JP2882981B2 - Speed control method of hydraulic ejector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the speed of a hydraulic ejector that ejects a molded product by being protruded by a hydraulic cylinder mechanism in a mold clamping device used in a resin injection molding machine or the like.

[0002]

2. Description of the Related Art Conventionally, as a mold clamping device used in a resin injection molding machine or the like, an apparatus provided with an ejector driven by a hydraulic cylinder mechanism to release and remove a molded product is known. . By the way, from the viewpoint of improving the molding cycle, it is preferable that the ejecting speed of the ejector is high, but if it is too fast, a large force acts on the molded product at the time of mold release, and damage such as whitening phenomenon and cracks is caused. Easy to occur.

Therefore, in the conventional mold clamping device, for example, by gradually increasing the ejecting speed of the ejector in accordance with the amount of projecting or the projecting position, the ejecting speed of the ejector can be sufficiently increased when the molded product is released from the mold. In addition to preventing the molded product from being damaged by slowing down, the projecting speed after releasing the mold is increased to improve the molding cycle.

However, in a mold clamping device, generally,
The hydraulic pump that supplies hydraulic oil to the hydraulic cylinder mechanism for driving the ejector is shared with the hydraulic pump that supplies hydraulic oil to the hydraulic cylinder mechanism for opening and closing the mold, and the hydraulic cylinder mechanism for driving the ejector is Since the diameter is very small compared to the hydraulic cylinder mechanism for opening and closing the mold, if the initial ejection speed of the ejector is set to be sufficiently low, the required supply flow rate of hydraulic oil to the hydraulic cylinder mechanism for driving the ejector However, the discharge flow rate of the hydraulic pump corresponds to an extremely small discharge amount in an unstable region, and there is a problem that it is extremely difficult to stably control the ejection speed of the ejector.

Further, conventionally, in general, a projecting position of an ejector is generally detected by a limit switch or the like, and a discharge flow rate of a hydraulic pump supplying hydraulic oil to a hydraulic cylinder mechanism for driving the ejector is determined in accordance with the projecting position of the ejector. If the initial speed does not come out due to oil leakage or oil temperature rise due to aging, the ejector will not move at all, and the molding cycle may be interrupted. there were.

[0006]

Here, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to make the ejection speed of an ejector from a sufficiently low ejection speed in the initial stage of ejection to the final ejection speed. It is an object of the present invention to provide a method for controlling the speed of a hydraulic ejector that can be advantageously and stably controlled until the speed is reached.

[0007]

In order to solve the problem, a feature of the present invention is a method for controlling the speed of a hydraulic ejector as described above, wherein an increasing pattern of the projecting speed according to the projecting amount of the ejector is provided. The reference flow rate control signal of the hydraulic cylinder mechanism corresponding to the projecting position of the ejector is determined in advance according to the increasing pattern of the ejecting speed, and the amount of change in the position of the ejector within a unit time satisfies a preset minimum value. If not, the reference flow control signal is increased to obtain a corrected flow control signal, and the hydraulic cylinder mechanism is controlled based on the corrected flow control signal. After the projecting position of the ejector that has become equal to or less than the signal value,
The feature is that the hydraulic cylinder mechanism is controlled based on the reference flow control signal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 2 shows a specific example of a hydraulic circuit for driving an ejector in a mold clamping device for an injection molding machine for carrying out the method of the present invention. In this figure, a hydraulic cylinder mechanism 10 is connected to an ejector (not shown) and is reciprocated integrally with the ejector, although not explicitly shown in the drawing. ing. In addition, such a piston 1
2, a potentiometer 13 is attached,
The protruding position of the piston 12, that is, the protruding position of the ejector, is detected.

Further, the hydraulic cylinder mechanism 10 has a three-position switching type solenoid valve 14 and a supply line 18 for hydraulic oil and a drain line 2 by a variable discharge pump 16.
0 is connected. Thereby, the solenoid valve 1
In accordance with the switching position of 4, hydraulic fluid is supplied to and discharged from the hydraulic cylinder mechanism 10, and the piston 12 is driven to reciprocate, so that an ejector (not shown) is driven to project and retract. Note that a proportional electromagnetic relief valve 2 is provided between the supply line 18 and the drain line 20.
2 are provided, and the pressure of the supply line 18 can be adjusted.

As shown in FIG. 3, the operation of the solenoid valve 14, the variable discharge pump 16 or the proportional electromagnetic relief valve 22 is controlled by the control device 24 so that the ejector performs an intended operation. It has become. That is, the drive direction of the ejector is determined by the operation control of the solenoid valve 14, and the hydraulic cylinder mechanism 1 is controlled by the operation control of the variable discharge pump 16 or the proportional electromagnetic relief valve 22.
The drive speed and the protrusion output of 0 are determined.

More specifically, the control device 24 is generally constituted by a microprocessor,
U26, ROM28 and RAM30 are provided. The potentiometer 13 is connected to the control device 24 via an A / D converter 32. The position signal of the ejector detected by the potentiometer 13 is input to the control device 24. I have. Further, the control device 24 is connected to the control device 24 via the I / O interface 38.
The solenoid valve 14 is connected and D / A
The variable discharge pump 16 or the proportional electromagnetic relief valve 22 is connected via the converter 34 and the amplifier 36, and a control signal is sent to the solenoid valve 14, the variable discharge pump 16 or the proportional electromagnetic relief valve 22. It is output.

That is, in the ejector drive device having the hydraulic system and the control system configured as described above,
When a start signal for releasing and removing the molded product is input, the CPU 26 of the control device 24 uses the storage function of the RAM 30 in accordance with a program stored in the ROM 28 in advance, and the solenoid valve 14, the variable discharge pump 16 or A control signal is output to the proportional electromagnetic relief valve 22 so that the operation of the hydraulic cylinder mechanism 10 is controlled.

Here, the solenoid valve 1
4 is a switching control signal for switching the supply / discharge direction of the hydraulic oil to / from the hydraulic cylinder mechanism 10 in order to control the drive direction of the ejector. The control signal is supplied to the variable discharge pump 16 or the proportional electromagnetic relief valve 22. The output control signal is a flow control signal for adjusting the supply and discharge flow rate of hydraulic oil to and from the hydraulic cylinder mechanism 10 in order to control the drive speed of the ejector.

At the time of releasing and removing the molded product, the solenoid valve 14 is switched so that the piston 12 of the hydraulic cylinder mechanism 10 is driven in the projecting direction, and the ejector is ejected at a sufficiently low speed in the initial stage. The operation of the variable discharge pump 16 or the proportional electromagnetic relief valve 22 is controlled so that the speed is increased continuously or stepwise after the start.

Here, the variable discharge pump 1
The operation control of the 6 or the proportional electromagnetic relief valve 22 by the control device 24 is performed, for example, by determining the control signal: V according to the flowchart shown in FIG.

Specifically, first, an intended speed increase pattern of the ejector speed is set according to the shape and material of the molded product. The speed increase pattern is generally determined by the relational expression between the ejector position and the ejector speed. For example, as shown in FIG. 4, a plurality of types (NO. (10 types) can be determined by preparing the speed increasing patterns and selecting from them.

Further, the acceleration pattern is divided into an appropriate number of control sections (for example, equally divided into 10) on the ejector position axis, and the acceleration data of the ejector (the ejection speed of the ejector in the section) is divided for each control section. Is calculated with respect to the final speed set value), and the calculation result is stored in the speed increasing data table. This speed-up data table is obtained, for example, by collecting the speed at the intersection of the curve of each speed-up pattern and the dividing line of a plurality of control sections as speed-up data in FIG. Can be created.

Then, in FIG. 1, in step S1,
The ejection drive control of the ejector is started, and the subsequent step S2
, The potentiometer 13 to the A / D converter 32
Is input to A as the current position of the ejector.

Subsequently, in step S3, it is confirmed from the value of A that the control section is currently in the predetermined control section in the predetermined speed increase pattern.
In, it is determined whether or not the confirmed result is the final control section. If it is not the last control section, in step S5, speed increase data in the current control section is selected from the preset speed increase data table. On the other hand, if it is the last control section, immediately step S1
Subsequent to 4, after setting the final speed set value to the control signal: V, in step S15, the control signal: V is set and output to the D / A converter 34, and the process ends.

Further, if it is not the final control section, following step S5, in step S6, based on the selected acceleration data, an output operation value: v is obtained according to the following equation. That is, the calculated value: v thus obtained is a reference control signal (reference flow rate control signal) theoretically obtained based on the target increase pattern of the ejector speed.

Output calculated value = K (Acceleration data × End speed set value × GAIN + NULL) + Initial speed set value K: Constant for changing the speed increase pattern GAIN: Flow rate set value for obtaining the specified speed of the ejector NULL ： Constant considering idling at low rotation of pump

Then, in step S7, it is determined whether or not the time of the fixed-period timer has expired. If the time has expired, the process immediately follows step S8. If not, the process immediately proceeds to step S11. It should be noted that this fixed-period timer is reset immediately after a time-up, restarts, and repeats the time-up for each unit time. The unit time is desirably adjustable, for example, about 20 ms. Is set.

In step S8, the signal input from the potentiometer 13 via the A / D converter 32 is input to B as the current position of the ejector. Thereafter, in step S9, the change amount of the ejector position within the time from step S2 to step S8:
BA is determined, and it is determined whether or not such a change amount is larger than a minimum value of the position change amount within a unit time set in advance: d. The value of d is desirably adjustable, and is set to, for example, about 0.1 mm.

Then, the change amount of the ejector position: BA
Is not larger than the minimum value: d, in step S10, a value obtained by adding a preset signal increase amount: α to the currently set control signal: v is set as a control signal: V, and then, in step S11. followed by. The value of the signal increase: α is preferably adjustable, and is set to, for example, 2.5 mV. On the other hand, if the change amount of the ejector position: BA is larger than the minimum value: d, the process immediately proceeds to step S11.

Thereafter, in step S11, it is determined whether or not the control signal: V is smaller than the operation value calculated in step S6. If V is smaller than the calculated value, the calculated value is set to the control signal: V in step S12, and then the process proceeds to step S13. On the other hand, V
If is not smaller than the calculated value, the process immediately proceeds to step S13.

Further, in step S13, it is determined whether or not the control signal V is smaller than the final speed set value. If V is not smaller than the end speed set value, the end speed set value is set to the control signal: V in step S14, and then the process proceeds to step S15. On the other hand, if V is smaller than the final speed set value, the process immediately proceeds to step S15.

Then, in step S15, the control signal V is set and output to the D / A converter 34, thereby ending the processing.

Steps S1 to S15 described above are repeated, and the control signal: V is sequentially rewritten, whereby the ejector is driven to protrude along the intended speed-up pattern. Become.

That is, in such a control method, in steps S7 to S10, the movement of the ejector is confirmed, and when the amount of movement of the ejector is equal to or smaller than the minimum value, the control signal (theoretically obtained by calculation) The increase correction is added to the reference flow control signal), and a correction control signal (corrected flow control signal) is output.

Therefore, even if the initial speed of the ejector is set sufficiently low, it is possible to completely prevent the starting failure of the ejector.
The protrusion operation can be stably performed at a sufficiently low speed. Therefore, the supply flow rate of the hydraulic oil to the hydraulic cylinder mechanism 10 is extremely small, so that the variable discharge pump 1
6 is a sufficiently slow speed while effectively preventing malfunction of the ejector caused by the unstable region 6 and malfunction of the ejector caused by oil leakage or oil temperature rise due to aging of the equipment. To eject the ejector,
It is possible to prevent damage during release and removal of the molded product.

In this control method, after the ejector is activated and reaches the predetermined projecting speed, the correction is not performed in steps S7 to S10, and based on the control signal theoretically obtained by the calculation. Since the ejecting speed of the ejector is controlled in this manner, the ejector is driven at an increased speed in accordance with the intended increasing pattern of the ejecting speed, and the improvement of the molding cycle can be advantageously achieved.

Although the embodiment of the present invention has been described in detail, this is a literal example, and the present invention is not construed as being limited to such a specific example.

For example, a unit time for repeating the position detection of the ejector, a minimum value (d) of the position change amount of the ejector within the unit time, or a control signal when the position change amount of the ejector is less than the minimum value. The value of the added signal increment (α) is not limited at all, and is determined as appropriate.

In the above-described embodiment, the target speed increase pattern of the ejector speed is divided into an appropriate number of control sections.
Although the data table is created by calculating the speed increase data of the ejector for each control section, it is also possible to directly calculate the output calculation value from the relational expression of the target speed increase pattern.

Further, it is, of course, possible to use a detector other than the potentiometer as illustrated in order to detect the projecting position of the ejector.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0038]

As is clear from the above description, according to the method of the present invention, when the ejector does not have the minimum ejection speed, the control signal is corrected. Even if the setting is made late, malfunctions of the ejector due to unstable operation of the hydraulic pump and aging of the equipment are effectively prevented, and stable ejection speed control of the ejector can be realized.

[0039] Therefore, it is possible to set the ejection speed of the ejector in the initial stage to be sufficiently low while sufficiently securing the operation stability, thereby improving and stabilizing the molding cycle and improving the molding cycle. Prevention of damage during release and removal of the product can both be advantageously achieved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an ejector speed control method according to the present invention.

FIG. 2 is an explanatory view schematically showing a specific example of a hydraulic circuit for driving an ejector controlled according to the flowchart shown in FIG. 1;

FIG. 3 is a block diagram showing an example of a control system applied to the hydraulic circuit shown in FIG.

FIG. 4 is a graph showing a specific example of a preset speed increase pattern of a plurality of types of ejector speeds.

[Explanation of symbols]

 Reference Signs List 10 hydraulic cylinder mechanism 12 piston 13 potentiometer 14 solenoid valve 16 variable discharge pump 22 proportional electromagnetic relief valve 24 controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-201222 (JP, A) JP-A-4-97813 (JP, A) JP-A-60-247533 (JP, A) JP-A-3- 270920 (JP, A) JP-A-62-117720 (JP, A) JP-A-59-189060 (JP, A) JP-A-63-83404 (JP, A) JP-A-3-74923 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) B29C 45/40-45/44 B29C 45/76-45/82 F15B 11/04 B22D 17 / 22,17 / 32

Claims (1)

(57) [Claims] 1. A method of controlling the speed of an ejector provided in a mold clamping device and ejecting a molded product by being ejected and driven by a hydraulic cylinder mechanism, wherein an increasing pattern of an ejecting speed according to an ejecting amount of the ejector is set in advance. When the reference flow rate control signal of the hydraulic cylinder mechanism corresponding to the projecting position of the ejector is obtained according to the pattern of increase in the projecting speed, while the position change amount of the ejector within a unit time is less than a preset minimum value. The reference flow control signal is increased to obtain a corrected flow control signal, the hydraulic cylinder mechanism is controlled based on the corrected flow control signal, and the value of the corrected flow control signal is equal to the reference flow control signal. Controlling the hydraulic cylinder mechanism based on the reference flow rate control signal after the position of the ejector projecting below the predetermined value. Speed control method for a hydraulic ejector, characterized.