KR20050121771A - A spiral die - Google Patents

Abstract

The inflow resin with the following structure is uniformly dispersed and molded around, and excellent tubular body of homogenization and homogenization, inflation non-stretching, stretched film and functional film are obtained, and it can cope with various kinds of melt resins and extrusion conditions. Can provide a spiral die. Spiral groove in the range of a part of the die cylinder part which forms the inner surface of the die main body 1 while installing the mandrel 2 which has the helical groove 3 in the outer surface inside the die main body 1, and is provided. The rotating ring 5 having a desired width in a portion corresponding to the portion from the beginning to the end of (3) is rotated freely along the outer circumferential surface of the spiral groove 3.

Description

Spiral Die {A SPIRAL DIE}

The present invention relates to a spiral die suitable for molding a tubular body by extrusion molding.

As a die used for forming a tubular body by a conventional extrusion method, a spider die in which spider marks frequently occur, and a straight die with a thickness bias are gradually used, but are shown in Figs. 4 (a) and (b). As described above, a spiral groove 3 is provided on the outer surface of the mandrel 2 inserted and installed in the die main body 1, the molten resin supplied from the extruder is introduced into the mandrel at the inlet, and the split inlet 32 In many cases, it is divided into two to eight flow paths and moves past the spiral groove 3 to the die lip (right end of the drawing). The helical groove 3 becomes shallow in order from the tip to the end in order, so that the molten resin partially shifts between the die cylinder inner surface and the mandrel in the process of moving the helical groove, and sees the collecting portion 33 (Fig. 4 (b)). ) And a straight line (land part: lip cap part), and the structure which reaches a die lip in a laminar flow state as a conventional example. In addition, there is also a use of a spiral die of a gathering part depending on the application (see Fig. 4 (a)).

In addition to the spiral dies described above, various proposals have been made to obtain homogenization and homogenization of molten polymer at the die lip outlet.

1) A porous pipe made of highly viscous elastic material is produced by friction heating of the material between the cylinder and the mandrel by raising the temperature due to the dispersion of the strand after the breaker plate or the adhesion and crosslinking of the raw material powder. The frictional heat is obtained by rotating the entire cylinder. This suggests that "the mold and the molding of the extrusion molding are rotated relatively, and the rotation is good even in the continuous or vibration, and the characteristics of the molding are controlled by controlling the direction and the degree of rotation" (see Fig. 5). (See, for example, Japanese Patent Application Laid-Open No. 8-57936).

2) In the case of pipe extrusion, the thickness correction is performed by detecting the gap between the die and the rotatable eccentric nipple (mandrel) and the temperature difference in the circumferential direction. A thickness anti-extrusion apparatus having a temperature sensor for detecting the resin temperature in the circumferential direction of the cross head and the resin flow passage, wherein either one of the dice or the nipple is rotated around the shaft center '' (see Fig. 6). (See Reference 2: Japanese Patent Application Laid-Open No. 59-9035).

3) "A case where a plurality of laminates are manufactured from different materials, and the material which consists of the leakage flow in the plural spiral flow path grooves rotates the mandrel with which a spiral is installed, (See Fig. 7) is disclosed (see, for example, Japanese Patent Laid-Open No. 10-29237).

In general, the die body is a molten resin that moves along the inner wall of the cylinder (hereinafter referred to as a land flow) and a molten resin that moves a spiral groove (hereinafter referred to as a spiral flow) in a quantitatively balanced manner to the die lip. However, this balance is important, and if this balance is broken, the appearance of the tubular body may be poor, leading to squeezing, marring, deviating thickness, shiwa, and strength marring.

The proper balance of land flow and spiral flow is empirically determined by the width, groove depth, pitch and the like of the spiral groove. However, the proper balance of each flow is also changed by melt flow rate, temperature, viscoelasticity, etc. However, since there is no suitable means to cope with the change, welding marks are frequently generated, and by kneading, the temperature is increased to reduce the viscoelasticity. This results in a thickness bias, and causes a problem such as causing dirt (die marks, etc.) of the die lip due to deterioration of the resin.

As the die used for molding the melt-kneaded polymer material into the desired shape in the extruder, there are a round die and a flat die.

As molded using a round die, tubular bodies such as films, pipes, bro vessels, nets, and the like may be mentioned, and none of them is the case in which the same cylindrical shape of the molten polymer extruded from the die lip is intended for release. The performance of the die has a big impact on the quality of the molded parts. If the same cylindrical shape is not uniform or homogeneous, (1) thickness bias, (2) appearance defects (welding marks, swages, mars, shiwa, etc.), (3) strength decreases, (4) electrical properties decrease, etc. Cause. In addition, in the case of the replacement of the dissimilar raw materials, the replacement of the spiral grooves and the like is difficult, resulting in a long replacement time and a problem of high replacement loss.

Since the flow of material in the die varies depending on the flow rate as long as the viscoelasticity as a property of the material depends on the temperature and pressure, the flow inhibiting means is not fixed but needs to be varied, but the straight portion close to the die lip ( For the rectification as a function required for the land portion), fixed restraining means is preferable.

In this case, the welding mark (welding line) means a thin line that occurs when the flow of the molten resin flowing through the helical grooves does not become uniform or homogeneous, that is, a “wrinkle state”.

Also in the said prior art (helical die and references 1-3 shown to FIG. 4 (a), (b)), the said subject is not solved.

Since the present invention has been made in view of the above situation, the inflow resin is uniformly dispersed and molded around, thereby obtaining an excellent tubular body of uniformity and homogenization, inflation non-stretching, stretched film and functional film, An object of the present invention is to provide a spiral die that can cope with molten resin and extrusion conditions.

The present invention can solve the above problems by having the following configuration.

(1) In the range of a part of a part of the die cylinder which forms the inner surface of a die main body, while installing the mandrel which has a spiral groove on the outer surface inside the die main body, at the same time from the beginning to the end of the spiral groove. Rotating ring of desired width is rotatably mounted along the outer circumferential surface of the helical groove in a portion corresponding to the gap between the rotating ring and the sliding part adjacent to the sliding part of the die body, and used as lubricant. A spiral die formed by installing a discharge mechanism having a flow path for discharging this lubricant outside the apparatus by having a needle valve with an adjustable flow rate.

(2) The spiral die according to the above (1), wherein the rotation ring is capable of rotation control at a rotation speed of 60 rpm or less.

(3) The inner surface of the rotating ring is a mirror surface in the surface flaw specification (value according to JIS B 0601-1976: 0.1 S to 6.3 S), rough surface (depth of depth 4 µ to 150 µ) The helical die according to the above (1), which has any one configuration of a tooth surface (flat shape, spiral tooth shape).

Note: A value of 0.1 S according to JIS (Japanese Industrial Standard) shows that the average distance between adjacent peaks of surface roughness in a predetermined length is 0.1 mm.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the spiral die which concerns on this invention is described with reference to drawings.

As shown in Fig. 1, the spiral die suitable for molding the tubular body by the extrusion method according to the present invention has a spiral groove 3 inside the die body 1 on its outer surface and integrally includes the flange portion 2a. In the range of a part of the die cylinder portion which press-fits and inserts the molded mandrel 2 into the die main body 1 and forms the inner surface of the die main body 1, the first part of the spiral groove 3 at the same time. From the end to the end, characterized in that the rotation is freely mounted along the outer circumferential surface of the helical groove (3) of the rotary ring 5 of the desired dimensions. The flange 2a is connected to the extruder so that the molten resin from the extruder is supplied from the inlet 31 to the spiral groove 3 through the split inlet 32.

The depth of the helical groove 3 provided on the outer surface of the mandrel 2 gradually decreases from the start point to the end point, and gradually decreases from the inner surface of the assembly 33 and the mandrel 2 and the die body 1. It consists of the structure which leads to the linear part to form.

The rotary ring 5 has a function of uniformly and homogenizing by appropriately dispersing the flow of the molten resin in the circumferential direction, and is configured to select the rotation direction and the rotation speed of the forward and reverse rotation according to the characteristics of the material, the extrusion conditions and the like.

Rotating ring 5 that can be freely rotated freely can be controlled to rotate at a rotation speed of 60 rpm or less, and the inner surface 5b of the rotating ring 5 that can be freely rotated is a surface flaw standard (JIS B 0601-1976). ), The finish of the mirror surface is 0.1 S to 6.3 S, preferably 0.1 S to 1.6 S, and the degree of roughness is 4 to 150 μs of easy depth, preferably easy to depth. It is set to 4 micrometers-50 micrometers, and it consists of either the structure of a tooth surface (flat shape, a spiral tooth shape) (refer FIG. 3 (a), (b), (c)).

The surface flaw of the inner surface 5b of this rotary ring 5 can be selected so that an appropriate dispersion degree may be obtained according to material properties, extrusion conditions, and the like.

The rotary ring 5 has teeth 5a which form a tooth on the outer circumferential surface, and a plurality of pinions 4 having a tooth 4a that meshes with the teeth 5a, It is axially supported by the shaft 4b to the die main body 1, and can be rotated freely via the pinion 4. As shown in FIG. When three or more pinions (small gear) 4 are provided, it is comprised by the structure which ensures the precision of the axial center of rotation.

In the mandrel 2 which has the helical groove 3 on the outer surface, the assembly part 33 is provided between the end of the helical groove 3 to the straight part (land part: lip cap part) of the die lip 2b. It is characterized by. The rectifying property of the inflow resin can be further improved by setting the collection portion 33 to an appropriate size.

In order to prevent the rotary ring 5 from burning out, the raw material is leaked into the sliding parts adjacent to the rotary ring 5 and the die main body 1 to form a lubricant, and a flow path 6 through which the lubricant is discharged outside the machine. Equipped with a ventilator not shown. The discharge mechanism is equipped with a needle valve to adjust the discharge flow rate, and has a cooling fan around the outside of the discharge pipe, and is configured to discharge the lubricant made of the cooled raw material to the outside of the device.

Furthermore, the width dimension of the rotary ring 5 can be determined with a margin over the front end of the helical groove, i.e., the front end of the helical groove 3 and the rear end of the helical groove 3, and the mandrel At the position corresponding to the spiral groove 3 provided on the outer surface of (2), the "helical pitch + groove width" having the minimum width and the "spiral groove starting point to the end point" having the maximum width can be set. Can be satisfied.

Lubrication of the sliding part between the rotary ring 5 and other parts and heat resistance to a high extrusion temperature are required, and in order to avoid mixing of different types of lubricants in the material, the outer peripheral surface of the rotary ring 5 and the teeth 5a Lubrication of the leaked amount of the molten resin managed in the annular groove (hereinafter referred to as the bearing link) provided in the sliding surface in the die main body 1 corresponding to the portions of both sides) is guided by a lubricant and I make a structure to discharge.

The embodiment which changed various conditions is shown and demonstrated below.

The spiral die which concerns on this invention is attached to an extruder, and film production of the inflation film made from polypropylene is performed.

<Specifications of the device>

Screw external diameter D = Ø50mm, screw effective length L = 1433mm, L / D = 28, flight pitch 50mm constant, screw compression ratio 3.8, spiral diameter exit diameter Ø155mm, air ring inner diameter 300mm, cooling ring , Stabilizer, pitch roll and product winding machine.

(Test 1)

The raw material for inflation (polypropylene resin) is used, and it is set as the temperature conditions, and it is set as the extruder 200 degreeC, the head 200 degreeC, the die 200 degreeC, the extrusion amount 33 kg / h, the take-up speed 30m / min, and is shown in FIG. One spiral die is provided to stably set an inflation film having a film width of 320 mm and a thickness of 30 mu to prepare a film.

<Example conditions 1B-4B>

Run the rotary ring and make the membrane.

  Real    Direction of rotation     Revolutions    Rotation time      rpm     Seconds / turn    1B      turn right      0.4      150    2B      turn right      0.8       75    3B      turn left      0.4      150    4B      turn left      0.8       75

1) Right turn is the same direction as the spiral screw direction of the spiral die.

2) Left turn is reverse to the helical screw direction of the helical die.

(Test 2)

15 kg of a material (hereinafter referred to as a coloring material) in which 1% of the pigment is mixed with a raw material for inflation is made, and 5 kg of the material is extruded within this range until it is returned to its original state. Sprinkle) At this time, the consumption non-colored material is measured when the rotary ring is operated and when it is not operated.

Below is a comparison of the test.

Comparative Example 1  Real  Direction of rotation   Revolutions  Rotation time  Weld Mark  thickness  Thickness bias    rpm   Seconds / turn    μ     Rμ   1A  Does not rotate     -     -      U   28     9   1B  turn right    0.4    150      radish   27     6   2B  turn right    0.8     75      radish   27     6   3B  turn left    0.4    150      radish   27     5   4B  turn left    0.8     75      radish   27     4

8 (shows the thickness bias state of the resultant film in Example 1A)

9 (shown the thickness bias state of the produced | generated film in Example 1B)

10 (the thickness bias state of the produced film in Example 3B) is shown.

8-10, the horizontal axis X is a longitudinal direction of a film, and the vertical axis Y shows the change of thickness (micro).

(Review)

1) In Table 2, in the case where the rotary ring of the implementation condition 1A is fixed, a weld mark is formed, and the wound shape gradually deteriorates when the product is wound on the branch pipe.

2) In the presence or absence of rotation, the appearance of the shape in which the case of the rotation was certainly wound was good.

3) In the case of rotating in Table 2, the wound shape with the faster rotational speed was good.

4) In the graph of FIG. 8, local thickness bias was remarkable.

5) In the graph of FIG. 9, the local thickness bias was thin, and there was an effect of improvement.

6) In the graph of FIG. 10, there was no tendency of local thickness bias, and a suitable state was confirmed.

Comparative Example 2  Real   Direction of rotation   Revolutions  Rotation time   Coloring material  Consumption and Time of Uncolored Material    rpm   Seconds / turn     Kg     Kg     minute  1AA  Does not rotate     -      -     5     10     40  1BB  turn right    0.8     75     5      5     20  2BB  turn left    0.8     75     5     3.5     14

1) When not rotating at an extrusion rate of 15 kg /, it took about 40 minutes until the color disappeared.

2) When operating at a right turn at an extrusion rate of 15 kg / hour, it took about 20 minutes until the color disappeared.

3) When operating at a left turn at an extrusion rate of 15 kg / hour, it took about 14 minutes until the color disappeared.

4) The rotation was completed in almost half the time compared to the case without rotation.

5) Compared to the right turn, the left turn consumed less of the uncolored material.

(Evaluation method)

<Evaluation 1>

Under the same conditions, the stability of the film production and the product were tightly wound around the paper tube to see the wound shape. At the same time, the thickness of the film just produced is measured continuously.

<Evaluation 2>

Under the same conditions, the consumption and time for replacing the coloring material are compared.

(Evaluation results)

<Evaluation Result 1>

In the comparative example 1, the effect of rotating a rotating ring was assured in Table 2 and the graph of FIGS. 8-10.

<Evaluation Result 2>

In Comparative Example 2, the effect of color replacement was assured that a suitable effect was obtained by moving the rotary ring, and it was also confirmed that the reverse rotation was more effective with respect to the spiral screw direction of the spiral die.

As described above, by using the spiral die of the present invention, the inflow resin is uniformly dispersed and molded around, thereby obtaining an excellent tubular body of uniformity and homogenization, inflation non-stretching, stretched film and functional film, It is possible to provide a spiral die that can cope with molten resin and extrusion conditions.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the principal structure of the helical die which concerns on this invention, (a) Typical explanatory drawing which shows the engaged state of a rotating ring and a pinion (small gear), (b) A cut surface,

2 is a perspective view of a rotating ring according to the present invention,

3 is an explanatory view showing an example of the tooth shape of the inner surface of the rotating ring (a), (b), (c),

4 is a cross-sectional view of the spiral die for forming a tubular body in a conventional example, (a) when there is no gathering portion, (b) when there is gathering portion,

Fig. 5 is a cross-sectional view showing the main part structure according to Ref. 1 in the conventional example,

Fig. 6 is a cross-sectional view showing the main part structure according to Ref. 2 in the conventional example.

Fig. 7 is a cross-sectional view showing the main part structure according to Ref. 3 in the prior art example,

8 is a graph showing a situation of appearance (thickness bias) of a film-shaped molded article under conditions when the rotary ring is not rotated.

FIG. 9 is a graph showing a situation of appearance (thickness bias) of a film-form molded article under conditions when the rotary ring is rotated to the right,

FIG. 10 is a graph showing a situation of appearance (thickness bias) of a film-form molded article under conditions when the rotary ring is rotated leftward. FIG.

(Explanation of reference numerals)

51 ... die carrier,

52 ... breaker plate die,

53 cylinder body, 54 mandrel,

55 ... central passage, 61 ... extruder,

62.cross head,

63 ... the main body of the cross head,

65 ... nipple, 67 ... circular die lip,

613 thermal sensors, 614 bearings,

616 ... gear, 71 ... circular spiral die,

72 ... die lip, 71a ... outer die ring,

71b ... circulating inner ring,

M ... motor,

Claims (3)

In the range of a part of the die cylinder part which forms the inner surface of a die main body, while inserting the mandrel which has a spiral groove on the outer surface inside a die body, At the same time, the rotating ring of the desired width can be freely mounted along the outer circumferential surface of the spiral groove in the corresponding portion between the beginning and the end of the spiral groove, and used for the adjacent sliding part of the rotary ring and the die body. A spiral die comprising a discharge valve having a flow path for discharging the lubricant to the outside and having a needle valve for adjusting the discharge flow rate, and for discharging the lubricant outside the apparatus. The method of claim 1, The rotating ring is a spiral die characterized in that the rotational speed to enable the rotation control at 60rpm or less. The method of claim 1, The inner surface of the rotating ring is formed of a mirror surface (0.1 S to 6.3 S), a rough surface (4 to 150 microns in depth), and a tooth surface (flat shape, spiral tooth shape) in a surface flaw standard. Spiral die, characterized in that any one configuration.