JPH0270366A - Accumulator filling pressure adjustment method for injection molding equipment - Google Patents

Abstract

PURPOSE:To obtain an injection molding product having stable quality by leading gas pressure into a sub-bottle at the time of high gas pressure in a main bottle and working a piston accumulator at the time of low gas pressure to adjust it to the standard pressure. CONSTITUTION:The accumulator device is constituted with the main bottle 11 at upper end part of the piston accumulator 13 connecting with an injection cylinder 1 through a first shut-off valve 14 and the sub-bottle 12 through a second shut-off valve 15. Then, at the time of becoming high in the gas pressure in the main bottle 11, the second shut-off valve 15 is opened to lead the gas pressure into the sub-bottle 12. On the other hand, at the time of becoming low in the gas pressure in the main bottle 11, after lowering the piston 13a in the piston accumulator 13, it is lifted to adjust the gas pressure in the main bottle 11 to the standard pressure. By this method, the injection molding product having stable quality can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for adjusting the filling pressure of an accumulator in an injection molding device such as a die-casting machine. This invention relates to an accumulator filling pressure adjustment method for an injection molding device that allows the gas pressure to be easily adjusted to a predetermined standard gas pressure even if the gas pressure changes, and to operate an injection cylinder at a predetermined injection speed. .

[Conventional technology]

As is well known in the past, the injection circuit of a die casting machine as an injection molding device includes, for example, a piston accumulator whose lower end is connected to a circuit between an injection cylinder and a hydraulic pump that is a hydraulic pressure source, and this piston accumulator. It consists of a main bottle as a gas accumulator connected to the upper end by piping, and a hydraulic pump is operated to raise the piston of the piston accumulator and compress the nitrogen gas or other gas in the main bottle to a constant high pressure. By supplying hydraulic pressure to the injection cylinder all at once during injection, the injection cylinder is operated at high pressure and high speed, and a plunger injects the molten metal into the mold cavity to obtain a molded product. By always keeping the injection pressure constant during injection, a molded product with stable quality can be obtained.

[Problem to be solved by the invention]

However, conventionally, there have been the following difficulties in maintaining the injection pressure constant during injection.

That is, in the bottle of the accumulator of the injection circuit,
Nitrogen gas is filled at a constant high pressure that matches the molding conditions, and during injection, this constant gas pressure lowers the piston of the piston accumulator to supply high-pressure oil to the injection cylinder, which maintains the injection cylinder at a constant injection speed. However, due to changes in the outside air temperature, the gas filling pressure inside the accumulator bottle changes, which changes the injection speed, making it impossible to maintain a constant quality of the molded product. Ta.

For example, an increase in outside air temperature as the seasons change from spring to summer or from winter to spring, or conversely, a decrease in outside air temperature as the seasons change from summer to autumn or from autumn to winter. Furthermore, the gas filling pressure in the accumulator bottle changes due to changes in the outside temperature.

Note that during operation, the temperature of the hydraulic oil in the injection circuit also rises, but since the hydraulic oil is cooled by the oil cooler and kept almost constant, changes in the filling pressure of nitrogen gas due to oil temperature have little effect.

The present invention has been made in view of these problems, and it is an object of the present invention to easily adjust and change the gas filling pressure in the accumulator bottle to a predetermined standard gas pressure when the gas filling pressure in the accumulator bottle changes due to a change in outside air temperature. It is an object of the present invention to provide a method for adjusting accumulator filling pressure of an injection molding apparatus.

[Means to solve the problem]

In order to achieve the above object, the present invention fills gas into the upper end of a piston accumulator whose lower end is connected to an injection cylinder and connected to a tank via a normally closed third on-off valve. Using an accumulator device, the main bottle filled with gas is connected via a first on-off valve that is always open, and the sub-bottle filled with gas is connected via a second on-off valve that is normally closed. The gas pressure in the sub-bottle is adjusted so that it is lower than the gas pressure in the main bottle when the temperature is at a specified standard temperature, and when the outside air becomes higher than the specified standard temperature, the gas pressure in the main bottle is adjusted to the specified level. When the gas pressure in the main bottle reaches a predetermined standard pressure, the second on-off valve is opened to release the gas pressure in the main bottle into the sub-bottle. Conversely, when the outside air temperature is lower than a predetermined standard temperature and the gas pressure in the main bottle is lower than the predetermined standard gas pressure, the first on-off valve is closed and the second on-off valve is closed. Open the on-off valve and the third on-off valve to lower the piston in the piston accumulator, then close the third on-off valve and the second on-off valve, open the first on-off valve, and lower the piston in the piston accumulator. The piston is raised to adjust the gas pressure inside the main bottle to a predetermined standard pressure.

[Function] When the outside air temperature becomes higher than the predetermined standard temperature and the gas pressure inside the main bottle becomes higher than the predetermined standard gas pressure,
The second on-off valve is opened, and the high gas pressure in the main bottle is released into the sub-bottle, and when the gas pressure in the main bottle reaches a predetermined standard gas pressure, the second on-off valve is closed. .

Conversely, when the outside air becomes lower than the predetermined standard temperature and the gas pressure inside the main bottle becomes lower than the predetermined standard gas pressure, the first on-off valve is closed and the second on-off valve is closed. Third
The on-off valve is opened and the piston in the piston accumulator is lowered, then the second on-off valve and the third on-off valve are closed, and the first on-off valve is opened and the piston in the piston accumulator is raised. Then, the gas pressure in the main bottle is adjusted to a predetermined standard pressure.

In this way, the gas pressure within the main bottle is adjusted to a predetermined standard pressure in response to changes in outside air temperature.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are an injection circuit diagram and a flowchart of an injection molding apparatus for explaining an accumulator filling pressure adjustment method of an injection molding apparatus according to an embodiment of the present invention, respectively.

In Fig. 1, an injection cylinder 1 is connected to an electromagnetic switching valve 2 via a pipe 9, a flow rate adjustment valve 3 which also serves as an on-off valve for injection, a check valve 7, an electromagnetic switching valve 5, a reverse A stop valve 8 and a hydraulic pump 19 are connected. Reference numeral 4 is a tank, and 6 is a relief valve for setting circuit pressure. and,
A lower end of a piston accumulator 13 is connected to a piping 9 between the flow regulating valve 3 and the check valve 7 by a piping 10.
A third on-off valve 1 is installed in the pipe connecting this pipe 10 and the tank 4.
6 is interposed. Between the upper end of the piston accumulator 13 and the main bottle 11 of the accumulator is the first
The piping 17 between the first on-off valve 14 and the piston accumulator 13 has a second on-off valve 15 attached thereto.
The sub-bottles 12 are connected by. Note that a piston 13a is inserted into the piston accumulator 13 so as to be vertically movable. Further, the volume of the sub-bottle 12 may be smaller than the volume of the main bottle 11.

A method for adjusting the accumulator filling pressure using the accumulator device of the injection circuit configured as shown in FIG. 2 will be explained in conjunction with FIG.

First, for example, when the outside air is 20'C, the standard temperature is set, and the gas filling pressure in the main bottle 11 at this standard temperature is set to, for example, 135 kg/c+11, which is set as the standard gas pressure. The gas pressure in the main bottle 12 is adjusted to a pressure lower than the standard gas pressure of the main bottle 11, for example, 110 kg/c+fl.

In addition, at this time, the second on-off valve 15 and the third on-off valve in FIG.
The on-off valve 16 is closed, and the first on-off valve 14 is opened. Further, hydraulic pressure is applied to the piston accumulator 13 from the hydraulic pump 19 via the piping 9.10, and the piston 13a is at the upper limit, and at this time, the gas pressure in the main bottle 11 is equal to the standard value of 135 kg/aft. It is considered to be gas pressure.

In this state, the operation of the injection circuit equipped with the accumulator device is started, and when the electromagnetic switching valve 2 is switched from the state shown and the flow rate adjustment valve 3 is opened, the piston 1 of the piston accumulator 13 is
A is lowered, high-pressure oil of 135 kg/crM acts on the head end side of the injection cylinder 1, and the injection cylinder 1 moves forward at high speed to inject the molten metal into the mold cavity by a plunger (not shown). This operation is repeated to obtain a large number of molded products.

As the operation continues, if the temperature of the outside air changes from the standard temperature of 20°C, the operation shown in FIG. 2 is performed.

That is, first, in the temperature comparison section 30, step 31
A standard temperature of 20° C. is set on a temperature setting device, etc., and this set value is converted into an amount of electricity in step 32 and further inputted to the comparison section in step 35. on the other hand,
In step 33, the outside air temperature is measured using a thermometer with a contact point, etc., and this measured value is converted into an amount of electricity in step 34 and sent to the comparison section in step 35. As a result of the comparison in step 35, the temperature of the outside air becomes, for example, 40°C, which is higher than the standard temperature of 20°C. adjusted to the gas pressure, i.e. in this case:
The gas pressure in the main bottle 11 exceeds the initially set standard gas pressure of 135 kg/c [for example, 144 kg/c].
c+fl, and the gas pressure in the sub-bottle 12 has risen to, for example, 117 kg/c+11, exceeding the initial set pressure of 110 kg/ci. In addition, the gas pressure P of the main bottle 11 when this outside temperature changes
, and the gas pressure P2 of the sub-bottle 12 is also the standard temperature. , outside temperature, main bottle 11 and sub-bottle I2
If the initial gas pressures of are Pol and PO2, respectively, it is expressed by the following equation.

PI(PZ)=PO1(P(12)
t)/(273+t fi)) −−−−−−・−・・
- First, in step 41, hydraulic pressure is supplied from the hydraulic pump 19 to the piston accumulator 13 to raise the Vislon 13a, and in step 42, the piston 13a reaches its upper limit, and in step 43, the second opening/closing, which is normally closed, is Open valve 15 (.

Note that the first on-off valve 14 is always open. By this step 43, the pressure of the main bottle 11 is increased to the sub-bottle 1.
2, and the second on-off valve 15 is closed when the gas pressure in the main bottle 11 and sub-bottle 12 reaches the standard gas pressure of 135 kg/cml.

Note that the pressure P3 at this time can be confirmed by the following equation, assuming that the volume of the main bottle 11 is Vl, the volume of the sub-bottle 12 is V2, and ignoring the piping volume.

P:+ = ((P+ xv+)+(Pi XVz))
/(L +Vz) ・−・−・−■ It is confirmed in step 44 that the pressure has reached this 135 kg/ctA. This confirmation is performed by a separately provided main bottle gas pressure comparison section 100.

In this main bottle gas pressure comparing section 100, in step 101, a standard gas pressure in the main bottle 11 of 135 kg/CI6 is set using, for example, a pressure setting device.

This is then converted into an electrical quantity in step 102 and sent to step 103. On the other hand, in step 104, the gas pressure in the main bottle 11 is measured with a pressure gauge, and in step 105 this is converted into an amount of electricity, which is further compared with the standard gas pressure in step 103. The gas pressure measurement value in the main bottle 11 in step 104 continues to be measured even when the gas pressure in the main bottle 11 is released and falling due to the operation in step 43,
When the gas pressure in the main bottle 11 finally matches the standard gas pressure, the confirmation in step 44 is performed. When the confirmation in step 44 is performed, step 45
The second on-off valve 15 is closed, and preparation for injection is completed (step 46).

From then on, the gas in the main bottle 11 of the accumulator is maintained at a standard gas pressure of 135 kg/C11 l during operation.

Next, when the outside air temperature becomes lower than the standard temperature of 20°C from the above state, for example, when the outside air temperature becomes 5°C, this is determined by the air temperature comparison section 30, and step 35 is performed. The signal from the comparison section is sent to the main bottle gas pressure increase operation section in step 50, where the gas pressure in the main bottle 11 is adjusted to the standard gas pressure. In this case, for example, when the outside temperature reaches 5°C, the gas pressure in the main bottle 11 increases to 135k, which was adjusted in the above operation.
g/crM has decreased to, for example, 128 kg/Cll1, and the gas pressure in the sub-bottle 12 has also decreased from the pressure of 135 kg/cIII in the above operation to, for example, 128 kg/crM.
kg/CI! I (this case is also the same as the formula (2) above), and it is necessary to adjust and change the gas pressure in the main bottle 11 to the standard gas pressure of 135 kg/d.

Therefore, first, upon receiving the signal from step 35, the first on-off valve 14 is closed in step 51, and the second on-off valve 15 is opened. Next, in step 52, the third on-off valve 16 is opened, and the hydraulic pressure in the piston accumulator 13 is released to the tank 4.
The piston 13a is lowered. Through the operations up to step 52, the gas pressures in the piston accumulator 13 and the sub-bottle 12 both decrease to, for example, 103 kg/Cl11 while the piston 13a is descending.

In addition, the pressure P at this time is the gas pressure of the piston accumulator 13 and the sub-bottle 12 before operation P4(" 1
28 kg/cbo), piston accumulator 13
If the volume of is 3 and the volume of the piping is ignored, it can be expressed by the following formula.

Ps = (P4 XV2)/(V2 +V3)'-'
----0 Next, in this state, the third on-off valve 16 and the second on-off valve 15 are closed in step 53, and the first on-off valve 14 is opened in step 54. Then, in step 55, the hydraulic pump 19
When hydraulic pressure is supplied to the piston accumulator 13 to raise the piston 13a, the gas pressure inside the main bottle 11 increases to reach the standard gas pressure of 135 kg/C11l. Note that the value P6 at this time can also be confirmed from the following equation.

P6 = ((P4 XVI)+, (Ps XV:l)
)/V+・−・−■ Confirmation that this standard gas pressure has reached 135 kg/crfl is performed in step 10 of the main bottle gas pressure comparison section 100.
Step 56 is performed in response to the comparison value of 3. In this state, injection preparation is completed in step 57, and operation is resumed thereafter. Note that the boosting operations in steps 51 to 55 are as follows:
For example, depending on the initial setting pressure of the sub-bottle 12, the volume of the sub-bottle 12, the volume of the piston accumulator 13, etc., the process is not limited to once, but may be repeated multiple times.

The filling pressure adjustment of the accumulator explained above is performed by the first
．． By using the on-off valves 14, 15, and 16 of 2.3 as electromagnetic on-off valves, all operations can be performed automatically.

In addition, in the flowchart of FIG. 2 explained above,
Instead of the temperature comparison section 300, this is set as the main bottle gas pressure comparison section, step 31 is set as "standard gas pressure setting in main bottle", step 33 is set as "gas pressure measurement in main bottle", and the main bottle 11 is set as "standard gas pressure setting in main bottle". The gas pressure inside the main bottle 11 is the standard gas pressure of 135 kg/c+.
If it becomes larger than fl, perform the main bottle gas pressure reduction step 40, and conversely, the main bottle 11
If the gas pressure in the bottle becomes lower than the standard gas pressure of 135kg/c+fl, step 5 to increase the main bottle gas pressure.
0 operation may be performed to adjust the filling pressure of the accumulator 11.

Also, instead of steps 51 to 53 in the main bottle gas pressure increasing step 50 in FIG. 2, "the first on-off valve 14 is closed" (step 5) as shown in FIG.
1a), "Open the third on-off valve 16, drain the hydraulic pressure in the piston accumulator 13 to the tank 4, and lower the piston 13a" (step 52a), "Open the second on-off valve 15" (step 53a), [ "When the gas pressure in the piston accumulator 13 reaches a predetermined pressure PA kg/cni, close the second on-off valve 15" (step 54a),
It is also possible to do this.

Note that step 54a in FIG.
The second on-off valve 15 may be closed when the

[Effects of the Invention] As described in detail above, the present invention has the configuration as described in the claims, so that the gas pressure in the main bottle of the accumulator can be easily adjusted to a predetermined level in response to changes in outside temperature. Since the gas pressure can be adjusted and changed to the standard gas pressure, the injection molding apparatus can always be operated at a constant injection pressure and injection speed, and molded products with stable quality can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are an injection circuit diagram and a flowchart of an injection molding apparatus for explaining an accumulator filling pressure adjustment method of an injection molding apparatus according to an embodiment of the present invention, respectively, and FIG. 3 is a flowchart of an injection molding apparatus according to another embodiment of the present invention. 3 is a flowchart showing an example. 1... Injection cylinder, 2.5... Solenoid switching valve, 4...
...Tank, 11...Main bottle, 12...Sub bottle, 13...Piston accumulator, 13a...
・・Piston, 14...first on-off valve, 15...
Second on-off valve, 16... Third on-off valve, 19... Pump, 30... Temperature comparison section, 40... Main bottle gas pressure reduction operation section, 50... Main bottle gas pressure Pressure increase operation section, 100... Main bottle internal gas pressure comparison section. Patent applicant: Ube Industries, Ltd.

Claims (1)

[Claims] A main bottle filled with gas is connected to an upper end of a piston accumulator whose lower end is connected to an injection cylinder and which is connected to a tank via a normally closed third on-off valve. connected via an open first on-off valve, and
Using an accumulator device that connects a sub-bottle filled with gas via a second on-off valve that is normally closed, when the outside air is at a predetermined standard temperature, the gas pressure in the sub-bottle is lower than the gas pressure in the main bottle. When the outside air temperature becomes higher than the specified standard temperature and the gas pressure inside the main bottle becomes higher than the specified standard gas pressure, open the second on-off valve and open the main bottle. The gas pressure inside the bottle is released into the sub-bottle, and when the gas pressure inside the main bottle reaches the specified standard pressure, the second on-off valve is closed. When the gas pressure in the bottle becomes lower than a predetermined standard gas pressure, the first on-off valve is closed, the second on-off valve and the third on-off valve are opened to lower the piston in the piston accumulator, and then The third on-off valve and the second on-off valve were closed, and the first on-off valve was opened to raise the piston in the piston accumulator and adjust the gas pressure in the main bottle to a predetermined standard pressure. Accumulator filling pressure adjustment method for injection molding equipment.