JPS5935320B2 - Work equipment operation control device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an operation control device for a work machine.

More specifically, the present invention relates to an operation control device for a working machine such as a friction welding machine that processes a workpiece using a rotating machine and a sliding machine. Conventionally, two types of operation control methods have been generally used for this type of device: a mechanical-electrical operation control method and a hydraulic pump operation control method.

That is, a device using the former method transmits the driving force of an electric motor to a rotating machine and a sliding machine via a continuously variable speed control mechanism using belts, gears, etc. This system controls the operation of the machine to process the workpiece, but the entire continuously variable speed control mechanism is complicated, large and expensive, and the speed control section of this mechanism is expensive. The drawback was that it made a lot of noise.

The latter method uses two fixed displacement hydraulic pumps, one of which is connected to a rotating machine and the other pump to a sliding machine, and connected to the connecting line of the sliding machine. This is achieved by connecting a control device that can control the operation of feeding and transport.

However, according to this method, when the sliding machine is transported by the control equipment, problems such as the pulsation of the discharge pressure being amplified and the discharge amount changing greatly due to changes in liquid temperature and pressure occur. Because of this, it is not possible to reliably and stably control the transportation of the sliding machine, and there is a problem in that it is not possible to obtain products of constant quality with little variation. Moreover, since it requires a large number of control devices, there is a problem that the external dimensions are large and it is expensive.Furthermore, since two pumps are used, there is a problem that power loss is large. However, this latter method will be described in more detail using the operation control device for a friction welding machine shown in FIG. 3 as an example. 5. In recent years, this friction welding machine has been widely used because the welding process time is short, it can weld with high welding strength with little variation in strength, it can be easily automated, and it can be provided at low cost.

That is, in the case shown in FIG. 3, a workpiece 3 attached to a sliding machine 2 equipped with a hydraulic cylinder 5 is rotated by a rotating machine 1 equipped with a hydraulic motor 4. This is an operation control device for a friction welding machine in which friction welding is performed by bringing the welding parts close to each other using a continuous force using a hydraulic cylinder 5, and then transporting them and bringing them into contact with each other to perform friction welding.

That is, in this device, constant displacement hydraulic pumps 80 and 81 are connected to the rotating machine 1 and the sliding mechanism 2, respectively, and a flow control valve 82 and an electromagnetic switching valve are connected to the connecting line between the rotating machine 1 and the pump 80. 83, etc., and the connecting line between the sliding machine 2 and the pump 81 is provided with an electromagnetic switching valve 84, two flow control valves 85, 86 with different degrees of restriction, an electromagnetic switching valve 87, and a check valve 88. A flow rate control circuit 89 is connected to the cylinder 5 which can perform fast feeding of the cylinder 5 under light loads and slow feeding under heavy loads. Note that 90 and 91 are relief valves, 17 is a flywheel, and 18 and 21 are chucks.

First, the hydraulic motor 4 is driven by the pump 80 to achieve a predetermined rotation speed, and then the electromagnetic switching valve 87 is switched to one side and the cylinder 5 is rapidly fed by the pump 81, and then the electromagnetic switching valve 87 is switched to the other side and the cylinder 5 is moved quickly. The workpieces 3, 3 are brought into contact with each other by slow feeding to perform friction welding.

However, in this device, first of all, it is not necessary to operate the hydraulic motor 4 and the hydraulic cylinder 5 at the same time.Although they are operated sequentially, both pumps 80 and 81 are constantly operated, so there is no power loss. There was a growing problem. Second, friction welding of the workpieces 3, 3 is performed with the hydraulic cylinder 5 in a slow feed state, but in this case, even though it is necessary to control the pump discharge amount to a low flow rate, the flow rate control valve 85 or 86
Generally, low flow rate control performance is poor, for example, pulsations in pump discharge pressure or changes in liquid pressure and liquid temperature are amplified, making it impossible to obtain a stable low flow rate, resulting in the problem of large variations in welding accuracy, and It was difficult to adjust the feed and slow feed, and it was necessary to make frequent adjustments. Furthermore, thirdly, as a friction welding process, one of the rotating workpieces 3V is simply
Although it is a simple process of rapidly feeding and slow feeding the other workpiece 3 to C, it requires as many as 11 hydraulic devices, resulting in a problem of high cost. This invention was invented to solve the above problems, and the first purpose is to reliably, stably, and accurately perform not only fast-feeding operation control but also slow-feeding operation control of a sliding machine in a working machine. The second purpose is to provide a device that can maintain a constant product quality with little variation.The second purpose is to significantly reduce the number of control devices used, and therefore, the overall N configuration is simple and the external size is small. The third object is to provide an economically advantageous device that can be made small in size and inexpensive, and a third object is to provide an economically advantageous device in which the power loss of the pump can be minimized. That is, the present invention is an operation control device for a working machine that processes a workpiece using a rotating machine and a sliding machine, which includes a hydraulic motor for the rotating machine, a hydraulic cylinder for the sliding machine, and a variable control device. a variable displacement hydraulic pump having a variable displacement element, each of the machines is connected to the discharge line of the pump through a switching valve, and a plunger is connected to the pump to adjust the displacement amount of the variable control element. The plunger is provided so as to be freely movable with respect to the control element, and the movement of the plunger is restricted to a certain range, and the rear chamber of the plunger is communicated with the discharge line via a switching valve to change the discharge rate of the pump from the maximum discharge rate to an intermediate discharge rate. It is characterized by controlling the amount.

Embodiments of the apparatus of the present invention will be described in detail below with reference to FIG.

What is shown in FIG. 1 is an operation control device for a friction welding machine in which friction welding is performed between workpieces 3a and 3b by a rotating machine 1 and a sliding machine 2. It consists of a motor 4, a variable displacement hydraulic pump 7 having a hydraulic cylinder 5 for the sliding machine 2, and a variable control element 6, and a switching valve 8 for controlling the rotating machine 1 and the sliding machine 2, respectively.
and 9 to the discharge line 10 of the pump 7, and the pump 7 is provided with a plunger 11 which is freely movable relative to the variable control element 6 and which adjusts the amount of displacement of the variable control element 6. 11 is restricted to a certain range, and the back chamber 12 of this plunger 11 is communicated with the discharge line 10 via the switching valve 13, and the discharge amount of the pump 7 is adjusted to the maximum discharge amount QH as shown in FIG. The configuration is such that the discharge amount is controlled from to an intermediate discharge amount QL.

The rotating machine 1 connects the hydraulic motor 3t4 to the motor 4.
The rotary shaft 14 is fixed to the friction welding machine main body 15 so that it is horizontal, and the rotary shaft 14 is supported by passing through a rotary bearing 16, and a flywheel 17 and a chuck 18 are attached to the tip of the rotary shaft 14 that has passed through the rotary shaft 14. A work bead 3a can be attached to and detached from the chuck 18. Further, the sliding machine 2 includes the friction welding machine main body 1
The hydraulic cylinder 5 is fixed to the hydraulic cylinder 5, and the driving direction of the rod 20 provided on the piston 19 of the hydraulic cylinder 5 coincides with the rotation axis 14 of the hydraulic motor 4. A chuck 21 is provided at the tip of the chuck 20, and the workpiece 3b can be attached to and removed from the chuck 21. That is, in the friction welding machine formed as described above, each chuck 18 of the rotating machine 1 and the sliding machine 2,
The workpieces 3a and 3b are respectively attached to the hydraulic motor 21, first, a predetermined flow rate of liquid is supplied to the hydraulic motor 4, and when the workpiece 3a reaches a predetermined rotation speed, the supply of liquid to the hydraulic motor 4 is stopped. Thereafter, the flywheel 17 continues to rotate due to its inertia. Then, a large volume of low pressure liquid is supplied to the head side chamber 22 side of the hydraulic cylinder 5, and is discharged from the rod side chamber 23 side, so that the piston 1
9 is rapidly fed to the left in FIG. 1, and the workpiece 3b is rapidly fed close to the rotating workpiece 3a to a predetermined proximity position via the rod 20 provided on the piston 19. When the two workpieces 3a and 3b are close to each other, a high-pressure, small-volume liquid is supplied from the head side chamber 22 of the hydraulic cylinder 5 to create a slow feed state, so that both workpieces 3a and 3b can be brought into contact and friction welding can be performed. be. Furthermore, after the friction welding is completed, a large volume of low-pressure liquid is supplied to the rod side chamber 23 of the hydraulic cylinder 5 and discharged from the head side chamber 22, and the piston 19 is quickly sent back to the right in FIG.
One step of friction welding can now be completed. The variable displacement hydraulic pump 7 mainly uses a swash plate type axial piston pump, and 24 is a housing that constitutes the main body of the pump.

The housing 24 consists of a hollow housing body 25, a valve block 26, and a control block 27, and a cover 28 is fixed to one side of the housing body 25.

As shown in FIG. 1, a main shaft 31 is pivotally supported inside the housing body 25 via bearings 29 and 30.
The main shaft 31 has a spline portion 32 formed at its intermediate portion.
The cylinder block 33 is fixed so that it can rotate together. This block 33 is provided with a large number of pistons 34 that can freely reciprocate with a predetermined stroke, and a housing 36 supported by a retainer 35 is attached to the tip of each piston 34.
6, it is in contact with a swash plate (hereinafter referred to as 6) constituting the variable control element 6.

This swash plate 6 can swing freely within a certain range of inclination angle using a trunnion shaft 37 as a fulcrum, and a spring is provided between the back surface of the side that contacts the shutter 36 and the inner surface of the housing body 25. 38 is interposed to act in a direction that always increases the inclination angle of the swash plate 6. The plunger 11 is provided on the opposite surface of the swash plate 6 from the surface to which the spring 38 is applied so as to counteract the load of the spring 38. However, the lever plunger 11 is inserted into a cylinder chamber 44 provided in the housing body 25 so as to be freely movable, and its movement range is from a position where the swash plate 6 is held at the maximum inclination angle to a position where the swash plate 6 is held at an intermediate inclination angle. It is limited to a certain range.

That is, the cylinder chamber 44 has a front half near the swash plate 6 and a rear half with a smaller diameter, forming a step 68 at the boundary, while the plunger 11 has a large diameter section 11a and a small diameter section 11b arranged in series. The large diameter part 11a is closely inserted into the rear half of the large diameter part in the cylinder chamber 44 to be freely movable, and the small diameter part 1
The tip of 1b is opposed to the swash plate 6 which is pressed by the spring 38 in a direction that increases the angle of inclination.

That is, when the plunger 11 is located at the rearmost side in the cylinder chamber 44, the swash plate 6 is held at the maximum inclination angle, and when the plunger 11 is in contact with the stepped portion 68 of the cylinder chamber 44, the swash plate 6 is held at the maximum inclination angle. , the swash plate 6 is held at an intermediate angle of inclination.
With the plunger 11 positioned at the rearmost side of the cylinder chamber 44 and the swash plate 6 held at the maximum inclination angle without applying pressure to the rear end of the large diameter portion 11a, the main shaft 3 is
1 to rotate the cylinder block 33, each piston 34 reciprocates, and this reciprocating movement increases the maximum discharge amount Q.
H is obtained, and the main shaft 31 is driven while applying pressure to the rear end of the plunger 11 to move the plunger 11 to a position where it contacts the step portion 68 and holding the swash plate 6 at an intermediate angle of inclination. By doing so, an intermediate discharge amount QL can be obtained.

In FIG. 1, an operating plunger 42 is provided separately from the plunger 11 on the small diameter side of the cylinder chamber 44, and one end of the operating plunger 42 is brought into contact with the swash plate 6, and the other end is connected to the plunger 42. The plunger 4 controls the movement of the flange 11a by touching the tip of the small diameter portion 11b of the flange 11.
2 to the swash plate 6.

Further, in FIG. 1, reference numeral 67 is a stroke adjustment bolt of the operating plunger 42, which adjusts the maximum inclination angle of the swash plate 6, that is, the maximum discharge amount QH.

Further, in order to adjust the stroke of the plunger 11, a screw may be provided in the small diameter portion 11b, an adjusting body may be screwed onto the screw, and the adjusting body may be brought into contact with the stepped portion. Further, in FIG. 1, 39 is a valve plate, 40 is a spring, and 41 is a receiver for the spring 40.

Reference numerals 46 and 47 refer to spools for controlling the operation plunger 42, and spool holes 48 and 47 provided in the valve block 26, respectively.
The spool holes 48 and 49 are open at one side of the valve block 26 and are connected to the introduction passages 50 and 51 which lead the discharge pressure from the discharge line 10 through the control block 27. The spool 46
. The spools 46, 49 counter the discharge pressure introduced into the spool holes 48, 49 until the discharge pressure exceeds a certain pressure.
This prevents the movement of 47. Moreover, this pressing body 52,
The pressing forces of the spools 46 and 47 by the spools 53 are different,
Pressure P during low pressure control is controlled by a pressing body 52 corresponding to the spool 46, and a pressing body 53K corresponding to the spool 47.
Therefore, the pressure P2 at the time of high pressure control is set respectively, and these pressing bodies 52, 53 are provided with a pressure that adjusts the pressing force,
Pressure adjusting screws 54 and 55 are provided to set the discharge pressure at which the spools 46 and 47 move to a predetermined value.The valve block 26 also controls opening into the introduction passages 50 and 51 by the movement of the spools 46 and 47. Passage 56, 57
The high pressure side control passage 57 of these control passages 56 and 57 communicates with the space on the swash plate 6 side of the plunger 11 in the cylinder chamber 44, that is, the front chamber 45, and the low pressure side control passage 56 communicates with the spool 47. When the spool 47 is not moving, it communicates with a control passage 57, and when the spool 47 moves, the passage 57 is closed by the land 47a of the spool 47.

Further, in FIG. 1, 58 is a discharge passage provided in the cover 28 and communicates with the discharge line 10.
A high-pressure passage 59 is formed midway through this discharge passage 58, passes through the housing body 25 and the valve block 26, and opens at one side of the block 26. 6 is a control pressure introduction passage for introducing control pressure into the chamber 12;
1 is the pressing body 52, 5 from the back side of the spool 46.
The control pressure introducing passage 6 is an open passage that opens into the housing main body 25 through the housing chambers 52a and 53a of 3.
0 and the open passage 61 are both the introduction passages 50 and 5 described above.
1 and high pressure passage 59, it is opened on one side of the valve block 26.

The control block 27 is a combination of the block main body 62 and the switching valve 13.

This switching valve 13 has, for example, 4 ports and 2 positions and a solenoid 1.
3a is used, and the block main body 62 has a first communication passage 63 that communicates the first port P of the electromagnetic switching valve 13 with the high pressure passage 59 of the valve block 26, a second port T, and a second port T. A second communication passage 64 that communicates with the open passage 61
, a third communication passage 65 that communicates the third port A with the introduction passage 50 to the spool 46, and a fourth communication passage 65 that communicates the fourth port B with the introduction passage 51 to the Subur 47 and the control pressure introduction passage 60. A passage 66 is provided. By using the electromagnetic switching valve 13 in the position shown in FIG. 1, that is, with the solenoid 13-a demagnetized, the introduction passage 50 provided at one end of the Subur 46 can be opened as the third communication passage. 65, the electromagnetic switching valve 13, which communicates with the high pressure passage 59 which passes through the discharge passage 58 via the first communication passage 63, the low pressure side control passage 56, the control passage 57 and the operating plunger 42 from the back side of the spool 47. It communicates with the front chamber 45 on the back side of the.

Further, the control pressure introduction passage 60 and the introduction passage 51 of the spool 47 that pass through the rear chamber 12 are communicated with the open passage 61 via a fourth communication passage 66, the electromagnetic switching valve 13, and a second communication passage 64. However, when the pump is operated in a levered state, the discharge pressure is guided to one end of the spool 46, and when this discharge pressure increases, the spool 46 moves and opens the control passage 56. The control pressure is transmitted from 56 through the path to the front chamber 4 on the back side of the operating plunger 42.
5, the operation plunger 42 is moved to the right, and the swash plate 6 is moved to the right.
The inclination angle of the needle is made small, and the discharge amount is made zero at the low pressure P1 set by the pressing body 52.

This case is the low pressure, large capacity control shown by the curve M passing through points A, B, and E in FIG. Then solenoid 1
3a and switches the switching valve 13 to the position opposite to that shown in FIG. 14, the high pressure and small capacity control shown by the curve N passing through points C, D, and E in FIG. 2 can be performed. It can be done. That is, by this switching, the high pressure passage 59 communicates with the introduction passage 51 of the Subur 47 and the control pressure introduction passage 60 that passes through the back chamber 12 via the first communication passage 63, the electromagnetic switching valve 13, and the fourth communication passage 66. Therefore, the introduction passage 50 of the spool 46 is communicated with the open passage 61 via the third communication passage 65, the electromagnetic switching valve 13, and the second communication passage 64. Thus, the discharge pressure is introduced into the back chamber 12 of the plunger 11 along with one end of the subur 47.

Therefore, at this time, if the discharge pressure is higher than the sum of the rotational moment of the spring 38 and the swash plate 6, the plunger 1 is immediately
1 moves to the right to reduce the inclination angle of the swash plate 6, and is controlled to have a high voltage and small capacity characteristic. When the discharge pressure further increases, the spool 47 moves, and the discharge amount is controlled to zero at the maximum discharge pressure as shown by curve N in FIG. Two-pressure, two-capacity control characteristics can be obtained: the low-pressure large-capacity characteristic and the high-pressure small-capacity characteristic shown in FIG.

However, the variable displacement hydraulic pump 7 configured as described above
The discharge line 10 is connected to the hydraulic motor 4 and the hydraulic cylinder 5 through the switching valves 8 and 9, respectively.The switching valve 8 has, for example, a 4-port 2-position electromagnetic switching valve 8 equipped with a solenoid 8a. The first port P of the electromagnetic switching valve 8 is connected to the discharge line 10, the second port T is connected to the tank 69, and the third port A and the fourth port B are connected to the hydraulic motor 4.
connected to the inlet and outlet sides of the solenoid 8a.
By demagnetizing or exciting the discharge line 10 and the hydraulic motor 4, the discharge line 10 and the hydraulic motor 4 are cut off or communicated with each other. The switching valve 9 uses, for example, an electromagnetic switching valve 9 equipped with solenoids 9a and 9b at 4 boat 3 positions, and the first one of the electromagnetic switching valve 9 is
Port P is connected to the discharge line 10, and the second port T is connected to the tank 6.
9, the third port A and the fourth port B are connected to the hydraulic cylinder 5.
are connected to the rod side chamber 23 and the head side chamber 22, respectively. By energizing the solenoid 9a, the discharge line 10 communicates with the head side chamber 22 of the hydraulic cylinder 2, and the rod side chamber 23 communicates with the tank 69.
The piston 19 moves to the left in FIG. 1, and by energizing the solenoid 9b, the discharge line 10 communicates with the rod side chamber 23 and the head side chamber 22.
is switched so that it communicates with the tank 69, and the piston 19
moves to the right in FIG. Therefore, in order to weld the workpieces 3a and 3b attached to the chucks 18 and 21 of the friction welding machine using the operation control device of the friction welding machine configured as described above, the workpieces 3a and 3b are to be welded in accordance with the work order shown in Table 1. That is, as shown in FIG. 1, the solenoid 13a of the electromagnetic switching valve 13 in the pump 7 is demagnetized, and the solenoids 9a and 9b of the electromagnetic switching valve 9 are both demagnetized to cut off the hydraulic cylinder 5 from the discharge line 10. In this state, the solenoid 8a of the electromagnetic switching valve 8 is energized, the electromagnetic switching valve 8 is switched from the state shown in FIG. 1, the discharge line 10 is communicated with the hydraulic motor 4, and the hydraulic motor 4 is rotated.

In this case, the back chamber 12 of the plunger 11 is a passage 60,
Since the swash plate 6 is opened to the drain line 70 via the electromagnetic switching valve 13 and the communication path 64, the swash plate 6 is maintained at the maximum angle of inclination.

Therefore, the pump 7 is operated at the operating point A where the discharge pressure has increased to PA while maintaining the maximum discharge volume QH, and the hydraulic motor 4 rotates at a predetermined rotation speed. When the number of rotations of the hydraulic motor 4 reaches a predetermined value, the solenoid 8a is demagnetized, communication from the discharge line 10 to the hydraulic motor 4 is cut off, and the hydraulic motor 4 is connected to the flywheel 1.
It is in a state of rotation due to the inertia of 7.

Next, the solenoid 9a of the electromagnetic switching valve 9 is energized to communicate the discharge line 10 with the head side chamber 22 of the hydraulic cylinder 5, thereby moving the piston 19 to the left in FIG.

However, in this case as well, the back chamber 12 of the plunger 11 is opened to the drain line 70 and the swash plate 6 is maintained at the maximum inclination angle, so that the pump 7 has a maximum discharge volume Q.
At H, the discharge pressure becomes PB, as shown in Figure 2, and the operating state is at a low pressure and large capacity at the operating point B, the piston 19 is moved rapidly, and the workpiece 3b is rapidly fed until just before it contacts the rotating workpiece 3a. It will be done.

Then, the solenoid 1 of the electromagnetic switching valve 13
3a, the electromagnetic switching valve 13 is switched, and the discharge passage 58 of the pump 7 is connected to the back chamber 12 of the plunger 11 via the high pressure passage 59, the communication passage 63, the electromagnetic switching valve 13, the communication passage 66, and the passage 60 in this order. The plunger 11 is moved to an intermediate position, that is, a position where it abuts the step portion 68, thereby displacing the swash plate 6 to an intermediate angle of inclination.

Therefore, the pump 7 has a discharge amount QL that is intermediate to the maximum discharge amount QH, and the discharge pressure is at the operating point C of the PB, so the piston 19 is retarded. Due to the slow movement of the piston 19, the workpiece 3
b is slowly fed toward the workpiece 3a, and finally they come into contact with each other.In this way, both the workpieces 3
When a and 3b come into contact, the discharge amount of the pump 7 becomes the intermediate discharge amount Q.
While maintaining the state L, the discharge pressure rises from point C to point D, resulting in a high-pressure, small-capacity operating state at operating point D, where workpiece 3b presses rotating workpiece 3a with high pressure PO. state, both workpieces 3a, 3
b will be touched by friction welding.If the workpiece 3b is in a position close to the workpiece 3a from the beginning, the workpiece 3b will not be rapidly fed and the solenoid 13a of the electromagnetic switching valve 13 will be touched from the beginning. Friction welding of both workpieces 3a and 3b can be performed simply by energizing the solenoid valve 13, switching the electromagnetic switching valve 13, and performing slow feed.

The flywheel 17 automatically stops when the friction welding is completed by consuming kinetic energy for friction welding the workpieces 3a and 3b. After the friction welding is completed as described above, the solenoid 13a in the energized state By demagnetizing and opening the back chamber 12 of the plunger 11 to the drain line 70, the swash plate 6 is returned to the maximum inclination angle state and the pump 7 is brought to the state of the maximum discharge amount QH.
The solenoid 9a of the electromagnetic switching valve 9 is demagnetized and the solenoid 9
By energizing b, the discharge line 10 is connected to the rod side chamber 2.
3, the head side chamber 22 is made to communicate with the tank 69, and the piston 19 is quickly returned to the right in FIG. 1 to the end position.

However, in the friction welding work process as described above, if an accident occurs in which the discharge line 10 becomes abnormally high pressure, the spool 46 or 47 is activated and the operating plunger 42 is activated to adjust the inclination angle of the swash plate 6. This makes the discharge amount zero.

That is, when the solenoid 13a of the electromagnetic switching valve 13 is in a demagnetized state, the discharge passage 58 communicates with the spool 46 via the introduction passage 50, so if the discharge line 10 becomes abnormally high pressure, the abnormal high pressure is transferred to the spool 46. 46 is moved, control pressure is introduced into the front chamber 45 through the control passages 56 and 57, and the operation plunger 42 is actuated to make the tilt angle of the swash plate 6 zero. When the solenoid 13a of the electromagnetic switching valve 13 is energized, the discharge passage 58 is connected to the introduction passage 51.
Since the discharge line 10 is in communication with the spool 47 through the spool 47, when the discharge line 10 becomes abnormally high pressure, the high pressure moves the spool 47 and the control pressure passes through the control passage 57 and is introduced into the front chamber 45, causing the plunger 42 to move. When activated, the angle of inclination of the swash plate 6 is made zero. However, when comparing the device according to the embodiment of the present invention described above with the conventional device described above, the results are as shown in Table 2. In other words, the number of hydraulic devices used is variable, whereas the conventional product required a total of 11 units. Since 71 positive displacement hydraulic pumps can have both the functions of a pressure control valve and a flow rate control valve, the number of hydraulic devices used can be simply three, one pump and two directional control valves. Therefore, the external dimensions can be reduced, and it is easy to manufacture and can be provided at low cost.

In addition, compared to the conventional products mentioned above, the hydraulic motor 4 and the hydraulic cylinder 5 do not need to be driven at all when they are not needed, and both can be driven to the minimum necessary state, which greatly reduces power loss and reduces running costs. It can be done.

In addition, since the pressure and flow rate of the liquid supplied to the hydraulic motor 4 and the hydraulic cylinder 5 can be controlled by the pump 7 without using any equipment other than the pump 7, each pressure value and flow rate value can be kept stable with little fluctuation. In particular, since the flow rate is the pump discharge amount itself, the fluctuation range can be made sufficiently small, and the pulsation of the discharge pressure during slow feeding can be significantly reduced.

Furthermore, since the number of control valves is greatly reduced, the length of the piping can be shortened, and therefore the pressure drop due to the piping can be greatly reduced. Further, although the above description is for a swash plate type axial piston pump, the same applies to all other variable displacement piston pumps and variable displacement vane pumps. In this case, the tilting yoke, eccentric ring or cam ring becomes the variable control element. As described above, the rotating machine and the sliding machine of the present invention are each connected to the discharge line of a variable displacement hydraulic pump via a switching valve, and the plunger for adjusting the displacement of the variable control element of the pump is variably controlled. The plunger is provided so as to be freely movable relative to the element, and the movement of the plunger is restricted to a certain range, and the back chamber of the plunger is communicated with the discharge line via a switching valve, so that the discharge amount of the pump can be changed from the maximum discharge amount to the intermediate discharge amount. Since the variable displacement hydraulic pump can adjust the discharge amount and discharge pressure, it is possible to control not only the fast feed operation of the work equipment but also the slow feed operation with high precision. In addition, it is possible to obtain products of constant quality with little variation, and it is also possible to reduce power loss when controlling the operation of the work equipment, the number of control devices used is small, the overall structure of the equipment is extremely simple, and the external dimensions are small. It can be provided in a small size and at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a pump discharge pressure-discharge rate characteristic diagram, and FIG. 3 is an explanatory diagram showing a conventional example. 1...Rotating machine, 2...Sliding machine, 3a, 3b...
・Workpiece, 4... Hydraulic motor, 5... Hydraulic cylinder, 6... Variable control element (swash plate), 7... Variable displacement hydraulic pump, 8, 9... Switching Valve, 10...Discharge line, 11...Plunger, 12...Back chamber,
13...Switching valve.

Claims (1)

[Claims] 1. An operation control device for a working machine that processes a workpiece using a rotating machine and a sliding machine, which comprises a hydraulic motor for the rotating machine, a hydraulic cylinder for the sliding machine, and a variable control element. The machine is connected to the discharge line of the pump through a switching valve, and the pump is provided with a plunger for adjusting the displacement of the variable control element. The plunger is freely movable, the movement of the plunger is limited to a certain range, and the back chamber of the plunger is communicated with the discharge line via a switching valve to control the discharge rate of the pump from the maximum discharge rate to an intermediate discharge rate. A working machine operation control device that is characterized by the following: