JPS61171322A - Manufacture of plastic tank - Google Patents

Abstract

PURPOSE:To contrive to improve the strength of a baffle plate, preventing the root portion of the baffle plate from the thinning thereof by projecting a baffle molding member, after a parison has been caused to lie parallel with the inner surface of a mold. CONSTITUTION:First, a baffle molding plate 4 is retracted, shortening a driving cylinder 5, and at this state, a parison 6 is pushed out. The parison 6 is caused to lie parallel with the inner surface of a mold 3, and before its solidification by cooling, when the baffle molding plate 4 is projected into the mold, extending the driving cylinder 5, the parison 6 is stretched in the internal direction of the mold, and a baffle plate 6c is molded. Thus, after the parison 6 has been caused to lie parallel with the inner surface of the mold 3, the baffle molding plate 4 is projected, whereby the root portion 6d of the baffle plate 6c may be prevented from the thinning of its wall thickness, and the strength of the baffle plate 6c is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing a plastic tank used for a vehicle fuel tank, etc., and particularly relates to a manufacturing method that can improve the strength of the baffle plate portion thereof. It is something.

[Prior art]

In recent years, vehicle fuel tanks have been made of plastic to reduce cost and weight, and blow molding has conventionally been used as a manufacturing method. In this blow molding method, a parison made by extruding semi-molten resin into a cylindrical shape using an extrusion head is clamped by a mold that is divided into two parts, and in this state, pressurized gas is blown into the parison from a blow nozzle. This is a method in which the parison is inflated and molded along the inner surface of the mold.

By the way, conventionally, steel fuel tanks for vehicles have been formed with baffle plates to reduce the noise of fuel vibration, but of course, this baffle plate is also necessary for plastic tanks, so As for manufacturing methods, various methods for integrally forming the baffle plate have been proposed in the past, and one example thereof is described in Japanese Utility Model Application Publication No. 57-4314. As shown in FIG.
The baffle plate is formed by forming the baffle plate 2 in a protruding manner and by blow molding the parison 13 along the baffle forming plate 12.

In this conventional publication, in the baffle plate forming process, the parison 13 is first moved to the baffle forming plate 1.
4 (see al), this is extended toward the base of the molding plate 12, that is, toward the inner surface of the mold 11, thereby forming a baffle brake (13a). Therefore, the shaped baffle plate 13a
(Figure 4).

As shown in (C), the portion near the root 13b is thinner. On the other hand, the bending force that acts on the baffle plate due to external forces such as swinging of the fuel reaches its maximum at the base 135. Therefore, in the conventional plastic tank described above, there is a problem that the baffle plate 13a is weak in strength. .

[Purpose of the invention]

The present invention was made to solve these conventional problems, and provides a method for manufacturing a plastic tank that can prevent the base of the baffle plate from becoming thinner and improve the strength of the baffle plate. It is intended to.

[Structure of the invention]

In a method for manufacturing a plastic tank, the present invention provides a mold in which a baffle molding member is protrusively provided, and during blow molding, the baffle molding member is moved to a retracted position until the parison is along the inner surface of the mold. position,
The parison is made to protrude along the inner surface of the mold and before being cooled and fixed. Accordingly, in the present invention, the baffle plate is formed by stretching the parison inward from the inner surface of the mold, contrary to the conventional method, so that the wall thickness of the baffle plate is thicker at the portion near the base. .
′ [Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

Figures 1 to 3 are for explaining a method of manufacturing a plastic tank according to an embodiment of the present invention.
In FIG. 2 showing an apparatus for carrying out the method of this embodiment, 1 is an extrusion head of a parison forming apparatus for extruding a cylindrical parison, and is located below an extrusion die 1a formed in the extrusion head 1. A blow nozzle 2 is arranged to face the blow nozzle 2, and the blow nozzle 2 is connected to a supply source of pressurized gas 9, such as compressed air.

Further, below the extrusion head 1, there are left and right molds 3a, 3b.
A mold 3 consisting of left and right molds 3a is provided.
, 3b are movable in the left-right direction in the figure, and when they are closed, the inner surface shape is the same as the outer surface shape of the plastic tank to be manufactured. A baffle molding plate 4 is disposed on the left mold 3a so as to be able to protrude inward from the mold, and this baffle molding plate 4 is connected to a piston rod of a drive cylinder 5 fixed to the outer surface of the left mold 3a. ing.

Next, the case where the method of this embodiment is implemented by the apparatus shown in FIG. 2 will be explained using FIGS. 1 to 3.

(1) First, the drive cylinder 5 is contracted to move the baffle molding plate 4 backward, and in this state, the mold 3 is opened left and right as in conventional blow molding, and a parison of a predetermined shape is formed from the extrusion die 1a of the extrusion head 1. 6 (see Figure 2).

(It) When the parison 6 is extruded to a length that reaches the bottom surface of the mold 3, the left and right molds 3a and 3b are closed.

Then, the upper and lower ends 5a and 5b of the parison 6 are on the left.

It is held between the right molds 3a and 3b and fused together.

When compressed air is supplied into the parison 6 from the blow nozzle 2 in this state, the parison 6 expands into a shape that conforms to the inner surface of the mold 3. In this case, as shown in Figure 1(a),
Since the baffle molding plate 4 is in its retracted position and its tip 4a only slightly protrudes into the mold, the parison 6 is also substantially flat in this baffle plate molding portion.

(I[) When the parison 6 extends along the inner surface of the mold 3 and reaches a predetermined temperature and before being cooled and solidified, the drive cylinder 5 is extended to protrude the baffle molding plate 4 into the mold. The baffle plate 6 is stretched inward.
c is formed. In this case, the parison of the baffle plate portion is stretched from the inner surface of the mold toward the inside of the mold, contrary to the case of the prior art described above, so the portion of the powerful plate 6c near the base 6d is If the mold 3 is opened and the part corresponding to the blow nozzle 2 is sealed, the mold as shown in FIG. 3 will be formed. A plastic fuel tank 7 in which a puff full plate 6c is integrally formed.
is obtained. Note that 7a is a fuel supply port.

In this way, in the method of this embodiment, the baffle molding plate 4 is made to protrude after the parison 6 has moved along the inner surface of the mold 3, so that the thickness of the root 6d of the baffle plate 6C can be prevented from becoming thinner. baffle play), and the strength of the baffle play (6a) can be improved.

In the above embodiment, the baffle molded plate 4 is directly projected by the same number of drive cylinders 5, but various other structures are conceivable for protruding the baffle molded plate 4. For example, A plurality of baffle forming plates can be protruded by a single cylinder using a link mechanism, or, of course, a driving source other than a cylinder can be used.

Further, in the above embodiment, compressed air is supplied after the left and right molds 3a and 3b are completely closed, but the supply of compressed air is started before the left and right molds 3a and 3b are completely closed. You may.

Furthermore, although the above embodiments have been explained using a fuel tank for a vehicle as an example, the present invention can be applied to anything other than a fuel tank as long as it is a plastic tank that has a partition wall etc. that protrudes inward. be.

! [Effects of the Invention] As described above, according to the method for manufacturing a plastic tank according to the present invention, a mold including a puffful molding member that can protrude into the mold is prepared, and during blow molding, the parison is formed on the inner surface of the mold. Since the powerful molding member is made to protrude after along the baffle plate, the baffle plate can be formed so that the root part thereof is within the thickness, which has the effect of improving the strength of the baffle plate portion.

[Brief explanation of drawings]

Fig. 1 (71) to C) is a process diagram of a method for manufacturing a plastic tank according to an embodiment of the present invention, Fig. 2 is a block diagram of a manufacturing apparatus thereof, and Fig. 3 is a fuel produced by the method of the above embodiment. The sectional views of the tank, FIGS. 4(a) to 4(c), are process diagrams for explaining the conventional manufacturing method. 1a... Extrusion die, 2... Blow nozzle, 3...
Molding mold, 4... Baffle molding plate (baffle molding member), 6... Parison, 7... Plastic tank. Patent applicant: Mazda Motor Corporation agent, patent attorney Ken Hayase - Figure 1 (Q) (b) (c)
)Figure 2

Claims (1)

[Claims] (1) In a method of manufacturing a plastic tank having a baffle plate by blow molding, a mold equipped with a baffle molding member that can protrude inward at a position corresponding to the baffle plate molding part is prepared, and the mold is extruded from an extrusion die. When the parison is clamped in a mold and blow molded by supplying pressurized gas from a blow nozzle, the baffle molding member is positioned at its retracted position until the parison is along the inner surface of the mold, and the parison is A method for manufacturing a plastic tank, characterized in that the plastic tank is made to protrude inward from the mold after being along the inner surface.