JPH068023B2 - Thermal displacement type T-die - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal displacement T-die.

[Prior art]

U.S. Pat. No. 3,940 is a representative example of this type of T-die.
No. 221, which is well known, adjusts the lip gap 3 formed between the fixed lip 1 and the flexible lip 2 by displacing the flexible lip 2 with a die bolt 4, as shown in FIG. ing. One side of the die bolt 4 penetrates the steel heating block 5 to reach the flexible lip 2, and the other side is screwed and attached to the head projection of the die body 2A. Further, the central portion thereof is inserted into a heating block 5 having a cartridge heater 6 for heating a die bolt and a cooling hole 7. Therefore, when the die bolt 4 is heated by the cartridge heater 6, the die bolt 4 expands, and as a result, the flexible lip 2 is pushed and bent to narrow the lip gap 3. When the die bolt 4 is cooled, the lip gap 3 is widened.

Even with such a thermal displacement type T die, the lip gap can be adjusted. However, since this conventional device is a system in which the lip gap pattern is changed by utilizing the thermal expansion and contraction of the die bolt to adjust the flow rate of the molten resin, a considerably large temperature difference, for example, 100 ° C. or more occurs between the plurality of die bolts. In some cases. This temperature difference has some effect on parts other than the die bolt, and particularly affects the viscosity of the molten resin flowing between the lips. Therefore, a heat insulating material 8 is usually provided between the heating block 5 and the die body 2A provided with the flexible lip 2 to prevent the influence of the temperature on the die bolt 4 side from being transmitted to the molten resin as much as possible, but complete heat insulation. Is not originally possible, and in addition, there is another heat transfer route, such as the die bolt 4 to the flexible lip 2 etc., and even if there is a difference in degree, a change in viscosity cannot be avoided and the temperature of the molten resin is adversely affected. Was affecting.

In addition, when the die bolt is heated and expanded, the lip gap is narrowed to reduce the flow rate of the molten resin, while the molten resin heated via the heat transfer route has a reduced viscosity and an increased flow rate. Conversely, when the die bolt contracts, the lip gap widens and the flow rate increases, while the viscosity of the molten resin increases and the flow rate decreases. In this way, the change in the flow rate due to the change in the lip gap and the change in the viscosity interfere with each other in a weakening direction. For example, despite the intention of narrowing the lip gap to reduce the flow rate, there is a contradiction that the resin viscosity decreases and the flow rate increases, and the profile adjustment of the lip gap cannot be performed completely. The same applies when the lip gap is widened.

[Object of the Invention] The present invention eliminates such drawbacks, and its object is to:
It is an object of the present invention to provide a thermal displacement T-die in which the effect of flow rate change due to lip gap and the effect of flow rate change due to viscosity change on molten resin work in mutually reinforcing directions.

[Points of the Invention] In order to achieve the above object, a plurality of thermal displacement type T dies of the present invention are provided in the width direction of a flexible lip of a T die in which a lip gap is formed between a fixed lip and a flexible lip. In a thermal displacement type T-die in which the lip displacement is adjusted by controlling the thermal displacement of the thermal displacement unit having a die bolt by thermal expansion or thermal contraction, the flexible lip of the flexible lip of the die main body on the side opposite to the lip gap is attached. One end is attached to the protrusion facing the surface, the other end is a free end, and a through hole with a bottom is provided in the center from one end to the other end. It is provided in the bottomed through hole of the unit, and the tip of one side is pressed against the surface of the flexible lip opposite to the lip gap,
Alternatively, it shall be connected to a flexible lip and the other side shall consist of a die bolt attached to the free end of the thermal displacement unit, the thermal expansion coefficient of the thermal displacement unit being equal to or greater than that of the die bolt. And a thermal displacement type T-die.

[Embodiment of the Invention] FIG. 1 showing one embodiment of the present invention will be described below. A flexible lip 13 and a fixed lip 14 are formed at the tips of the A die main body 11 and the B die main body 12, respectively.
A lip gap 15 is formed on the opposing surfaces of 3 and 14.
The lip gap 1 is formed on the protruding portion 26 at the tip of the A die body 11 and facing the surface C of the flexible lip 13 on the side opposite to the lip gap.
5, one side of a plurality of thermal displacement units 16 provided in the width direction is attached by screwing, the other side has a free end, and a through hole having a bottom is opened in the center from one side to the other end. There is. The tip of the die bolt 17 inserted into the through hole of the thermal displacement unit 16 is pressed against the surface C of the flexible lip 13 on the side opposite to the lip gap, and the other end is screwed to the free end side of the thermal displacement unit 16, and A thermocouple 18 is inserted inside the thermal displacement unit 16 and a heater 19 is provided outside. Here, when the thermal expansion coefficient of the thermal displacement unit 16 and the die bolt 17 is α1 · α2, α1 ≧ α2.

In such a configuration, the thermal displacement unit 16 is connected to the heater 1
Heating by 9 also heats the die bolt 17 somewhat. In the thermal displacement unit 16, the free end side extends upward in the drawing due to heating, and when the thermal expansion coefficient of the thermal displacement unit 16 is larger than that of the die bolt 17, the expansion amount of the thermal displacement unit 16 is obviously larger than that of the die bolt 17. The other end of the die bolt 17 is the thermal displacement unit 16
Since it is screwed to the free end of the die bolt 17, the die bolt 17 is lifted upward and tends to separate from the flexible lip 13, and the pressing load of the lip 13 decreases and the lip 13 bends upward. Even when the thermal displacement unit 16 and the die bolt 17 have the same coefficient of thermal expansion, the thermal displacement unit 16 uses the heater 19 as a heating source.
Since the amount of expansion is larger than that of the die bolt 17, the die bolt 17 is similarly hung. In this way, the lip gap 15 becomes wider and the flow rate of the molten resin flowing through the lip gap increases, but at the same time, the flexible lip 13 receives heat from the die bolt 17 and its temperature rises, and the viscosity of the molten resin decreases. It works in the direction that the flow rate increases.

On the other hand, if the thermal displacement unit 16 is cooled by cutting off the power supply to the heater 19 and the thermal expansion coefficient of the thermal displacement unit 16 is larger than that of the die bolt 17, it is possible that the contraction amount of the thermal displacement unit is larger than that of the die bolt 17. Flexible lip 1
3 is pushed by the die bolt 17 and bends downward in the drawing. Even if the thermal displacement unit 16 and the die bolt 17 have the same thermal expansion coefficient, the thermal displacement unit 16 is outside the die bolt 17 and the temperature drop is large, so that the contraction amount is large and the flexible lip 13 bends downward in the die bolt. . When the thermal displacement unit 16 is cooled in this way, the lip 15 becomes narrower and the flow rate of the molten resin flowing through the lip gap 15 decreases, and the molten resin self-cools, the viscosity increases and the flow rate decreases. .

FIG. 2 shows another embodiment of the present invention. In this example, the thermal displacement unit 21 has one side fixed to the A-die body tie 11 with bolts 22 and the other side having a free end.
One side of the die bolt 23 penetrates the thermal displacement unit 21 and is screwed to the surface C of the flexible lip 13 on the side opposite to the lip gap, and the other side is provided with a presser 24 fixed to the thermal displacement unit 21 by a screw (not shown). The thermal displacement unit 21 is attached to the free end side of the thermal displacement unit 21 with its movement restricted in the axial direction, although it is freely rotatable. Therefore, when the die bolt 23 is rotated, the tip screwed to the lip 13 pushes and pulls the lip 13, and the lip 15 can be opened and closed.

Reference numeral 25 is a heater, and a thermocouple is inserted in the thermal displacement unit 21, although not shown. Reference numerals 11 to 15 are the A die main body, the B die main body, the flexible lip, the fixed lip and the lip gap, respectively. Since the operation of this embodiment is almost the same as that of the above-mentioned first embodiment, its explanation is omitted.

[Effects of the Invention] As described in detail above, according to the present invention, when the thermal displacement unit is heated, the die bolt is lifted and the lip gap is widened to increase the flow rate of the molten resin. The flow rate is increased by receiving heat and increasing the temperature to reduce the viscosity of the molten resin. As described above, in the present invention, contrary to the conventional example, since the effect of the flow rate change due to the lip gap and the effect of the flow rate change due to the viscosity change work in mutually reinforcing directions, profile adjustment is easier and more precise than the conventional method. You can do it.

Furthermore, the present invention measures the sheet or film thickness with a thickness gauge such as infrared rays provided in the downstream region of the thermal displacement type T die,
Controlling the heater that heats the thermal displacement unit based on this measured value enables automation, and has the advantage of improving controllability because the above two effects work in the same direction.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of another embodiment of the present invention, and FIG. 3 is a sectional view of a conventional example. 11 ・ 12 …… Die body, 13 …… Flexible lip, 15…
… Lip gap, 16 ・ 21 …… Thermal displacement unit, 17 ・
23 …… Die bolt.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Nozawa Kenji Nozawa 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Business Office Judgment Panel Judgment Director Yasuo Hori Judge Ebisawa Ryosuke Ebino Watanaya Akihiro

Claims (1)

[Claims] 1. A thermal displacement unit having a plurality of die bolts provided in the width direction of a flexible lip of a T-die, in which a lip gap is formed between a fixed lip and a flexible lip, is thermally controlled to cause thermal expansion or thermal contraction. In the thermal displacement type T-die for adjusting the lip gap, one end is attached to the protruding portion of the die main body to which the flexible lip is attached facing the surface on the side opposite to the lip gap, and the other end is set as the free end. In addition, at the center thereof, a through hole having a bottom is provided from the one end to the other end, and a thermal displacement unit to which a heater is attached, and a through hole having a bottom of the plurality of thermal displacement units are provided. The tip of the flexible lip is pressed against the surface on the side opposite to the lip gap, or is joined to the flexible lip, and the other side is composed of a die bolt attached to the free end of the thermal displacement unit. Thermal expansion Thermal displacement type T-die, characterized in that it is constituted by equal to or greater in coefficient of thermal expansion of the die bolts to.