JPH05253998A - Extrusion molding method and extrusion molding device - Google Patents

Abstract

PURPOSE:To provide a molding method and molding device whose productivity is high. CONSTITUTION:Half split casings 7, 8 of a transfer squeezing sectional area varying device 6 and a flange 21 of a flat head 20 are piled upon the tip flange 3 of a barrel 2 provided with an extruding screw which is turned and driven on the inside and clamped them together integrally by a bolt 19, a mouthpiece 23 is fitted integrally to a tip flat part 22 of the flat head 20, a slide plate 16 provided with a circular hole 17 which is in the same form as those 9, 10 of the half split casings 7, 8 is fitted slidably freely into guide grooves 11, 12 of the slide plate of the half split casings 7, 8 and a rod of a hydraulic cylinder 15 fitted to the lower part of a support frame 13 which is one with the half split casing 7 is connected with the lower end of the slide plate 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion molding method for applying a pressure to a molding material such as a rubber compound or a thermoplastic resin with a screw to extrude a molding material having a required cross-sectional shape from a die at the tip of a head. And an extrusion molding apparatus.

[0002]

2. Description of the Related Art In order to mold a rubber strip-shaped member having a predetermined cross-sectional shape to be used in a tire manufacturing process, conventionally, an extrusion molding apparatus using a screw has been used. Since the molding material heated to the required temperature is filled in this extrusion molding device, if the molding operation is interrupted for a long time, the filling molding material will cool and become solid, and the next extrusion molding operation will be performed. It will not be possible to restart smoothly. In order to avoid such a situation, after the completion of the molding operation, the extrusion molding apparatus was disassembled and the filling molding material in the apparatus was removed.

Next, when the extrusion molding operation is restarted,
When the extrusion screw is driven to rotate while the molding material is supplied from the molding material supply hopper provided at the rear portion of the barrel with the die attached to the tip of the flat head, the molding material is transferred forward in the barrel. It is pushed into the flat head at the tip and extruded from the mouthpiece opening at the tip of the flat head, but immediately after the work is started, the molding material is not filled around the extrusion screw without any gaps, and irregular voids exist. However, when the molding material is sent to the flat head while enclosing the air in the void, and the molding material is squeezed and extruded from the die opening having an opening area significantly narrower than the cross-sectional area of the passage of the flat head. In addition, it was unavoidable that the air in the voids was not released into the atmosphere and remained as a large number of bubbles in the molding material.

Since the extruded member in which air bubbles remain in this way cannot be used in the tire manufacturing process, it has been conventionally used.
With the die removed from the tip of the flat head, the extrusion screw is driven to rotate while the molding material is fed from the molding material supply hopper, so that the molding material with voids is discharged from the flat head. After the molding material with no voids is discharged from the flat head, the rotation of the extrusion screw is stopped once and the molding material discharged from the flat head is removed. The base had to be attached to the tip of the head and the extrusion screw had to be rotated again.

[0005]

[Problems to be Solved] In order to restart the extrusion molding work, not only such an emptying work is additionally required, but also after the extrusion screw is once stopped and the die is mounted,
In order to rotate the extrusion screw again, at the beginning of extrusion, the cross-sectional shape of the molded member extruded from the die is different from the desired shape for the die opening shape, and the center part in the width direction is thick and both sides are thin. Therefore, it cannot be used as a molding member as it is, and it is necessary to re-knead the molding material whose cross-sectional shape is incorrect or the above-mentioned blank molding material, and the productivity is low when the extrusion molding is restarted.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to an improvement in an extrusion molding method and an extrusion molding apparatus which overcomes the above problems, and relates to a flat head portion located in front of an extrusion screw by a molding material by the extrusion screw. In the extrusion molding method of extruding from the opening of the die of the flat head part, in the state that there is no molding material in the transfer passage, start to supply the molding material to the carry-in side of the extrusion screw, Until the molding material to be fed reaches the mouthpiece part of the flat head portion, the cross-sectional area of the flat head portion inlet is greatly narrowed, and when the molding material pressure in the transfer passage upstream from this exceeds a predetermined value. It is characterized in that the cross-sectional area of the inlet of the flat head portion is increased.

In the present invention, as described above, in the extrusion molding method in which the molding material is transferred to the flat head portion located in front of the extrusion screw by the extrusion screw and is extruded from the opening of the die of the flat head portion, a transfer passage Starting to supply the molding material to the carrying-in side of the extrusion screw in the state where there is no molding material therein, and until the molding material sent by the extrusion screw reaches the mouthpiece part of the flat head portion, the flat head portion inlet Since the cross-sectional area of the molding material is narrowed to a large extent, the pressure of the molding material in the extrusion rail screw chamber (in the barrel) rises rapidly, and the bubbles in the molding material are quickly discharged to the outside. It is possible to prevent bubbles from being included in the extruded molded member. In addition, it becomes possible to raise the temperature of the molding material to the specified temperature at an early stage.

When the molding material passes through the portion where the cross-sectional area of transfer is reduced and reaches the mouthpiece portion of the flat head portion, the pressure in the screw receives the back pressure from the molding material that has reached the mouthpiece and is further increased. To rise. This pressure increase is detected by a pressure sensor described later, and if the cross-sectional area of the flat head inlet is increased in accordance with the timing, an extruded member without bubbles is extruded from the die at the tip of the flat head. It As described above, according to the present invention, not only the conventional emptying work becomes unnecessary, but also the emptying molding material and the kneading work due to the defective shape of the extrusion molding material become unnecessary, and the productivity is greatly improved. It will be possible.

The present invention also includes an extrusion screw that is rotationally driven, a barrel that covers the outer periphery of the extrusion screw,
In an extrusion molding apparatus including a molding material supply hopper provided at a rear portion of the barrel, a flat head coupled to a tip of the barrel, and a die provided at a tip of the flat head, the barrel and the flat head are provided. And a molding material pressure detecting means for detecting a molding material pressure in the transfer passage are provided at a boundary portion between the extrusion molding apparatus and the transfer throttling sectional area varying means. Thus, the extrusion molding method described above can be smoothly performed.

[0010]

EXAMPLE An example of the present invention shown in FIGS. 1 to 4 will be described below. In an extrusion molding apparatus 1 for molding a rubber strip-shaped member having a predetermined cross-sectional shape that is used in a tire manufacturing process, a cylindrical barrel 2 has a heating means for heating a molding material 27 built therein. A molding material supply hopper 4 is provided above the rear end of the barrel 2, and an extrusion screw 5 is concentrically fitted in the barrel 2 and is rotatably supported in a rotatable manner. It is designed to be rotated.

The flange-shaped flange 3 at the tip of the barrel 2 is in contact with one half casing 7 in the transfer throttle sectional area varying means 6, and in the other half casing 8 in the transfer throttle sectional area varying means 6. Flat head 20 flange
21 is applied, the flange 21, half casings 7, 8
The tip of a bolt 19 penetrating through is screwed onto the flange 3, and the flange 3, the half casings 7, 8 and the flange 21 are fastened together.

Further, circular holes 9 and 10 are formed in the centers of the half casings 7 and 8, and sliding plate guide grooves 11 and 12 oriented in the vertical direction are formed on the mating surfaces thereof to form the half casings 7. The upper end of the support frame 13 is integrally fixed to the lower end by welding or the like, and the hydraulic cylinder 15 is attached to the lower horizontal portion 14 of the support frame 13 and its rod 15a is provided.
The tip of the is screwed to the lower end of the sliding plate 16. Further, a circular hole 17 having the same diameter as that of the circular holes 9 and 10 is formed in the sliding plate 16, and the bolt 19 is inserted into the upper and lower guide holes 18 of the sliding plate 16 so that the hydraulic cylinder 15 has By driving the rod 15a up and down, the sliding plate 16 can be moved up and down to fully open the moving cross-sectional area or to significantly reduce the cross-sectional area. Furthermore, the flat end of the flat head 20
The mouthpiece 23 is applied to 22 and is attached detachably with a bolt 25. Moreover, a molding material pressure detection sensor 26 (see FIG. 1) is attached near the tip of the barrel 2.

Since the embodiment shown in FIGS. 1 to 4 is configured as described above, the extrusion molding apparatus 1 can be disassembled, and the flat head can be used when the extrusion molding operation is interrupted for a long period. 20 can be disassembled and all the molding material 27 in the extrusion molding apparatus 1 can be removed. Then, to restart the extrusion molding operation, assemble the flat head 20 and
After the mouthpiece 23 is integrally attached to the tip flat part 22 with the bolt 25, the sliding plate 16 is lowered to a position where the upper end of the guide hole 18 of the sliding plate 16 comes into contact with the bolt 19, and the half casing is 7,
After the opening areas of the circular holes 9 and 10 of 8 are reduced to the minimum, the molding material 27 may be supplied from the molding material supply hopper 4 into the barrel 2 while rotating the extrusion screw 5.

Then, at the initial stage of supplying the molding material 27, the molding material 27 is not filled around the extruding screw 5 in the barrel 2 and there are wide gaps.
As time passes, the amount of the molding material 27 in the barrel 2 increases and the void becomes narrower. More barrel 2
In the state in which the molding material 27 initially supplied into the barrel 2 reaches the tip space in the barrel 2, the molding material 27 is small and the voids are wide in its vicinity, but the half casing 7 in the transfer throttle cross-sectional area varying means 6 is used. Since the circular holes 9 and 10 of 8 and 8 are narrowed by the sliding plate 16, the molding material 27 reaching the tip space in the barrel 2 is blocked by the sliding plate 16 while the hopper 4 continues to Since the molding material 27 is supplied, the pressure of the molding material 27 in the barrel 2 rises, and the bubbles taken in the molding material 27 are discharged to the outside early.

Next, the molding material 27 that has passed through the transfer throttle sectional area varying means 6 reaches the die 23 through the flat head 20.
Since the cross-sectional area of the molding material 27 is further reduced at the mouth opening 24, a back pressure is generated in the molding material 27, and the pressure of the molding material 27 in the barrel 2 is further increased. At this time, the molding material pressure detection sensor 26 installed near the tip of the barrel 2
Detects this increase in pressure, raises the sliding plate 16 with the hydraulic cylinder 15 by this signal, and matches the circular hole 17 of the sliding plate 16 with the circular holes 9 and 10 of the half casings 7 and 8. , The cylindrical molding material 27 enters into the flat head 20 through the circular hole 10,
The strip-shaped extruded member 28 is stably extruded from the opening 24 of the die 23 through the flat head 20.

According to this embodiment, since the strip-shaped extruded member 28 made of rubber or the like in which air bubbles are not mixed can be extruded, it is not necessary to perform emptying with the die 23 removed, and the die at an inappropriate time The mounting work of can be omitted. Further, in the conventional extrusion molding apparatus which does not include the transfer throttle cross-sectional area varying means 6 of this embodiment, the strip-shaped extrusion molding member 28 immediately after the start of extrusion molding has a flow time required at the central portion in the flat head 20 at both sides. Since it is shorter than the flow required time, the rubber viscosity of the central portion is lower than the rubber viscosity of both side portions, so that the central portion is thicker and both side portions are thinner, resulting in a contour different from that in the steady state. However, in this embodiment, since the contour is constant from the beginning, no rework is necessary.

As described above, according to the present embodiment, there is no delay in the normal extrusion molding start time due to the emptying work, and there is no work for mounting the die and reworking after the emptying, so that labor can be saved. At the same time, the productivity at the start of extrusion molding can be greatly improved, and the quality of the extruded material can be improved.

In the embodiment shown in FIGS. 1 to 4, the sliding plate 15 is slidable up and down, but as shown in FIG. 5, the rotary plate 29 is inserted into the circular holes 9 and 10. It is rotatably provided in an eccentric state, a circular hole 30 is formed at a position eccentric to the rotation center of the rotary plate 29, a drive gear 32 is meshed with an external gear 31 of the rotary plate 29, and a drive gear 32 is driven by a motor (not shown). The opening area of the circular holes 9 and 10 may be changed by rotationally driving.

In the embodiment shown in FIGS. 1 to 4, the sliding plate 16 is moved up and down by using the fluid pressure cylinder 15, but instead of the fluid pressure cylinder 15, a motor is used as a driving source. The moving plate 16 may be moved up and down, and further, as shown in FIG. 6, a screw rod 34 rotated by a manual handle 33 may be attached to the lower horizontal portion 14 of the frame 13 to move the sliding plate 16 up and down. Further, since the apparatus for varying the opening ratio of the various barrel tip portions described in the present invention is used and the discharge rate of the extruded material is changed when the opening ratio is changed, the method and the apparatus of the present invention are used. It can also be used as a method and apparatus for controlling the discharge amount.

[Brief description of drawings]

FIG. 1 is a fragmentary perspective view showing an embodiment of an extrusion molding apparatus according to the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a front view of a main portion with a partial cutaway in FIG.

FIG. 4 is a vertical sectional side view cut along the line IV-IV in FIG.

FIG. 5 is a fragmentary front view showing a main part of another embodiment.

FIG. 6 shows another embodiment for driving the sliding plate 16.

[Explanation of symbols]

1 ... Extrusion molding device, 2 ... Barrel, 3 ... Flange, 4 ...
Molding material supply hopper, 5 ... Extrusion screw, 6 ... Transfer throttling sectional area varying means, 7, 8 ... Half casing, 9,
10 ... Circular hole, 11, 12 ... Sliding plate guide groove, 13 ... Support frame, 14 ... Lower horizontal part, 15 ... Hydraulic cylinder, 16 ... Sliding plate, 17 ... Circular hole, 18 ... Guide hole, 19 ... Bolt, 20 ... Flat head, 21 ... Flange, 22 ... Flat end portion, 23 ... Base, 24 ... Opening portion, 25 ... Bolt, 26 ... Molding material pressure detection sensor, 27
... Molding material, 28 ... Band-shaped extruded member, 29 ... Rotary plate, 30
… Circular hole, 31… External gear, 32… Drive gear, 33… Manual handle, 34… Screw rod.

Claims (2)

[Claims] 1. In an extrusion molding method in which a molding material is transferred to the flat head portion located in front of the extrusion screw by the extrusion screw and is extruded from an opening of a die of the flat head portion, the molding material is present in a transfer passage. Starting to supply the molding material to the carry-in side of the extrusion screw in the state not to perform, until the molding material sent by the extrusion screw reaches the die part of the flat head portion, the cross-sectional area of the flat head portion inlet is greatly increased. And the cross-sectional area of the flat head inlet is increased when the molding material pressure in the upstream transfer passage exceeds a predetermined value. 2. An extrusion screw that is driven to rotate, a barrel that covers the outer periphery of the extrusion screw, a molding material supply hopper that is provided at the rear portion of the barrel, a flat head that is connected to the tip of the barrel, In an extrusion molding apparatus including a die provided at the tip of a flat head, a transfer throttle cross-sectional area varying means at a boundary portion between the barrel and the flat head,
An extrusion molding apparatus, comprising: a molding material pressure detecting means for detecting a molding material pressure in the transfer passage.