JPS5926235A - Injection molding machine - Google Patents

Abstract

PURPOSE:To prevent the back flow of molten resin by using a system in which the starting position of injection is controlled to mutually couple a nozzle with a screw head during the stamping molding period in an injection molding machine for stamping molding. CONSTITUTION:During the stamping molding period, a nozzle 4 is contacted with the sprue 7b of molds 2, the screw 6 is advanced, molten resin is injected, and at the same time as the packing of the resin is finished, the starting point of injection, or the position of the screw 6 for weighing completion, is regulated to fit the convexed portion 9a of the screw head 9 into the concaved portion 4b of the nozzle 4 by a much as l1. Subsequently, stamping molding is made. In this case, the resin in the molds 2 is compressed by a great force resulting from the variations in the volume of the molds 2 and is ready to flow back into an injection cylinder 5 from the gate 7d, but the back flow is prevented by the close fitting of the concaved portion 4b with the convexed portion 9a. Good appearance molding with high accuracy and without sink caused by cooling can be attained.

Description

[Detailed Description of the Invention] This invention deals with the problem of heat melting and crosstalk. The present invention relates to an injection molding machine that injects and fills a mold into a mold for a predetermined period of time, cools and solidifies it, and then takes it out as a molded product, and particularly relates to an injection molding machine that enables stamping molding.

When injection molding a resin such as plastic, there is a problem in which the molten resin filled in a mold contracts during the cooling process, causing so-called molding sink. As a means to prevent this "sink 2", when clamping the C1 mold, stop the clamping a little before the mold clamping is completed, inject the f1 molten resin, and then After the injection into the mold is completed, the mold is clamped until the mold is closed, and the molten resin inside the closed mold is pressurized to prevent so-called "sink marks" that occur on the surface of the molded product due to cooling and shrinkage. Stamping molding is being carried out.

However, in this stamping molding, the mold is first filled with molten resin and then the mold is clamped, so a huge pressure is applied to the molten MIII resin in the mold when the mold is clamped, so the molten resin in the mold is Backflow/nozzle into the injection cylinder through the nozzle
There are some things. When this reverse 3f occurs, in order to prevent the depression phenomenon 1' which occurs on the surface fil of the molded product due to cooling shrinkage, it is necessary to reduce the temperature of the mold. 8/il! The pressure applied to the oil will escape, and the anti-sink effect will be lost.

For this reason, the following method has conventionally been used to prevent the backflow of molten resin.

(1,) Key for filling the mold with molten resin) - Keep the injection gate to the biddy as small as possible, melt the gate, cool and solidify the resin early, and shut off the gate and melt the inside of the cavity () 7J Prevents fat from flowing back through the dirt.

■ Make the gate 41 yen so that it can be opened and closed, and close it only during injection to prevent backflow.

However, in the case of (2), the application of the molded product to be molded is limited (and since the gate is made as small as possible, it is inevitable that the injection resistance will be large and the injection time will be long, etc.).

In the case of freezing, it is necessary to incorporate a device for closing the gate υ] into the mold, and disadvantages such as the need for control and a miscellaneous force to synchronize the movement of all IJFI closing devices. There is.

This invention was devised in view of the above-mentioned problem (WK), and its purpose was to provide a mechanism that has a simple structure and reliably prevents the backflow of molten resin in the nozzle part that injects molten resin into the mold. By setting up the gold bar 1 and the inner tree 1]
]) In the 7th hour to prevent backflow in step 1, the inside of the mold is equipped with additional measures, and stamping molding is possible without the need for a special control device in the mold. Our objective is to provide an injection molding solution.

According to this invention, the nozzle is brought into contact with the sprue of the mold (I): Insertion (after filling the molten resin, the second mold clamping (stamping) is performed with the gate closed with the nozzle).
This is to prevent the molten resin in the key Y bit f from flowing backwards into the injection cylinder through the gate and runners.

The invention will now be described with reference to the embodiment shown in FIG.

Stamping molding nJ'61'! Injection molding 11
is the injection stamp mold 2, the number of molds to be removed from this mold 2 (; J plate 3, and the number of molds injected into the metal adhesive 2
Is this nozzle the tip of the nozzle 4 that is in contact with the sprue 7b, which will be described later? '? An injection cylinder 5 installed in the injection cylinder 5, a screw 6 installed in the injection cylinder 5 so as to be rotatable and movable, and a drive device neck (Fig. 1
The supply device that supplies resin to the injection cylinder 5
, (not shown).

The mold 2 has a cavity mold 7 having four parts 7 (F).
The cavity mold 7 and the core mold 8 are each mounted on the mounting plate 3. Then, a convex part 8α is formed in the concave part 7a so that the vff can be lowered from each other, and as shown in FIG. The mold is injected into a mold 7, and after being injected, the mold can be further clamped by a distance L2 for stamping molding. In addition, attach the sprue 7b to the cavity mold 7 and the part where the nozzle 4 comes into contact with it, and also apply the thinner 7
C and the gate portion 7d have been formed.

The nozzle 4 has a nozzle hole 4α for injecting the molten resin.
A fitting recess 4b is formed which is connected to the nozzle hole 4cL.

Furthermore, the screw head 9 is struck at the tip of the screw 6 with t, I4, and the tip of this screw spatula 1°9? V
B Vc#” 1, front flil of nozzle 4 1tl+
4b An Ic-tight fitting protrusion 9a is formed.

Therefore, the fitting protrusion 9α of the screw head 9 is fitted into the (1'J4 fitting recess 4b) of the nozzle 4 after the screw 6 moves forward and injection of the molten 4I111Jtj is completed.

This invention e"2 does not consist of 4.
The nozzle 4 is placed in contact with the nozzle 4, and the screw 6 is driven while feeding the raw material ψ into the injection cylinder 5 by the fat feeding device tffi. Heat well, melt, and mix 1.

The molten W (crosswired resin t'1) is gradually sent out in front of the screen IJ- (i), and the pressure causes the SIF IJ j--6 to retreat, and in front of the injection cylinder 5 +;++ (nozzle 4 When the molten fat is accumulated (screw 6 position when one plate is completed), the screw 6 is retracted at the predetermined distance 1 (16).

-6 stops rotating and also stops moving backward. On the other hand, mold clamping was performed leaving a distance N#, t2 between the cavity mold 7 of the mold 2 and the core IFH'J8 as shown in the tn1 diagram.

Next, set the A motion, move the screw 6 forward, and inject 1ill of resin into the mold 2. Simultaneously with the completion of injection and filling into the mold 2, the fitting protrusion 9n of the screw head 9 is fitted into the fitting recess 9a of the nozzle 4 by a distance t1 as shown in FIG. The injection C to 1 starting point by the screw 6 (screw G(i)': I hood of completed cutting depth) is accumulated.

Next, after completing the filling of the molten resin into the mold 2, the amount remaining after mold closing (the first
Perform mold clamping or stamping with a distance of 1'll & t2) shown in the figure.

At this time, the rlW melted wood 1I that has been injected into the mold 2 in advance
) H is compressed with a strong force due to the volume change inside the mold 2. At this time, -fi1 (re1,
Gate part 7d and runner 7 o Th from inside mold 2
;in') The flow tries to flow backward from the nozzle hole 4a into the injection cylinder 5, but is it the other way around? If, 4 nozzles are 1)
As shown in FIG. 2, this can be prevented because the IJχ self-convex portion 9a of the screw head 9 is tightly fitted into the fitting recess 4b of the nozzle 4. At this time, the forward force F of the screw head 9 is controlled by 11 rivers so that the diameter of the fitting convex portion (L is dl). When the fitting protrusion 9α is inserted into the fitting recess 4b of the nozzle 4, the forward force F of the screw head 9 is concentrated on the diameter d of the fitting protrusion 9a when filling is completed. ,
The high pressure that comes with it can make you bleed.

Then, in mold 2, is the tree lIl+? After cooling and solidifying,
Gold 4jlJ 20 mold clamping 4: Release and take out the molded product IIQυ.

Next, turn the screw 6 again to III to melt the resin.
? , Irl! l? When I start, it's like IVJ
The oil is injected into the front of the screw 6 through the injection cylinder 5, and the screw 6 is retracted by the pressure of the oil (frJ). When it is pulled out and the 131 pores Jn' are completely filled, it is injection molded into the mold 2 in the same manner as described above.

Injection molding is performed by repeating this process one after another.

FIG. 116 shows another embodiment of the nozzle 4 and the screw 6, in which the nozzle hole 4α of the nozzle 4 is connected to the screw head 9.
It is formed so as to be closed by pressure. The pressing force y at this time is F'=F---d''xP, where dl is the diameter of the part that contacts the nozzle hole 4a of the screw head 9. HM 1
By doing this, backflow can be prevented.

This invention has the effects described in υυ(J-) with the above-mentioned configuration.

By forming a screw head in the nozzle hole of the nozzle to a tight fit and controlling it so that it fits tightly during scumbing molding, the resin in the mold can be tightly fitted into the mold during scumbing molding by using a relatively simple n-piece construction. It is possible to reliably prevent the injection from flowing back into the injection cylinder.
It is possible to mold high-precision and clean molded products without cooling shrinkage.

[Brief explanation of the drawing]

Figure 112 is a 411°C schematic cross-sectional view of the injection molding machine capable of stamping molding of the present invention, Figure 112 is a cross-sectional view showing the state of the nozzle and screw when injection is completed, and Figure 6 is a diagram showing the relationship between the nozzle and the screw. It is a sectional view showing an aspect. 1...Injection molding machine, 2...Mold, 3.
...Mounting plate, 4...Nozzle, 4α...
... Nozzle hole, 4b... Fitting recess, 5...
Injection cylinder, 6... Screw, 7...
・Cavidy type, 7a, ・・Recessed part, 7b...
... Sprue, 7 (+ ... Runner, 7d
......Gate part, 8...Core type, 8a.
...Protrusion, 9...Screw head, 9
a...Fitting convex portion, l-1, t2...Distance, dt, dx-...Diameter. Figure 1 Figure 3

Claims (1)

[Claims] It is arranged so that it can rotate and move forward and backward inside the injection cylinder.
! ! The screw head of the screw that can be injected into the mold through the nozzle hole is formed so that it can be held in the nozzle hole, and after injecting the resin of a predetermined claw into the mold, stamping molding is performed. /f? This is an injection molding machine that is capable of stamping molding.