JP2000094501A - Side-blowing blow molding method and apparatus and needle for ventilation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively, accurately perform blow mold by forming a cutting edge for cutting a predetermined position of a parison at its front end in a ventilating nozzle for supplying the air by laterally piercing the parison, thereby effectively laterally passing the needle through the parison. SOLUTION: In the state that mold members 11 is opened, a parison 5 of a raw material is disposed therebetween. When an expansion pin 62 is raised by a moving means 63 and advanced into a lower end opening of the parison 5, the air is preliminarily blown off to expand the parison 5. Then, pinch plates 53 are moved to be approached to one another by a moving means 54. Subsequently, a pair of molds 21, 22 are moved to be approached to one another, a blowing pin 31 is moved immediately before the members 11 are closed by coming on contact with the parison 5 to pierce the parison 5, and the pin 31 at this time is smoothly advanced into the parison 5 while cutting the parison 5 by a knife edge 1a of a cutting blade 1 formed at its front end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side-blowing blow molding apparatus, and more particularly to an improved ventilation needle for piercing a parison from the side and sending air.

[0002]

2. Description of the Related Art A blow molding apparatus preforms a resin material into a tube shape by extruding or injecting a thermoplastic material, inflates the resin material by sandwiching the air into a mold, and presses the resin material against the mold. This is an apparatus for forming a product having a predetermined shape. The molten resin preformed in a tube shape is usually called a parison.

[0003] As one method of blowing air into such a parison, a side-blowing method is known. This lateral blowing method is a method in which air is blown into the inside of the tube-shaped parison from the lateral direction. In a blow molding apparatus using a side-blowing method, that is, a side-blowing blow molding apparatus, a ventilation needle for sending air is pierced into the parison from the lateral direction.

FIGS. 8 and 9 are a cross-sectional view and a perspective view, respectively, of a ventilation needle of a conventional side-blowing blow molding apparatus. As shown, the tip of the needle 101 is formed in a conical shape.

[0005] In the case of performing the side-blowing blow molding, the needle 101 is moved from the lateral direction toward the parison by driving an air cylinder or the like. Then, the parison is pierced by the tip 102 of the tip, and subsequently, the needle 101 enters into the inside while breaking the parison by inertia due to the moving speed of the needle 101. Next, passage 1
03 is blown out from the blowing hole 104 into the inside of the parison, and pressed against the inner surface of a mold (not shown) to form a predetermined shape.

[0006]

However, the above-mentioned conventional side-blowing blow molding employs a method in which the parison is penetrated by the pointed tip 102 of the needle 101 and the needle 101 is advanced into the parison. There is a problem that a penetration error occurs.

That is, as shown in FIGS. 10 (A) and 10 (B), a “burr” is easily generated in which the parison 105 is deformed so as to be pressed inward by the pressing of the needle 101, and the burr amount L is large. In some cases, the needle 101 may not penetrate the parison 105 sufficiently.

[0008] As a result, as shown in FIG.
The needle 101 cannot penetrate the parison 105, and the inside cannot be filled with air. This causes a problem that the mold shape is not transferred to the parison 105. Further, as shown in FIG. 10B, even if the parison 105 can be pierced by the needle 101, if the burr amount L is large, air enters the inside of the parison 105 to some extent but is not sufficient. Therefore, the same problem that the mold shape is not transferred to the parison 105 occurs.

The present invention has been made in view of such problems of the prior art, and it is an object of the present invention to reliably and accurately blow a ventilation needle through the parison from the lateral direction. It is to perform molding.

[0010]

According to the first aspect of the present invention, a hollow molded product having the same shape as the inner surface of a mold is obtained by blowing air from the lateral direction into the inside of a parison. In a ventilating needle used in a blow-type blow molding device for piercing the parison from the lateral direction to send air, a cutting edge for cutting a predetermined portion of the parison is formed at a tip end thereof.

According to a second aspect of the present invention, in the ventilating needle for the side-blowing blow molding apparatus according to the first aspect, the tip portion is a plane inclined at a predetermined angle with respect to the axial direction of the needle. It is characterized by being formed in a cut shape.

According to a third aspect of the present invention, in the ventilating needle for the side blow type blow molding apparatus according to the second aspect, the predetermined angle is 10 ° to 30 °.

According to a fourth aspect of the present invention, there is provided a lateral blow blow molding apparatus for obtaining a hollow molded product having the same shape as the inner surface of a mold by blowing air from the lateral direction into the inside of the parison. It is characterized in that it has a ventilation needle for cutting air from the side of the parison and sending air by forming a cutting edge at the tip of the parison.

According to a fifth aspect of the present invention, there is provided a horizontal blow blow molding method for obtaining a hollow molded product having the same shape as the inner surface of a mold by blowing air from the lateral direction into the inside of the parison. At a location, by piercing the parison from the lateral direction of the parison with a ventilation needle having a cutting edge formed at the tip, the parison is cut to allow the ventilation needle to penetrate and send air. .

[0015]

According to the present invention, the following effects can be obtained for each claim. According to the first, fourth and fifth aspects of the invention, the ventilation needle can enter the inside of the parison while cutting the parison with the cutting edge formed at the tip. For this reason, it becomes possible to extremely reduce the inward burrs formed through the parison.

Moreover, the ease with which the parison penetrates into the inside and the amount of burr are hardly influenced by the moving speed of the ventilation needle. In addition, there is an advantage that the burr penetrates through the inside of the parison and the burr amount is reduced.

Therefore, the ventilation needle can be reliably penetrated from the lateral direction of the parison, and reliable and accurate blow molding can be performed.

According to the invention of claim 2, according to claim 1,
In addition to the effects of the invention described in (1), a cutting edge can be easily formed at the distal end of the ventilation needle, and the cut surface of the distal end of the needle can be smooth and the burr of the parison can be further reduced.

According to the invention of claim 3, according to claim 2,
In addition to the effects of the invention described in (1), it is possible to prevent the cutting surface of the needle tip from becoming large and the stroke of the ventilation needle from increasing unnecessarily while securing good parison cutting.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a side-blowing blow molding apparatus according to one embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view around the blowing needle shown in FIG. 1, and FIG. FIG. 4 is a sectional view of the insertion needle, and FIG.

The side-blowing blow molding apparatus 10 shown in FIG.
Is a pinch means 5 for sandwiching the lower part of the mold member 11 and the parison 5 which is a molten resin preformed in a tube shape.
1 and expansion means 61 for pre-expanding the parison 5
And

Further, the side-blowing blow molding apparatus 10 further comprises an extruder for plasticizing and extruding the resin as a raw material, and an accumulator head for changing the flow of the resin extruded from the extruder to produce a tube-shaped parison 5. And a mold clamping device for opening and closing the mold member 11 (both are not shown).

The mold member 11 includes a pair of a first mold 21 and a second mold 22, and can be moved close to and away from each other in the horizontal direction (the direction of arrow A in the figure) by driving the mold clamping device.
The inner surfaces 23 and 24 of the dies 21 and 22 are formed by the molding apparatus 1.
For example, it is formed so as to conform to the outer shape of a hollow molded article such as a resin fuel tank which is molded at 0.

As shown in FIG. 1, the first mold 21 is provided with a blowing needle (hereinafter referred to as a "blow pin") 31 and an exhausting needle 32 as ventilation needles. The configuration is such that air is blown and exhausted by piercing the parison 5 having a shape from the lateral direction. The needles 31 and 32 will be described later in detail.

The pinch means 51 includes a pair of arms 52, 52 extending inward from each other,
A pair of pinch plates 53, 53 provided at the tip of 52;
These pair of arms 52, 52 and pinch plate 53,
A moving means 5 for moving the 53 toward and away from and in the direction of arrow B in the figure.
4 are provided on a pair of support bases 55, 55 which are provided on the base 52 at regular intervals. Then, when the pair of pinch plates 53, 53 move close to each other, the pinch plates 53, 53 can be brought into contact with the lower part of the parison 5 and sandwiched therebetween.

The expansion means 61 includes an expand pin 62 for injecting air to be preliminarily expanded by entering under the parison 5 and an expand pin 62 indicated by an arrow C in FIG.
And a moving member 63 for moving toward and away from the parison 5 in the direction.
Is installed at the center of the pair of support tables 53, 53.

As shown in FIG. 2, the blow pin 31 is slidably inserted into a through hole 34 along the axis of a drum 33 disposed in the first mold 21. The rear end of the blow pin 31 is connected to a manifold member 35, and the blow pin 31 and the manifold member 35 are configured to be able to move forward and backward along the axial direction toward the inside of the first mold 21 by the moving means 36. Have been. As the moving means 36, for example, an air cylinder is used. This moving means 36
The support member 46 is attached to the support member 46.
Is fixed to a housing 38 fixed to the first mold 21 at a site (not shown).

Air supply holes 3 are provided in the manifold member 35.
The air supply hole 37 communicates with a passage 38 (see FIG. 3) formed at the center of the axis of the blow pin 31. A tube (not shown) is connected to the air supply hole 37, and this tube is connected to an air supply source (not shown).

The drum 33 is rotatably supported by a housing 38 via bearings 39,39. Screw inserts 40 and 41 are fixed to the tip side of the drum 33, and a female screw portion 42 is formed on the inner surface of the screw insert 41. On the other hand, a gear 43 is fixed to the rear end side of the drum 33, and the gear 43 is engaged with a gear 44 fixed to a main shaft of a motor 45. The above screw inserts 40 and 41
Is used to form a boss with a male screw on the molded product, and is also used when the molded product is separated from the mold by screw driving by rotating the drum 33 by driving the motor 45 when the mold is separated. You. A through hole 48 is formed at the center of the screw insert 40 so that the vicinity of the tip of the blow pin 31 can be protruded and retracted toward the inside of the first mold 21.
In addition, the code | symbol 47 in a figure has shown the water hole for cooling.

As shown in FIGS. 3 and 4, a cutting edge 1 for cutting a predetermined portion of the parison is formed at the tip of the blow pin 31. Specifically, the cutting edge 1 is formed by forming the tip of the blow pin 31 into a shape cut by a plane inclined at a predetermined angle with respect to the axial direction of the blow pin 31. As shown in the drawing, the cutting edge 1 has a knife edge portion 1a formed in a predetermined range of the circumference of the coastal circle at the tip end of the blow pin 31 to perform a cutting action.

If the tip of the blow pin 31 is formed into a shape cut by a plane inclined at a predetermined angle, the cutting edge 1 can be easily formed at the tip of the blow pin 31. The cut surface 3 at the tip is smooth, and the burr of the parison can be reduced. In addition, the above-mentioned predetermined angle is from 10 ° to 30 ° from the viewpoint of securing the goodness of parison cutting and preventing the cut surface 3 at the tip of the blow pin from becoming too large to increase the stroke of the blow pin 31 unnecessarily. ° is preferable.

The passage 38 formed at the center of the axis of the blow pin 31 has a plurality of blowout holes 2 (three in the illustrated case, but can be changed as appropriate) near the distal end portion, which are opened from the passage 38 in a direction perpendicular to the axis. There is).

Since the exhaust needle 32 has the same configuration as the blow pin 31, its description is omitted.

Next, the operation of the present embodiment configured as described above will be described.

First, with the mold member 11 opened, the parison 5 preliminarily formed into a tube shape by extruding a plasticized resin as a raw material is positioned therebetween. When the expand pin 62 is raised by the moving means 63 and enters the lower end opening of the parison 5, the expand pin 62
The air is preliminarily blown out of the parison 5 to expand the parison 5.

Subsequently, the pinch plates 53, 53 are moved closer to each other by the moving means 54, 54. Pinch plate 5
3 and 53 have expanded pins 62 at their tips.
The pinch plates 53, 53 sandwich the lower part of the parison 5 together with the expand pins 62 to form a pinch portion.

The pair of first molds 2 of the mold member 11
When the first and second molds 22 are moved closer to each other, a mold clamping operation is started. Immediately before the molds 21 and 22 come into contact with the parison 5 and the mold member 11 closes, the moving means 36 is driven, and the blow pin 31 is moved leftward in FIG.

The blow pin 31 is moved to the position shown by the two-dot chain line in FIG. 2 and breaks through the parison 5 as shown in FIG. At this time, the blow pin 31 enters the inside of the parison 5 while cutting the parison 5 by the knife edge 1a of the cutting edge 1 formed at the tip.

Next, air is supplied to the supply hole 37 from an air supply source (not shown).
Is blown into the inside of the parison 5. As a result, the parison 5 is inflated and pressed against the molds 21 and 22 to form a hollow molded product having a predetermined shape.

As described above, conventionally, the parison was pierced by the tip of the tip and then pierced by pushing the parison, but according to the present embodiment, the parison 5 was cut by the cutting edge. The blow pin 31 can be made to enter by slipping into the slit. For this reason, it is possible to extremely reduce the inward burrs formed by breaking through the parison 5.

Further, according to the blow pin of the present embodiment, there is an advantage that the ease of penetration into the inside of the parison and the size of the burr are hardly affected by the moving speed of the blow pin. That is, as shown in FIG. 6, in a conventional blow pin having a conical tip (indicated by Q in the figure), when the blow pin speed is low, the amount of burr inward of the parison increases, and the parison is sufficiently removed. Satisfactorily blow molding cannot be performed. On the other hand, the blow pin (P in FIG.
In order to cut the parison with the cutting edge,
Even if the blow pin speed slightly fluctuates, the blow pin 31 is surely penetrated into the parison 5 and the burr amount is reduced.

Accordingly, the blow pin 31 can be reliably penetrated from the lateral direction of the parison 5, and reliable and accurate blow molding can be performed. Such effects are of course the same for the exhaust needle 32.

The embodiments described above are not described to limit the present invention, and various modifications can be made by those skilled in the art within the technical concept of the present invention.

In the above-described embodiment, the cutting edge 1 is formed by cutting the tip of the blow pin 31 by one plane inclined at a predetermined angle with respect to the axial direction. Is not limited to such a shape. For example, as shown in FIG.
The cutting edge 1a may be formed by cutting the tip portion of the blade at two planes inclined at a predetermined angle opposite to the axial direction, and forming the cutting edge 1a into a shape like a cutter or a flathead screwdriver bit.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a side-blowing blow molding apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view around a blow pin shown in FIG. 1;

FIG. 3 is a partial sectional view of a blow pin.

FIG. 4 is a partial perspective view of the same.

FIG. 5 is a diagram showing a state in which a blow pin enters the inside of a parison.

FIG. 6 is a diagram showing a relationship between a blow pin speed and a parison burr amount.

FIG. 7 is a partial perspective view of a blow pin according to another embodiment.

FIG. 8 is a partial sectional view of a conventional blow pin.

FIG. 9 is a partial perspective view of the same.

FIGS. 10A and 10B are diagrams showing a problem caused by a conventional blow pin.

[Explanation of symbols]

1, 1a: cutting edge, 5: parison, 11: mold member, 31, 31a: blow pin, blowing needle (ventilating needle), 32: exhaust needle (venting needle) 36 ... moving means.

Claims (5)

[Claims] 1. A horizontal blow blow molding apparatus for obtaining a hollow molded product having the same shape as the inner surface of a mold by blowing air from the lateral direction into the interior of the parison. The air is sent by piercing the parison from the lateral direction. A cutting blade for cutting a predetermined portion of the parison is formed at a tip end thereof, the ventilation needle for a side-blowing blow molding apparatus. 2. The ventilation device according to claim 1, wherein the distal end is formed in a shape cut by a plane inclined at a predetermined angle with respect to the axial direction of the needle. needle. 3. The ventilation needle according to claim 2, wherein the predetermined angle is 10 ° to 30 °. 4. A horizontal blow blow molding apparatus for obtaining a hollow molded product having the same shape as the inner surface of a mold by blowing air from the lateral direction into the inside of the parison, wherein a cutting edge for cutting a predetermined portion of the parison is provided at a tip end. And a ventilating needle for piercing the parison from a lateral direction and sending air therethrough. 5. A horizontal blow blow molding method for obtaining a hollow molded product having the same shape as the inner surface of a mold by blowing air from the lateral direction into the inside of the parison, wherein a cutting edge is provided at a tip of a predetermined portion of the parison. A side-blowing blow molding method, characterized in that the formed parison needle is pierced from the lateral direction of the parison, thereby cutting the parison, allowing the ventilating needle to enter, and sending air.