JPS6359369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to injection and injection stretch blow molding equipment using the hot parison method.

Conventionally, an injection blow molding apparatus using the hot parison method has, for example, a fixed platen equipped with an injection female mold, a movable platen equipped with a blowing female mold, and a support positioned between these two platens movably disposed so as to move back and forth. A rotary body is supported on a support body so that it can be rotated intermittently by 180° with an axis perpendicular to the moving direction of the platen, and a male mold for both injection and blowing having an air slit is fixed to the rotary body, and both male molds are alternately rotated. It is known that the injection mold and the blow mold are engaged with each other to enable injection and blow molding.

However, in this conventional injection blow molding apparatus, (a) After the male mold and the female blowing mold equipped with the parison are closed, air is blown through the air slit of the male mold to perform blow molding, but in this case, the parison and the male mold are Since the parison is in close contact with the mold, and the degree of adhesion differs in each part of the parison, even when blow molding, the parison does not separate uniformly from the male mold and swells unevenly, resulting in the final molded product (container) The thickness distribution of the mold becomes uneven, and in severe cases, molding defects may occur, such as streaks remaining on the molded product as it separates from the male mold.

(b) The male air slit is used during blow molding and must be closed during injection molding, so it is inevitable that the male mold will have a sliding part, and the looseness will cause the parison to have a circumferential slit. Extremely high precision is required in manufacturing the male mold to avoid uneven thickness.

I couldn't escape this drawback.

In addition, as a drawing method based on a conventional injection blowing device, a drawing rod having an air blowing port is slidably incorporated into the male mold, and after injection molding, the injection molded parison is stretched with the drawing rod. Attempts have already been made to stretch-blow by blowing air through an air inlet; Because of this, the parison cannot be cooled sufficiently after injection molding, and it takes time to cool down, lengthening the molding cycle. Especially when molding PET, if cooling is not sufficient, the parison may turn white. .

(b) Although the inner surface of the parison in contact with the male mold is cooled by the male mold from injection to just before blowing, the above (a)
As mentioned above, since it is difficult to cool the parison sufficiently, it is difficult for the parison to reach the drawing temperature.

(c) It is inevitable that the stretching rod etc. inside the male die will have looseness.
If uneven thickness occurs in the parison in the circumferential direction, and the parison and the male die are in close contact, the degree of close contact will differ in each part of the parison, making it difficult to achieve a uniform thickness during stretch blow molding, resulting in defective molding. Otherwise, the final molded product will have a very large uneven thickness.

I couldn't escape this drawback.

The present invention was devised to solve the above-mentioned conventional problems, and includes a movable platen that is movable forward and backward relative to a fixed platen, an injection female mold and a blowing female mold on the fixed platen, and an injection male mold on the movable platen. A mold and a blowing male mold are provided in correspondence with each other so as to be concentrically engaged with each other, a support is provided between the fixed platen and the movable platen so as to be movable relative to the fixed platen, and a rotating body is injected onto the support, The blowing female mold is supported so as to be able to rotate intermittently through 180° with the center between the center lines of the blowing female mold as the center of rotation, and a neck mold that can be opened and closed is supported on the rotating body concentrically with the injection and blowing female molds, and the injection male mold, the female mold, and By configuring the blowing male mold and the female mold so that they can be clamped freely by sandwiching the neck mold, the parison is supported by the neck mold after injection molding and is completely separated from the injection female mold and the male mold, and only the neck mold is used. By transferring the parison to the blowing station by rotation of the blower, the disadvantages of the conventional apparatus are overcome.

Hereinafter, the present invention will be explained with reference to illustrative examples.

In the figure, reference numeral 1 denotes a fixed platen, on which an injection female mold 2 and a split blowing female mold 4 which is opened and closed by an opening/closing device 3 are mounted so that their center lines are vertically or horizontally parallel. 5 is an injection device. Reference numeral 6 denotes a movable platen, which is slidably attached to the tie bar 7 and supported by a mold clamping device (not shown) so as to be movable relative to the fixed platen 1, and an injection female mold 2 mounted on the fixed platen 1. and a blowing male die 10 which has an injection male die 8 and a stretching rod 9 slidably built therein in the axial direction, each of which corresponds concentrically to the blowing female die 4.
is installed.

Reference numeral 11 denotes a frame-shaped support, which is slidably attached to the tie bar 7 between the fixed platen 1 and the movable platen 6, and is attached to the fixed platen 1 by a hydraulic cylinder 12.
It is supported so that it can move forward and backward.

Reference numeral 13 denotes a rotating body, which is rotatably mounted around the center between the center lines of the injection female mold 2 and the blowing female mold 4, and is supported by a rotating device 14 so as to be rotatable through 180 degrees. This rotating device 14 has one end connected to a rotating body 13.
The platen 6 is fixed at the center of rotation and moved at the other end.
A shaft 16 is engaged and connected to a boss 15 rotatably mounted in the center between the injection and blowing male molds 8 and 10 by a sliding key 17, and a pinion 18 formed at the end of the boss 15 meshes with the shaft 16 to move the movable platen. 6 and a rack 20 slidably supported by a hydraulic cylinder 19.
It is composed of.

21 is a split neck type, for injection of the rotating body 13;
It is attached to the side of the female blowing molds 2 and 4 via an opening/closing device 22 so as to be coaxial with both female molds 2, 4, and the opening/closing device 22 opens and closes in the same direction as the opening/closing direction of the female blowing molds. Possibly supported.

Reference numeral 23 denotes a molded product discharge chute, which is provided below the female blow mold 4.

Next, the molding process using this apparatus will be explained with reference to FIGS. 3 and 4.

Figure 3 shows the mold clamped state. In this illustrated state, at the injection station, the female injection mold 2, the neck mold 21, and the male injection mold 8 are clamped together to form a cavity having the same shape as the molded parison, and the molten resin is injected into the cavity by the injection device 5. Thus, a parison P is formed. At the same time as this parison P is formed, at the blowing station, a neck mold 21 holding the previously formed parison P and a blowing female mold 4 are used.
and the male blow mold 10 are clamped together to form a cavity having the same shape as the molded product, and by protruding the stretching rod 9 of the male blow mold 10 and blowing air while stretching the parison P, the molded product W Stretch blow molding.

When injection molding and blow molding are completed, the mold is opened by the mold clamping device, and the movable platen 6 is moved backward. After the movable platen 6 retreats by a predetermined stroke, the support body 11 connected to the movable platen 6 via the shaft 16 of the rotating device 14 follows and retreats by the predetermined stroke to complete the mold opening.

FIG. 4 shows a state in which the molded product W is dropped and discharged after opening the mold. In this illustrated state, at the injection station, the parison P is separated from the female injection mold 2 and the male injection mold 8 and is supported only by the neck mold 21.
At the blowing station, at the same time as the mold opens,
The blowing female mold 4 begins to open left and right, and the neck mold 21
starts to open while contacting the female blow mold 4 so as to move away from the rotating body 13 by the opening/closing device 22, and the molded product W falls into the chute 23 as the female blow mold 4 and the neck mold 21 are opened.

After opening the mold, the neck mold 21 and the female blowing mold 4 are closed, and the neck molds 21 and 21 are rotated 180 degrees by the rotating device 14 to transfer the previously injection-molded parison P to the blowing station and the empty neck mold 21. Transfer to injection station. Next, the support body 11 and the movable platen 6 are moved together to the fixed platen 1 side, the mold is clamped again, injection molding is performed at the injection station, and blow molding is performed at the blowing station, resulting in the state shown in FIG. 3. Repeat each step.

As described above, according to the present invention, the male injection mold 8 is used exclusively for injection molding and cooling the parison after injection molding, and is not used for transporting the parison or stretching blowing, so it has a simple cylindrical shape in terms of structure. The structure can provide a large cooling effect. For this reason, like conventional male molds used for both injection and blowing, heat is gradually accumulated in the male mold over time and the temperature of the male mold rises, causing the parison (male There is no difference in temperature between molds.

Furthermore, uneven thickness of the parison P does not occur due to sliding play, unlike the conventional injection male mold incorporating a blowing slit and a drawing rod.

In addition, in the conventional two-station device configuration, the male die is fixed to an inverter that can rotate 180 degrees in order to be used for both injection and blowing, and the rotating device is large-scale. For example, the support body 11 corresponding to the inverted body is not rotated, and the neck type 21 is
Since it only rotates, it can be rotated easily and the rotating device can be simplified.

Furthermore, since the injection male mold 8 is exclusively used for injection molding, the number of expensive injection male molds 8 can be halved, and the structure is simple, making it possible to manufacture high-precision injection male molds with uniform wall thickness. It is possible to form a parison with a uniform thickness, and since the parison can be formed and cooled (and heated) reliably, uniform (stretching) blowing is possible, and beautiful molded products with uniform wall thickness can be efficiently formed. have an effect.

[Brief explanation of drawings]

Figure 1 is a side view showing one embodiment of the present invention, Figure 2 is a side view showing one embodiment of the present invention;
The figure is a plan view showing the main part in cross section, Figure 3,
FIG. 4 is a side cross-sectional view showing the state when the mold is closed and after the mold is opened, respectively. 1...Fixed platen, 2...Injection female mold, 3...
Opening/closing device, 4... Blowing female mold, 5... Injection device, 6
...Moving platen, 7...Tie bar, 8...Male injection mold, 9...Stretching rod, 10...Male blowing mold, 11...
...Support, 12...Hydraulic cylinder, 13...Rotating body, 14...Rotating device, 21...Net type, 22
...Switching device, 23...Shoot.

Claims (1)

[Scope of Claims] 1. A movable platen is provided so as to be movable back and forth with respect to a fixed platen, and a female injection mold and a female blowing mold are concentrically engaged with the fixed platen, and a male injection mold and a male blowing mold are respectively concentrically engaged with the movable platen. A support body is provided between the fixed platen and the movable platen so as to be movable relative to the fixed platen, and a rotating body is injected onto the support body, with the center of rotation between the center lines of the blowing female mold as the center of rotation. A neck mold which can be rotated intermittently through 180 degrees and which can be opened and closed on the rotating body is supported concentrically with the injection and blowing female molds, and the injection male mold and the female mold, and the blowing male mold and the female mold are connected to the neck molds respectively. An injection blow molding device characterized in that the mold can be freely clamped by sandwiching the mold. 2. A movable platen is provided so as to be movable forward and backward relative to a fixed platen, and a female injection mold and a female blowing mold are provided on the fixed platen, and a male injection mold and a male blowing mold are provided on the movable platen in such a manner that they are engaged with each other concentrically. , a support body is provided between the fixed platen and the movable platen so as to be movable relative to the fixed platen, and a rotating body is injected onto the support body, so that the rotating body can be intermittently rotated by 180° around the center between the center lines of the blowing female mold. A neck mold that can be opened and closed on the rotating body is supported concentrically with the female injection and blowing mold, and the male injection mold and the female mold, and the male and female blowing molds can be freely clamped by holding the neck mold. An injection stretch blow molding apparatus characterized in that the male blow mold has a built-in stretch rod that is slidable in the axial direction of the male blow mold.