JPH06182831A - Injector in injection molding machine - Google Patents

Abstract

PURPOSE:To obtain a compact injector in which a sliding load is small and a pressure can be changed over during injection by a method wherein two accumulators of different pressurizing capacities are provided on an injection cylinder. CONSTITUTION:As an injection cylinder 9, a double-rod differential pressure cylinder is used, which is so constructed as to have a difference in effective cross sectional area between piston bodies of a progressing hydraulic chamber 10 and a retracting hydraulic chamber 11. A pair of accumulators 13, 14 are provided upward and downward of each of the injection cylinders 9. In the accumulator 13 or 14, a pressurizing piston rod 13b or 14b is pressed forward by a travel block 8 to pressurize and deliver oil when the oil is supplied to an ACC chamber 13a or 14a. In addition, the pressurizing capacity of the accumulator 14 is set larger than that of the accumulator 13. In this manner, an injection speed condition and an injection pressure condition can be selected out of eight patterns of combination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device of an injection molding machine, and more particularly, to an injection hydraulic cylinder (hereinafter referred to as an injection cylinder) that is constantly operating and a plurality of accumulators (ACC) that selectively perform a boosting operation. The invention relates to an injection device of an injection molding machine in which the injection speed condition and the injection pressure condition can be variably set by appropriately combining

[0002]

2. Description of the Related Art As is well known, injection speed and injection pressure, which are important for injection molding, are determined by the driving horsepower of a hydraulic pump of a machine (injection molding machine). That is, the driving horsepower, the injection speed and the injection pressure of the hydraulic pump are as follows: Driving horsepower of the hydraulic pump = injection speed × injection pressure / 61
There is a relationship of 2, and the product of the injection speed and the injection pressure is proportional to the driving horsepower of the hydraulic pump. Therefore, the condition range of the injection speed and the injection pressure (capacity range of the injection speed and the injection pressure) that can be satisfied by one machine is naturally limited.

However, there are a wide variety of injection molding targets, and a wide range of molding conditions are required depending on the type of resin, mold shape, etc. As described above, one machine can handle a wide range of molding conditions. Since it is not possible to cover all of them, it is inevitable to purchase multiple types of machines depending on the application. For this reason, the demand for an injection molding machine that can satisfy a wide range of molding conditions with one machine has recently been increasing.

Therefore, a plurality of injection cylinders are mounted on one machine (for example, a plurality of injection cylinders are arranged in a straight line or a plurality of injection cylinders are arranged side by side symmetrically), and required molding conditions. In recent years, an injection molding machine is being developed in which a combination of injection cylinders to be used is selected to set the conditions of injection speed and injection pressure to predetermined ones.

[0005]

However, in the injection molding machine having a plurality of injection cylinders as described above, the mechanism is such that the piston rod of each injection cylinder moves forward and backward integrally with the screw. Not used because it does not exist (pressure oil is not supplied during the injection process)
When the injection cylinder is set, the unused injection cylinder also idles, which causes a problem that sliding resistance increases and energy loss increases.

Depending on the molding conditions, the filling process (1
In the injection molding machine equipped with multiple injection cylinders, a low-pressure high-speed is often required in the next injection stroke, and a high-pressure low-speed is often required in the pressure-holding stroke. Since the high-pressure injection cylinder is not used, the pressure cannot be switched during the injection, and there is a problem that it is not possible to simultaneously satisfy both the low pressure and high speed of the filling process and the high pressure of the pressure holding process.

Furthermore, it has been pointed out that the mounting of a plurality of injection cylinders complicates the shape of the machine and increases the size of the machine.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art,
The purpose is to have a wide range of conditions of injection speed and injection pressure, less sliding load compared to the above-mentioned conventional technology, and the pressure can be switched during injection, which is relatively compact. An object is to provide an injection device of an injection molding machine that can be configured.

[0009]

In order to achieve the above object, an injection device of an injection molding machine according to the present invention is connected to a piston rod of an injection cylinder and also connected to a rear end portion of a screw. Oil can be selectively supplied to the moving block that moves forward and backward together, and while the oil is supplied, the boosting operation is performed via the moving block that moves forward by the driving force of the injection cylinder.
For example, two accumulators having different boosting capacities are provided to supply the boosted oil to the advancing oil chamber of the injection cylinder. By selecting whether or not each accumulator is boosted, the injection speed condition and the injection speed are controlled. It is configured to variably set the pressure condition.

Further, in the present invention, preferably, the injection cylinder is a differential pressure cylinder, and a normal speed operation mode in which only oil from the hydraulic pump is sent to the forward oil chamber,
It is possible to select a high-speed operation mode in which the oil from the hydraulic pump and the oil from the reverse oil chamber are sent together to the forward oil chamber,
Composed.

[0011]

In the injection stroke, the injection cylinder is always driven, and the moving block and the screw advance together with the piston rod of the injection cylinder. Two accumulators having different boosting capacities are provided in the vicinity of this injection cylinder, and the accumulator to be used (pressurized) is selected according to the required molding conditions, and the accumulator chamber of the accumulator to be used (hereinafter,
Oil is supplied to the ACC chamber). In the accumulator to which oil is supplied, the boosting piston rod retracts, which causes the boosting piston rod to come into contact with the moving block that is advanced by the driving force of the injection cylinder, and is pushed and advanced by the forward force of the moving block. Then, the pressure of the oil in the ACC chamber is increased, and this increased pressure oil is sent to the forward oil chamber of the injection cylinder. Therefore, the oil from the hydraulic pump and the oil from the accumulator are supplied to the advancing oil chamber of the injection cylinder, and the advancing force is small compared to the case where only the injection cylinder is used without using the accumulator ( In other words, the resin pressure is low) but high speed is achieved.

Further, the injection cylinder is used as a differential pressure cylinder, and a normal speed operation mode in which only the oil from the hydraulic pump is sent to the forward oil chamber, and the oil from the hydraulic pump and the backward oil chamber are supplied to the forward oil chamber. A high-speed operation mode in which oil and oil are sent together can be selected. When the high-speed operation mode is selected, oil (excess oil) from the reverse oil chamber is sent to the forward oil chamber by a differential pressure circuit, so-called regeneration. Because it does the action
Compared to the normal speed operation mode, the forward force is small (that is, the resin pressure is low), but high speed is achieved.

Therefore, the selection of whether to use one or two accumulators having different boosting capacities or not to be used at all and the selection of the normal speed operation mode and the high speed operation mode of the injection cylinder described above are combined. This makes it possible to set eight injection speed conditions and injection pressure conditions.

By doing so, the accumulator that is not used is in a state where the mechanical contact with the member that is driven forward by the injection cylinder is cut off (the edge is cut).
The sliding load can be reduced as much as possible, and energy loss can be suppressed. Further, since the injection cylinder is always operating in the injection stroke, it is possible to easily switch from low pressure to high pressure by, for example, relieving oil from the ACC chamber to the tank during injection. Since the accumulator can be made relatively small and simple as compared with the configuration in which a large number of injection cylinders are mounted, the entire machine can be made relatively compact.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a main part of an injection device of an injection molding machine according to this embodiment, and FIG. 2 is a front view of a main part of the injection device of an injection molding machine according to this embodiment.

In FIGS. 1 and 2, 1 is a holding block that is fixedly arranged during a continuous molding operation, 2 is a heating cylinder whose base end side is held by the holding block 1, and 3 is the heating cylinder 2. A nozzle mounted on the tip side, 4 is a screw arranged so as to be able to rotate and move forward and backward in the heating cylinder 2, and 5 is a raw material resin on the base end side of the heating cylinder 2 (the rear end side of the screw 4). It is a hopper for charging and supplying.

Reference numeral 6 denotes a screw rotation driving motor (electric motor or hydraulic motor) which is connected to the rear end side of the screw 4 via a rotation connecting member 7, and is used during the kneading / plasticizing / measuring process. The rotation drives the screw 4 to rotate. Reference numeral 8 denotes a moving block that holds the rotary connecting member 7 rotatably via bearings, and moves forward and backward together with the screw 4 and the motor 6.

Reference numeral 9 denotes an injection cylinder (hydraulic cylinder) which is a drive source for injection, and in the present embodiment, a pair is provided symmetrically with respect to the screw 4 when viewed in plan.
The two injection cylinders 9 have the same structure. The injection cylinder 9 is a double rod type differential pressure cylinder, and includes a forward oil chamber 10 and a reverse oil chamber 11
There is a difference in the effective cross-sectional area of the piston body in the backward movement oil chamber 11 in FIGS. 12 is a double rod type piston rod of the injection cylinder 9 (hereinafter referred to as piston rod 12
Is referred to as "), and the tip side of the rod portion on the small diameter side of the piston rod 12 (advancing oil chamber 10 side) is the moving block 8.
Is attached to. Therefore, when the piston rod 12 of the injection cylinder 9 moves forward and backward, the moving block 8 also moves forward and backward together with this.

Reference numeral 13 is an accumulator (A), and 14 is an accumulator (B). In this embodiment, one pair is provided above and below each injection cylinder 9 when viewed in the horizontal direction. The accumulator (A) 13 has A
A pressure increasing piston rod 13b is provided which is capable of moving forward and backward in a CC (accumulator) chamber 13a. One end side of this pressure increasing piston rod 13b projects outward from the ACC chamber 13a and faces the moving block 8. ing.
In addition, the accumulator (B) 14 also has an ACC chamber 14
Boosting piston rod 14b capable of moving forward and backward in a
Is provided, and one end side of the boosting piston rod 14b also projects outward from the ACC chamber 14a and faces the moving block 8. The above-mentioned accumulators (A), (B) 13, 14 used in the present invention are different from general accumulators that pressurize oil by high-pressure gas or spring to store and discharge the accumulated oil, in the ACC chamber 13a or 14a. When oil is supplied, the pressure-increasing piston rod 13b or 14b moves the moving block 8 as described later.
The oil is pushed up and moved forward (leftward in the drawing) to pressurize and discharge the oil. In this embodiment, the boosting capability of the accumulator (B) is set larger than the boosting capability of the accumulator (A) 13.

FIG. 3 shows the essential structure of the hydraulic circuit including the injection cylinder 9 and the accumulators (A), (B) 13, 14 (a pair of hydraulic circuits for only one side of the injection cylinder 9 is shown). Shown). In the same 3, 21 is
The switching control valve for controlling the forward movement of the piston rod 12 of the injection cylinder 9 is selected in the neutral position in the figure, but by switching the switching control valve 21 to the left position in the figure, a hydraulic pump (not shown) is operated. Oil is sent into the forward oil chamber 10 of the injection cylinder 9. Reference numeral 22 denotes a switching control valve for differential pressure operation control, which is arranged in a pipe line between the backward oil chamber 11 and the forward oil chamber 10 of the injection cylinder 9.
Although the neutral position is selected in the same figure, by switching the switching control valve 22 to the left position in the drawing, the forward movement oil chamber 10 and the reverse movement oil chamber 11 are brought into a connected state, and the forward movement oil chamber 10 Oil can flow from the reverse drive oil chamber 11 to the reverse drive oil chamber 11 and vice versa. The changeover control valve 22 is used in the known kneading / plasticizing / measuring process (the charging process) in which the screw 4 is retracted by the stored molten resin pressure, and the injection differential pressure of the injection cylinder 9 described later. During the operation (acceleration operation or high speed operation), the forward oil chamber 10 and the reverse oil chamber 11 are switched to the left position in the drawing (at least at this time, the forward oil chamber 10 and the reverse oil chamber 11 are not oiled). Will be in the state).

Reference numeral 23 is a switching control valve for the accumulator (A) 13. The neutral position is selected in FIG. 3, but by switching the switching control valve 23 to the right position in the figure, a hydraulic pump (not shown) is operated. Oil is replenished in the ACC chamber 13a of the accumulator (A) 13, and the boosting piston rod 13b projects toward the moving block 8 side. Also, by switching the switching control valve 23 to the left position in the drawing, oil is returned from the ACC chamber 13a to the tank. Furthermore, when the switching control valve 23 is switched to the neutral position and the injection stroke is executed in a state where the ACC chamber 13a is filled with oil, the moving block 8 that moves forward integrally with the piston rod 12 of the injection cylinder 9 boosts the pressure. The piston rod 13b moves forward, and the ACC chamber 13
The pressure of the oil in a is increased, whereby the pressurized oil in the ACC chamber 13a is sent to the advancing oil chamber 10 of the injection cylinder 9.

Reference numeral 24 is a switching control valve for the accumulator (B) 14. The neutral position is selected in FIG. 3, but by switching the switching control valve 24 to the right position in the figure, a hydraulic pump (not shown) is operated. Oil is replenished into the ACC chamber 14a of the accumulator (B) 14, and the boosting piston rod 14b projects toward the moving block 8 side. Also, by switching the switching control valve 24 to the left position in the drawing, oil is returned from the ACC chamber 14a to the tank. Furthermore, when the switching control valve 24 is switched to the neutral position and the injection stroke is executed in a state where the ACC chamber 14a is filled with oil, the moving block 8 that moves forward integrally with the piston rod 12 of the injection cylinder 9 boosts the pressure. The piston rod 14b moves forward, and the ACC chamber 14
The pressure of the oil in a is increased, whereby the pressurized oil in the ACC chamber 14a is sent to the advancing oil chamber 10 of the injection cylinder 9.

Next, the operation of the above configuration will be described with reference to FIGS. 4 to
Corresponds to in each column of FIG.

FIG. 4 shows an accumulator (A),
(B) A state in which only the injection cylinder 9 is operated at normal speed operation without using 13, 14 (that is, the forward movement oil chamber 10 and the reverse movement oil chamber 11 of the injection cylinder 9 are cut off without communicating with each other). In this state, an operation state in which oil is sent to the forward movement oil chamber 10 is shown. In the operation mode of FIG. 4,
The piston rod 12 of the injection cylinder 9 is the forward oil chamber 1
It moves forward by the force of the pressure oil sent directly from the hydraulic pump to 0,
In the operation mode of the present embodiment, the highest injection pressure (highest resin pressure) is realized, even at the lowest speed. In the column of FIG. 5, the resin pressure (corresponding to the injection pressure) of the entire machine and the relative value of the injection speed at this time are shown. The injection speed in this case is the same as the conventional standard machine before the machine in which the operations of a plurality of injection cylinders are selectively combined, and the injection speed is 100%.

FIG. 4 shows the accumulator (A) 13
Is used and the injection cylinder 9 is operated at the normal speed operation. In this case, as the piston rod 12 of the injection cylinder 9 advances, the accumulator (A)
The pressure-increasing piston rod 13b of 13 moves forward by the moving block 8, and the ACC of the accumulator (A) 13 moves.
The pressure of the oil in the chamber 13a is increased, which causes the ACC chamber 13a
The oil inside is sent to the advancing oil chamber 10 of the injection cylinder 9 in a form of being added to the oil from the hydraulic pump. Therefore, since the oil in the ACC chamber 13a is sent to the advancing oil chamber 10 by the propulsive force of the piston rod 12 of the injection cylinder 9, the injection speed becomes higher and the resin pressure becomes lower than in FIG.

FIG. 4 shows the accumulator (B) 14
Is used and the injection cylinder 9 is operated at the normal speed operation. In this case, as the piston rod 12 of the injection cylinder 9 advances, the accumulator (B)
14 is moved forward by the moving block 8 and the ACC of the accumulator (B) 14 is moved.
The pressure of the oil in the chamber 14a is increased, which causes the ACC chamber 14a
The oil inside is sent to the advancing oil chamber 10 of the injection cylinder 9 in a form of being added to the oil from the hydraulic pump. Since the capacity of the accumulator (B) 14 is higher than the capacity of the accumulator (A) 13, the injection speed becomes higher and the resin pressure becomes lower than in FIG.

FIG. 4 shows the accumulator (A) 13
And the accumulator (B) 14 are used and the injection cylinder 9 is operated at the normal speed operation. In this case, the piston rod 12 of the injection cylinder 9
In accordance with the forward movement, the pressure increasing piston rod 13b of the accumulator (A) 13 and the pressure increasing piston rod 14b of the accumulator (B) 14 are advanced by the moving block 8 to increase the pressure of the oil in the ACC chamber 13a and the ACC chamber 14a. As a result, the oil in the ACC chambers 13a, 14a is fed to the forward oil chamber 10 of the injection cylinder 9 in a form of being added to the oil from the hydraulic pump. Therefore, A is generated by the propulsive force of the piston rod 12 of the injection cylinder 9.
Since the oil in the CC chambers 13a and 14a is sent to the forward oil chamber 10, the injection speed becomes higher and the resin pressure becomes lower than in FIG.

FIG. 4 shows the accumulator (A),
(B) A state in which only the injection cylinder 9 is operated by acceleration operation (differential pressure operation) without using 13, 14 (that is, the forward movement oil chamber 10 and the reverse movement oil chamber 11 of the injection cylinder 9 are communicated with each other). The operating state in which the differential pressure circuit is formed is shown. In the operation mode of FIG. 4, the piston rod 12 of the injection cylinder 9 receives the forward force by the force of the pressure oil directly sent from the hydraulic pump to the forward oil chamber 10, and the forward oil chamber 10 and the reverse In accordance with the difference in cross-sectional area with the oil chamber 11, the forward force by the oil discharged from the reverse oil chamber 11 and sent to the forward oil chamber 10 via the differential pressure circuit (regeneration circuit) is also received. Therefore, as a matter of course, the injection speed becomes faster and the resin pressure becomes lower than that in FIG. 4, and in this embodiment, in the case of the operation mode of FIG. 4, the injection speed becomes faster than that in FIG. It is configured to have a low pressure.

FIG. 4 shows the accumulator (A) 13
Is used and the injection cylinder 9 is operated by acceleration operation (differential pressure operation). In this case, the differential pressure operation of the injection cylinder 9 and the operation of the accumulator (A) 13 in the case of FIG. 4 are combined, and the injection speed becomes higher than that of FIG. The pressure becomes low.

FIG. 4 shows the accumulator (B) 14
Is used and the injection cylinder 9 is operated by acceleration operation (differential pressure operation). In this case, the differential pressure operation of the injection cylinder 9 and the operation of the accumulator (B) 14 in the case of FIG. 4 are combined,
The injection speed becomes higher and the resin pressure becomes lower than that in FIG.

FIG. 4 shows the accumulator (A) 13
Both of the accumulator (B) 14 and the accumulator (B) 14 are used, and the injection cylinder 9 is operated in an acceleration operation (differential pressure operation). In this case, the differential pressure operation of the injection cylinder 9 and the accumulators (A) and (B) 1 of FIG.
The operation is combined with the operations of 3 and 14, and the injection speed becomes higher and the resin pressure becomes lower than that in FIG.

As described above, in the present embodiment, selection of whether to use one or two accumulators (A) and (B) 13, 14 or not to use them at all,
By combining the selection of the normal speed operation mode and the high speed operation mode of the injection cylinder 9 described above, eight injection speed conditions and injection pressure conditions can be set.

Further, by doing so, the unused accumulator (A) 13 or (B) 14 is cut off from the mechanical contact with the moving block 8 driven forward by the injection cylinder 9 (the edge is cut off). In this case, the sliding load can be reduced as much as possible and energy loss can be suppressed.

Since the injection cylinder 9 is constantly operating in the injection stroke, during the injection, for example, the ACC chamber 13a,
By relieving the oil from 14a to the tank,
It is easy to switch from low pressure to high pressure.

Since the accumulator of this embodiment can be made relatively small and simple as compared with the conventional structure in which a large number of injection cylinders are mounted, the entire machine can be made relatively compact.

The present invention has been described above with reference to the illustrated embodiments, but it goes without saying that various modifications can be made by those skilled in the art without departing from the spirit of the present invention.
If three or more accumulators are attached to the injection cylinder, the injection speed and injection pressure can be selected and set more finely. Further, in the above-described embodiment, an example in which a pair of injection cylinders is mounted on the machine is shown, but a single injection cylinder may be mounted on the machine.

[0037]

As described above, according to the present invention, for example, two accumulators having different boosting capacities are attached to the injection cylinder and either one or two accumulators are used, or no accumulator is used at all. And the selection of
By combining the selection of the normal speed operation mode and the high speed operation mode of the injection cylinder described above, it is possible to set eight kinds of injection speed conditions and injection pressure conditions.

Further, since the accumulator which is not used is in a state where the mechanical contact with the moving block driven forward by the injection cylinder is cut off (the edge is cut), the sliding load can be reduced as much as possible, and the energy consumption can be reduced. It is possible to suppress loss. Further, since the injection cylinder is always operating in the injection stroke, it is possible to easily switch from low pressure to high pressure by, for example, relieving oil from the ACC chamber to the tank during injection. Since the accumulator can be made relatively small and simple as compared with the configuration in which a large number of injection cylinders are mounted, the entire machine can be made relatively compact. Play.

[Brief description of drawings]

FIG. 1 is a fragmentary plan view of an injection device of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a fragmentary front view of an injection device of an injection molding machine according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a main part hydraulic circuit used in an injection device of an injection molding machine according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing eight types of operation modes realized by one embodiment of the present invention.

5 is an explanatory diagram showing a relationship between a combination of operations of an injection cylinder and two accumulators corresponding to FIG. 4, a resin pressure, and an injection speed.

[Explanation of symbols]

 2 Heating Cylinder 4 Screw 8 Moving Block 9 Injection Cylinder 10 Forward Oil Chamber 11 Backward Oil Chamber 12 Piston Rod 13 Accumulator (A) 13a ACC (Accumulator) Chamber 13b Boosting Piston Rod 14 Accumulator (B) 14a ACC (Accumulator) Chamber 14b Booster piston rod

Claims (4)

[Claims] 1. An injection device of an injection molding machine for injecting a molten resin into a mold by advancing a screw in a heating cylinder, which is connected to a piston rod of an injection hydraulic cylinder and has a rear end portion of the screw. And a moving block that moves forward and backward integrally with the screw, and is capable of selectively supplying oil, and in the state where oil is supplied, pressurization is performed via the moving block that moves forward by the driving force of the injection hydraulic cylinder. And at least one accumulator for performing the operation and supplying the pressurized oil to the advancing oil chamber of the injection hydraulic cylinder,
An injection apparatus of an injection molding machine, wherein an injection speed condition and an injection pressure condition can be variably set by selecting whether or not the accumulator is boosted. 2. The injection molding machine according to claim 1, wherein a plurality of the accumulators are provided for the injection hydraulic cylinder, and whether or not each accumulator is operated to perform a boosting operation can be individually selected. Injection device. 3. The injection device of an injection molding machine according to claim 2, wherein the plurality of accumulators have different boosting capabilities. 4. The injection hydraulic cylinder according to claim 1, 2 or 3, wherein the injection hydraulic cylinder is a differential pressure cylinder, and a normal speed operation mode in which only the oil from the hydraulic pump is sent to the forward oil chamber, and the forward oil chamber. There is a high-speed operation mode in which the oil from the hydraulic pump and the oil from the reverse oil chamber are sent together.
An injection device of an injection molding machine characterized by being selectable.