JPH0490321A - Kneading and injection apparatus for viscous material - Google Patents

Abstract

PURPOSE:To prevent biting inferiority and to attempt to stabilize inside density of a material by providing a plunger surrounding a screw between the inner wall of a cylinder and the screw and forwarding a viscous body in the screw apex direction under pressure. CONSTITUTION:When a plunger 3 is retreated to the rear part of a hopper 4A through a hydraulic cylinder and a brim, a resin 5 enters into a cavity 1C of a heating cylinder 1. Then, a screw 2 is rotated and the plunger 3 for press-forwarding is forwarded while the pressure is controlled, the resin 5 is forcibly pressed in a compression part 8 of an inner wall 1A of a small diameter by rotation of the screw and press-forwarding force of the plunger 3 and is furthermore forwarded to its forwarding direction while it is melted and kneaded. As the result, the resin is started to be stored at the front of the screw 2 and the screw 2 is retreated by the pressure of the resin and when the screw reaches at a preset position, rotation of the screw 2 is stopped to finish kneading and metering. Under this condition, the screw 2 is forwarded to inject the kneaded and metered resin from a nozzle 9.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a viscous material kneading/injection device that is applicable to a plasticizing device of an injection molding machine.

[Conventional technology]

In an injection molding machine or the like, plasticization treatment is performed prior to molding. "Plasticization" refers to pellet-shaped resin in the hopper being taken into the cylinder one by one by rotating the screw and conveyed forward, and at the same time being uniformed by heating from the cylinder's external heater and frictional heat between the resins. This refers to storing a predetermined amount of molten resin at the tip of a cylinder. When resin begins to be stored at the tip of the cylinder, if the molten resin does not leak from the tip, the pressure of the resin itself, which is fed one after another by the rotation of the screw, increases and the screw retreats. Here, when a stop signal for screw rotation is given at a predetermined stroke position, the rotation and retraction of the screw are stopped at that position, and mixing (and metering) is completed. Then, by pushing the screw forward, the kneaded resin is injected from the nozzle tip.

[Problem to be solved by the invention]

However, conventional crosstalk/injection equipment maximizes the frictional force between the heating cylinder and the resin and minimizes the frictional force between the screw and the resin to take in the resin and feed it forward. Heating is essential to ensure strength, and as a result, if the above situation breaks down, so-called poor biting (idling phenomenon) occurs, and there is a problem that it may become impossible to feed the resin with the screw. . That is, the supply section under the hopper serves to feed the resin to the nozzle side, but if there is an obstacle in the supply section, the resin will not move. This obstacle is a ring-shaped object in which molten or semi-molten resin is wrapped around the screw. This occurs because the resin temperature in the supply section is too high (overheated), and because the viscosity of the resin at room temperature is originally too low and it occurs due to backflow from the compression section. When poor biting occurs, the density of the viscous material inside becomes coarse, resulting in a problem that a perfect molded product cannot be produced. In addition, in the past, when two or more materials were mixed and plasticized, if the melting points of the materials were different, there were major constraints on screw drive due to frictional force and viscosity. There were also problems such as receiving the necessary information. The present invention has been made in view of these conventional problems, and aims to prevent poor biting (idling phenomenon) that would make it impossible to continue molding, stabilize the density inside the material, and lower the melting point. Kneading of viscous materials that can be used in combination with virtually any new materials without any restrictions, and also enables low-temperature molding and molding of objects that are already viscous at room temperature without causing clogging defects.・The purpose is to provide injection equipment.

[Means to solve the problem]

The present invention provides an apparatus for kneading and injecting a viscous material such as resin from a hopper into a cylinder using a screw disposed in the cylinder, in which a plunger surrounding the screw is provided between the inner wall of the cylinder and the screw. The above object has been achieved by providing a plunger that can freely reciprocate in the axial direction, and by using this plunger to force-feed a viscous material such as resin that is introduced into the cylinder from the hopper toward the tip of the screw. It is.

[Effect]

In the present invention, a grunger surrounding the screw is provided, and by reciprocating the plunger in the axial direction, the resin between the screw and the inner wall of the cylinder can be forced forward. This makes it possible to cross-mix and stir the resin while forcibly pushing the resin from behind toward the compression part at the tip of the screw, making it possible to prevent poor biting and stabilize the density of the inside of the material. When high kneading is required, this can be achieved by increasing the pumping force of this plunger. For this reason, there is no need to raise the material temperature in the supply section in order to increase the frictional force to 1lffl, so it is necessary to prevent the resin temperature from rising too much to prevent biting defects.
This makes it possible to omit the need for sophisticated material temperature control systems, and enables low-temperature molding if necessary. vinegar,
Materials with different melting points can now be mixed and used with almost no restrictions, and even materials that are already viscous at room temperature can be used without clogging defects.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 1 is a partially cutaway plan view of a plasticizing device for an injection molding machine to which the present invention is applied, and FIG. 2 is a sectional view taken along the line n--2 (when the plunger is retracted). In the figure, 1 is a heating cylinder, 2 is a screw, and 3 is a plunger for pressure feeding. Also, 4A is the hopper mouth, 5
is the resin to be kneaded. The heating cylinder 1 includes a small diameter inner wall IA and a large diameter inner wall IB. Further, the heating cylinder 1 can be separated by a bolt 11 at the joint 10, and by removing the portion having the small-diameter inner wall IA, the screw 2 can be separated.
It is now possible to fully expose the Note that heating in the heating cylinder 1 is performed only in the portion having the small-diameter inner wall IA. The pressure-feeding plunger 3 has a cylindrical shape with a pointed tip 3A, and is disposed between the large-diameter inner wall IB of the heating cylinder 1 and the screw 2. The plunger 3 is configured to be able to reciprocate in the axial direction from the position shown in the figure to the rear of the hopper mouth 4A along with the movement of the piston 7A of the hydraulic cylinder 7 via a flange 6 projecting in the horizontal direction. In addition, the code|symbol 8A of a figure is a resin supply part, 8B is a compression part, and 9
12 indicates a nozzle, and 12 indicates a hydraulic cylinder for pushing out (injecting) the screw 2 in the forward direction. Conventionally, the screw 2 has a spiral shape in the supply section 8 as well, but in this embodiment, since the feeding by the plunger 3 is attempted, the supply section 8 is formed into a simple columnar shape. Next, the operation of this embodiment device will be explained with reference to FIGS. 3 to 5. The resin 5 is stored in the hopper 4, and the hopper mouth 4
It is possible to insert it into the heating cylinder 1 from A. Here, when the plunger 3 is retracted via the hydraulic cylinder 7 and the collar 6 to the state shown in FIG. Next, the screw 2 is rotated, and the pressure-feeding plunger 3 is advanced while controlling the pressure. As a result, the resin 5 is forcibly extruded by the rotation of the screw and the pumping force of the plunger 3 into the compression section 8 of the small-diameter inner wall IA, and is further conveyed to the front of the screw 2 while being melted and kneaded. As a result, resin begins to be stored in front of the screw 2, and the pressure of this resin causes the screw 2 to be retracted (see FIG. 4). When the screw 2 reaches a preset position due to this retreat, the rotation of the screw 2 is stopped, and mixing (and measurement) is completed. From this state, the screw 2 is advanced by the hydraulic cylinder 12, and the mixed and measured resin is injected from the nozzle 9 as shown in FIG. Thereafter, the conditions shown in FIGS. 3 to 5 are repeated. In addition, when high kneading is required, it can be handled by increasing the pumping force of the plunger 3 by the hydraulic cylinder 7. Also, when charging the resin from the hopper 4, the plunger 3
It is also possible to charge a large amount of the resin 5 into the heating cylinder 1 by reciprocating the cylinder several times. Furthermore, in this embodiment of the apparatus, since a part of the heating cylinder can be removed with the bolts 11, maintenance can be easily performed. To explain more specifically, conventionally, there was almost no gap between the inner wall IB of the heating cylinder 1 and the screw 2, so the heating cylinder 1
If you divide the was the number of countries. However, in this embodiment, the hole where the cavity IC exists,
There is no problem, and there is no need for delicate temperature control, so there is no problem (2), so it can be divided. Additionally, since heating in the supply section is not required, low-temperature molding is possible in some cases, and it is also possible to mold products that are already viscous at room temperature without causing clogging defects. . Furthermore, it becomes possible to mix and use materials with different melting points with almost no restrictions. Further, the present invention can be applied not only to kneading for injection molding of resin as described above, but also as a stirring device for extrusion molding, injection blowing, and other viscous materials at room temperature. In addition, it is also effective in injection molding of metal powders and ceramics, which has been attracting attention in recent years, in that it prevents defects in biting and stabilizes compactness.

【Effect of the invention】

As explained above, according to the present invention, since the viscous material is forcibly pumped by the plunger, it is possible to prevent poor biting (idling) that would make it impossible to continue molding, and to stabilize the density and density inside the material. This has the excellent effect of making it possible to increase the In addition, since there is no need to raise the temperature to ensure traction force, delicate temperature control regarding cylinder heating in the supply section, which was previously essential, is no longer necessary, and low-temperature molding can be performed if necessary. This effect can also be obtained. Furthermore, in connection with this, it is possible to use substances having different melting points in a mixture with almost no restrictions, and it is also possible to use substances that are viscous at room temperature.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view showing a plasticizing device of a resin injection molding machine to which the present invention is applied, and FIG.
The sectional views taken along the line II and FIGS. 3 to 5 are front sectional views for explaining the operation of the apparatus of the above embodiment. 3... Plunger, 4... Hopper 4A... Hopper mouth, 5... Resin, 6... Tsuba, 7... Hydraulic cylinder (for plunger drive) 8A...
Supply part, 8B... Compression part, 9... Nozzle, 10... Joint part, 1... Bolt, 12... Hydraulic cylinder (for injection). Sub-agent Takehiro Makino Matsu Kei Yama Yutakaya 1... Heating cylinder, 2... Screw

Claims (1)

[Claims] (1) In a device for kneading and injecting a viscous material such as resin from a hopper into the cylinder using a screw placed in the cylinder, a plunger surrounding the screw is provided between the inner wall of the cylinder and the screw. A method for kneading a viscous material, characterized in that the plunger is capable of reciprocating in the axial direction, and the viscous material such as resin thrown into the cylinder from the hopper can be pumped toward the tip of the screw by the plunger. Injection device.