JP3056680B2 - Pre-plastic injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-plastic injection device used for injection molding of a synthetic resin.

[0002]

2. Description of the Related Art In general, a plastic injection machine has a plasticizing cylinder inside a screw and a plasticizing cylinder inside a plunger, and the tip of the plasticizing cylinder has a large diameter and a short cylindrical body. After the resin melted and kneaded (hereinafter referred to as "plasticization") in a plasticizing cylinder is measured at a front portion of an injection cylinder, the cylinder is used as a resin path, and injection is performed by advancing a plunger. It consists of a configuration.

The reason why the resin path is constituted by a large-diameter, short cylinder or the like is to reduce the flow resistance of the molten resin sent from the plasticizing cylinder in the resin path and to inject the molten resin into the injection cylinder as soon as possible. .

[0004]

In such a pre-plastic injection device, since the resin is plasticized by a screw rotating at a fixed position, an in-line screw injection device in which the plasticizing is performed by a screw that retreats while rotating. It is said that the plasticization can be performed more uniformly than the equipment, but the plasticization is not always performed uniformly. Plasticization often becomes non-uniform depending on the design, the state and characteristics of the material, and the like. In particular, since the resin does not have good thermal conductivity, the unevenness in temperature during the flow process is not improved and the plasticized state is not uniform, and the resin is metered to the injection cylinder as it is.

Conventionally, as shown in FIG. 4, an inflow passage 111 at a portion corresponding to a plunger advance limit at a tip end portion of the injection cylinder 110 is bored toward a center portion of the injection cylinder 110. For this reason, the plasticized resin from the resin path 112 is divided into right and left along the inner peripheral surface 110a by the tip of the plunger located at the forward limit in the initial stage of measurement and thereafter by the resistance of the resin which has flowed in first. To form a junction on the opposite side of the inflow path 111.

If this confluence occurs at the bottom of the plunger advance limit, it tends to stay, and it takes time to remove the stay resin at the bottom when exchanging the material resin or changing the color. The removal of the stagnation resin is time-consuming because the blanking of a new material is repeatedly performed, and also results in a loss of material and power consumption.

In a conventional apparatus in which a resin path connecting a plasticizing device and an injection device is disposed at an angle of about 90 ° with respect to the axis of a plasticizing cylinder, an intersection between the resin path and an outflow path and an inflow path is provided. A corner is formed inside the portion, and the corner makes it easier for a part of the resin to stay on the downstream side, which may impair the flow of the resin.

The present invention has been conceived in order to solve the above-mentioned conventional problems, and has as its object to equalize the temperature of a resin plasticized by a plasticizing cylinder in a resin path and to generate a retained resin. Is to provide a new pre-plastic injection device that can prevent the above problem by obliquely providing a resin path or an inflow path.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a plasticizing cylinder is juxtaposed to an injection cylinder provided inside a plunger, and the injection cylinder and the plasticizing cylinder are connected to a portion of the tip of the injection cylinder which corresponds to a plunger advance limit. In a prepra-type injection device in which a resin pipe of a thin tube having a temperature control means is provided on the outer periphery provided over the inflow path of the plasticizing cylinder and the outflow path at the tip of the plasticizing cylinder, the inflow path is formed by the injection cylinder. Is formed to be inclined toward the inner peripheral surface so as to flow in one direction along the inner peripheral surface.

In such a structure, the flow resistance is easily generated by the resin path formed by the thin tube, and the temperature of the resin flowing through the resin path is equalized before flowing into the injection cylinder due to the flow resistance, and the plasticized state is also uniform. In addition, all of the resin flows in one direction along the inner peripheral surface of the injection cylinder due to the inclined inflow path, and there is no confluence due to branching there, and the resin caused by the confluence is Stagnation is also eliminated.

Further, according to the present invention, the front end of the plasticizing cylinder is set rearward from the front end of the injection cylinder, and the resin passage extending between the outflow passage and the inflow passage of both front end portions is inclined at an acute angle toward the front. Preferably, it is provided so as to be inclined at an outer angle of 40 ° to 50 ° with respect to the axis of the plasticizing cylinder.

In such a configuration, the crossing angle between the resin path and the outflow path and the inflow path is formed large, and the inclination of the resin path is set at an outer angle of 40 ° to 50 ° with respect to the axis of the plasticizing cylinder.
The crossing angle when set in the angle range of 130 ° to 14 °
0 °, which makes it difficult for resin to stay at the intersection.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, reference numeral 1 denotes an injection device, and 2 denotes a plasticizing device. The plasticizing device 2 has a tip 22a of a plasticizing cylinder 22 located behind the tip 12a of the injection cylinder 12. It is juxtaposed on the injection device 1. In addition, both devices are provided with a resin path 3 provided diagonally over the tip portions 12a and 22a.
Is communicated with.

The injection device 1 includes an injection plunger 10.
And a hydraulic cylinder 14 for injection in which a piston 13 is connected to a rear end of the injection cylinder 12 and a piston 13 is connected to the plunger 10. ing.

The injection cylinder 12 has an inflow path 15 for the resin path 3 at an upper portion corresponding to a plunger advance limit of the distal end portion 12a. The inflow path 15 has the same diameter as the resin path 3 and extends from the resin path 3. The resin is inclined toward the inner peripheral surface 12b so that the resin flows in one direction along the inner peripheral surface 12b of the injection cylinder 12.

Further, resin injection holes 16 are provided above and below the plunger stroke of the injection cylinder 12, and a band heater 17 is provided around the cylinder after the resin extraction hole 16 so that the heater zone is set long. is there.

The plasticizing device 2 has a plasticizing screw 20 rotatably mounted therein, and has an outlet passage 2 at a tip end 22a.
1, a holding cylinder 23 at a rear end for holding the plasticizing cylinder 22, a hydraulic cylinder 24 for screw advance / retreat connected to a rear end of the holding cylinder 23, and a hydraulic cylinder 24. And a rotation drive device 25 for the screw 20 attached to the rear end.

The drive shaft 25a of the rotary drive 25 is
Insert the rear end into the piston 24a of the hydraulic cylinder 24,
The shaft 20 is movably connected in the axial direction to a rotating shaft 23a which is supported inside the holding cylinder 23. The rear end of the screw 20 is connected to the tip of the rotating shaft 23a. The rotating shaft 23a is connected to the piston 24a and moves forward and backward together with the piston 24a to rotate and move the piston 24a forward and backward.

A band heater 26 is attached to the outer periphery of the plasticizing cylinder 22, and a supply hole 27 is provided upward at the rear end of the plasticizing cylinder 22 fitted to the holding cylinder 23. A mushroom-shaped valve body 28 is attached to the tip of the screw 20. The tip of the plasticizing cylinder 22 in which the valve body 28 is located is formed in a conical shape, and the valve body 28 and the valve body 28 have the same shape. A required flow gap communicating with the outflow passage 21 is formed, and an annular valve seat 29 is provided at a portion where the inclined back surface of the valve body 28 faces.

The resin path 3 is made of a thin metal tube 30 having an inner diameter of about 5 to 10 mm, and is provided with a temperature control means such as a band heater 31 on the outer periphery. The narrow tube 30 is formed between the inflow passage 15 having the same diameter as the injection cylinder 12 and the plasticizing cylinder 2.
2 joints 30a, 30
It is provided obliquely at an acute angle forward with b.

The inclination angle of the resin path 3 is shown in FIG.
As shown in the figure, the outer angle B is set to 45 ° with respect to the axis AA of the plasticizing cylinder 22, but the inclination angle is 40 °.
The angle may be in the range of ゜ to 50 °, and in this angle range, the interior angles C and D at the intersections of the resin path 3 and the outflow path 21 and the inflow path 15 are formed as large as 130 ° to 140 °, respectively. The angle formed inside the intersection becomes an obtuse angle, and there is no portion on the downstream side where a portion of the resin rests.

The injection device 1 and the plasticizing device 2 are integrally connected in two upper and lower stages by mounting and holding the holding cylinder 23 on a support base 18 provided on the hydraulic cylinder 14.
The hydraulic cylinder 14 of the injection device 1 is mounted and fixed on a machine base 7 on a slidable base block 6 connected to a fixed plate 4 of a mold clamping device via a nozzle touch cylinder 5. .

In the above structure, the material resin is supplied to the supply hole 27.
From the plasticizing cylinder 22, the material resin is plasticized by the heating by the band heater 26 and the rotation of the screw 20, and is sequentially fed forward. Since the resin pressure applies a forward pressure to the screw 20, a resin flow gap is secured between the valve body 28 at the tip and the valve seat 29, and the plasticized resin is sequentially discharged from the outflow passage 21. Road 3
To be pumped. At this time, since the intersection angle between the resin path 3 and the outflow path 21 is formed to be large due to the inclination of the resin path 3, the entire amount of the resin flows into the resin path 3 without staying downstream of the intersection. Go on.

In the resin passage 3, the resin flows into the inflow passage 15 while being further plasticized or mixed by the flow resistance while passing through the thin tube 30. Further, the resin flows obliquely into the injection cylinder 12 by the inclined inflow path 15, and pressurizes the distal end surface of the plunger 10,
The plunger 10 is accumulated in the cylinder tip while moving backward. This accumulation is performed until the plunger 10 moves back to the set position to complete the weighing.

During this measurement, the resin flows in one direction from the inclined inflow path 15 along the inner peripheral surface 12b of the injection cylinder 12, as shown by the arrow in FIG. In addition, the flow flows from the inflow path 15 to the deep portion of the cylinder so as to swirl due to the retreat of the plunger 10 due to the resin pressure. For this reason, a junction does not occur on the opposite side of the inflow path 15.

When the plunger 10 retreats to the set position, the hydraulic cylinder 24 retreats and the screw 20
Is forcibly moved backward to press the valve body 28 against the valve seat 29. As a result, the inside of the tip of the plasticizing cylinder 22 is closed, and the pressure feed of the plasticized resin is temporarily stopped. As a result, a predetermined amount of resin is accumulated in the front part of the plunger of the injection cylinder 12. The process so far is generally called measurement, and thereafter, the measured resin is injected.

With the valve body 28 closed, the plunger 1
0 moves forward, the resin in the injection cylinder
Injection filling from 1 into a mold (not shown). The injection pressure by the plunger 10 also acts on the plasticizing cylinder side via the resin remaining in the resin path 3. However, since the valve body 28 is in the valve closed state, backflow of the resin to the plasticizing cylinder side is prevented, and the entire amount of the metered resin is
Emitted from.

When the completion of the injection step is confirmed, the hydraulic cylinder 24 moves forward to move the screw 20 forward by a required dimension. As a result, the valve element 28 at the tip is
A flow path is formed that is further apart and communicates with the flow gap formed on the front surface of the valve body. Thereafter, the rotation drive device 25 is operated to rotate the screw 20, plasticization is performed, and new plasticized resin is measured.

Although the plasticizing cylinder of the above embodiment has a screw inside, the present invention is also applicable to a plunger inside. Therefore, the present invention is particularly limited to a screw pre-plastic injection device. is not.

[0030]

As described above, according to the present invention, the injection cylinder and the plasticizing cylinder are provided on the outer circumference provided over the inflow path at the portion corresponding to the plunger advance limit at the tip of the injection cylinder and the outflow path at the tip of the plasticizing cylinder. Since the resin was communicated by the resin path of the thin tube having the temperature control means, the resins were mixed due to the flow resistance during the passage through the resin path, thereby eliminating the temperature unevenness and the color unevenness, and the resin to be injected and filled was more than before. It will be homogeneous.

The inflow passage is formed so as to be inclined toward the inner peripheral surface so that the resin from the resin passage flows in one direction along the inner peripheral surface of the injection cylinder. Since there is no occurrence of a resin confluence that occurs when the resin flows into and separates from each other, there is no longer any stagnation of the resin caused by the confluence,
The time required for material resin exchange and color change is shorter than before, and material resin and power consumption are also reduced.

Further, also in the structure, it is only necessary to form the resin path by a thin tube and to incline the inflow path toward the inner peripheral surface of the injection cylinder. Due to the inclination of the road, the angle of the intersection between the resin path and the inflow path and the outflow path is formed to be large, so that there is a feature that the retention of the resin in the intersection is also improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a pre-plastic injection device according to the present invention.

FIG. 2 is an enlarged view of a main part of the above.

FIG. 3 is a vertical sectional front view of the same.

FIG. 4 is a vertical sectional front view of an injection cylinder showing a conventional inflow passage.

FIG. 5 is a schematic view of a main part showing an inclination angle of a resin path.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection apparatus 2 Plasticizer 3 Resin path 10 Injection plunger 12 Injection cylinder 12a Tip part 15 Inflow path 16 Resin extraction hole 20 Plasticizing screw 21 Outflow path 22 Plasticization cylinder 22a Tip part 30 Thin tube 31 Band heater

Claims (3)

(57) [Claims] 1. A plasticizing cylinder is juxtaposed to an injection cylinder inside a plunger, and the injection cylinder and the plasticizing cylinder are connected to each other by an inflow path at a portion corresponding to a plunger advance limit at a tip end portion of the injection cylinder and an outflow at a tip end of the plasticizing cylinder. In a pre-plastic injection device, which is communicated with a resin path of a thin tube having a temperature control means on an outer periphery provided over a path, a resin from the resin path flows in one direction along an inner peripheral surface of an injection cylinder through the inflow path. A pre-plasticity type injection device characterized by being formed so as to be inclined toward the inner peripheral surface. 2. A front end of the plasticizing cylinder is set rearward from a front end of the injection cylinder, and the resin passage extending between an outflow passage and an inflow passage at both end portions is provided at an acute angle toward the front. 2. The pre-plastic injection apparatus according to claim 1, wherein: 3. A pre-plastic injection apparatus according to claim 2, wherein said resin path is provided so as to be inclined at an outer angle of 40 ° to 50 ° with respect to the axis of said plasticizing cylinder.