JPH042035Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a stretch blow blow molding device.

(B) Prior Art A stretch blow blow molding device is a device that stretches a parison using a stretching rod and blows high-pressure air into the parison to form a blow molded product. Therefore, a pneumatic sealing device is required to prevent air pressure from leaking. Conventional pneumatic sealing devices for stretch blow blow molding machines include one in which an O-ring is inserted into the inner diameter of the parison opening, and one in which an annular rubber is pressed against the end of the parison opening.

(c) Problems that the invention aims to solve However, in the case of the type in which an O-ring is inserted into the inside diameter of the parison mouth, the O-ring moves while being compressed by the inside diameter of the parison mouth, so the wear particles of the O-ring may enter the inside of the hollow molded product, so it cannot be used especially in the case of hollow molded products for food, hollow molded products for pharmaceuticals, etc. In addition, the type that presses the annular rubber against the end of the parison mouth has an air pressure sealing capacity of about 20 kg/cm ² , so it is not possible to mold hollow molded products with complex shapes that require high-pressure blow molding. In addition, if the strength of the parison opening is low, pressing the annular rubber with a large force may deform the parison opening, and in such cases, this type cannot be applied.
Another problem is that the annular rubber can last only about 20,000 times and has a short lifespan. Furthermore, since high-pressure air also acts on the inner diameter of the parison mouth, there is a problem that the parison mouth, which does not need to be deformed, may also expand. In addition, in the above-mentioned conventional stretch blow blow molding apparatus, the air passage into the inside of the parison must be provided on the outer periphery of the stretching rod or on the inner periphery of the guide cylinder that guides the stretching rod, so the diameter of the stretching rod can be reduced. There is also the problem that if it has to be made smaller, it is not possible to secure a sufficient area for the air passage. If the area of the air passage is small and the air flow rate is insufficient, the temperature of the parison will drop during stretch blow blow molding, causing problems such as poor molding and uneven wall thickness. The present invention aims to solve the above problems.

(d) Means for Solving the Problems The present invention solves the above problems by bringing an elastic seal member into close contact with the parison brim to seal the air pressure. That is, in the stretch blow blow molding apparatus according to the present invention, an annular elastic seal member is provided at the lower end of the inner diameter of the hollow member (cylinder 34 in the embodiment described later) that can move up and down together with the parison conveying device and come into contact with the upper surface of the blow mold mold. is provided,
This elastic seal member is configured to tightly contact the entire circumference of the upper surface of the parison brim when the hollow member contacts the upper surface of the hollow mold, thereby sealing the air pressure acting inside the parison.

(E) Effect When the hollow member descends and contacts the upper surface of the hollow mold, the elastic seal member comes into close contact with the upper surface of the parison brim. This seals the air pressure, so that stretch blow blow molding can be performed by applying air pressure to the inside of the parison. The force acting on the parison collar from the elastic sealing member is supported by the upper surface of the hollow mold which contacts the lower surface of the parison collar, so that the parison mouth does not deform. The elastic seal member is provided with an inner protruding edge that is pressed against the upper surface of the parison brim when air pressure is applied, and an upper protruding edge that is pressed against the inner diameter of the hollow member when air pressure is applied. As the size increases, both protruding edges can be brought into close contact with the parison collar and the inner diameter of the hollow member, thereby increasing the sealing effect. In addition, with the above configuration, there is no need to provide a sealing member at the parison mouth, so a groove for air passage can be provided on the outer periphery of the guide cylinder inserted into the inside diameter of the parison mouth, resulting in a larger passage area. can be ensured. A large passage area allows a large amount of air to be supplied in a short period of time, which prevents the parison from cooling down and dropping its temperature during stretch-blow blow molding, resulting in high-quality, even wall thickness. Molded products can be obtained.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 3 of the accompanying drawings.

A substantially cylindrical cylinder 34 (hollow member) is attached to the base plate 30 by bolts 32. Also, the base plate 30 has a fixing plate 3.
A guide tube 36 is attached by 3 and bolts 35. The guide tube 36 is arranged concentrically with the cylinder 34, and the piston 37 is fitted into an annular gap formed by the two. The outer diameter of the lower end 36a of the guide tube 36 is sized to fit into the inner diameter of the opening 38a of the parison 38. Note that the parison 38 can be held within the hollow molding die 74 with its collar portion 38b in contact with the upper surface of the hollow molding die 74.
A groove 36e serving as an air passage is provided on the outer periphery of the lower end 36a of the guide tube 36, as shown in FIG. The inner diameter and outer diameter of the piston 37 are sealed by seal members 40 and 42, respectively. Further, the space between the base plate 30 and the cylinder 34 is sealed by a seal member 45.
Air pressure can be supplied to and discharged from the upper end surface of the piston 37 through a passage 80 by a solenoid valve 78, and from the solenoid valve 66 to the passage 64 and from the radial hole of the guide tube 36 to the lower end surface of the piston 37. 36b, axial hole 36c, and radial hole 36d, air pressure can be supplied and discharged. Note that an extension rod 62 passes through the axial hole 36c of the guide tube 36. The space between the guide tube 36 and the base plate 30 is sealed by seal members 90 and 91, the space between the fixed plate 33 and the guide tube 36 is sealed by a seal member 92, and the space between the fixed plate 33 and the guide tube 36 is sealed by a seal member 92. A seal member 94 seals between the stretching rod 62 and the stretching rod 62 . A gripper rubber 54 is supported on the lower portion of the cylinder 34 . The gripper rubber 54 has its outer circumference and lower end surface restrained by the cylinder 34, and the upper end surface is in contact with the lower end of the piston 37. The gripper rubber 54 has an inner diameter slightly larger than the outer diameter of the mouth 38a of the parison 38 in the free state. However, when pressure is applied from the piston 37, the gripper rubber 54 is deformed toward the center as described later, and its inner diameter becomes smaller. An elastic seal member 72 is provided at the lower end of the inner diameter of the cylinder 34 to tightly contact the collar portion 38b of the parison 38 to seal air pressure. The elastic seal member 72 has a cross-sectional shape as shown in an enlarged view in FIG.
It has an inner peripheral protruding edge 72a that can be brought into close contact with the upper surface of b, and an upwardly protruding edge 72b that can be brought into close contact with the inner diameter part 34a of the cylinder 34.

Next, the operation of this embodiment will be explained. The base plate 30 is connected to a parison conveying device of an injection stretch blow blow molding device, and is movable in the vertical and horizontal directions. The parison 38 is gripped by gripper rubbers 54. That is, solenoid valve 7
When air pressure is supplied to the passage 80 by the solenoid valve 66 and air pressure is discharged from the passage 64 by the solenoid valve 66, a downward force acts on the piston 37, and the gripper rubber 54 is compressed by this force. Since the gripper rubber 54 receives compressive force from above and below while its outer peripheral portion is restrained, it can deform only toward the inner diameter, and deforms in a direction that reduces the inner diameter. Therefore, the mouth portion 38a of the parison 38 is gripped by the inner diameter portion of the gripper rubber 54. In this state, the base plate 30 is lowered onto the hollow molding die 74 to bring the lower surface of the cylinder 34 into close contact with the upper surface of the hollow molding die 74. Next, the solenoid valve 78 is switched to exhaust the air pressure in the passage 80,
At the same time, the solenoid valve 66 is switched to blow air pressure through the passage 64 and the holes 36b, 36c, and 36d of the guide tube 36. Due to this air pressure, an upward force acts on the piston 37, and the gripper rubber 5
4, the inner diameter of the gripper rubber 54 returns to its original state and the parison 38 is released. At the same time as the electromagnetic valve 66 is switched, the stretching rod 62 begins to descend and applies a stretching force to the parison 38. At the same time, the air pressure supplied to the lower end of the piston 37 passes through the groove 36e to the parison 3.
The parison 38 enters the interior through the opening 38a of the parison 38 and exerts a force to expand the parison 38. In this way, the stretching rod 6
The well-known stretch blow blow molding is carried out by the joint action of 2 and air pressure. At that time, the elastic seal member 7
2, the air pressure is reliably sealed. That is, the inner peripheral protruding edge 72 of the elastic seal member 72
a is in close contact with the upper surface of the collar portion 38b of the parison 38,
Further, the upwardly protruding edge portion 72b is in close contact with the inner diameter portion 34a of the cylinder 34. Moreover, the elastic seal member 72
Since the air pressure acting on a acts in the direction of pressing the inner peripheral protruding edge 72a and the upper protruding edge 72b against the collar 38b of the parison 38 and the inner diameter 34a of the cylinder 34, respectively, the higher the air pressure, the greater the adhesion force becomes. . In this way, as the air pressure increases, the sealing effect increases, so that no air leakage occurs. Therefore, it becomes possible to carry out stretch blow molding using extremely high air pressure, and it becomes possible to mold complex hollow molded products. Furthermore, since the pressure is the same on the inside and outside of the opening 38a of the parison 38, the opening 38a does not expand due to air pressure. In addition, all the force for pneumatic sealing is applied to the collar 3 of the parison 38.
8b, the mouth portion 38a will not be deformed. Since the elastic seal member 72 does not move under compressive force, it does not suffer from wear or damage, and a sufficient lifespan can be ensured.
Furthermore, as shown in FIG. 2, since the air passage into the parison 38 is formed by the groove 36e of the lower end 36a of the guide tube 36, a large passage area can be secured and a large amount of air can be passed through the parison 38. It becomes possible to rapidly supply the parison 38, and it is possible to prevent the occurrence of wall thickness unevenness due to a temperature drop during molding of the parison 38.

(g) Effects of the invention As explained above, according to the invention, the elastic seal member is brought into close contact with the parison brim to seal the air pressure, which improves the sealing ability and makes it possible to mold complex shapes. It is possible to carry out high-pressure blow-hollow molding, and also to prevent deformation and expansion of the parison opening, and to ensure a sufficient lifespan. Further, there is no possibility that abrasion powder from the O-ring will enter the inside of the hollow molded product. Furthermore, by configuring the elastic seal member to have a shape that increases the sealing effect in accordance with the applied air pressure, it becomes possible to seal even higher air pressure. Further, by forming the air passage by the groove on the outer periphery of the lower end of the guide cylinder, the area of the air passage can be increased, and a stretch-blown hollow molded product of higher quality can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a stretch blow blow molding apparatus according to the present invention, Fig. 2 is a sectional view taken along line II-II in Fig. 1, and Fig. 3 is an enlarged sectional view of the vicinity of the elastic seal member shown in Fig. 1. It is. 34...Cylinder (hollow member), 38...Parison, 38b...Brim portion, 62...Stretching rod,
72...Elastic seal, 72a...Inner peripheral protruding edge,
72b...Upward protruding edge, 74...Blow molding die.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. The parison held in the blow molding mold is stretched by a stretching rod with the lower surface of the parison collar in contact with the upper surface of the blow molding mold, and high-pressure air is introduced into the inside of the parison. In a stretch blow blow molding device that performs stretch blow molding by applying pressure, an annular elastic seal member is provided at the lower end of the inner diameter of a hollow member that moves up and down with the parison conveying device, and this elastic seal member is attached to the parison collar. A stretch blow blow molding apparatus characterized in that the apparatus is configured to tightly contact the entire circumference of the upper surface of the parison to seal air pressure acting inside the parison. 2. The elastic seal member has a protruding inner edge that is pressed against the upper surface of the parison brim when air pressure is applied, and an upper protruding edge that is pressed against the inner diameter of the hollow member when air pressure is applied.Registered as a utility model. A stretch blow blow molding apparatus according to claim 1. 3. The stretch blow blow molding apparatus according to claim 1 or 2 of the utility model registration claim, in which an air passage into the parison is formed by a groove provided on the outer periphery of the lower end of the guide tube inserted into the inner diameter of the parison opening. .