JP3310771B2 - Injection equipment of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device for an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, there are various devices for molding a product by injecting a synthetic resin at a high pressure. For example, as shown in FIG. By rotating the screw 11, the synthetic resin is melted and sent to the tip of the barrel 13, and the screw 11 is retracted as the molten resin is stored at the tip of the barrel 13, and is provided integrally with the fixed portion of the barrel 13 for injection. There is a device for injecting molten resin from a nozzle into a mold by advancing a screw 11 by a hydraulic cylinder 20.

The hydraulic circuit of the injection device 10 adjusts the pressure oil from a pump 31 in a hydraulic power source circuit 30 by a relief valve 32 and sends it to a hydraulic cylinder 20 through an injection control switching valve 35 to measure the molten resin. In many cases, a relief valve 37 serving as a return oil passage from the piston rear chamber 23 is provided, and a relief valve control circuit 38 for adjusting the opening pressure of the relief valve 37 is provided.
Is composed of a pump 31, a relief valve 32, an accumulator 33, and the like. Many of the pumps have a constant discharge pressure and a constant discharge capacity. Are provided to make the discharge flow rate variable.

[0004] The hydraulic power supply circuit 30 is also used for other hydraulic devices such as clamping of a mold, so that the pump 31 is used efficiently.

[0005]

Today, the injection pressure and the injection speed must be changed depending on the type of synthetic resin to be injected and the shape and size of the product formed in the mold. It is performed by changing the discharge pressure and the discharge flow rate from the hydraulic pressure source circuit by a relief valve, a flow control valve, and the like. By the way, recently, as the kinds of synthetic resins have been diversified, the production of small lots and many kinds of products has increased, and the frequency of adjustment of the injection pressure has to be increased and the adjustment width has to be increased.

However, increasing the adjustment range of the hydraulic pressure in the hydraulic power source circuit has the disadvantage that the circuit configuration is complicated and the cost is high.

SUMMARY OF THE INVENTION The present invention, which focuses on the above-mentioned conventional problems, provides an injection apparatus capable of easily changing the injection pressure by improving an injection hydraulic cylinder.

[0008]

According to a first aspect of the present invention, a piston or ram is moved forward by sending pressure oil from a hydraulic power supply circuit to a hydraulic cylinder. An injection device for injecting a synthetic resin, wherein a plurality of pairs of the hydraulic cylinders that form a point-symmetric pair are provided on both sides of a barrel that constitutes the injection device, and a sectional area of the ram and the piston is defined as an effective sectional area. Value and the effective area value of each hydraulic cylinder is 25
%, 30%, and 45%. Also, the second
In the invention of the present invention, rams and pistons having different effective cross-sectional areas are provided so as to be able to move forward and backward in hydraulic cylinders having different diameters, and a seven-stage cylinder output is obtained by combining a plurality of pairs of hydraulic cylinders forming a point-symmetric pair on both sides of the barrel. It was configured to obtain.

[0009]

According to the present invention, three pairs of hydraulic cylinders are provided on both sides of the barrel in a point-symmetrical manner, and the ratio of the total value of the effective cross-sectional areas of the ram and piston to the effective cross-sectional area of each hydraulic cylinder is provided. Are set to 25%, 30% and 45%, hydraulic cylinders are appropriately selected and used, and three pairs of hydraulic cylinders are provided with independent opening / closing valves in piston rear chambers or supply / discharge chambers. In the remaining hydraulic cylinders in which the pressure oil does not act on the effective sectional area, the tank or piston is recirculated from the front chamber to the rear chamber via an opening valve provided independently for each hydraulic cylinder, and the injection pressure and injection speed in seven stages are increased. Obtainable.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a synthetic resin injection apparatus according to the present invention.

FIG. 1 is a diagram showing an example of a hydraulic circuit of the injection device according to the present invention, FIG. 2 is a cross-sectional view of the injection device according to the present invention, and FIG. 3 is a vertical cross-sectional view as viewed from A to A in FIG. .

An embodiment of the present invention, as shown in FIG.
Plural pairs to move 1 forward and backward (three-stage type in this embodiment)
The injection device 10 is provided with the hydraulic cylinders 60, 70, and 80 on both sides of the barrel 13 in the fixed portion of the barrel 13.

The hydraulic cylinders 60, 70, 80 are shown in FIG.
As shown in the figure, the barrel 13 is configured to form a point-symmetric pair on both sides. The hydraulic cylinders 70 and 80 are integrated with a piston slidable back and forth in the hydraulic cylinders 70 and 80, and the front covers 77 and 87 and the rear cover 7 as lids that constitute the hydraulic cylinders 70 and 80 are provided.
6 and 86, and piston rods 78 and 88 passing through the front covers 77 and 87 and the rear covers 76 and 86, respectively.
Are fixed before and after each of the pistons 75 and 85.

The rear ends of the piston rods 78 and 88 are connected to a movable base 17 for moving the screw 11 back and forth. Although the piston rods 78 and 88 have the same diameter before and after each of the pistons 75 and 85, the piston rods 78 and 88 have a diameter larger than that of the piston rod 78. I have.

As shown in FIG. 3, a front cover 6 is provided on a cylinder body 61 having a U-shaped cross section to constitute the hydraulic cylinder 60.
7, a ram 64 which can move forward and backward is provided, and together with the front ends of the piston rods 78 and 88, the connecting plate 1 is provided.
8 is connected.

The hydraulic circuit of the injection device 10 includes an oil pressure source circuit 30 and an injection control switching valve 35 of a 4-port 3-position switching valve.
, The supply / discharge chamber 62 of the hydraulic cylinder 60 and the hydraulic cylinders 70, 80 via opening / closing valves 60A, 70A, 80A arranged independently of the hydraulic cylinders 60, 70, 80, respectively.
The pressure oil can be sent to the piston rear chambers 74 and 84 of this embodiment.

In the present invention, each of the on-off valves 60A, 70
Opening valves 60B, 70B, 80B are provided in association with A, 80A. By selectively operating the release valves 60B, 70B, and 80B, the constant pressure and constant flow pressure oil supplied from the hydraulic power source circuit 30 are supplied through the injection control switching valve 35 to the supply / discharge chamber 62 and the piston rear chamber 74. , 84 so that a seven-stage speed switching adjustment described later can be performed.

Each of these on-off valves 60A, 70A, 80A
And the open / close valves 60B, 70B, 80B are electromagnetic open / close switching valves 60Aa, 70Aa, 80Aa, and 60B, respectively.
a, 70Ba, 80Ba and cartridge valves 60Ab, 7
It is composed of 0 Ab, 80 Ab, 60 Bb, 70 Bb, and 80 Bb.

Each of the electromagnetic open / close switching valves 60Aa, 70A
a, 80Aa, 60Ba, 70Ba, and 80Ba are excited to release the pressure oil from the pilot pressure source 40 to each cartridge valve 6
0 Ab, 70 Ab, 80 Ab, 60 Bb, 70 Bb, 8
0Bb, each cartridge valve 60Ab, 70A
b, 80Ab, 60Bb, 70Bb, 80Bb can be reliably closed.

A state in which no pilot pressure is applied, that is, so-called electromagnetic on / off switching valves 60Aa, 70Aa, 80Aa are turned on.
The cartridge valves 60Ab, 70Ab, 80
Ab is free to open, and the pressure oil from the hydraulic power supply circuit 30 passes through the injection control switching valve 35 and the cartridge valves 60Ab, 7A.
The supply / discharge chamber 62 and the piston rear chamber 7 via 0 Ab and 80 Ab
4, 84 are communicated.

An O-ring 90 for preventing leakage of pressurized oil is provided at a sliding portion and an abutting portion of each component constituting each of the hydraulic cylinders 60, 70, 80.

Reference numeral 92 denotes a relief valve. When the screw 11 moves forward and backward, the solenoid valve b of the back pressure relief valve 94 is set to O.
When N-OFF is performed, pressure oil is supplied to and discharged from the supply / discharge chamber 62 and the piston rear chambers 74 and 84. Reference numeral 96 denotes a hydraulic motor, and a part of the pressure oil from the hydraulic power source circuit 30 is supplied to the hydraulic motor 96 through a pipe (not shown) to be driven to rotate, and the screw 11 is moved backward to melt the molten resin on the head side of the screw 11. It is possible to store while measuring.

The hydraulic cylinders 60, 7 having such a structure
The ram 64 and the pistons 75 and 8 can move forward and backward within 0 and 80.
5, when the ram diameter is d ₁ in the hydraulic cylinder 60, the effective cross-sectional area a _{0 in which} the pressure oil acts on the ram 64 with respect to the cylinder cross-sectional area A, the cylinder diameter is D ₂ in the hydraulic cylinder 70, and the piston diameter is Is d ₂ , the effective sectional area b _{0 of} the hydraulic oil acting on the piston 75 with respect to the cylinder sectional area B, and the cylinder diameter of the hydraulic cylinder 80 is D ₃ , and the piston diameter is d _3. Piston 85
Assuming that the effective cross-sectional area where the pressure oil acts is c ₀ , the sum of the cross-sectional areas of the hydraulic cylinders 60, 70 and 80 is A + B + C = X
Becomes

In this embodiment, the ratio between the total value X of the sectional areas of the hydraulic cylinders 60, 70, 80 and the effective sectional areas a ₀ , b ₀ , c ₀ of the hydraulic cylinders 60, 70, 80 is X
₁ = a ₀ / X = 25%, X ₂ = b ₀ / X = 30%, X ₃
= C ₀ / X = 45%. In comparison of the cross-sectional area of each hydraulic cylinder 60, 70, 80, C>
B> A, and the configuration is such that c ₀ > b ₀ > a _{0 in} comparison of the effective area. The diameter of the piston rod 78 before and after the piston 75 of the hydraulic cylinder 70 and the piston rod 8 before and after the piston 85 of the hydraulic cylinder 80
Each of the eight diameters has the same diameter. Reference numeral 14 denotes a nozzle, 50, 51, and 52 denote tanks, and 55 denotes a hopper.

The hydraulic cylinder 6 constructed as described above
The operation of the injection device 10 having 0, 70, 80 and a hydraulic circuit is as follows.

Here, the state in which the molten resin stored in the head side of the screw 11 by the advance of the screw 11 is injected and filled into the cavity of a mold (not shown) will be described.

First, the solenoid valve b of the back pressure relief valve 94 is turned off, and the electromagnetic open / close switching valves 60Aa, 70Aa,
80Aa ON, 60Ba, 70Ba, 80Ba OF
If F, cartridge valves 60Ab, 70Ab, 80A
b is open and 60Bb, 70Bb and 80Bb are closed. In this state, when pressure oil is supplied from the hydraulic power source circuit 30 to the hydraulic motor 96 via a pipe (not shown), the screw 11 rotates and the metering is started.

The rotation of the screw 11 causes the screw 11
The molten resin is gradually stored (measured) in the head portion of the screw 11, and the screw 11 retreats by the pressure of the stored molten resin.

At this time, the hydraulic oil in the piston rear chambers 74, 84 and the supply / discharge chamber 62 is discharged from the cartridge valves 60Ab, 70Ab, 80Ab to the tank 50 via the relief valve 92 as the screw 11 retreats. .

When the metering is completed, the solenoid valve a of the injection control switching valve 35 is turned ON, and suckback is performed in order to prevent the molten resin from dripping from the tip nozzle 14 of the barrel 13.

When the suckback is completed, the solenoid valve b of the injection control switching valve 35 is turned ON, and in the present invention, when the hydraulic oil is supplied by combining the following hydraulic cylinders 60, 70, and 80, the screw is screwed. At the time of the injection advance of 11, the speed adjustment of seven stages as shown in Table 1 can be performed.

Since the hydraulic cylinders 60, 70, 80 are symmetrical with respect to the left and right, respectively, the hydraulic cylinders 60R, 60L, 70
R, 70L, 80R, and 80L form a set.

[0033]

[Table 1]

By changing the ratio of X ₁ , X ₂ and X ₃ shown in Table 1, a desired injection speed can be obtained.

Here, the method of adjusting the speed of the screw 11 shown in Table 1 will be described in detail. For example, in order to obtain a quadruple speed of the first speed, it is sufficient to supply the pressure oil from the hydraulic power supply circuit 30 only to the supply / discharge chamber 62 of the hydraulic cylinder 60, and the piston rear chambers 74 of the other hydraulic cylinders 70 and 80, No pressure oil is supplied to 84.

That is, the solenoid valve b of the injection control switching valve 35 is set to O
N, electromagnetic open / close switching valves 60Aa, 70Ba, 80Ba are O
N, when the solenoid valve b of the back pressure relief valve 94 is turned on and the solenoid on / off switching valves 60Ba, 70Aa, 80Aa are turned off, the pressure oil of the hydraulic power supply circuit 30 passes through the injection control switching valve 35, and the hydraulic oil from the cartridge valve 60Ab to the hydraulic cylinder. 60 is supplied to the supply / discharge chamber 62. For this reason, the pressure oil P acts on the cross-sectional area a ₀ of the ram 64, and the screw 11 moves forward with a force of a ₀ × P.

In this case, the pressure oil in the piston front chambers 72, 82 of the hydraulic cylinders 70, 80 is passed through the cartridge valves 70Bb, 80Bb, respectively, to the piston rear chambers 74, 84.
And the screw 11 is moved to 4 by the advance of the ram 64.
With a double speed advance, the molten resin is injected into a mold cavity (not shown).

The desired speed adjustment as shown in Table 1 can be similarly performed. For example, in order to obtain 3.3 times speed shown in Table 1, it is sufficient to supply the pressure oil from the hydraulic power supply circuit 30 to the supply / discharge chamber 62 of the hydraulic cylinder 60 and the piston rear chamber 74, No pressure oil is supplied to the piston rear chamber 84.

That is, the solenoid valve b of the injection control switching valve 35 is set to O
N, the electromagnetic switching valve 60Aa, 70Aa, 80Ba is O
N, when the solenoid valve b of the back pressure relief valve 94 is turned on and the solenoid on-off switching valves 60Ba, 70Ba, and 80Aa are turned off, the pressure oil of the hydraulic power source circuit 30 passes through the injection control switching valve 35, and from the cartridge valves 60Ab and 70Ab. Each is supplied to the supply / discharge chamber 62 and the piston rear chamber 74. For this reason,
Pressure oil P acts on the cross-sectional area b ₀ of the cross-sectional area a ₀ and the piston 75 of the ram 64, the screw 11 will be advanced by the force of _{(a 0 × P) + (} b 0 × P).

In this case, the pressure oil in the piston front chamber 82 of the hydraulic cylinder 80 is supplied back to the piston rear chamber 84 via the cartridge valve 80Bb, and the ram 64 and the piston 75
The screw 11 advances at 3.3 times speed by the advance of the molten resin, and the molten resin is injected into a mold cavity (not shown). The pressure oil in the piston front chambers 72 and 82 is discharged from the injection control switching valve 35 to the tank 51 via the pipe as the screw 11 advances.

[0041]

As is apparent from the above description, in the first invention according to the present invention, the hydraulic oil from the hydraulic power source circuit is sent to the hydraulic cylinder to advance the ram or the piston so that the synthetic resin is formed. An injection device for injecting, wherein a plurality of pairs of the hydraulic cylinders forming a point-symmetric pair are provided on both sides of a barrel constituting the injection device, and a total value obtained by setting a cross-sectional area of the ram and a piston to an effective cross-sectional area, and The ratio to the effective area value of each hydraulic cylinder is 25%, 3
According to the second aspect of the present invention, a plurality of rams and pistons having different effective cross-sectional areas are provided in a hydraulic cylinder having different diameters so as to be able to move forward and backward, and a point-symmetric pair is formed on both sides of the barrel. By adopting a configuration that obtains seven levels of cylinder output by combining a pair of hydraulic cylinders, even if the hydraulic source circuit sends out hydraulic oil of a constant pressure, it can be easily injected by selecting the open / close valve and the open valve appropriately. Injection suitable for the injection material can be performed by switching the pressure and the injection speed. Further, since the injection device is different from the speed increase by the hydraulic differential circuit, the pressure loss of the hydraulic pressure during operation can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a hydraulic circuit of an injection device according to the present invention.

FIG. 2 is a transverse cross-sectional view of the injection device according to the present invention.

FIG. 3 is a longitudinal sectional view taken along the line AA of FIG. 2;

FIG. 4 is a diagram showing an example of a conventional injection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Injection apparatus 11 Screw 13 Barrel 14 Nozzle 17 Movable base 18 Connecting plate 20 Hydraulic cylinder 30 Hydraulic power supply circuit 35 Injection control switching valve 40 Pilot pressure source 50, 51, 52 Tank 60 (60R, 60L) Hydraulic cylinder 60A, 70A, 80A On-off valve 60B, 70B, 80B Opening valve 60Aa, 70Aa, 80Aa, 60Ba, 70Ba,
80Ba electromagnetic open / close switching valve 60Ab, 70Ab, 80Ab, 60Bb, 70Bb,
80Bb Cartridge valve 61 Cylinder main body 62 Supply / discharge chamber 64 Ram 67 Front cover 70 (70R, 70L) Hydraulic cylinder 72 Piston front chamber 74 Piston rear chamber 75 Piston 76 Rear cover 77 Front cover 78 Piston rod 80 (80R, 80L) Hydraulic cylinder 82 Piston front chamber 84 Piston rear chamber 85 Piston 86 Rear cover 87 Front cover 88 Piston rod 92 Relief valve 94 Relief valve for back pressure 96 Hydraulic motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-147227 (JP, A) JP-A-63-94811 (JP, A) JP-A-60-139421 (JP, A) 169512 (JP, A) JP-A-5-104598 (JP, A) JP-A-3-264324 (JP, A) JP-A-53-135480 (JP, U) JP-A-1-95321 (JP, U) Hikaru Hei 2-146017 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/50 B29C 45/77

Claims (2)

(57) [Claims] 1. An injection device for injecting a synthetic resin by feeding a hydraulic oil from a hydraulic pressure source circuit to a hydraulic cylinder to advance a ram or a piston, and to symmetrically symmetrically point both sides of a barrel constituting the injection device. A plurality of pairs of the hydraulic cylinders are provided, and the ratio between the total value of the sectional areas of the ram and the piston as the effective sectional area and the effective sectional area value of each hydraulic cylinder is 25%, 30%, and 45%. An injection device for an injection molding machine, characterized in that: 2. A ram and a piston having different effective cross-sectional areas are provided in hydraulic cylinders having different diameters so as to be able to move forward and backward, and a seven-stage cylinder output is provided by a combination of a plurality of pairs of hydraulic cylinders forming a point-symmetric pair on both sides of the barrel. An injection device for an injection molding machine, characterized in that: