenoid A of the electromagnetic switching valve 7 for hydraulic cylinder forward/backward movement is energized while the electromagnetic switching valve 22 for assisting hydraulic cylinder backward movement is de-energized, and the oil path 1 leading to the hydraulic pump is energized.
1 and the oil passage 4 and the oil tank 12
The oil passage 13 and the oil passage 8 are connected to each other. Pressure oil from the hydraulic pump enters the oil path 4 from the oil path 11 through the electromagnetic switching valve 7, passes through the variable throttle valve with check valve 6, the pilot operated check valve 5, and then enters the hydraulic cylinder 1.
into the head side of the piston 2.
Apply pressure in the direction of moving forward. Further, the pressure oil in the oil passage 4 enters the pilot port of the pilot operated check valve 10 in the oil passage 8 through the pilot oil passage 14 from between the variable throttle valve with check valve 6 and the pilot operated check valve 5. This pressure oil increases the pilot pressure in the pilot operated check valve 10, and the check valve 10 opens. Then,
The oil on the rod side of the hydraulic cylinder 1 enters the oil path 13 from the oil path 8 through the flow rate adjustment valve 9 with a shut-off, the opened pilot operation valve 10, the variable throttle valve 6 with a check valve, and the electromagnetic switching valve 7. oil tank 1
2. Oil is drained. Due to the action of the oil as described above, the movable portion of the feed unit together with the piston 2 and rod 3 of the hydraulic cylinder 1 are moved to the forward end.
On the other hand, pressure oil is supplied to the head side of the hydraulic cylinder 15 for the accumulator from the oil passage 19 connected between the variable throttle valve with check valve 6 and the pilot operated check valve 5, and the piston 16 and the rod 17 are
is moved to the forward end.

In order to relieve the movable part of the feed unit by a minute amount from its forward end, as shown in Fig. 3, while the hydraulic cylinder reversing assist electromagnetic switching valve 22 is de-energized, the solenoid of the hydraulic cylinder reversing electromagnetic switching valve 7 is activated. B is excited, and the oil passage 11 connected to the hydraulic pump is connected to the oil passage 8, and the oil passage 4 is connected to the oil passage 13 connected to the oil tank 12. Pressure oil from the hydraulic pump enters the oil path 8 from the oil path 11 through the electromagnetic switching valve 7, and is then passed through the variable throttle valve 6 with a check valve.
It flows into the rod side of the hydraulic cylinder 1 through the pilot operated check valve 10 and the flow rate adjustment valve 9 with a shutoff, and applies pressure in the direction of returning to the piston 2. When the hydraulic pressure in the backward direction acts on the piston 2, the oil on the head side of the hydraulic cylinder 1 flows into the oil path 4.
However, there is a pilot-operated check valve 5 in the oil passage 4, which prevents the oil from flowing out through the oil passage 18. the piston 16, which was at the forward end, is moved to the reverse end. That is, the oil on the head side of the hydraulic cylinder 1 flows out by the volume on the rod side of the hydraulic cylinder 15 for the accumulator, and the piston 2 moves backward or relieved by that amount. As can be seen from this action, the amount of relief of the piston 2 of the hydraulic cylinder 1 is determined by the rod side backward displacement volume of the hydraulic cylinder 15 for the accumulator. The oil on the head side of the hydraulic cylinder 15 enters the oil path 4 from the oil path 19 and is discharged into the oil tank 12 via the variable throttle valve 6 with a check valve and the electromagnetic switching valve 7.

To stop the movable parts of the feed unit, that is, to stop the hydraulic cylinder 1, the electromagnetic switching valve 22 is de-energized and the solenoids A and B of the electromagnetic switching valve 7 are turned off.
Both are de-energized, the switching valve 7 is set to the neutral position, and the supply of pressure oil from the hydraulic pump is cut off. This causes the hydraulic cylinder 1 to stop. Hydraulic cylinder 1
Even if an external force acts on the rod 3, the piston 2 will not move because the pilot operated check valves 5 and 10 block the flow of oil.

When moving the hydraulic cylinder 1 backward, as shown in FIG. The solenoid C of the switching valve 22 is energized to connect the oil passage 23 and the pilot oil passage 21. Pressure oil from the hydraulic pump is oil path 1
1, enters the oil passage 8 through the electromagnetic switching valve 7, passes through the variable throttle valve 6 with check valve, the pilot operated check valve 10, and the flow rate adjustment valve 9 with shutoff, flows into the rod side of the hydraulic cylinder 1, and enters the piston 2. Apply pressure in the reverse direction. On the other hand, pressure oil passes through an oil passage 23 branching from the oil passage 8, passes through an electromagnetic switching valve 22, enters the pilot oil passage 21, and from there enters the pilot port of the pilot operation check valve 5.
The pilot pressure of the check valve 5 increases due to the pressure of this pressure oil, and the check valve 5 opens. Then,
The oil on the head side of the hydraulic cylinder 1 enters the oil path 13 from the oil path 4 through the pilot operated check valve 5, the variable throttle valve with check valve 6, and the electromagnetic switching valve 7, and is discharged into the oil tank 12, where it is discharged from the piston 2 and the rod. 3 goes backwards.

In the above embodiment, the hydraulic cylinder 1 is provided with backward relief, but it is also possible to provide forward relief by changing the hydraulic circuit.
In addition, a hydraulic cylinder 1 is used as a fluid pressure actuator.
If an oil motor is used instead, forward rotation or reverse rotation relief is also possible. Note that although oil is used as the fluid in the above embodiment, similar relief can be achieved using air. However, since air has greater compressibility than hydraulic pressure, the relief stop position will be worse than with hydraulic systems.

As described above in detail based on the embodiments, according to the fluid pressure relief mechanism according to the present invention, it is possible to perform a certain amount of relief corresponding to the cylinder chamber volume of the fluid pressure cylinder for the accumulator from any stop position. It becomes possible. Further, since it is operated using fluid pressure, no mechanical mechanism such as a wedge mechanism is required, and the operation is easy.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of an embodiment of the fluid pressure relief mechanism according to the present invention, Figs. 2 to 4 are explanatory diagrams of its operation, and Figs. 5 and 6 are sectional views of the tip of the head of a dedicated machine tool. It is. In the drawing, 1 is a hydraulic cylinder, 5 is a pilot operated check valve for preventing the hydraulic cylinder from moving backward, 6 is a variable throttle valve with a check valve for fast forwarding the hydraulic cylinder,
7 is an electromagnetic switching valve for forward and backward movement of the hydraulic cylinder, 6 is a flow rate adjustment valve with a shut-off for slowing the forward movement of the hydraulic cylinder, 10 is a pilot operation check valve for preventing the movement of the hydraulic cylinder from moving forward, 15 is a hydraulic cylinder for the accumulator, and 22 is an assist for the backward movement of the hydraulic cylinder. This is a solenoid switching valve for use.

Claims (1)

[Claims] 1. First and second pressure fluid paths connected to the pressure fluid supply/discharge side are respectively connected to two pressure fluid supply ports of a double-acting fluid pressure actuator, and a predetermined pressure fluid path of the fluid pressure actuator is connected to the first pressure fluid path. One pressure fluid supply port of a fluid pressure cylinder having a cylinder chamber volume corresponding to the operating amount is connected, and the pressure fluid supply and discharge side is connected to the first pressure fluid path from this connection part on the pressure fluid supply and discharge side. A pilot operated check valve is provided with the fluid pressure actuator side as the outlet side, and the other pressure fluid of the fluid pressure cylinder is supplied from the pilot operated check valve to the first pressure fluid path on the pressure fluid supply/discharge side. A fluid pressure relief mechanism characterized in that the pilot port of the pilot operated check valve is connected to the second pressure fluid path via a switching valve that connects the pilot port to the second pressure fluid path.