JP3165874B2 - Injection pressure selection mechanism 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 molding machine, and more particularly to an injection pressure selecting mechanism.

[0002]

2. Description of the Related Art Conventionally, an injection pressure is used as a primary pressure used when filling a molten material into a mold and a holding pressure for preventing sink marks, shrinkage, etc. after the filling of the mold is completed. And secondary pressure. In this case, the injection primary pressure is generally set high and the injection secondary pressure is set low.

[0003] Recently, low-pressure, high-speed injection of resin into a low-viscosity state eliminates burrs and shots.
Further, molding with less deformation such as warping and twisting has been performed. In such molding, it is necessary to switch the injection pressure in multiple stages so as to mold from a general-purpose resin to a low-viscosity resin.

[0004]

However, the injection pressure selection mechanism for performing the above-described multi-stage switching tends to have a somewhat complicated structure. Also, in order to change the injection pressure and speed, it was necessary to replace the entire cylinder.

An object of the present invention is to provide a relatively simple structure capable of performing multi-stage switching of the injection pressure, and to easily change the injection pressure and speed as required without changing the cylinder. To provide a possible injection pressure selection mechanism.

[0006]

Means for Solving the Problems In order to achieve the above object, the constitution of the present invention is as follows. That is, a two-piston piston in which a piston is formed in an intermediate portion and large-diameter and small-diameter rods facing the piston are formed, and a cylinder inscribed in an outer peripheral surface of the piston and disposed around the rod A small-diameter bush penetrating the center of the small-diameter rod and attached to one side of the cylinder; and a large-diameter bush penetrating the center of the large-diameter rod and attached to the other side of the cylinder. A side bush, an end cover having an atmosphere communication portion, one end of which is detachably attached to the large-diameter side bush of the cylinder,
A ram bush detachably attached to an end of the large-diameter rod, one end detachably attached to the other end of the end cover, and the other end penetrating through the center of the ram bush; A ram having an inner hole inserted into a bore formed toward the piston from the end of the side rod, wherein both rod pistons are provided so as to be able to reciprocate the entire stroke of the injection screw, and the piston, A space defined by the small diameter rod, the cylinder and the small diameter bush is defined as a first chamber, and a space defined by the piston, the large diameter rod, the cylinder and the large diameter bush is defined as a second chamber. The space formed in the bore of the large-diameter side rod is a third chamber, and the pressure receiving area of the piston in the first chamber is equal to the pressure receiving area of the piston in the second chamber. The pressure receiving area of the piston in the second chamber is set to be larger than the pressure receiving area of the ram related to the third chamber, including the pressure receiving area including the inner hole of the ram. The first chamber, the second chamber, and the third chamber are connected to a hydraulic operating circuit that changes the injection pressure of the screw stepwise through a connecting member connected to an end of the small-diameter rod. The configuration is characterized by being connected to each other.

[0007]

With the above-described structure, the operation of the hydraulic operation circuit selectively introduces or discharges the operating oil into the first chamber, the second chamber or the third chamber formed in the injection cylinder. By applying a hydraulic pressure to the rod in a stepwise manner, the injection pressure and the moving speed of the screw can be changed in a stepwise manner.

To change the injection pressure and speed, remove the end cover attached to the large-diameter bush, remove the ram attached to the end cover, remove the ram from the ram bush, and attach it to the large-diameter rod. The removed ram bush is removed, the ram is replaced with one having a different outer diameter, and the ram bush through which the ram is penetrated is replaced with one having an inner diameter adapted to the ram. Since the ram and the ram bush can be easily replaced, the pressure receiving area of the third chamber can be easily changed, so that the injection pressure and the speed can be changed without replacing the cylinder and also both rod pistons. Can be.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. The injection pressure selection mechanism of the present embodiment includes a double rod type injection cylinder 10 shown in FIG. 3 and an operation circuit shown in FIG.
60 is a four-stage switching type injection pressure selection mechanism.

First, referring to FIG. 3 and FIG.
Will be described. The injection cylinder 10 includes a cylinder 18,
A piston 12 is formed at an intermediate portion by being inserted into the cylinder 18, and a two-rod piston 11 composed of a rod 14 composed of a large-diameter rod 14a located on the left side in the drawing and a small-diameter rod 14b located on the right side, And a ram 16 inserted concentrically into a bore 15 formed in the radial rod 14a.

An outer peripheral surface of the piston 12 is slidably inscribed on an inner peripheral surface of a cylinder 18 connected to an injection device main body (not shown). A small-diameter bush is provided between the small-diameter rod 14b and the cylinder 18 so as to face the piston 12.
A flange 22 integrally formed with the small-diameter bush 20 is fixed to a side surface of the cylinder 18 by a bolt 24.

On the other hand, a large-diameter bush 90 is fitted between the large-diameter rod 14a and the cylinder 18 so as to face the piston 12, and a flange 92 formed integrally with the large-diameter bush 90. Are removably attached to the side surface of the cylinder 18 by bolts 94. An end cover 26 is arranged concentrically around the large diameter rod 14a,
a so that the end of a
Is removably attached to the flange 92 attached to the side surface of the bracket by bolts 28.

An opening 30 is formed on the side surface 26b of the end cover 26 opposite to the enlarged diameter portion 26a.
The flange 16 formed on the ram 16 is removably attached to the side surface 26b of the end cover 26 by bolts 34, and a ram bush 96 is fitted between the ram 16 and the large-diameter rod 14a. And a flange 98 formed integrally with the ram bush 96 is fixed to a side surface of the large-diameter rod by a bolt 100, and the ram 16 is inserted into a lumen 15 formed in the large-diameter rod 14a. . Note that an inner hole 36 is formed along the longitudinal direction of the ram 16.

With such a configuration, the piston 12, the small-diameter rod 14b, the cylinder 18, and the small-diameter bush 20 form a first space, that is, a first chamber 38.
2, Large diameter rod 14a, cylinder 18 and large diameter bush 9
0, a second chamber 40 is formed. Further, a third chamber 42 is formed in the lumen 15 of the large diameter rod 14a, and expands and contracts as the rod 14 moves forward and backward. It communicates directly with the inner hole 36. Also, the outer peripheral surface of the ram 16 and the end cover 26
The space 44 formed between the inner cover and the inner peripheral surface of the
It is open to the atmosphere via cutouts 46 provided at two places on both sides of the. That is, the end cover 26 may cause dust existing around the injection cylinder 10 to adhere to the outer circumference of the ram 16 or the large-diameter rod 14a,
It is desirable to have a structure that does not stain the periphery even if a small amount of oil leaks from the outer periphery of a, and allows the outer periphery of the ram 16 and the large diameter rod 14a to be visually inspected.
The first chamber 38 is connected to a later-described operating circuit 60 via a passage 48, the second chamber 40 is connected via a passage 50, and the third chamber 42 is connected via an inner hole 36 and a port 52 of the ram 16. Have been.

In the above configuration, for example, FIGS.
(= Diameter of piston 12)
A is 125 mm, diameter B of the small diameter side rod 14b is 75 m
m, the outer diameter C of the large diameter side rod 14a is 106 mm, and the ram 1
6 is 40 mm, the pressure receiving area of the piston 12 in the first chamber 38 (the cross-sectional area of the diameter A−the cross-sectional area of the diameter B) is equal to the pressure receiving area of the piston 12 in the second chamber 40 (the cross-sectional area of the diameter A). It is larger than the sum of the area—the cross-sectional area of the diameter C) and the pressure receiving area of the third chamber 42 (the cross-sectional area of the outer diameter D of the ram 16). The area—the cross-sectional area of the diameter C) is set larger than the pressure receiving area of the third chamber 42 (the cross-sectional area of the outer diameter D of the ram 16). Due to the difference between these pressure receiving areas, a plurality of injection rates and injection pressures can be obtained when hydraulic oil is introduced or discharged simultaneously and selectively into each chamber.

Further, in this embodiment, at least a pair of injection cylinders 10 are used, and the proximal end of the small diameter rod 14b is connected to a connecting member as schematically shown in FIG.
It is connected to screw 56 via 54,
The screw 56 moves forward and backward with respect to a mold (not shown) by the action of the injection cylinder 10.

Next, the operation circuit 60 will be described with reference to FIG. A hydraulic motor 62 is connected to the screw 56, and thereby the screw 56 is rotated to melt and knead the appropriately supplied resin. The first chamber 38 is connected to a three-position four-way switching valve 66 via a first two-position four-way switching valve 64, and further connected to a hydraulic oil tank T. The hydraulic motor 62 is the first
It is connected to a screw rotation back pressure relief valve 68 via a position 4-way switching valve 64. The second chamber 40 is connected to a three-position four-way switching valve 66 via a second two-position four-way switching valve 70,
Further, it is connected to a hydraulic oil tank T via a hydraulic pump 72. An original pressure safety relief valve 74 is interposed between the three-position four-way switching valve 66 and the hydraulic pump 72.

The port 52 of the ram 16 is connected to the hydraulic oil tank T via a third two-position four-way switching valve 76.
Also, a three-position four-way switching valve 66 and a first two-position four-way switching valve
Two branch pipes 80 and 82 are branched from a pipe 78 connecting the pipes 64, and one of the branch pipes 80 is a second and third two-position four-way switching valve 70,7.
6 and the other branch pipe 82 is connected to a fourth two-position four-way switching valve 84. Also, the fourth two positions 4
The hydraulic oil tank T and the injection pressure relief valve 86 are connected via the direction switching valve 84. This injection pressure relief valve 86
Thereby, an operating oil pressure higher than a predetermined pressure is released to the tank.

Next, regarding the operation of the injection pressure selection mechanism configured as described above, an operation circuit diagram of FIG. 1, a function table of FIG. 2, and a schematic diagram showing a supply state of the operation oil in each stage of FIG. This will be described with reference to FIG. First, in the case of the first injection stage, as shown in FIG. 2, the solenoids I of the three-position four-way switching valve 66 and the second, third, and fourth two-position four-way switching valves 70, 76, and 84 are used. , I ₂ ,
I ₃ and I ₄ are excited. Thereby, the injection cylinder 1
The first chamber 38 of 0 is switched through a first two-position four-way switching valve 64, the second chamber 40 is switched through a second two-position four-way switching valve 70, and the third chamber 42 is switched through two-position four-way switching. All via a valve 76 and further via a three-position four-way switching valve 66
It is communicated to 2.

Therefore, the hydraulic oil in the hydraulic oil tank T is
As shown in the first stage of FIG.
Via the position four-way switching valve 66, further to the first chamber 38 via the first two-position four-way switching valve 64, to the second chamber 40 via the second two-position four-way switching valve 70, and The liquid is introduced into the third chamber 42 via the third two-position four-way switching valve 76. The pressure receiving area (cross-sectional area of diameter A-cross-sectional area of diameter B) of the piston 12 in the first chamber 38 is equal to the pressure receiving area of the piston 12 in the second chamber 40 (cross-sectional area of diameter A-diameter C).
Of the third chamber 42 (the outer diameter D of the ram 16)
The pressure receiving area of the piston 12 in the second chamber 40 (the cross-sectional area of the diameter A-the cross-sectional area of the diameter C) in the second chamber 40 is larger than the pressure receiving area of the third chamber 42 (the outer diameter D of the ram 16). The working oil pressure introduced into the first chamber 38 and applied to the piston 12 to the left in the drawing is introduced into the second chamber 40 and applied to the piston 12 in the drawing. The hydraulic pressure applied to the right and the third chamber 4
2, the piston 12 and the rod 14 are overcome at a low pressure and a high speed in the direction shown in FIG. Move to

At this time, the first chamber 38, the second chamber 40, and the third
The chamber 42 passes through a corresponding pipe, and is further connected to an injection pressure relief valve 86 via a branch pipe 82 and a fourth two-position four-way switching valve 84, so that a hydraulic pressure equal to or higher than a predetermined pressure acts on each chamber. Has been prevented.

In the case of the second stage of injection, 3 positions 4
Directional switching valve 66, second and fourth two-position four-way switching valves 70, 8
The solenoids I, I ₂ and I ₄ of FIG. ₄ are excited. As a result, the first chamber 38 and the second chamber 40 are connected to the hydraulic pump 72 via the first or second two-position four-way switching valves 64 and 70, and further via the three-position four-way switching valve 66. You. At this time, the third chamber 42 is in communication with the hydraulic oil tank T via a third two-position four-way switching valve 76.

Therefore, the hydraulic oil in the hydraulic oil tank T is
The hydraulic pump 72 passes through a three-position four-way switching valve 66 and further through a first two-position four-way switching valve 64 to the first
It is introduced into the chamber 38 and into the second chamber 40 via the second two-position four-way switching valve 70, respectively. At this time, since the third chamber 42 communicates with the hydraulic oil tank T, no hydraulic pressure is generated in the third chamber 42 and no resistance is given to the movement of the rod 14. The pressure receiving area of the piston 12 in the first chamber 38 (the cross-sectional area of the diameter A−the cross-sectional area of the diameter B) is set to be larger than the pressure receiving area of the piston 12 in the second chamber 40 (the cross-sectional area of the diameter A−the cross-sectional area of the diameter C). Therefore, the operating oil pressure in the first chamber 38 overcomes the operating oil pressure in the second chamber 40, and moves the piston 12 and the rod 14 in the direction shown in FIG. 4 and moves the screw 56 to the left in the drawing. Therefore, in this case, a larger injection pressure can be applied to the screw 56 as compared with the first stage of injection, and the moving speed of the screw 56 can be reduced as compared with the moving speed of the first stage of injection described above.

In the case of the third stage of injection, three positions 4
Directional switching valve 66, third and fourth two-position four-way switching valves 76, 8
The solenoids I, I ₃ and I ₄ of FIG. ₄ are excited. As a result, the first chamber 38 and the third chamber 42 become the first or third chambers, respectively.
It is connected to the hydraulic pump 72 via the three-position four-way switching valve 66 via the four-position four-way switching valve 64,76. Also, at this time,
The second chamber 40 is connected to the hydraulic oil tank T via a second two-position four-way switching valve 70 and a three-position four-way switching valve 66.

Therefore, the hydraulic oil in the hydraulic oil tank T is
The hydraulic pump 72 passes through a three-position four-way switching valve 66 and further through a first two-position four-way switching valve 64 to the first
It is introduced into the chamber 38 and into the third chamber 42 via a third two-position four-way switching valve 76, respectively. At this time, since the second chamber 42 communicates with the hydraulic oil tank T, no hydraulic pressure is generated in the second chamber 42 and no resistance is given to the movement of the piston 12. Piston 12 in 38 in the first chamber
Pressure receiving area (cross-sectional area of diameter A-cross-sectional area of diameter B) is the third
Since the pressure receiving area of the chamber 42 (cross-sectional area of the outer diameter D of the ram 16) is set to be larger, the operating oil pressure of the first chamber 38 overcomes the operating oil pressure of the third chamber 42, and the piston 12 and the rod 14 4, and the screw 56 is moved to the left in the drawing. Therefore, in this case, a larger injection pressure is applied to the screw 56 as compared with the second injection stage, and the moving speed of the screw 56 is set to the above-described second injection stage.
It can be reduced as compared with the moving speed of the step.

In the case of the fourth stage of injection, three positions 4
Solenoid I of the directional control valve 66 and a fourth two-position four-way switching valve 84, I ₄ is energized. As a result, only the first chamber 38 has the first two-position four-way switching valve 64 and the three-position four-way switching valve 66.
Through the hydraulic pump 72. The second chamber 40 is connected to the hydraulic oil tank T via a second two-position four-way switching valve 70 and a three-position four-way switching valve 66, and the third chamber 42 is provided with a third two-position four-way switching valve 76. The hydraulic fluid is communicated with the hydraulic oil tank T through the intermediary.

Therefore, the hydraulic oil in the hydraulic oil tank T is
It is introduced into the first chamber 38 via the three-position four-way switching valve 66 and further through the first two-position four-way switching valve 64 by the hydraulic pump 72. On the other hand, since the second chamber 40 and the third chamber 42 are in communication with the hydraulic oil tank T, no hydraulic pressure is generated in both chambers, and there is no resistance to the movement of the piston 12 or the rod 14, respectively. Not. As a result, the piston 12 and the rod 14 are moved in the direction shown in FIG. 4 and the screw 56 is moved leftward in the drawing without any resistance to the operating oil pressure of the first chamber 38. Therefore, in this case, a larger injection pressure can be applied to the screw 56 as compared with the third injection stage, and the moving speed of the screw 56 can be reduced as compared with the above-described third injection stage movement speed.

Next, a case where the screw 56 is retracted will be described. In this case, only the solenoid B of the three-position four-way switching valve 66 is excited, and the second chamber 40 is hydraulically driven through the second two-position four-way switching valve 70 and further through the three-position four-way switching valve 66. It is connected to the pump 72. On the other hand, the first chamber 38 and the third chamber 42 are connected to the hydraulic oil tank T via a three-position four-way switching valve 66 or a third two-position four-way switching valve 76, respectively.

Therefore, the hydraulic oil in the hydraulic oil tank T is
Introduced only to the second chamber 40 by the hydraulic pump 72, the piston
Since the hydraulic pressure acts on the valve 12 in the reverse direction, the first chamber 38 and the third chamber 42 are both in communication with the hydraulic oil tank T.
The piston 12 and rod 14 are moved, ie, retracted, to the position shown in FIG.

When rotating the screw 56,
3-position 4-way switching valve 66 and first 2-position 4-way switching valve 64
The solenoids I and P are excited, and the hydraulic motor 62
Is connected to the hydraulic pump 72 via the two-position four-way switching valve 64 and the three-position four-way switching valve 66. At this time, injection cylinder
The ten first chambers 38 are connected to a screw rotation back pressure relief valve 68 via a first two-position four-way switching valve 64. Therefore, the hydraulic oil in the hydraulic oil tank T is introduced into the hydraulic motor 62 by the hydraulic pump 72, and the screw 56 rotates in a predetermined direction, so that the raw material is transferred forward while being melted and kneaded.

The diameter A of the piston 12 and the small diameter rod 14b
In this embodiment, the diameter B of the large diameter, the diameter C of the large diameter rod 14a, and the diameter D of the ram 16 are set as described above.
Injection pressure and screw 56 acting on screw 56 in the case of the fourth stage of injection where only first chamber 38 is supplied with hydraulic oil
In the third stage of injection, the injection pressure is 0.84, the moving speed is 1.19, and in the second stage of injection, the injection pressure is 0.56, the moving speed is 1.78, The first stage of injection
The injection pressure changes to 0.40 and the moving speed changes to 1.78. When changing the injection pressure and speed, use the large-diameter bush 9
0, the ram 16 attached to the end cover 26 is removed, the ram 16 is removed from the ram bush 96, and the ram bush 96 attached to the large diameter rod 14a is removed.
The ram 16 is replaced by one having a different outer diameter, and the ram bush 96 through which the ram 16 passes is replaced by one having an inner diameter that matches the ram 16. The diameter D of the ram 16 is 4
When the diameter is changed from 0 mm to 56 mm, as in the above-described embodiment, only the first chamber 38 is supplied with the hydraulic oil. Assuming that the speed is 1, the third stage of injection has an injection pressure of 0.68 and a moving speed of 1.46, and the second stage of injection has an injection pressure of 0.56, a moving speed of 1.78, and a third stage of injection. The first stage has an injection pressure of 0.25 and a moving speed of 4.04.
Changes to In this manner, the ram 16 and the ram bush 96 can be easily replaced, so that the pressure receiving area of the third chamber 42 can be easily changed. Instead, the injection pressure and speed can be changed.

[0032]

As is apparent from the above description, the injection cylinder is provided with large-diameter and small-diameter rods facing each other with the piston as a boundary, and is detachably attached to the side surface of the cylinder and penetrated by the large-diameter rod. A large diameter bush, an end cover detachably attached to the large diameter bush, a ram bush detachably attached to an end of the large diameter rod, and a detachably attached end cover. And a ram having an inner hole penetrating through the ram bush and inserted into a bore formed from the end of the large-diameter side rod toward the piston. Forming a second chamber and a third chamber, wherein the pressure receiving area of the piston in the first chamber is larger than the sum of the pressure receiving area of the piston in the second chamber and the pressure receiving area including the inner hole of the ram associated with the third chamber;
By setting the pressure receiving area of the piston in the second chamber to be larger than the pressure receiving area including the inner hole of the ram, and further connecting the first chamber, the second chamber, and the third chamber to a hydraulic operation circuit, the first chamber,
Hydraulic oil can be selectively introduced or discharged into the second chamber or the third chamber, and hydraulic pressure can be applied to the piston or rod in a stepwise manner. In addition, by adopting such a structure, the injection cylinder can use a pressure selection mechanism. Since a normal cylinder having no component can be used as it is, there is no increase in cost or complexity in component change and component management. In addition to this, the injection pressure and the speed of the relatively inexpensive screw can be easily changed by simply changing the ram and the ram bush as necessary. An injection pressure selection mechanism capable of performing multi-stage switching can be obtained.

[Brief description of the drawings]

FIG. 1 is an operation circuit diagram showing one embodiment of the present invention.

FIG. 2 is a function table of the operation circuit diagram of FIG. 1;

FIG. 3 is a sectional view showing a state in which a piston of the double rod type cylinder according to the present invention is retracted.

FIG. 4 is a sectional view showing a state in which a piston of a double rod type cylinder according to the present invention has moved.

FIG. 5 is a conceptual diagram showing a state of supply of hydraulic oil in each stage of the double rod type cylinder according to the present invention.

[Explanation of symbols]

 10 Injection cylinder 11 Double rod piston 12 Piston 14 Rod 14a Large diameter rod 14b Small diameter rod 16 Ram 18 Cylinder 20 Small diameter bush 26 End cover 38 First chamber 40 Second chamber 42 Third chamber 54 Connection member 56 Screw 60 Hydraulic pressure Operating circuit 90 Large diameter bush 96 Ram bush

Continuation of front page (56) References JP-A-2-147227 (JP, A) JP-A-6-114902 (JP, A) JP-A-5-177678 (JP, A) JP-A-5-169512 (JP) , A) Japanese Utility Model Application Hei 6-29822 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/46-45/63 B29C 45/76-45/84

Claims (1)

(57) [Claims] 1. A piston is formed in an intermediate portion, and both rod pistons having large-diameter and small-diameter rods facing each other with respect to the piston are inscribed in an outer peripheral surface of the piston.
And a cylinder disposed around the rod, a center penetrated by the small-diameter rod, and a small-diameter bush attached to one side of the cylinder, and a center penetrated by the large-diameter rod, and A large-diameter bush attached to the other side surface of the cylinder; an end cover having an atmosphere communication portion, one end of which is detachably attached to the large-diameter bush of the cylinder; and an end of the large-diameter rod. A ram bush detachably attached to the end cover, one end of the ram bush is detachably attached to the other end of the end cover, and the other end penetrates the center of the ram bush and moves from the end of the large diameter rod to the piston. A ram having an inner hole inserted into a lumen formed toward the piston, wherein both rod pistons are provided so as to be able to reciprocate the entire stroke of the injection screw; A space formed from the radial rod, the cylinder and the small diameter bush is defined as a first chamber, and a space formed from the piston, the large diameter rod, the cylinder and the large diameter bush is defined as a second chamber, The space formed in the lumen of the large diameter side rod is a third chamber, and the pressure receiving area of the piston in the first chamber is the second chamber.
Greater than the sum of the pressure receiving area of the piston in the chamber and the pressure receiving area including the bore of the ram associated with the third chamber,
The pressure receiving area of the piston in the second chamber is the third area.
A connection member having an injection cylinder set to be larger than a pressure receiving area including an inner hole of the ram associated with a chamber, wherein the first chamber, the second chamber, and the third chamber are connected to an end of the small-diameter side rod; An injection pressure selecting mechanism for an injection molding machine, which is connected to a hydraulic operating circuit that changes the injection pressure of a screw in a stepwise manner through a hydraulic circuit.