JPS6130821Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hot runner mold structure for an injection molding machine. In injection blow molding,
The injection-molded bottomed parison is taken out of the cavity mold in a semi-molten state and transferred to a blowing mold. For this reason, since the gate portion was also semi-molten, twining was likely to occur, but this problem was resolved by adjusting the molding conditions.

In the present invention, the nozzle of the hot runner is rotated while being pressed against the cavity gate at a constant pressure, and is mechanically shut off and cut to prevent stringing.

Conventional hot runners can be roughly divided into two types: 1) open type gates and 2) valve type gates, but the former requires high precision in nozzle temperature control, and is economical because it is controlled for each nozzle. Sexually undesirable. Also, as a result of insufficient temperature control,
If the temperature of the nozzle part is too high, stringing will occur and the resin in the nozzle will flow into the cavity. On the other hand, if the temperature of the nozzle part is too low, the gate part becomes overcooled, resulting in a blind plug state, which causes problems such as making injection impossible. In the latter case, a needle is placed in the resin passage and the gate is mechanically opened and closed using this needle, so there is no phenomenon of the thread flowing into the thread or the cavity, but since the needle is incorporated, the structure becomes complicated.
Weld lines, spider marks, and torpedo marks may occur depending on the plastic material used.

The present invention is an improvement over the prior art as described above, and will be explained below with reference to the drawings. Reference numeral 1 denotes a platen, to which one or more female cavities 2 for injection molding are removably attached. A is a cavity gate, around which a heat insulating plate 6 is press-fitted. A nozzle 5 built into the hot runner body 3 whose temperature is controlled by a heater 4 contacts the end face of the cavity gate A only during injection; , drive cylinder 10
As a result of the output of
The nozzle 5 can be positioned on the heat insulating plate 6 by rotation.

Reference numeral 11 denotes a stopper which limits the position at which the rotation returns during injection. 7 is a spring, and even when the injection molding machine main body 12 is retreated after injection is completed,
A constant pressure acts to press the nozzle 5 against the heat insulating plate 6 for heat insulation of the cavity, thereby preventing resin leakage within the hot runner. Note that the shaft 9 is a bearing 8
It is pivoted on. 13 is a cooling groove. Further, in this embodiment, the cavity 2 is attached to the platen 1, but it is possible to use a movable platen or to use a hydraulic cylinder or the like instead of the spring 7 to bring the hot runner 3 into contact with the platen. Needless to say, the configuration can be changed.

In addition, in order to ensure that the gate hole of the nozzle part is located on the insulating plate after rotation, when installing multiple hot runner blocks, the hot runner block is divided into multiple rotation axes so that each block can be rotated independently. (Figure 3).

With the above configuration, the nozzle 5 is in contact with the heat insulating plate 6 at a constant pressure by the spring 7 etc. except during injection molding.
Since the nozzle 5 is thermally insulated from the high temperature and the low temperature of the cavity 2, the resin remaining at the tip of the nozzle 5 for the next shot is also kept at a constant temperature. Furthermore, since resin leakage from the nozzle part due to the internal pressure of the hot runner can be prevented, the shot will not be adversely affected.

Next, when the hot runner main body 3 is rotated by the drive cylinder 10 with the shaft 9 as the rotation axis, it is stopped by the stopper 11 and the cavity gate and nozzle gate are aligned, so that the molding machine main body immediately contacts the hot runner inlet and injection starts. It becomes moldable.

When the injection molding is completed, the molded product is cooled and then taken out from the cavity 2. However, before taking it out from the cavity 2, the molding machine is moved backwards, and then the nozzle is rotated by the action of the drive cylinder 10, and the cavity gate and nozzle gate are Mechanically interrupts and cuts the resin that is connected to the Therefore, the gate cut portion is beautiful, strings are less likely to occur, and the molding conditions such as cooling water temperature, water amount, cooling time, etc. do not affect much.

Therefore, in the conventional open gate, the thread
Molding conditions (resin temperature, cooling water temperature, water volume, cooling time) were adjusted to prevent resin leakage due to hot runner internal pressure, but the range of optimal conditions was extremely narrow as this was related to other causes of molding defects. limited to a range,
Setting it requires great skill.

In addition, valve type gates have a complicated structure, resin leaks from the valve, and in cases where good appearance is not required, weld lines from the needle holding mechanism and torpedo marks may be formed poorly, so there are restrictions on the materials that can be used. There is. However, according to the present invention, the gate part is mechanically cut off and there is no obstruction in the resin passage in the hot runner, so weld lines and torpedo marks do not occur. The nozzle gate is completely sealed except during injection and is located on a heat insulating material, so it is possible to maintain perfect temperature and there is no resin leakage, improving the quality of molded products and molding operability. It is possible to improve the

[Brief description of the drawings]

Figure 1 is a longitudinal sectional view of the hot runner mold, Figure 2
The figure is a left side view of FIG. 1, and FIG. 3 is an embodiment in which the rotating shaft 9 is complicated. In the figure; A...gate, θ...movement angle,
1... platen, 2... cavity, 3... hot runner mold, 4... heater, 5... nozzle,
6...Insulation plate, 7...Spring, 8...
Bearing, 9...shaft, 10...drive cylinder, 11...
...Stopper, 12...Injection molding machine body, 13...
...Cooling grooves.

Claims (1)

[Scope of utility model registration request] A platen 1 has a cavity 2 provided at a certain distance from a rotary shaft 9 rotatably provided in the center, and a cavity 2 facing the platen 1 and fixed to one end of the rotary shaft 9, always on the platen 1 side. A hot runner main body 3, which is attracted to the nozzle A of the cavity 2, has a nozzle 5 concentric with the nozzle A of the cavity 2, and is rotatable around a rotation axis 9 by a drive device. Runner mold structure.