JPH0521056B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a biaxial stretch blow-molded bottle made of synthetic resin, particularly polyethylene terephthalate resin.
This invention relates to a heating device for a preform that is a next molded product, and more specifically, the purpose is to heat a preform in the shape of a cylinder with a bottom well from both the inside and outside.

[Conventional technology]

Biaxially stretch blow-molded bottles made of synthetic resin, especially polyethylene terephthalate resin, have the advantages of being able to obtain large-capacity bottles with a small amount of synthetic resin material, and by imparting biaxial stretch molding to the synthetic resin material. As a result, it has been shown to have excellent effects such as being able to effectively bring out the excellent physical properties of this synthetic resin material, but recently there has been a trend to form larger bottles by increasing the amount of stretching. It's getting stronger.

In this way, in order to mold a larger bottle with a larger amount of stretching, the wall thickness of the cylindrical portion of the preform, which is the primary molded product, must be set to a sufficiently large value.

It is easy to mold a preform with a sufficiently large cylindrical wall thickness, but it is difficult to form a preform with a large cylindrical wall thickness into a bottle by biaxial stretch blow molding. There has been no effective means to uniformly heat the material to a certain temperature that can effectively make it appear.

In other words, if the preform is rotated and run through a heating furnace using a heater and heated only from the outside, as with conventional heating methods, the entire cylindrical part of the preform cannot be heated to a uniform temperature. It takes a long time to heat the bottle, and it takes too much time to form a single bottle, resulting in extremely low productivity.The heating furnace also becomes larger, which increases equipment costs. will occur.

For this reason, it is possible to raise the heating temperature sufficiently to increase the heating rate for the preform, but if the preform is heated rapidly, there are disadvantages such as whitening or hardening of the rapidly heated outer part of the preform. However, there are significant limitations on increasing the heating rate.

Therefore, conventionally, as a heating means for a preform whose cylindrical portion has an increased wall thickness, a means has been adopted that simultaneously heats the preform from both the inside and outside.

Heating the preform from both the inside and outside has the effect of increasing the heating rate and uniformly heating the entire cylindrical part of the preform, thereby achieving extremely good biaxial stretch blow molding. There are advantages that can be achieved.

[Problem that the invention seeks to solve]

Conventional methods for heating the preform from both the inside and outside sides include arranging a heater in an upright position within the preform, or arranging a rod-shaped heating element that generates heat through high-frequency induction heating within the preform. However, in the case of a heater placed inside the preform, the structure for supplying power to the heater becomes complicated, and the structure for supplying power becomes prematurely damaged due to the high temperature inside the heating furnace. Furthermore, since the inside of the preform forms a nearly closed space, there is a problem that the heating of the inside of the preform by the heater tends to overheat. In the case of a device in which a heating element is arranged, there is a problem in that it is difficult to control the temperature of the heating element and it is impossible to obtain the required heating temperature value and heating temperature change.

[Means to solve the problem]

The present invention is configured to solve the problems and drawbacks of the conventional example described above and achieve rapid heating of a good preform, and uses a heat pipe as a heating source from the inside of the preform. It is composed of

Hereinafter, a heating device according to the present invention will be described with reference to drawings showing an embodiment of the present invention.

The heating device according to the present invention is a heating device for a preform P which is a primary molded product of a biaxially stretched blow-molded bottle made of synthetic resin, and includes a heating furnace 4 for heating the preform P from the outside, and a heating furnace 4 for heating the preform P from the outside. A heat pipe 1 is held in a fixed position with one end of the action part 2 inserted therein and the other end of the input part 3 facing the heat source 7, and the action of this heat pipe 1. Preform P in part 2
and an assembly mechanism 8 for assembling and holding in a fixed posture in a fitted state.

The heat pipe 1 is capable of transmitting heat extremely efficiently and at an extremely fast speed by using the heat of vaporization of a liquid. It is quickly transmitted to the kiln making section 2 and acts to cause the operating section 2 to generate heat at a desired temperature.

The heating furnace 4 that heats the preform P from the outside of the heat pipe 1 has exactly the same structure as a conventional heating furnace, and generally uses an infrared far-infrared heater 6 as a heating source. wall 5
They are arranged in parallel inside.

The heating control of the preform P by the heating furnace 4 is achieved by controlling the supply of electric power to each heater 6.

The heat source 7, which the input part 3 of the heat pipe 1 is located opposite to, is not specified in its heat source or structure, and may use the same infrared far-infrared heater as the heater 6, or may use a high-frequency induction heating mechanism. Alternatively, a heating fluid such as a heating liquid or a heating gas may be used.The point is that the input section 3 of the heat pipe 1 can be heated accurately to the desired temperature. It's good to have it.

The assembly mechanism 8 attaches the preform P to the heat pipe 1 until the heating of the preform P is completed.
However, maintaining the preform P in a constant position with respect to the heat pipe 1 means that the position of the heating furnace 4 is It is necessary to hold the preform P in a constant position with respect to each heater 6, and therefore, this assembly mechanism 8 needs to be assembled in a constant position with respect to both the heat pipe 1 and the heating furnace 4. It turns out.

[Effect]

Since the heating device according to the present invention has the above-described configuration, the preform P is in the state shown in the drawing.
When the preform P is assembled, power is supplied to each heater 6 of the heating furnace 4 to cause each heater 6 to generate heat, and the input part 3 of the heat pipe 1 is heated by the heating source 7. Each heater 6 on the outside
Since the inside of the heat pipe P is heated by the working part 2 of the heat pipe P, it is heated from both the inside and outside at the same time.

Therefore, the entire preform P is heated extremely rapidly, and the heating state can be made uniform.

Furthermore, the heating of the preform P by the action part 2 of the heat pipe 1, that is, the amount of heat generated by the action part 2 is:
Since the degree of heating of the input section 3 by the heating source 7 is faithfully followed, by appropriately controlling the amount of heat of the heating source 7, the preform P by the heating furnace 4 can be
Similarly to the heating of the preform P by the working part 2,
Inner heating can be controlled freely.

〔Example〕

In the illustrated embodiment, the heat pipe 1 is held in an upright position by a holding mechanism 9, with its lower end serving as an input section 3 and its upper end serving as an action section 2.

The assembly mechanism 3 is configured to be detachably assembled to the holding mechanism 9 while being fitted to the heat pipe 1, and is thus assembled to the holding mechanism 9 while being fitted to the heat pipe 1. As a result, it is possible to assemble the heat pipe 1 while maintaining a constant positional relationship and a constant posture without applying a mechanical load to the heat pipe 1.

The heating furnace 4 is configured such that the heater 6 disposed within the furnace wall 5 is positioned only on one side of the preform P into which it is inserted;
This is because the preform P that has entered the interior moves while rotating on its axis, and since the moving preform P rotates on its axis, it is not necessary to arrange the heaters 6 on both sides of this preform P.

Corresponding to the structure of the heating furnace 4, it goes without saying that the holding mechanism 9 is installed so that it can travel while holding the heat pipe 1 in a fixed position, that is, in an upright position. It is necessary to have a configuration that can heat the input section 3 of the heat pipe without any trouble regardless of the displacement of the traveling heat pipe 1.

In this regard, the input section 3 of the heat pipe 1 can be located sufficiently far away from the inside of the heating furnace 4, so that the heating source 7 can be configured almost freely, thereby making it possible to configure the input section 3 with no interference. It is easy to obtain a heating source 7 that can be heated without any heating.

For example, when the heat source 7 is configured with the same heater as the heater 6, this heater may be placed along the traveling locus of the heat pipe 1 in the same way as the heater 6 of the heating furnace 4; When the heat pipe 7 is configured using a heating fluid, a groove structure capable of storing and holding the heating fluid may be arranged along the travel locus of the heat pipe 1.

Further, it is preferable that the heat pipe 1 be allowed to move downward relative to the assembly mechanism 8, so that the heat pipe 1 and the assembly mechanism 8 can be easily attached and detached.

Furthermore, in order to rotate the preform P, the assembly mechanism 8 is assembled so as to be rotatable around the heat pipe 1, but the reason why the heat pipe 1 is fixed as a rotating shaft is because the heat pipe 1 is mechanically attached to the assembly mechanism 8. Since the preform P is multiplied by a negative value, when the preform P is rotated, this preform P
That is, the heat pipe 1 is integrated with the assembly mechanism 8.
Advantageously, it is configured such that the device also rotates.

〔Effect of the invention〕

As described above, since the heating device according to the present invention uses the heat pipe 1 as a heating source from the inside of the preform P, temperature control of the heat source for heating the preform P from the inside can be achieved smoothly and accurately. As a result, good heating control of the preform P can be achieved.

In addition, since various heat sources can be used freely as the heating source 7 of the heat pipe 1, the heating to the preform P can be set freely, and thereby the heating form for the preform P from the outside can be changed. Since the entire preform P can be heated in a suitable heating state, more uniform heating of the preform P can be achieved.

Furthermore, since the part that heats the inside of the preform P, that is, the action part 2, and the part that faces the heat source 7, that is, the input part 3, can be sufficiently separated, the configuration of the heat source 7 can be set freely. Moreover, since it can be installed without being obstructed by the heating furnace 4, the entire apparatus can be manufactured easily and satisfactorily.

Furthermore, since the acting part 2 of the heat pipe 1 generates heat at a uniform temperature over its entire surface, the heating of the preform P becomes uniform, thereby making the heating state of the preform P more uniform. Become.

As is clear from the above description, the heating device according to the present invention can smoothly and efficiently heat the preform from the inside, and therefore can be used in combination with conventional heating means from the outside to heat the preform from the inside. The heat pipe can be heated quickly and easily, and the heating source of the heat pipe can be freely selected and used without being specified. It has many advantages, such as smoother, more accurate and easier heating control, and its simple configuration means it can be implemented inexpensively and easily in both new and existing installations. It has a very effective effect.

[Brief explanation of the drawing]

The drawing is a front sectional view showing the basic configuration of the heating device according to the present invention. Explanation of symbols 1; heat pipe, 2; action part,
3; input section, 4; heating furnace, 5; furnace wall, 6; heater, 7; heating source, 8; assembly mechanism, 9; holding mechanism, 10; preform.

Claims (1)

[Claims] 1 A heating device for a preform P which is a primary molded product of a biaxially stretched blow-molded bottle made of synthetic resin, including a heating furnace 4 that heats the preform P from the outside, and one end portion inside the heating furnace 4. The acting part 2 is
the input section 3 which is the other end.
a heat pipe 1 which is held in a constant position facing a heat source 7; and an assembly mechanism 8 which assembles and holds the preform P in a fixed position in a fixed position on the working part 2 of the heat pipe 1. A heating device consisting of.