JPH0790587B2 - Automatic T-die for extrusion molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic T-die that discharge-molds a sheet or film of a thermoplastic resin, cellulose, rubber or the like, or a magnetic material coater, cellophane hopper, and other printing inks. .

[Conventional technology]

Generally, an automatic T-die is provided with a means for adjusting a flow rate distribution of a melted raw material (hereinafter, referred to as a thermoplastic resin) extruded from a molding slit. The adjusting means is usually a method of thermally displacing the die bolt to push and pull the flexible die lip portion to adjust the slit gap, or a resin temperature adjustment for changing the viscosity of the molten resin by changing the temperature of the die lip portion. Either a method or a method using both of the above methods in combination (hereinafter referred to as a composite adjustment method) is adopted. Next, these methods will be briefly described.

The slit gap adjusting method is, for example, shown in FIGS. 6 and 7 described in US Pat. No. 3,940,221, between the flexible lip portion 12 of the upper die body 10 and the fixed lip portion 16 of the lower die body 14. The extrusion slit 18 formed in the die has a gap between the die bolt means 20 provided on the upper die body 10.
It is configured to be adjusted by. That is,
By applying a voltage to the heater 22 to extend the die bolt 26, or by circulating a cooling medium in the cooling channel 24 to reduce the die bolt 26, the flexible lip portion 12 is pushed and pulled through the die bolt tip portion 26a. And extrusion slit 18
Reduce or widen the gap. As a result, the gap of the extrusion slit 18 at the required portion in the longitudinal direction is adjusted, and the flow rate distribution of the molten resin is adjusted. Reference numeral 28 indicates a heat insulating material.

The resin temperature adjusting method is shown in, for example, FIG. 8 of Japanese Patent Publication No. 56-3171, and the lip portion 30 of the upper die body 10 is used.
The temperature of the molten resin extruded from the extrusion slit 18 between the a and the lip portion 30b of the lower die body 14 is
It is configured to be adjusted by temperature adjusting means 34a, 34b provided on each lip segment 32a, 32b of 30a, 30b. That is, each lip segment 32a, 32b is connected via the heater / cooler 36a, 36b and the temperature sensor 38a, 38b.
Extrusion slit 18 by heating or cooling
The temperature of the molten resin extruded from is heated or cooled. As a result, the temperature of the molten resin, that is, the viscosity, at the required portion in the longitudinal direction of the extrusion slit 18 is adjusted, and the flow rate distribution of the molten resin is adjusted. Note that reference numerals 40a, 40b and 42a, 42b all indicate voids that define the lip segments 32a, 32b.

The compound adjusting method is formed between the flexible lip portion 12 of the left die main body 10 and the fixed lip portion 16 of the right die main body 14 in FIG. 9 described in JP-A-60-206615, for example. The extruding slit 18 is formed by setting the gap between the left die body 10 and
While being adjusted by the die bolt means 20 provided in, the molten resin extruded from the extrusion slit 18,
Further, the temperature is configured to be adjusted by the temperature adjusting means 44. The die bolt means 20 includes a heater 22,
It consists of cooling channel 24, die bolt 26, etc.
A heat insulating material 28 is interposed between 0 and the lip portion 12. The temperature adjusting means 44 has a heater / cooler 46 and a temperature sensor 48. In such a configuration, when the flow rate of the molten resin from the extrusion slit is reduced, for example, the temperature of the molten resin is lowered via the temperature adjusting means 44 and at the same time the slit gap is reduced via the die bolt means 20. .

However, each of the adjustment methods described above has the following drawbacks.

First of all, the slit gap adjusting method is, firstly, the die bolt means.
Since 20 is configured in the direct-acting thermal displacement system, that is, the die bolt 26 is expanded by heating and contracted by cooling, for example, the die bolt 26 is heated and slit to reduce the flow rate of the molten resin. When the gap 18 is reduced, on the other hand, the heating also heats the flexible lip portion 12 in the vicinity of the die bolt 26, and the temperature of the molten resin extruded from this portion rises. Therefore, the effect of reducing the flow rate due to the reduction of the gap of the slit 18 is offset by the effect of increasing the flow rate due to the decrease in the viscosity of the molten resin (hereinafter referred to as the effect of reducing the adjustment capability), and therefore the adjustment range of the flow rate is sandwiched at the same time. The adjustment accuracy is also reduced. Secondly, the flexible lip 12 in this type of system is constructed with a considerable rigidity, as generally shown, so that, for example, the first, second and third die bolt means 20a from the end respectively. , 20b, 20c, the deformation amount δ of the flexible lip portion 12, as shown by the graphs I, II, III in FIG. 10, respectively,
Beyond that part of the adjusted die bolt means, it is propagated to a considerable part. For this reason, the partial adjustment becomes impossible, and at the same time, the adjustment accuracy is lowered.

Next, the resin temperature adjusting method is as follows. First, the lip segment 32
Since the void portions 40 and 42 for effectively performing thermal insulation are required between the a and 32b, the structure is complicated and large. Secondly, even if the gaps 40 and 42 are interposed as described above, the flow rate is adjusted only by adjusting the temperature of the lip segments, so that the temperature difference between the lip segments requires a relatively large temperature difference. , Between the adjacent lip segments 32a and 32b, practically considerable heat transfer occurs. Therefore, it is difficult to precisely adjust the local flow rate of the molten resin, and the overall adjustment accuracy is reduced.

Finally, since the composite adjustment method uses the slit gap adjustment method and the resin temperature adjustment method together, first, the adjustment range of the flow rate is sandwiched by the effect of reducing the adjustment ability of the direct-acting die bolt means 20. Secondly, the characteristic of the temperature adjusting means 44 makes it difficult to locally adjust the flow rate. Thirdly, for example, when the flow rate is reduced and adjusted, the flexible lip portion 12 is heated while the fixed lip portion 16 is cooled, so that the molding film extruded from the slit 18 is shown due to the temperature difference between the front and back surfaces. As described above, the product is curled, which complicates the subsequent processing steps and deteriorates the quality of the product.

Therefore, the present applicant solves the above-mentioned problems, and as shown in FIG. 11, the slit gap adjusting system automatic T which does not diminish the adjusting ability of the die bolt means.
Die (Japanese Patent Application No. 61-189378, Japanese Patent Application Laid-Open No. 63-45024, Japanese Patent Publication No. 6)
-8023) and an automatic T-die with a slit gap adjusting method (Japanese Patent Laid-Open No. 62-122731) in which the deformation characteristic of the movable lip portion is improved, as shown in FIG. .

In the automatic T-die shown in FIG. 11, the means for adjusting the gap of the extrusion slit 18 is configured in the differential thermal displacement unit 50. That is, this unit 50 is
One end of the die bolt 26 is supported by the free end of the unit main body 52, and the lower end of the unit main body 52 is fixed to the projecting support of the upper die main body 10, and the thermal expansion coefficient α _a of the unit main body 52 and the heat die The relationship of α _a α _b is established between the thermal expansion coefficient α _b of the bolt 26. Therefore, if the heater 22 is energized or this energization is stopped and the entire unit 50 is heated or cooled, the die bolt
26 is contracted or expanded with respect to the flexible lip 12 to expand or contract the gap of the slit 18. On the other hand, at the same time, the temperature of the flexible lip 12 is increased or decreased, and the viscosity of the molten resin is decreased or increased. That is, for example, when the differential thermal displacement unit 50 is heated, the flow rate adjustment is achieved over a wide range and with good responsiveness due to the synergistic effect of an increase in the slit 18 gap and a decrease in the viscosity of the molten resin. It Reference numeral 14 is a lower die body, reference numeral 16 is a fixed lip portion, and reference numeral 54 is a temperature sensor.

In the automatic T-die shown in FIG. 12, a predetermined number of pressing convex portions 56 are arranged on the upper surface of the flexible lip portion 12 at equal intervals. A groove-shaped recess 58 is formed between the pressing protrusions 56. As a result, the rigidity of the flexible lip portion 12 in the automatic T-die is set to a predetermined value, and, for example, the die bolt means 20a, 20 of the first, second, and third die bolts from the end portion, respectively.
When b and 20c are adjusted and the corresponding pressing protrusions 56 are pushed and pulled, the deformation amount δ of the flexible lip portion 12 is displaced as shown in the graphs Ia, IIa and IIIa of FIG. 10, respectively. That is, the flexibility of displacement of the flexible lip portion 12 is greatly improved as compared with the conventional automatic T-die shown in FIGS. 6 and 7. Moreover, as can be seen from the smooth waveforms of the graphs Ia, IIa, and IIIa, the displacement continuity of the flexible lip portion 12 is set to a good and small range. Therefore, the partial adjustment of the flow rate is performed smoothly and accurately, and at the same time, the adjustment accuracy is improved. Reference numerals 10 and 14 denote die bodies, reference numeral 16 denotes a fixed lip portion, and reference numeral 18 denotes an extrusion slit.

[Problems to be solved by the invention]

As described above, according to the first and second techniques filed by the applicant of the present invention, it is possible to overcome various drawbacks of the conventional automatic T-die.

However, each of the above techniques cannot completely or effectively overcome the above drawbacks by itself. That is, in the first technique, the flow rate of the molten resin can be adjusted over a wide range and with good responsiveness, but on the other hand, for example, partial adjustment of the flow rate cannot be performed accurately. Further, in the second technique, the partial adjustment of the flow rate is performed smoothly and accurately, but on the other hand, it is insufficient to adjust the flow rate over a wide range and with good responsiveness.

Therefore, an object of the present invention is to perform an extrusion molding in which the flow rate of the molten resin can be adjusted over a wide range with good responsiveness and locally as needed, and the structure is simple and the operability is excellent. The purpose is to provide an automatic T-die for use.

[Means for solving problems]

In order to achieve the above object, an automatic T-die for extrusion molding according to the present invention has at least one of both lip portions forming an extrusion slit of molten resin with respect to a die body via a flexible neck portion in a slit gap direction. Displaceably connected, a predetermined number of pressing convex portions are formed on the outer surface of the flexible lip portion at substantially equal intervals in the slit longitudinal direction, and differential pressure is applied to each portion of the die body corresponding to the pressing convex portion. One end of a unit body of the thermal displacement unit is fixed, and one end of a die bolt for adjusting a slit gap is supported by pushing and pulling the pressing convex portion to a free end of the unit body. To do.

In this case, it is preferable that the thickness of the flexible lip portion between the pressing convex portions is thin, and both side surfaces of the thin portion are U-shaped concave portions continuous with the side surfaces of the pressing convex portions on both sides. Is.

[Action]

Since the gap of the extrusion slit is adjusted by the differential thermal displacement unit, the flow rate of the molten resin is adjusted by the product of two effects based on the increase / decrease in the slit gap and the increase / decrease in the viscosity of the molten resin. Therefore, the flow rate adjustment is performed over a wide range and with good responsiveness. Further, the pressing convex portion of the flexible lip portion has predetermined displaceability and displacement continuity set by the concave portion and the flexible neck portion, and the heat propagation between the pressing convex portions is effectively blocked by the concave portion. Therefore, partial adjustment of the flow rate can be performed smoothly and accurately. Moreover, although one of the lip portions is usually configured as a flexible lip portion, such a configuration particularly simplifies the configuration and reduces the cost. Further, in the automatic T-die having such a configuration, curl or the like does not occur in the extruded film, so that good operability can be obtained.

〔Example〕

Next, one embodiment of the automatic T-die for extrusion molding according to the present invention will be described in detail below with reference to the accompanying drawings.
For convenience of explanation, the same components as those of the conventional structure shown in FIGS. 6 to 12 are designated by the same reference numerals, and detailed description thereof will be omitted.

1 and 2, an automatic T-die for extrusion molding according to the present invention has a flexible lip portion 12 forming an extrusion slit 18 of molten resin, and a flexible neck portion 60 with respect to an upper die body 10. The slit 18 is movably connected in the gap direction, and a predetermined number of pressing convex portions 56 are formed on the outer surface of the flexible lip portion 12 at substantially equal intervals in the slit longitudinal direction, and the pressing convex portion in the upper die body 10 is formed. The lower end of the unit main body 52 of the differential thermal displacement unit 50 is fixed to each of the mounting bracket portions 10a corresponding to 56, and the pressing convex portion 56 is attached to the upper free end portion of the unit main body 52 via the front end portion 52a. Is configured to support the upper end of the heat die bolt 26 that pushes and pulls to adjust the gap of the slit 18. Reference numeral 14 indicates a lower die body, and reference numeral 16 indicates a fixed lip portion.

The flexible lip portion 12 is formed with a thin concave portion 58 between the pressing convex portions 56. The shape of the concave portion 58 is, for example, as shown in FIGS. 4 (a) and 4 (b). It is preferable that both side surfaces of 58 are formed in a U-shaped or semicircular groove shape continuous with the side surfaces of the pressing protrusions 56 on both sides.

FIG. 5 shows the displaceability (F _a ), the continuity of displacement (F _b ), and the total displacement characteristic (F _c ) of the flexible lip portion 12 configured as described above, which can be compared with the lower surface of the recess 58. Flexible neck 60
The ratio between the step size h _a between the step size h _b a pushing projection 56 top and the flexible neck portion 60 between, that is, those shown for the step ratio h = h _b / h _a. As can be seen from the figure, the displaceability F _a improves as the step ratio h decreases, that is, the depth of the recess 58 increases, while the displacement continuity F _b increases as the step ratio h increases, that is, the recess. It has been shown that the shallower depth of 58 improves. Therefore, when the displacement flexibility F _a is preferentially sets a relatively small level difference ratio h, relatively large set of step ratio h in the case of reverse displacement continuity F _b is prioritized. The concave portion 58 can change its shape, for example, along the position in the longitudinal direction of the lip portion according to the required displacement characteristics of the flexible lip portion 12, or can be formed at only a part of the position. good. Alternatively, the lip 12
Is a flexible neck portion without forming a concave portion 58
It is also possible to extend the plate 60 in a flat plate shape and implant the pressing convex portion 56 in this extended portion.

In the differential thermal displacement unit 50, a die bolt 26 is fixed in the hollow space of the unit main body 52 at the upper end thereof so as to be extendable and contractible in the axial direction, and a heater 22 is attached to the outer periphery of the unit main body 52. Has been done. Then, the thermal expansion coefficient of the thermal expansion coefficient alpha _a and die bolts 26 of the unit body 52 alpha _b
The relationship α _a α _b is established between and. Reference numeral 54 is a temperature sensor for temperature setting. Therefore, in such a configuration, if the heater 22 is energized or the energization is stopped to heat or cool the unit body 52 and the die bolt 26, the temperature rises from the unit body 52 during heating and the die bolt 26 in the space portion during cooling. The die bolt 26 is apparently shortened or extended with respect to the pressing convex portion 56 on the flexible lip 12 because the temperature is lowered. Therefore, the gap of the extrusion slit 18 is expanded or reduced by heating or cooling the differential thermal displacement unit 50. On the other hand, since the flexible lip portion 12 is heated through the die bolt 26 during the heating, the molten resin flowing in the extrusion slit 18 is heated or cooled by heating or cooling the differential thermal displacement unit 50, Its viscosity is reduced or increased. in this way,
Since the flow rate of the molten resin in the automatic T-die of the present invention is adjusted by the synergistic product of the double effect based on the increase / decrease in the slit gap and the increase / decrease in the viscosity of the molten resin, the flow rate adjustment can be performed over a wide range and with a good response. Performed with sex. Furthermore, since the flow rate adjustment is performed with good responsiveness,
Since the temperature difference between the thermal displacement units 50, that is, the temperature difference between the pressing convex portions 56 is set to be relatively small, and the pressing convex portions 56 are effectively thermally insulated from each other via the concave portions 58, The local flow rate adjustment is performed accurately and with high accuracy. In this case, it goes without saying that the excellent total displacement characteristic of the flexible lip portion 12 is contributed. Also, both lip parts 12, 16
Since the temperature difference is set to a small value, the operability is stabilized and the extruded film is not curled.

As described above, according to the automatic T-die of the present invention, it is possible to adjust the flow rate of the molten resin over a wide range with good responsiveness and locally with high accuracy. Further, such an automatic T-die has the advantages of simple structure and good operability.

FIG. 3 shows another embodiment of the automatic T-die for extrusion molding according to the present invention. The automatic T-die of this embodiment is an upper die body and a lower die body.
The differential thermal displacement units 70, 80 are attached to the respective 10, 14 to form the extrusion slit 18, and the upper and lower lip portions 72, 82
Are both configured as a flexible lip portion. When adjusting the flow rate of the molten resin, the pair of upper and lower thermal displacements located at the slit 18 portion to be adjusted is controlled so that the units 70 and 80 cooperate with each other. With this structure, the flow rate control performance can be further improved, but the structure is complicated.

Although the present invention has been described with reference to the preferred embodiments, it goes without saying that the present invention can be modified in many ways without departing from the spirit thereof. Further, the present invention is not limited to the thermoplastic resin, but can be similarly applied to, for example, discharge molding for a magnetic material coater or ink.

〔The invention's effect〕

As described above, the automatic T for extrusion molding according to the present invention
The die has at least one of both lip portions forming an extrusion slit configured as a flexible lip portion, and a die bolt means for displacing the flexible lip portion to adjust a slit gap is configured as a differential thermal displacement mechanism. Furthermore, since a predetermined pressing protrusion is arranged on the flexible lip through an insulating recess, and the displacement characteristic of the lip can be set to a predetermined value, the adjustment capability can be adjusted when adjusting the flow rate of the molten resin passing through the slit. Is greatly improved by the double effect based on the increase / decrease in the slit gap and the resin viscosity, and the local adjustment of the flow rate is smoothly performed by the displacement characteristic of the lip. That is, the flow rate can be adjusted over a wide range and with good responsiveness, and at the same time, local adjustment can be performed accurately and precisely as needed. Furthermore,
According to the present invention, it is possible to provide an automatic T-die having a simple structure and excellent operability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial front view showing an embodiment of an automatic T-die for extrusion molding according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. Another embodiment of the automatic T-die for extrusion molding according to the present invention is shown in FIG. 4 (a) and FIG.
An embodiment of a flexible lip portion in the automatic T die for extrusion molding according to the present invention shown in FIGS.
FIG. 4A is a side view, FIG. 4B is a front view, and FIG.
FIG. 6 is a graph showing displacement characteristics relating to the step size ratio h _b / h _a of the flexible lip shown in FIG. 6, and FIG. 6 is a front view of an automatic T die for explaining a conventional slit gap adjusting method in an automatic T die for extrusion molding. , FIG. 7 is a sectional view taken along line VII-VII of FIG. 6,
FIG. 8 is a perspective sectional view of a main part of an automatic T die for explaining a conventional resin temperature adjusting method in an automatic T die for extrusion molding,
FIG. 9 is a sectional view of a main portion of an automatic T-die for explaining a conventional composite adjusting method in an automatic extrusion-die for extrusion molding, and FIG. 10 is a diagram for explaining a deformation amount of a flexible lip portion in the automatic T-die for extrusion molding. A graph, FIG. 11 is a cross-sectional view of a main part showing a first extrusion automatic T-die for the applicant of the present invention, and FIG. 12 is a second extrusion automatic T-die for the applicant of the present invention. It is a principal part sectional view which shows a die. 10,14 …… Die body 12,72,82 …… Sweating lip 16 …… Fixed lip, 18 …… Extrusion slit 22 …… Heater, 26 …… Die bolt 50,70,80 …… Differential thermal displacement Unit 52 …… Unit main body, 54 …… Temperature sensor 56 …… Pressing protrusion, 58 …… Groove (concave) 60 …… Flexible neck F _a …… Displacement graph of flexible lip 12 F _b …… Displacement continuity graph of the flexible lip 12 F _c …… Comprehensive displacement characteristic graph of the flexible lip 12

Front page continued (72) Inventor Satoshi Nitta 2068-3 Ooka, Numazu City, Shizuoka Prefecture Numazu Plant, Toshiba Machine Co., Ltd. (56) References JP 62-122731 (JP, A) JP 63-45024 ( JP, A) Actual development Sho 62-166019 (JP, U)

Claims (3)

[Claims] At least one of both lip portions forming an extrusion slit of molten resin is movably connected to a die body via a flexible neck portion in a slit gap direction, and a slit is formed on an outer surface of the flexible lip portion. A predetermined number of pressing protrusions are formed at substantially equal intervals in the longitudinal direction, and one end of the unit main body of the differential thermal displacement unit is fixed to a portion of the die main body corresponding to the pressing protrusions. An automatic T-die for extrusion molding, characterized in that one end of a die bolt for adjusting a slit gap is supported by pushing and pulling the pressing convex portion to a free end portion of a main body. 2. The automatic T-die for extrusion molding according to claim 1, wherein the flexible lip has a thin wall between the pressing protrusions. 3. The automatic T-die for extrusion molding according to claim 2, wherein the thin portion is formed in a U-shaped concave portion continuous to the side surfaces of the pressing convex portions on both sides.