JPS59121203A - Method and apparatus for controlling fluid pressure cylinder - Google Patents

Abstract

PURPOSE:To stabilize the speed of a piston while it is shifted from high speed movement to high output movement by controlling the degree of opening of a flowrate control valve for supplying pressurized fluid by a preset valve opening coefficient. CONSTITUTION:As the pressure of oil in an oil feeding pipe 34 exceeds a preset pressure, a solenoid 38 operates, and a flow passage changeover valve 39 is changed over to the side of a tank line 40, and by this, the speed of a piston 43 tends to fall. However, an operating condition detector 48 detects the open/ close movement of the flow passage change-over valve 39, and it supplies a displacement value signal to an opening coefficient setter 49, and this signal is then supplied to a flowrate control valve control unit 52, and by this command, the opening of a flowrate control valve 35 becomes larger. Consequently, the piston can maintain high and constant speeds.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling piston speed and power in a hydraulic cylinder.

In many applications, fluid pressure cylinders using hydraulic pressure or the like have a characteristic that the output is small when the piston moves at high speed, and the piston moves at low speed when high output is required.

Figures 1 to 3 are hydraulic circuit diagrams of conventional hydraulic cylinders used for this type of use, and to explain them based on the figures, the one shown in Figure 1 without trenches is generally It's called a recirculation type! The head end chamber 2 of the hydraulic cylinder 2'1 is connected to a hydraulic power source 5 by a pipe 4 equipped with a flow control valve 3. Further, a pipe 8 provided with a pressure valve 6 and connected to a rod end chamber 7 of the hydraulic cylinder 1 and the pipe 4 are connected by a run-around pipe 10 provided with a check valve 9. The working end of the piston rod 11 of the hydraulic cylinder 1 is connected to an injection plunger (C) of an injection molding device such as a die-casting machine.
The oil supplied from the hydraulic source 5 passes through the flow control valve 3 and enters the head end chamber 2 to advance the piston 12. As a result, the rod end chamber 7 enters the head end chamber 2 through the check valve 9. Therefore, the piston 12 operates at the same speed as if it were actuating a cylinder whose diameter is the same as that of the piston rod 11, i.e., ,g,<)
y12o"-)2-R times, and the diameter of the histone rod 11 can be operated at high speed. Also, when the piston 12 moves forward and the load on the piston rod 11 increases, the pressure in the head end chamber 2 increases and the pressure The valve 6 is activated, and the oil in the rod end chamber 7 passes through the pressure valve 6 and is discharged to the outside.As a result, the cylinder output increases by R times, but the speed decreases by 100.

Next, what is shown in FIG. 2 is generally called a pressure increase cylinder, in which a hydraulic cylinder 13 for high-speed movement and a hydraulic cylinder 14 for high-output movement are coaxially and directly connected. Then, the oil supplied from the hydraulic source 5 passes through the flow control valve 3 and the check valve 9, enters the head end chamber 15 of the hydraulic cylinder 13, and moves the piston 16 forward. When the load on the piston rod 17 increases, the head end chamber 15
The pressure increases to actuate the pressure valve 6, and oil enters the head end chamber 18 of the hydraulic cylinder 14 through the pressure valve 6 and advances the piston 19. As a result, the output is ()4+so+
) for J2. = R times, but the speed is reduced to 100.

Furthermore, the one shown in Fig. 3 is generally called a cylinder switching type, in which a pair of high-speed transfer hydraulic cylinders 20 and 21 and a high-output transfer hydraulic cylinder 22 are arranged in parallel. A load is directly connected to the piston rod 23.24.25 of each cylinder 20, 21.22.

The oil supplied from the hydraulic source 5 passes through the flow control valve 3 to the head end chambers 25 and 26 of the hydraulic cylinders 20 and 21.
27. 28 to move the human piston forward. As the load increases, the pressure at the sult head end g25, 2s increases and the pressure valve 6 operates, passing through the oil pressure valve 6 to the hydraulic cylinder 22.
The piston 30 is advanced into the head end chamber 29 of the engine. As a result, the output is reduced to π.

Among the hydraulic cylinders shown above, those shown in Figures 1 and 2 are often used when the high speed exceeds 1% or when the boost ratio is about 2 to 5. The one shown in 1 is often used when the high-speed movement speed is less than 1% or the boosting ratio is about 5 or more.

FIG. 4(a) is a diagram showing the relationship between the piston stroke, output, and speed common to these conventional hydraulic cylinders, with the horizontal axis representing the stroke S of the histone rod directly connected to the load, and the output shown by the solid line and the dotted line. The vertical axis represents the piston speed.

As is clear from the figure, when the amount of hydraulic pressure supplied is constant, the output and speed are constant before the pressure valve 6 is activated.
When the pressure valve 6 operates, the output increases and the speed decreases. Such characteristics are good in cases where the compression ratio is small, such as in the case of a mechanism for tightening a mold, and where the switching characteristics are not a problem, but for example, in cases where the compression ratio is small, such as in the injection device of a die-casting machine, etc. If the load is large and it is necessary to maintain high speed even if the load increases to a certain extent, as shown in Figure (b1) corresponding to Figure (a), this cannot be handled.

Conventionally, this was compensated for by opening the flow rate fjLtl'1 control valve 3 using a command from a timer, limit switch, etc., but the operation timing of the flow rate control valve 3 did not match, and as shown in Figure (C).
As shown in Fig. 9 (d), which corresponds to Fig. 9 (a), a partial speed decrease or increase occurs near the start of the output rise, and the speed change becomes uneven and the required speed is shifted. It was not possible to obtain stable characteristics.

The present invention has been made in view of the above points, and is based on a valve opening coefficient preset in relation to the switching state of the flow path switching valve in the process of increasing and decreasing the output of the fluid pressure cylinder. The opening degree of the control valve is controlled, and for this purpose, a pressure setting device that operates a flow path switching valve provided in the bypass at a set pressure, and a flow control valve is set by detecting the operation of the flow path switching valve. Opening coefficient setting % once controlled by coefficient
A control method for a fluid pressure cylinder in which the performance is improved by providing a +'i so that the piston speed maintains a stable high-speed state in a state of transition from high-speed movement to high-output movement. and the equipment will be donated. Examples of the present invention will be described in detail below.

FIG. 5 is a hydraulic circuit diagram of an embodiment of the control device according to the present invention shown for explaining the control method according to the present invention, and this embodiment is a hydraulic circuit diagram of the embodiment of the control device according to the present invention shown in FIG. An example is shown in which the present invention is applied to a recirculation-operated hydraulic cylinder. In the figure, a head end chamber 32 of a hydraulic cylinder 31 and a pressure oil supply source 33 are connected by an oil feed pipe 34, and the opening degree of the oil feed pipe 34 is controlled by a control device to be described later. A flow control valve 35 is provided. Further, the hydraulic cylinder A 6 and the oil feed pipe 34 are connected by a flow path 37 between the hydraulic cylinder 31 and a flow rate control valve 35, and a flow path switching valve equipped with a solenoid 38 is provided in this flow path 37. 39 are arranged. Flow path switching valve 3
A tank line 40 is connected to 9, and the valve is configured to be switched between the side that communicates the flow path 3γ and the side that communicates with the tank line 40 by the operation of the solenoid 38. The switching valve 39 has a portion in the middle of opening and closing that communicates with both flows fRr37.40 through a throttle portion, as shown in the figure, depending on the shape of the spool. A pressure setting device installed on the electric circuit 42 connecting the pressure detection device at the flow path 3T connection point of v34 and the solenoid 38, and also equipped with a pressure detector and a comparator. , an arbitrary set pressure is compared with the oil pressure in the oil feed pipe 34, and when the oil pressure exceeds the set pressure, the solenoid 38 is activated to switch the flow path 37 to the tank line 40 side.Inside the hydraulic cylinder 31 In this embodiment, an injection plunger (not shown) is fixed to the working end of the piston rod 44 of the piston 43 which reciprocates with oil supplied from the pressure oil supply source 33. The forward movement of piston 4 pushes the molten metal and injects it into the mold cavity.
By further advancing the molten metal, a wafer 4 is formed so that the molten metal can be heated. Piste/rod 44
A striker 45 that reciprocates integrally with the striker 45 is fixed to the piston rod 44, and a position detector 46 such as a limit switch whose contact is closed when the striker 45 comes into contact with the piston rod 44 is located near the striker 45. It is provided to be movable and adjustable in the axial direction. The reference numeral 47 indicates a switching valve control device that controls the switching characteristics of the flow path switching valve 39, and includes a position detector 46, a pressure setting device 41. and the solenoid 38 are electrically connected. Further, an operating state detector 48 is connected to the flow path switching valve 39, and the operating state detector 48 detects the opening/closing operation of the valve and generates a signal. An opening coefficient setter 49 is connected to the opening coefficient setting device 49 for correcting the opening coefficient using a setting coefficient. Although the opening coefficient setter 49 is shown as being connected to the circuit on the switching valve control device 47 side, the circuit 5
It is sufficient that either one of 0°51 is connected. Reference numeral 52 indicates the opening coefficient setting device 49 and the flow rate control valve 3.
5 is a flow control valve control device provided in an electric circuit 53 that connects with the flow control valve 35, and is configured to be activated by a signal generated by the opening coefficient setting device 49 and to control the opening degree of the flow rate control valve 35. There is.

The operation of the control device configured as described above will be explained based on FIG. 5 and FIG. 4(b). The oil sent from the pressure oil supply source 33 to the head end chamber 32 via the flow control valve 35 moves the piston 43 forward, and the oil in the rod end chamber 36 is sent to the flow path switching valve 39 which is open to the flow path 31 side. The piston 43 continues to move forward through the flow path 37 toward the oil feed path 34 . Until the piston 43 moves forward and is in the middle of injection, no load is applied to the injection plunger directly connected to the piston rod 44, so the output is at a minimum and constant as shown by P.-Pl in Fig. 4 (bl). , and the speed of the piston 43 is constant as shown by V. - The oil pressure in the oil pipe 34 rises (a predetermined pressure is set in the pressure setting device 41 in advance), and when the rising oil pressure in the oil pipe 34 exceeds this set pressure, the detector of the pressure setting device 41 and The comparator and the υ pressure setting device 41 generate a signal to operate the solenoid 38. Therefore, the flow path switching valve 39
0 side, a part of the oil in the long end chamber 36 is released into the tank, and the speed of the piston 43 increases as shown in FIG. 4(b).
It attempts to descend as shown by the dashed lines V and -V.

However, in this device, the operating state detector 48 detects the opening/closing operation of the flow path switching valve 39 and the opening coefficient setting device 4
9 inputs a displacement value signal, this signal is corrected by the set count of the opening coefficient setter 49 and then input to the flow rate control valve control bag R52, and the opening degree of the flow rate control valve 35 is increased by the command. Otherwise, the speed of the piston 43 is kept high and constant as shown by V and -V2.

When the output increases to P2, the output increases rapidly and reaches P.

On the contrary, the speed suddenly decreases from v2 to V3. This P
In the region of 2-P3 + v2-V3, priority is given to the output characteristics, and the speed characteristics have a secondarily determined value. By performing such control, the characteristics shown in FIG. 4(b) can be easily and accurately obtained.

Note that, as described above, the output increase start point P1 is detected by the oil pressure in the oil feed pipe 34, but by providing the position detector 46, the output increase start point P1 can be detected.

When this point is reached and the striker 45 closes the contact of the position detector 46, the solenoid 38 is activated via the switching valve control device 47, so that a slight delay in the activation time can be prevented. The switching valve control device 47 controls the switching characteristics, that is, the switching speed, of the flow path switching valve 39, and is used when the characteristics cannot be obtained by simple fluid pressure pilot operation.

Therefore, if the command signal of this switching valve control device 47 is input to the opening coefficient setting device 49, the operating state detector 48
It is not necessary to use a control circuit including Since this is just a configuration, its explanation will be omitted.

In this device, a hydraulic cylinder 60 for high-output movement and a hydraulic cylinder 61 for high-speed movement are connected in series, and the piston rod 62 of the hydraulic cylinder 60 is engaged in the head end chamber 63 of the hydraulic cylinder 61. is included. Further, the flow path switching valve 39 which has a throttle switching part in the middle of opening and closing is only opened and closed by the solenoid 38 and is not connected to the tank line, but instead is connected to each hydraulic cylinder 6.
Tank line 6 in 0.61 rond end chamber 64°65
6.67 is connected.

Further, the pressure setting device 41 and the head end chamber 63 of the hydraulic cylinder 61 are electrically connected so that the oil pressure there is detected, and the flow path switching valve 390 circuit is also connected to the head end chamber 631C. Also provided within this circuit is a flow control valve 68 which is controlled by a flow control valve control bag FAT 52.

By configuring in this way, the v shown in FIG. 4(b)
. -v, , pop, the pressure oil flows through the flow path 37. Flow control valve 68. The hydraulic cylinder 61 passes through the flow path switching valve 39.
is sent to the head end chamber 63 and the rond end chamber 65
of oil is discharged into tank line 6γ. When the hydraulic pressure in the long end chamber 65 exceeds a predetermined pressure due to load, the pressure setting device 41 detects this and operates the flow path switching valve 39 in the direction of closing, and the operating state detector 48 detects this and operates the flow path switching valve 39 to close it. By sending a signal to the degree coefficient setter 49, the flow control valve 35 is opened via the flow control valve controller 52. Therefore, after points v, , p in FIG. 4(b), pressure oil is fed into the hydraulic cylinder 60 and the piston rod 62 moves forward, and the oil pressure in the head end chamber 63 of the hydraulic cylinder 61 also rises. continue. That is, after points v, , p, the two hydraulic cylinders 60 and 61 are integrated, and the flow rate control valve 35 is operated in the same way as the control device shown in FIG.
The opening degree of the opening is controlled. However, in this case, the flow path switching valve 39 is closed and control is performed by the circuit of pressure setting device 41 - switching valve control unit 47 - opening coefficient setting device 49.

Note that the illustration and description of the control device for the cylinder switching type fluid pressure cylinder shown in FIG. 3 will be omitted;
Control can be performed by a configuration completely similar to that of the control device shown in FIG.

In addition, although each of the control devices described above has been described as being operated by electrical processing for multi-purpose use, when the control is simple and the number of adjustment of characteristics is small, the flow path switching valve 39 and the flow rate control valve 35 may be operated mechanically. It is also possible to relate to Further, in the embodiments of each of the above-mentioned devices, an example was shown in which it was implemented in a hydraulic cylinder for an injection device of a die-casting machine, but it is also applicable to various fluid pressure presses, injection molding machine injections, compression presses, construction machinery, etc.

It can be applied to various types of hydraulic cylinders, and the effect is particularly noticeable when applied to hydraulic cylinders with high compression ratios.

As is clear from the above description, according to the present invention, the flow rate for supplying pressure fluid is controlled by the valve opening coefficient preset in relation to the switching state of the flow path switching valve during the output increase/decrease process of the fluid pressure cylinder. To control the opening degree of the valve,
For brackets, there is a pressure setting device that operates the flow path switching valve installed in the bypass at a set pressure, and an opening coefficient setting device that detects the operation of the flow path switching valve and controls the flow control valve with the set opening coefficient. By providing this, the speed of the piston is maintained at a stable high speed state in the state of transition from high-speed movement to high-output movement, so that the compression force is stabilized and the performance of the fluid pressure cylinder is significantly improved. If this is used in an injection molding apparatus, it is possible to reliably and easily obtain injection molded products with desired injection conditions and good quality.

[Brief explanation of drawings]

Figures 1 to 3 respectively show hydraulic circuit diagrams of conventional hydraulic cylinders, Figure 1 is a hydraulic circuit diagram of a recirculation type hydraulic cylinder, Figure 2 is a hydraulic circuit diagram of a pressure boosting hydraulic cylinder, and Figure 3 is a hydraulic circuit diagram of a conventional hydraulic cylinder. is the hydraulic circuit diagram of the cylinder switching type hydraulic cylinder, 4th grade.
The figure shows a relationship diagram between piston stroke, output, and speed, FIG. 4 (&) is a relationship diagram when a conventional control device is not used, and FIG. 4 (b) is a relationship diagram of a control device according to the present invention. FIGS. 4(e) and 4(d) are relationship diagrams when using the conventional correction means, respectively, and FIGS. 5 and 6 are relationship diagrams when using the fluid pressure cylinder according to the present invention. Different embodiments of the control device according to the present invention are shown to explain the control method, and FIG. 5 is a hydraulic circuit diagram of the control device for a recirculation-actuated hydraulic cylinder, and FIG. 6 is a hydraulic circuit diagram of the control device for a pressure-increasing hydraulic cylinder. FIG. 31... Hydraulic cylinder, 32... Head end chamber, 33... Pressure oil supply source, 34... Oil feed pipe, 3
5...Flow control valve, 36...Ron end chamber,
31...RR139...Flow path switching valve, 4o...
...Tank line, 41...Pressure setting device, 47...
...Switching valve control device, 48...Operating state detector, 4
9... Opening coefficient setting device, 52... Flow rate control valve control device, 60... Hydraulic cylinder for high output, 61...
...High-speed hydraulic cylinder, 63...Head end chamber, 68...Flow control valve. Patent applicant: Ube*Nami Co., Ltd. Agent: Masaki Yamakawa (and 1 other person) 1st
Figure 3 Figure 4 (C1) (b) (C)
(d)

Claims (3)

[Claims] (1) The opening of the flow rate control valve for supplying pressure fluid is controlled by a valve opening coefficient set in advance in relation to the switching state of the flow path switching valve during the output increase/decrease process of the fluid pressure cylinder. A method of controlling a fluid pressure cylinder. (2) A flow control valve provided in a fluid pipe between the head end chamber of the fluid pressure cylinder and the pressure fluid supply source, and a flow path between the fluid pipe and the rond end chamber of the fluid pressure cylinder. a flow path switching valve that is provided and capable of switching this flow path to a tank line; a pressure setting device that detects output increase/decrease-related specifications of the fluid pressure cylinder, compares it with a set pressure, and switches the flow path switching valve; and an opening coefficient setting device that detects the switching operation of the flow path switching valve, compares it with a set opening coefficient, and controls the opening of the flow rate control valve via a control device. Cylinder control device. (3) Provided in the flow path connecting the head end chamber of the fluid pressure cylinder for high-speed movement and the pressure fluid supply source, and the flow path connecting the head end chamber of the fluid pressure cylinder for high output movement and the pressure fluid supply source, respectively. Detects the flow rate control valve, the flow path switching valve that can be opened and closed provided in the high-speed movement fluid pressure cylinder side flow path, and the output increase/decrease related specifications of the high-speed movement fluid pressure cylinder, and determines the set pressure. A pressure setting device that compares and switches the flow path switching valve, and detects the switching operation of the flow path switching valve and compares it with a set opening degree coefficient to select the opening degree of one of the flow rate control valves through a control device. 1. A control device for a fluid pressure cylinder, comprising: an opening coefficient setting device for controlling the opening coefficient.