JPH0133318Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a temperature control device used when an injection molded parison with a bottom is stretch-blown molded into a hollow molded product.

The method of taking the injection-molded parison out of the injection mold, immediately adjusting it to a predetermined temperature, and then stretch blow molding it into a blow molded product has the advantage that the molding of the parison and the molding of the blow molded product can be performed continuously. However, the temperature of the parison freshly removed from the injection mold is often non-uniform.

If stretch blow molding is performed while the temperature distribution of the parison is uneven, the high-temperature parts will elongate more than the low-temperature parts, and the difference in elongation will cause the thickness distribution of the molded product to become non-uniform. In some cases, the elongation of the high-temperature portion may become so great that it may burst.

Therefore, when performing injection stretch blow molding, the parison temperature is adjusted before stretch blow molding. This temperature control is generally done by heating the parison, but in this case, the temperature of the parison is indirectly controlled using radiant heat, so the heat transfer effect is poor, so the parison temperature is made uniform by partially changing the temperature. It also takes experience to do so.

Some attempts have also been made to adjust the parison temperature by heat conduction. In this case, internal pressure is applied to the parison taken out from the injection mold to bring the outer surface of the parison into close contact with the temperature control member. Temperature control through this close contact has better heat transfer efficiency than when done indirectly, and can adjust the parison temperature to the stretch blow molding temperature in a short time. It is technically difficult to partially change the cooling temperature as in the case of heating, and all parison temperature control is performed at the same temperature.

This idea aims to provide a temperature control device that adjusts the temperature by pressing the parison against a temperature control member, but can also control the temperature from inside the parison, and can also partially adjust the temperature of the parison. It is something to do.

This invention for the above purpose includes a temperature regulating member which is composed of a pair of split molds and has a cavity for controlling the temperature of the parison inside, and a temperature regulating member located above the temperature regulating member.
A neck type having a hole for receiving a blowing rod from above, a core for temperature control and stretching which is inserted into the blowing rod and has a heating medium or coolant passage opened on the side, and a core around the core. It is characterized by consisting of a temperature regulating tube made of rubber or the like, which is fitted into the tube and partially secured in an airtight manner.

This invention will be explained in detail below using illustrated examples.

In the figure, reference numeral 1 denotes a temperature control member, which consists of a pair of split molds 1a and 1a having flow paths 2 and 2 for a heating medium or a coolant, and a hole into which a bottomed parison 3 is inserted is formed on the parting line. There is. Also, temperature control member 1
The cavity 4 varies depending on the molding material, but
The surface area is approximately 1.8 times that of the parison.

Reference numeral 5 is a neck type, which is attached to the lower surface of a transfer plate (not shown) so as to be openable and closable, and has a blowing rod 6 that passes through a core 7 for temperature control and stretching so as to be movable in the axial direction. It has a hole 8 for receiving from the plate side. Although the figure is omitted, this neck mold 5 stops at each position of the injection mold, the temperature control member, and the blowing mold arranged at equal intervals, and the above-mentioned parison 3 formed by the injection mold is stopped. It has a structure that holds the opening and transfers it together with the transfer plate.

The interior of the core 7 is a heat medium or coolant passage 9, and the passage 9 opens at a plurality of locations on the side surface of the core. Further, a tube 10 made of rubber or the like is fitted around the core 7, and the tube 10 is fitted with a member 10 such as a tape or a ring.
It is partially airtightly fastened to the core 7 by the tube a, and expands under the pressure of the heat medium or coolant pumped into the passage 9. Reference numeral 11 denotes an air blowing port provided on the blowing rod 6.

Next, parison cooling temperature control using the device of this invention will be explained in order with reference to FIGS. 1 to 5.

FIG. 1 The injection-molded parison 3 is taken out from the injection mold at the highest possible temperature and is transferred to the temperature control member 1 together with the neck mold 5 in a hollow state. Then, the temperature control member 1 is closed and the parison 3 is placed in the center of the cavity 4.
Set.

Fig. 2 The above core 7 is attached to the neck mold 5 together with the blowing rod 6.
After inserting it into the parison 3, extend it in the axial direction and
Extend it to the bottom of the cavity. As a result of this stretching, the thickness of the parison 3 is reduced in accordance with the stretching dimension.

Although not shown, the blowing rod 6 and the core 7 are connected to a plurality of air cylinders provided above the transfer plate, and are moved in the axial direction by the air cylinders.

FIG. 3 Next, refrigerant is forced into the passage 9 of the core 7 to expand the tube 10. The tube 10 is pressed against the inner surface of the parison 3 and cools the parison 3 from the inside. The cooling time by the tube 10 varies depending on the wall thickness of the parison 3.

FIG. 4 When the predetermined cooling time has been reached, compressed air is blown between the core 7 and the parison 3 from the blowing rod 6, the parison 3 is expanded, and the inside of the temperature control member 1 is expanded. The outer surface of the parison is brought into close contact with the surface under pressure. Since the temperature control member 1 is maintained at a lower temperature than the parison temperature, cooling is performed from the outer surface side of the parison 3 this time. Moreover, since the wall thickness of the parison 3 is further reduced by the expansion, the cooling efficiency is good, and the temperature adjustment can be done in a short time.

FIG. 5 Stops the pressure feeding of the refrigerant to the passage 9, and contracts the tube 10 to its returned state. Although the diagram is omitted, when cooling is completed, return the core 7 to its original position.
It is pulled out from the core mold 5 together with the blowing core 6 above the transfer plate. Further, the temperature-controlled parison 3a is transferred to a blow mold while being held in the neck mold 5 after the temperature control member 1 is opened.

Since this invention comprises the temperature control device as described above, it is possible to heat or cool the parison from both the inside. Furthermore, since temperature control from the inner surface is achieved by the tube's expansion and close contact, the cooling efficiency is better than when a temperature control core is inserted into the parison, and even thick parisons can be heated in a short time. can be adjusted.

In addition, since the tube can be fastened at any position, the expansion of the tube can be partially controlled by tightening, and the temperature of the parison can be partially controlled from the inside.

[Brief explanation of the drawing]

The drawings show one embodiment of the parison temperature control device according to this invention. Fig. 1 is a longitudinal sectional view when the parison is set, Fig. 2 is a longitudinal sectional view when the parison is stretched, and Fig. 3 is a longitudinal sectional view inside the parison. FIG. 4 is a longitudinal cross-sectional view of the outer surface of the parison during temperature control, and FIG. 5 is a longitudinal cross-sectional view of the outer surface of the parison during temperature control. 1...Temperature control member, 3...Parison, 4...Cavity, 5...Net type, 6...Blowing rod,
7... Core, 9... Heat medium or coolant passage, 10
...Tube.

Claims (1)

[Scope of utility model registration request] A temperature control member consisting of a pair of split molds and having a cavity for controlling the temperature of the parison inside, a neck mold located at the top of the temperature control member and having a hole for receiving a blowing rod from above, and a neck mold for receiving the blowing rod from above. A core for temperature control and stretching that is inserted into the rod and has a heating medium or coolant passage opened on the side, and a temperature control core such as rubber that is fitted around the core and partially tightened airtight. A parison temperature control device consisting of a tube.