JPH07276476A - Device for supplying resin to die - Google Patents

Abstract

PURPOSE:To eliminate the stagnation, deterioration and color irregularity of a resin and to facilitate the replacement of a resin or a color by providing the introducing port reaching the front end part of an injection plunger from an extruder through the interior of the injection plunger and radially branching the same. CONSTITUTION:A device 30 for supplying a resin to a die is equipped with an accumulator 32 wherein a front end resin passage 31 is connected to the die and the injection plunger 38 fitted in the inner bore of the accumulator 32 so as to freely advance and retreat. Herein, an extruder 33 directly connecting the front end resin passage 31 to the injection plunger 38 longitudinally is provided. The introducing port 40 reaching the front end part of the injection plunger 38 from the extruder 33 through the interior of the injection plunger 38 is provided and arranged so as to be radially branched in the vicinity of the front end part of the injection plunger 38. A resin is spirally emitted into the accumulator through the radial introducing ports and the resin stagnated in the accumulator is easily renewed by a new resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a cylindrical resin cylinder called a parison by injecting a resin in a die, sandwiching it with a mold, and then blowing gas such as air into the parison. The present invention relates to a resin supply device for a die that supplies resin extruded from an extruder to a die through an accumulator in a blow molding machine or the like that obtains a hollow product by cooling as it is.

[0002]

2. Description of the Related Art A blow molding machine of this type is conventionally constructed as follows. That is, a vertical die for ejecting the parison is aimed above the left and right mold cavities, which are divided into left and right with the vertical joint surface as a boundary and opened and closed by the mold opening and closing cylinder. It is provided, and a resin supply device is attached to this die.

FIGS. 6 and 7 are schematic cross-sectional views of a conventional resin supply device of this type. First, with reference to FIG. 6, a die 28 has an accumulator 32 formed in a cylindrical shape at its front end portion. The resin passage 31 is joined to the front end of the accumulator 32, and the resin passage 34 formed at the front end of the extruder 33 orthogonal to the front end of the accumulator 32 is joined. In the inner hole 33a of the extruder 33,
A screw 35 is rotatably fitted, and an injection plunger 38 that is driven by an injection cylinder (not shown) to move forward and backward is fitted in the inner hole 32a of the accumulator 32. Reference numeral 54 is an opening / closing valve for opening / closing the resin passage 34, and 53 is an opening / closing valve for opening / closing the resin passage 31. In addition, the extruder 33, the accumulator 32, the die 2
8. The resin passages 31, 34, etc. are heated to a temperature substantially equal to the resin temperature under the molding conditions.

With this structure, resin is supplied from the hopper (not shown) to the inner hole 33a of the extruder 33 to heat it with the on-off valve 54 opened and the on-off valve 53 closed. While rotating the screw 35 while
When the resin is melted, the molten resin 41 (hereinafter simply referred to as resin 41
Is stored in the accumulator 32 while retracting the injection plunger 38 as shown by the chain line 38a. Next, when the opening / closing valve 54 is closed and the opening / closing valve 53 is opened to advance the injection plunger 38, the resin 41 is transferred to the resin passage 3
It is supplied to the die 28 through 1.

The resin supply device for the die 28 shown in FIG. 7 will be described. The inner hole 3 of the accumulator 32 will be described.
A bush 37 is fitted and fixed to 2a, and an injection plunger 38, which is driven by an injection cylinder (not shown) and moves forward and backward, is fitted in an inner hole of the bush 37.
The bush 37 has an annular front end surface 37a.
Is inclined so as to approach the die 28 from the joining side of the extruder 33 toward the opposite joining side, and the joining side is located rearward of the joining portion of the extruder 33.
53 is an on-off valve that opens and closes the resin passage 31, and 5
An on-off valve 4 opens and closes the resin passage 34. In addition, the extruder 33, the accumulator 32, the die 28, the resin passage 3
1, 34, etc. are heated to a temperature substantially equal to the resin temperature under the molding conditions.

With this structure, pellet resin is supplied from the hopper (not shown) to the inner hole 33a of the extruder 33 with the on-off valve 54 opened and the on-off valve 53 closed. When the screw 35 is rotated while heating the resin, the resin is melted, and the molten resin 41 moves the injection plunger 38 backward while the accumulator 32 is retracted.
It is stored inside. Next, the on-off valve 54 is closed and the on-off valve 53
And the injection plunger 38 is moved forward, the resin 41
Is supplied to the die 28 through the resin passage 31.

[0007]

However, in the conventional resin supply device as shown in FIG. 6, the extruder 33 is used.
Since the resin passage 34 from is opened at the front end portion of the accumulator 32, the resin 41 which has entered the accumulator 32 later is supplied to the die 28 earlier than the resin 41A which has entered the accumulator 32 first. The resin 41A is not replaced with the resin 41, and as shown in the figure, the resin 41A stays at the farthest side on the side opposite to the resin passage 34 side and comes out after the resin 41. It becomes an expression. As a result, the resin 41A staying in the dead zone is
When it is supplied to No. 8, there is a problem that the resin 41A that has undergone a long heat history deteriorates and the quality of the molded product deteriorates. In addition, when the resin 41A partially retains extremely, the resin temperature varies, the heat history becomes non-uniform, and color unevenness occurs in the molded product. Therefore, there is a problem that a large amount of resin is wasted.

In order to solve the above-mentioned conventional problems,
As shown in FIG. 7, the front end resin passage 34 of the extruder 33 is located near the backward end of the tip of the injection plunger 38, and a cylindrical bush 37 is fitted on the inner peripheral surface of the accumulator 32. The annular front end surface 37a is inclined so as to approach the die 28 from the joining side of the extruder 33 toward the anti-joining side, and the fitting portion of the bush 37 is connected to the extruder 33 in the accumulator 32. It was attempted to prevent the resin 41 from being put in and out first by locating the resin 41 at a position farther from the die 28 than the joining part. However, even in this case, the problem that the resin 41 stays as a dead zone at the position B shown in FIG. 7 remains.

The present invention has been made in view of the above points, and eliminates resin retention, deterioration, color unevenness, and the like in the accumulator, and also makes it easy to perform resin change and color change. Is intended to provide.

[0010]

In order to achieve such an object, according to the present invention, an accumulator having a front end resin passage joined to a die and an injection plunger fitted in an inner hole of the accumulator so as to be able to move forward and backward. A device for supplying a resin to a die, comprising an extruder in which a front end resin passage is directly joined to the injection plunger in a tandem manner, and a front end portion of the injection plunger from the extruder through the injection plunger. Introducing holes extending all the way are provided, and the introducing holes are radially branched near the front end portion of the injection plunger.

[0011]

When the resin is supplied from the hopper to the inner hole of the extruder and the screw is rotated while heating the resin, the resin is melted and the molten resin is stored in the accumulator while retracting the plunger. Then, when the plunger is advanced, the resin is supplied to the die through the resin passage. When resin or color is changed after such repetitions, rotate the screw of the extruder, and the resin from the extruder will pass through the resin introduction hole provided in the axial direction of the injection plunger, and the front end of this injection plunger The resin accumulated in the accumulator is easily renewed with a new resin by being spirally discharged into the accumulator through the radial introduction holes near the portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of a resin supply device for a die according to the present invention will be described in detail below with reference to the drawings.

1 to 5 show an embodiment of a resin supply device for a die according to the present invention, FIG. 1 is a partially cut sectional view thereof, FIG. 2 is a sectional view of an essential part of an accumulator, and FIG. Two
4A is a front view seen from A to A, FIG. 4 is a schematic side view of a blow molding machine that carries out this, and FIG. 5 is an explanatory view showing a state of resin change or color change.

In FIG. 4, the blow molding machine 20 is provided with a pair of platens 21 erected on the floor, and the dies 22 and 23 having vertical joint surfaces are fixed to each platen 21, respectively. Each of the cylinder bases 24 provided outside the left and right platens 21 includes mold opening / closing cylinders 25, 26.
Are fixed, and each of these mold opening / closing cylinders 2
The molds 22 and 23 are attached to the piston rods 5 and 26, respectively, and the molds 22 and 23 are opened and closed by advancing and retracting the piston rods.

A vertical die 28 having a control device 27 is provided right above the joining surfaces of the molds 22 and 23.
The die 28 is provided with a resin supply device generally indicated by reference numeral 30. This resin supply device 30 is provided with an accumulator 32 which is formed in a cylindrical shape and has a resin passage 31 at the front end portion joined to a die 28. The accumulator 32 is provided at the tip end portion of an extruder 33 which is in tandem with the accumulator 32. It is connected through a resin passage 34.

The screw 3 is fitted in the inner hole 33a of the extruder 33.
5 is rotatably fitted, and the extruder 33 is provided with a hopper 36 as a supply port for supplying pelletized resin into the extruder 33.

A speed reducer 42 is arranged at the rear of the extruder 33 and is directly connected to the screw 35. The speed reducer 42 is configured to rotate the screw 35 after decelerating the rotation speed transmitted by the motor 46 via the belt 44 to a desired rotation speed.

The extruder 33, the speed reducer 42 and the motor 46 are mounted on a pedestal 51 as shown in FIG. A roller 50 is attached to a corner portion of the pedestal 51, and an injection hydraulic cylinder 48 disposed on a pedestal (not shown) is disposed at a rear end of the pedestal 51, and the pedestal 51 is expanded and contracted as the rod 48a expands and contracts. Can move forward and backward on the rail 49.

The extruder 33 and the accumulator 32 are arranged coaxially, and the injection plunger 38 slides back and forth in the accumulator housing 32b when the gantry 51 is moved back and forth by the operation of the injection hydraulic cylinder 48 described above. It is designed to move.

The injection plunger 38, which slides back and forth in the accumulator housing 32b, has an introduction hole 40 for supplying the molten resin 41 supplied from the extruder 33 to the resin reservoir 39 in the accumulator 32. It is provided along the axis of 38.

The resin introducing hole 40 is provided in the injection plunger 38.
2 and 3, the guide holes 40 are radially branched in the vicinity of the front end portion thereof, and the introduction hole 40 is open to the slope portion of the injection plunger 38 having a substantially conical tip. Reference numerals 53 and 54 represent open / close valves.

The operation of the blow molding machine configured as described above will be described. When the opening / closing valve 54 is opened and the opening / closing valve 53 is closed, pellet-shaped resin is supplied from the hopper 36 to the inner hole 33a of the extruder 33, and the screw 35 is rotated while heating the resin. The molten resin 41 is stored in the resin storage portion 39 of the accumulator 32 via the introduction hole 40 in the injection plunger 38.

At this time, if the piston head side of the injection hydraulic cylinder 48 is left free, the injection plunger 38 is gradually retracted to the retreat limit by the resin pressure stored in the resin storage portion 39.

Next, when the opening / closing valve 54 is closed and the opening / closing valve 53 is opened, the rod 48a of the injection hydraulic cylinder 48 is extended and the plunger 38 is advanced, so that the resin 41 is first accumulated by the pressing action of the injection plunger 38. Resin 41
From then on, the resin is transferred to the die 28 through the resin passage 31.

The resin 41 supplied to the die 28 is injected aiming at both the cavities of the opened molds 22 and 23 to form a parison which is a resin cylinder. After sandwiching, gas such as air is blown into the parison, and after this, when the resin is cooled and fixed,
A hollow molded product is obtained.

After the repeated molding of the hollow molded product is completed, in order to efficiently replace the old resin 41 remaining on the accumulator 32 with the new resin 41 due to the material change or the color change, the above-described operation is performed. However, the resin storage part 39 is fed from the extruder 33 through the introduction hole 40.
When the resin 41 is fed to the resin, it is spirally discharged from the radial introduction holes 40 to the resin reservoir 39. This spiral discharge prevents the resin from staying in the dead zone.

[0027]

As is apparent from the above description, the present invention is provided with the accumulator having the front end resin passage joined to the die and the injection plunger fitted in the inner hole of the accumulator so as to be able to advance and retract. A device for supplying resin to a die, in which the front end resin passage is directly joined to the injection plunger in a tandem manner, and an introduction hole extending from the extruder to the front end portion of the injection plunger through the inside of the injection plunger. With the provision of, by diverging the introduction hole radially near the front end of the injection plunger, there is no dead zone in which the resin stays, and when the plunger is advanced, the resin in the accumulator becomes uniform without staying. Since it is supplied to the die, deteriorated resin that has undergone a long thermal history is not supplied into the die,
The resin temperature and heat history are uniform, color unevenness is reduced, and the quality of molded products is greatly improved. Further, the time for changing the resin or the color is reduced, the productivity is improved, and the resin is not wasted during the preparatory work, and the consumption of the resin is reduced.

[Brief description of drawings]

FIG. 1 is a partially cut sectional view of a resin supply device for a die according to an embodiment.

FIG. 2 is a sectional view of a main part of an accumulator.

FIG. 3 is a front view seen from AA of FIG.

FIG. 4 is a schematic side view of a blow molding machine that carries out this.

FIG. 5 is an explanatory diagram showing a state of resin change or color change.

FIG. 6 is a vertical cross-sectional view of a conventional resin supply device for a die.

FIG. 7 is a vertical cross-sectional view of a resin supply device for another die shown in FIG.

[Explanation of symbols]

 20 Blow Molding Machine 22, 23 Mold 28 Die 30 Resin Supply Device 31, 34 Resin Passage 32 Accumulator 32b Accumulator Housing 33 Extruder 38 Injection Plunger 39 Resin Reservoir 40 Inlet Hole 41 Molten Resin 42 Reducer 46 Motor 48 Injection Hydraulic Pressure Cylinder

Claims (1)

[Claims] 1. A resin supply device for a die, comprising: an accumulator having a front end resin passage joined to a die; and an injection plunger fitted in an inner hole of the accumulator so as to advance and retreat. An extruder having the front end resin passages directly joined in tandem and an introduction hole from the extruder to the front end of the injection plunger through the inside of the injection plunger are provided, and the introduction hole is provided at the front end of the injection plunger. A resin supply device for a die, which is radially branched in the vicinity.