JPH06254922A - Plunger type injection molding device - Google Patents

Abstract

PURPOSE:To restrain generation of defective product due to irregularities in filling quantity and molding pressure of molding material for a cavity caused by irregularity in pressure loss due to a runner when a plurality of molded products are to be molded simultaneously and prevent the material from wasting due to the presence of the runner. CONSTITUTION:As many cylinder chambers 24 as the number of cavities are provided in an injection cylinder. Injection plungers 26 are inserted into each cylinder chamber 24. By advance of the injection plungers 26, molding materials in each of the cylinder chambers 24 are injected directly and simultaneously from nozzles 56 provided corresponding to the cylinder chambers 24 through injecting sections corresponding to the cavities of a mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type injection molding device, and more particularly to a device mainly having an injection device.

[0002]

2. Description of the Related Art An injection molding device for injecting a molding material such as rubber or resin from a nozzle portion of an injection device into a cavity of a molding die for molding is widely used. One type of this injection molding apparatus uses a plunger type injection apparatus that injects the molding material inside the injection cylinder by advancing the plunger housed inside the injection cylinder.

In the case of this type of conventional injection molding apparatus, the molding material injected from the nozzle portion at the front end of the injection cylinder is shown in FIG.
As shown in FIG.
4, through the runner portion 106 that is branched into a plurality of parts, flow into the inside of the cavities 108 of the molding dies 100 and 102, and mold into a predetermined shape in each cavity 108.

[0004]

However, in this case, the filling amount of the molding material into each cavity 108 is based on the non-uniformity of the flow resistance and the pressure loss in each of the runner portions 106 that are branched into a plurality of parts inside the molding dies 100 and 102. The molding pressure tends to vary, which is a cause of defective molding. In addition to this, the molding material hardened in the runner portion 106 is discarded, and there is a problem that the molding material is consumed in vain.

[0005]

The invention of the present application has been made to solve such a problem. Thus, the invention of the present application is a plunger-type injection molding in which the molding material supplied to the inside of the cylinder chamber of the injection cylinder is injected into the plurality of cavities from the nozzle section at the tip through the injection section of the molding die by the forward movement of the plunger. In the apparatus, a plurality of cylinder chambers corresponding to the plurality of cavities are continuously provided in the injection cylinder, a plunger is inserted into each cylinder chamber, and a molding material in each cylinder chamber is provided corresponding to each cylinder chamber. It is characterized in that the nozzle portion directly injects into each of the corresponding cavities through an injection portion provided corresponding to each cavity (claim 1).

Another aspect of the present invention is the injection molding apparatus according to claim 1, wherein an extrusion device for pre-plasticizing the molding material and supplying it to the cylinder chamber is provided.
A plurality of introduction passages for introducing the molding material extruded from the extrusion device into each of the cylinder chambers are provided, and a throttle portion is provided for making the inflow amount of the molding material into each cylinder chamber through the introduction passages uniform. It is characterized in that (claim 2).

[0007]

As described above, according to the first aspect of the present invention, a plurality of cylinder chambers corresponding to the cavities of the molding die are connected to the injection cylinder, and the plungers are housed in the respective cylinder chambers. The molding material is directly injected into each cavity by each plunger.

According to the present invention, it is not necessary to provide a runner portion for guiding the molding material injected from the injection cylinder to each of the plurality of cavities, and therefore, due to variations in flow resistance and pressure loss in the runner portion. It is possible to suppress variations in the filling amount of the molding material into each cavity and the molding pressure as much as possible, and it is possible to suppress the generation of defective products due to these.

Further, since it is possible to prevent the molding material from being hardened in the runner portion to cause a material loss in that portion, an effect of improving the material yield can be obtained.

According to the second aspect of the present invention, there is provided an introduction passage for guiding the molding material extruded from the extrusion device to each cylinder chamber, and to make the inflow amount of the molding material into each cylinder chamber through each introduction passage uniform. According to the present invention, even if there is a difference in the distance between the tip nozzle portion of the extruder and each cylinder chamber, the amount of the molding material supplied to each cylinder chamber can be reduced. It is possible to equalize, and in turn, it is possible to equalize the filling amount of the molding material into each cavity of the molding die.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 1, reference numeral 20 denotes an injection device, which includes an injection cylinder main body 22, and the injection cylinder main body 22 is provided with a plurality of cylinder chambers 24.

An injection plunger 26 corresponding to each cylinder chamber 24 is held by a common holding block 28, and is connected to a plunger driving cylinder 30 via the holding block 28.

The plunger drive cylinder 30 includes a sliding body 32.
Further, the slide body 32 is connected to the injection cylinder body 22 via a rod 34, and they are supported by a rail 36 provided on the frame 12 by a drive cylinder 38 attached to the slide body 32. Under the guidance, it can be moved back and forth in the horizontal direction in the figure. The drive cylinder 38 has a cylinder body with a sliding body 3
2 and the rod 40 is fixed to the block 42 whose position is fixed.

On the upper side and the lower side of the injection cylinder body 22, there are provided one pushing device 44 and one pushing device 45, respectively. These extruding devices 44 and 45 preliminarily plasticize a molding material and supply it to the cylinder chamber 24. The extruding cylinder main body 46 and an extruding plunger 48 fitted inside the extruding cylinder main body 46.
And a material injection opening 50 provided on the tube wall of the extrusion cylinder body 46 and a plunger drive cylinder 52 for pushing out the extrusion plunger.

In these extrusion devices 44 and 45, the tip end portion of the extrusion cylinder body 46 is connected to the injection cylinder body 22 via a connection block 54 as shown in FIG. Moves back and forth in the left-right direction in the figure together with 22.

The injection cylinder body 22 has a structure shown in FIG.
As shown in (A), an injection passage 58 for guiding the molding material in each cylinder chamber 24 to a nozzle portion 56 provided corresponding to the molding material and the extrusion device 44 or 45 is extruded. Introducing passages 59, 60 for guiding the molding material to the respective cylinder chambers 24 are provided, and the valve bodies 62, 6 are provided at the connecting portions between the injection passages 58 and the introducing passages 59, 60.
4 are provided.

The connection block 54 is provided with a distribution chamber 66 for distributing the extruded molding material to the respective introduction passages 59 or 60 as shown in FIG. 2B, and the connection block 54 is also provided. A block 70 having a throttle portion 68 for equalizing the distribution of the molding material from the distribution chamber 66 to the respective introduction passages 59 or 60 is interposed between the injection cylinder body 22 and the injection cylinder body 22.

As shown in FIG. 3, the valve bodies 62 and 64 communicate with the first passage 72 for communicating the cylinder chambers 24 with the injection passage 58 and the introduction passage 59 or 60 with the cylinder chamber 24. A plurality of second passages 74 are provided at different axial positions corresponding to the number of cylinder chambers 24, and one of these two types of passages 72, 74 is fixed to the side surface of the injection cylinder body 22. By axial movement of the valve bodies 62, 64 by the valve drive cylinder 76, the valve drive cylinder 76 can be selectively positioned at a position facing the cylinder chamber 24 and the injection passage 58.

Next, the operation of this apparatus will be described. Figure 3 (B)
As shown in (a), the valve bodies 62 and 64 are positioned so that the upper extruding device 44 and the respective cylinder chambers 24 communicate with each other, and the molding material is ejected from the extruding device 44 into the respective cylinder chambers 24.
Supply to.

At this time, the molding material extruded from the extrusion device 44 first flows into the distribution chamber 66, passes through the narrowed portion 68 and reaches the respective introduction passages 59, and further passes through these introduction passages 59 to the respective cylinder chambers. It is sent in 24. Then, by the action of the narrowed portion 68, the molding material is transferred to each cylinder chamber 2
It is sent into 4 with a uniform inflow.

In this way, the molding material is supplied to each cylinder chamber 24, and the injection cylinder body 22 is advanced rightward in the figure as shown in FIGS. 4 (A) and 4 (B).

On the other hand, when the injection of the molding material into the cylinder chamber 24 is completed, the valve body 62 is moved to the cylinder chamber 24 and the injection passage 58.
And a plurality of injection plungers 26 are simultaneously moved forward by the plunger driving cylinder 30 to move the molding material in each cylinder chamber 24 into a plurality of cavities of a corresponding number in the molding die. Direct injection through each injection part.

On the other hand, the extrusion device 44 in which the molding material is supplied to the cylinder chamber 24 by the extrusion of the extrusion plunger 48.
When the extrusion plunger 48 is retracted and the molding material is continuously extruded, but the extrusion of the molding material from the extrusion device 44 cannot catch up with the ejection material injection / molding cycle due to the ejection of the injection plunger 26, In the apparatus of this example, the lower extrusion device 4 with respect to each cylinder chamber 24
The molding material is supplied from 5.

That is, the positions of the valve bodies 62 and 64 are shown in FIG. 3 (B).
After switching to the state of (b), the molding material is supplied from the lower extruding device 45 to the cylinder chamber 24, the valve bodies 62 and 64 are continuously switched to the state of FIG. The injection / molding operation is performed.

As described above, in the case of the apparatus of this example, the molding material can be alternately supplied from the upper and lower extrusion devices 44 or 45 to the cylinder chamber 24, and therefore, when the injection / molding cycle time is short. Can handle this,
Molded products can be continuously produced.

The apparatus of this example does not necessarily consist of a set of extruders 4.
It is not necessary to alternately supply the molding material to the cylinder chambers 24 and 45, and when the molding cycle time is long to some extent, one of the extrusion devices 44 or 4
It is possible to supply the molding material by using only No. 5 and during this, the other extruding device 45 or 44 can be cleaned, inspected, prepared for the extruding operation, and the like.

Therefore, when molding various kinds of molded products with different colors or different kinds of materials, there is an advantage that the switching can be performed quickly and the time for switching can be shortened.

Further, in the case of injection molding the same material, if the two extruders 44 and 45 are used, the capacity of each of the extruders 44 and 45 can be reduced, whereby the length (stroke) of the extruder cylinder can be reduced. It has the advantage that it can be shortened and the injection device can be made compact.

The embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention can be configured in a form in which various modifications are made based on the knowledge of those skilled in the art without departing from the spirit of the invention. is there.

[Brief description of drawings]

FIG. 1 is a partially cutaway view of an injection molding apparatus that is an embodiment of the present invention.

FIG. 2 is a view of a connecting portion between an injection cylinder body and an extrusion device, a valve body for switching a flow path, and a peripheral portion in the same apparatus.

FIG. 3 is an explanatory view of the operation of the valve body in FIG.

FIG. 4 is an operation explanatory view of the injection molding apparatus shown in FIGS.

FIG. 5 is an explanatory diagram of a defect of a conventional injection molding device.

[Explanation of symbols]

 20 Injection Device 22 Injection Cylinder Body 24 Cylinder Chamber 26 Injection Plunger 30 Plunger Drive Cylinder 44,45 Extrusion Device 56 Nozzle Part 58 Injection Passage 59,60 Introduction Passage 62,64 Valve Body 68 Throttling Part

Claims (2)

[Claims] 1. A plunger-type injection molding apparatus for injecting a molding material supplied into a cylinder chamber of an injection cylinder into a plurality of cavities from a nozzle portion at a tip through a pouring portion of a molding die by a forward movement of a plunger to mold the molding material. A plurality of cylinder chambers corresponding to the plurality of cavities are continuously provided in the injection cylinder, and a plunger is inserted into each cylinder chamber, and a molding material in each cylinder chamber is provided from a nozzle portion provided corresponding to each cylinder chamber. A plunger-type injection molding apparatus characterized in that injection is directly performed into each of the corresponding cavities through an injection portion provided corresponding to each cavity. 2. The injection molding apparatus according to claim 1, wherein an extruding device for pre-plasticizing the molding material and supplying it to the cylinder chamber is provided, and the molding material extruded from the extruding device is stored in the cylinder chamber. A plunger-type injection molding apparatus comprising: a plurality of introduction passages introduced into each of them; and a throttling portion for equalizing the flow rate of the molding material into each cylinder chamber through the introduction passages.