JP2003053825A - Stretch blow molding method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow molding method and apparatus capable of favorably molding a container or the like even with polyethylene, polypropylene, a copolymer of polyethylene, or the like. SOLUTION: A preheating unit 10 for preheating a workpiece.
A non-heating unit 13 for keeping the preheated workpiece in a non-heating state, a main heating unit 11 for fully heating the workpiece after being placed in the non-heating state, and a workpiece after the main heating And a stretch-blow molding section 14 for stretch-blow-molding the workpiece, and a heat retaining section 12 for keeping the workpiece after the main heating. Further, a conveyor 6 is provided from the preliminary heating unit 10 to the main heating unit 11 and the heat retaining unit 12 for holding the workpiece and continuously transporting the workpiece.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch blow molding method and apparatus used for producing various containers and the like from resin.

[0002]

2. Description of the Related Art As is well known, the stretch blow molding method is a molding method suitable for molding resin containers and the like. Among these stretch blow molding methods, cold parison method has recently been used especially for manufacturing various bottle products. Is often used. This molding method
A bottomed tubular preform is molded in advance, and this preform is heated and fed into a mold for stretch-blow blow molding.

In this molding method, polyethylene terephthalate is frequently used as a material for molding various bottle products, for example. This kind of material is often used because, when a prefabricated preform is heated, the softening of the resin gradually progresses as the temperature rises, and it is easy to control the resin during stretch blow molding. . On the other hand, as a material for this type of product, it is desired to use a material such as polyethylene or polypropylene.

[0004]

However, when polyethylene or polypropylene is used in the cold parison method, when the preform is heated and heated in the heating step, it softens from the time when it exceeds a predetermined temperature.・ Melting progressed rapidly, making it difficult to control the resin molding and making it difficult to obtain the desired product. This tendency also applies to the copolymer of polypropylene and polyethylene, and it has been difficult to manufacture products.

The present invention has been made in view of the above circumstances, and an object thereof is a stretch blow capable of favorably forming a container or the like even when polyethylene, polypropylene, a copolymer of polyethylene or the like is used. It is to provide a molding method and apparatus.

[0006]

In order to achieve the above object, the present invention provides the following means. Claim 1
The invention according to, the first step of preheating the workpiece,
The second step of placing the preheated workpiece in the non-heated state, the third step of main heating the workpiece after the non-heated state, and the stretching of the workpiece after the main heating And a fourth step of blow molding. According to the stretch blow molding method of the present invention, the temperature of each part of the workpiece is made uniform by placing the workpiece after preheating in an unheated state. Then, after the main heating and the stretch blow molding, the intended product is obtained.

According to a second aspect of the present invention, in the stretch blow molding method according to the first aspect, there is provided a heat retaining step of retaining the temperature of the workpiece after the main heating. According to the stretch blow molding method of the present invention, since the workpiece is kept warm after the main heating, the temperature of each part of the workpiece is made uniform even in this warming step, and the stretch blow molding is performed well.

According to a third aspect of the present invention, in the stretch blow molding method according to the second aspect, the workpiece is continuously moved from the first step to the third step and during the heat retention step. It is characterized by that. According to the stretch blow molding method of the present invention, the workpiece can be continuously moved during each step, so that the molding process can be efficiently performed.

According to a fourth aspect of the present invention, there is provided a preheating section for preheating a workpiece, a nonheating section for keeping the preheated workpiece in an unheated state, and an unheated section after being placed in the unheated state. It is provided with a main heating part for main heating the work piece and a stretch blow molding part for stretch blow molding the work piece after the main heating. According to the stretch blow molding apparatus according to the present invention,
The preheated workpiece is kept in an unheated state in the non-heated portion, so that the temperature of each portion of the workpiece is made uniform. Then, after the main heating and the stretch blow molding, the intended product is obtained.

According to a fifth aspect of the present invention, in the stretch blow molding apparatus according to the third aspect, a heat retaining portion for retaining the temperature of the workpiece after the main heating is provided is provided.
According to the stretch blow molding apparatus of the present invention, the temperature of each resin portion is made uniform even in the heat retaining portion, and the molding is favorably performed.

According to a sixth aspect of the present invention, in the stretch blow molding apparatus according to the third aspect, the workpiece is held from the preheating section to the main heating section and the heat retaining section, and the work is continued. The present invention is characterized in that it is provided with a conveyer for carrying the material. According to the stretch blow molding apparatus of the present invention, the workpiece is automatically conveyed and the molding process is efficiently performed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a stretch blow molding apparatus A to which the present invention is applied. The stretch blow molding apparatus A includes an apparatus body 1 and a preform supply unit 2. In the apparatus main body 1, a conveyor 4 is provided in the frame 3. The conveyor 4 includes wheels 5 and 5, an endless belt 6 wound around the wheels 5 and 5, and a drive source (not shown) that rotationally drives the wheels 5 and 5.

The endless belt 6 is provided with a plurality of rotating plates 8 on which preforms (workpieces) 7 shown in FIG. 2 are mounted. It is designed to rotate. The endless belt 6 runs in the direction of the arrow. Endless belt 6 running path 9A
Preliminary heating units 10 and 10 are provided on the upper side, and main heating units 11 and 11 and heat retaining units 12 and 12 are provided on the traveling path 9B. A non-heating section 13 is provided between the preheating section 10 and the main heating section 11. Preheating unit 10,
The main heating section 11 and the heat retaining section 12 are each provided with an infrared heater (not shown), and each infrared heater performs preheating, main heating, and heat retention of the preform 7.

A stretch blow molding section 14 for stretching and stretch blow molding the preform 7 heated to a constant temperature is provided in the extending direction of the running path 9B of the endless belt 6.

FIG. 2 shows a preform 7 used in the stretch blow molding apparatus A, which is formed in a cylindrical shape with a bottom as a whole, and has a male screw for mounting a cap on the outer peripheral portion in the vicinity of the opening 16. The part 17 is formed. FIG. 3 shows a container 18 molded by the stretch blow molding apparatus A, and the container body 19 is stretch stretch blow molded with the male screw portion 17 remaining.

Next, a method of molding the container 18 by the stretch blow molding apparatus A configured as described above will be described. First, in the preform supply unit 2 shown in FIG.
A large number of preforms 7 shown in FIG. 2 are stored, these preforms 7 are sequentially supplied to the conveyor 4, and are held on the rotating plate 8 of the endless belt 6 with the opening 16 facing downward, The preheating unit 1 on the traveling path 9A while rotating.
It is transported in the 0 direction. As a first step, the preform 7 that has reached the preheating unit 10 is preheated by an infrared heater while moving and is heated to a constant temperature.
The preform 7 that has passed through the two preheating units 10 is conveyed to the non-heating unit 13.

Here, the preform 7 is made uniform in temperature of each part thereof. That is, the preform 7 is
While it is heated from the outer surface side while passing through the preheating section 10, it is released from the infrared heater when it moves to the non-heating section 13, and while passing through the non-heating section 13, the temperature of the outer surface and the vicinity thereof descend. On the other hand, heated air exists inside the preform 7, and the temperature of the inner surface of the preform 7 and the vicinity thereof rises. Thus, the temperature between the inner and outer surfaces of the preform 7 can be made uniform. This step constitutes the second step.

The preform 7 that has passed through the non-heating section 13
Reaches the main heating section 11 and is heated by an infrared heater in the third step, and is heated to a state where stretch-blow molding is possible, that is, a softening state. The preform 7 that has passed through the two main heating units 11 is conveyed to the heat retaining unit 12, where the temperature is kept constant by an infrared heater in the heat retaining unit 12 and the temperature of each part of the resin is made uniform. Stabilization is achieved. The preform 7 that has passed through the two heat retaining parts 12 is separated from the conveyor 4 and transferred to the stretch blow molding part 14 and, as a fourth step, is supplied into the mold in the stretch blow molding part 14 and stretched and stretch blown. Molded and thus the container 18 shown in FIG.
Is obtained.

As described above, this stretch blow molding apparatus A
In (1), the preform 7 is preheated and then passed through the non-heating part 13 to make the temperature of each part of the preform 7 uniform, and then the main heating is performed. Therefore, each part of the preform 7 can be accurately heated to a desired temperature by the preheating part 10 and the main heating part 11. As a result, it is possible to mold even a copolymer of polyethylene, polypropylene, or polyethylene, which has been considered difficult to control the temperature as a resin material.

In the above embodiment, two preheating units 10, two main heating units 11 and two heat retaining units 12 are provided, but each of them may be provided one by one. Good.

[0021]

As described above, according to the first aspect of the invention, the temperature of each part of the work piece is made uniform by keeping the work piece after preheating in an unheated state. In addition, the temperature control becomes easy, and even a material such as polyethylene which is softened and melted rapidly by heating can be molded.

Further, according to the second aspect of the present invention, since the work piece is heat-retained after the main heating, the temperature of each part of the work piece is made uniform even in this heat-retaining step, and the stretch blow molding is performed well. Can be done.

Further, according to the third aspect of the present invention, since the workpiece is continuously moved during each step, the forming process can be efficiently performed. Further, according to the invention of claim 4, the temperature of each part of the workpiece is made uniform by keeping the workpiece after preheating in the non-heated state in the non-heated portion, which facilitates temperature control. As a result, it is possible to obtain an effect that molding can be easily performed using a material such as polyethylene.

Further, according to the invention of claim 5, since the heat retaining portion for retaining the temperature of the workpiece after the main heating is provided, the temperature of each resin portion can be made uniform in this heat retaining portion. Good molding can be performed.

According to the sixth aspect of the invention, since the conveyor for holding the workpiece and continuously transporting the workpiece is provided, the molding process can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a plan view of a stretch blow molding apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a cross section of a half part of a preform (object to be molded) used in the stretch blow molding apparatus shown in FIG.

FIG. 3 is a front view in which a half part of a product obtained by the stretch blow molding apparatus shown in FIG. 1 is cross-sectionally viewed.

[Explanation of symbols]

A stretch blow molding machine 6 conveyor 7 Preform (workpiece) 10 Preheating section 11 heating units 13 Non-heated part 14 Stretch blow molding section

Continued front page    F-term (reference) 4F208 AG07 AH55 AR06 LA02 LA05                       LB02 LD05 LD13 LG03 LG28                       LH01 LH02 LH03 LH06 LH10                       LN28

Claims (6)

[Claims] 1. A first step of preheating a workpiece, and
The second step of placing the preheated workpiece in the non-heated state, the third step of main heating the workpiece after the non-heated state, and the stretching of the workpiece after the main heating A stretch blow molding method comprising a fourth step of blow molding. 2. The stretch blow molding method according to claim 1, further comprising a heat retaining step of retaining the temperature of the workpiece after the main heating. 3. The stretch blow molding method according to claim 2, wherein the workpiece is continuously moved from the first step to the third step and during the heat retention step. Stretch blow molding method. 4. A preheating section for preheating a workpiece,
An unheated part that keeps the preheated workpiece in an unheated state, a main heating part that fully heats the workpiece after it has been placed in an unheated state, and a stretch blow molding of the workpiece after the main heating. Stretch blow molding apparatus comprising: 5. The stretch blow molding apparatus according to claim 4, further comprising a heat retaining section for retaining the temperature of the workpiece after the main heating. 6. The stretch blow molding apparatus according to claim 5, wherein the workpiece is held and continuously conveyed over the preheating portion, the non-heating portion, the main heating portion and the heat retaining portion. A stretch-blow molding apparatus, characterized in that it is provided with a conveyor.