JPS637128B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the injection molding industry, diversification of products has forced high-mix low-volume production, and opportunities for resin changes and color changes are increasing. Normally, resin replacement involves repeating rotation and injection to purge the resin remaining in the screw cylinder. Next, the resin to be replaced is supplied, rotation and injection are repeated, and the same operation is repeated until the resin replacement is completed. However, the time and resin used during this time are completely wasted.

The present invention has been proposed in order to eliminate the above-mentioned conventional drawbacks, and includes a resin changing block that incorporates a temperature adjusting device and a pressure adjusting mechanism and is rotatably attached to the die head via a hinge mechanism. By applying forced back pressure to the screw and repeating the rotation and injection of the screw while the nozzle is crimped with the pullback cylinder of the injection unit, high pressure,
It is an object of the present invention to provide a method for changing the resin of an injection molding machine, which requires repetition of low pressure, allows rapid resin change, and saves resources, energy, and labor.

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show embodiments of the present invention, in which a resin replacement block 1 of an injection molding machine is connected to arms 4 and 5 by hinge pins 2 and 3. They are connected so that they can rotate freely within the range. Further, the arm 5 is connected via a hinge pin 6 to a hinge block 8 so as to be freely pivotable within a limited range.

The hinge block 8 is attached to the die head 9 with attachment bolts 7. Also, when changing the resin, the resin changing block 1 has one end connected to the hinge block 8.
The other end is rotated so that the arm 4 is in contact with the end surface of the die head 9, and is set on the front surface of the die head 9 as shown in FIG.

In FIG. 2, which is a side sectional view of FIG. 1, a heater 10 is built into the resin replacement block 1, and a temperature control thermocouple 11 is connected to a thermometer (not shown), and by turning the heater 10 on and off, ,
The resin exchange block 1 can be controlled to a constant temperature.

In FIG. 4 showing a detailed diagram of the main part of FIG. 2,
A resin passage ab is provided in the resin exchange block 1, and a pressure adjustment bolt 12 is disposed in the middle thereof as a pressure adjustment means. Then, by turning the spanner hook 13 and tightening or loosening the adjustment bolt 12, the gap d between the poppet 14 at the tip of the adjustment bolt 12 and the seat 15 on the block 1 side can be adjusted.
can be adjusted freely. Further, the straight shaft portion 16 of the adjustment bolt 12 and the hole portion 17 on the block 1 side are loosely fitted so that resin does not leak and can be slid by turning the spanner hook 13.

On the other hand, the entrance of the resin passage a is machined with a concave curved surface 18 that matches the convex curved surface of the nozzle tip so that the resin does not leak when the nozzle 21 is touched. Also, when changing the resin, as shown in FIG. 1, a pullback cylinder 22 fixed to the die head 9 advances an injection unit 23, a part of which is shown in the figure.
Connect the convex curved surface of the nozzle tip to the concave curved surface 1 of block 1.
8 to prevent resin leakage.

Furthermore, during molding operation, the resin changing block 1 is folded by pivoting around the hinge pins 2, 3, and 6 as shown in Fig. 3, and the heater is turned off and left idle on the non-operating side so as not to interfere with the work. It is becoming possible to do this.

Now, the areas where the most problems arise when changing the resin or color are the surface e of the torpedo 26 at the tip of the screw 25 and the inner wall surface f of the end cap 27. Conventionally, when changing the resin, the resin was simply dripped from the nozzle 21 while changing the resin, so in this case, the surface e was
However, since the pressure generated on the inner wall surface f was low, the resin change in this area was slow, and it was necessary to repeat the screw rotation and injection for a long time until the resin change was completed, resulting in extra time and resin was wasted.

To explain in more detail, when a control circuit (not shown) is used to select the screw back pressure and rotate the screw, high pressure can be generated on the screw tip surface e, but since there is no pressure generation mechanism, the molten resin is flows out, becomes an effective pressure, and the surface e
and does not act on the inner wall surface f.

In the present invention, since the resin is dripped from the nozzle 21 through the temperature-controlled resin changing block having a pressure generating mechanism, the resin changing block 1 is pressed with the nozzle 21 by the pullback cylinder 22, and the plastic is By repeating oxidation and injection, it is possible to constantly generate stable high pressure.

Also, the pressure adjustment bolt 12 of the resin replacement block 1
By setting the clearance d appropriately, even if the screw is rotated with back pressure applied,
The pressure back-up in the gap d is large, and the screw back pressure set by a control circuit (not shown) can be applied extremely effectively to the surface e and the inner wall surface f.

Furthermore, even during injection without rotation of the screw, the gap d
Since the screw tip pressure is maintained at an extremely high pressure similar to when the screw is rotated, shear shear stress acts on the surface e and the inner wall surface f under high pressure, and resin replacement is quickly promoted.

As explained in detail above, in the present invention, when changing the resin, forcible back pressure is applied to the screw while the nozzle is crimped to the resin changing block, and the screw is rotated and injected repeatedly to change the resin.
Since a pressure shock is automatically (unattended) applied to the stagnation area, resin replacement can be completed in a short time, resulting in significant energy and resource savings. Furthermore, since the resin replacement block of the present invention has a built-in temperature adjustment device, the flow of resin, that is, the resin replacement, can be performed extremely smoothly.Furthermore, the block is rotatably attached to the die head via a hinge mechanism. Therefore, the resin can be changed quickly. That is, when the resin is not being replaced, it is rotated to the opposite side of the operation so that it does not interfere with the work, and is left idle.
Since it can be quickly rotated and placed at the nozzle position when changing the resin, it has many excellent effects such as being able to quickly change the resin.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an apparatus for carrying out a resin changing method for an injection molding machine according to an embodiment of the present invention, Fig. 2 is a sectional view of the same side, and Fig. 3 is a molding operation in which the resin changing block is rotated. FIG. 4 is a detailed view of the resin replacement block in FIG. 2. Explanation of the main parts of the figure, 1...Resin replacement block, 9...Die head, 10...Heater, 11...
... Temperature control thermocouple, 12 ... Pressure adjustment bolt, 21
... Nozzle, 22 ... Pullback cylinder, 23
...Injection unit, 25...Screw.

Claims (1)

[Claims] 1. When changing the resin, the nozzle is forced into the screw with the pullback cylinder of the injection unit when changing the resin, which has a built-in temperature adjustment device and a pressure adjustment mechanism and is rotatably attached to the die head via a hinge mechanism. A resin change method for an injection molding machine, which is characterized by applying back pressure and repeating the rotation and injection of a screw to change the resin.