JPH0661819B2 - T-die - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin molding apparatus such as a T-die for extruding a molten synthetic resin into a sheet or film.

[0002]

2. Description of the Related Art FIGS. 3 and 4 (section B-B in FIG. 3) are cross-sectional views of a conventional T die, which shows a lower end of a resin supply pipe 15 in a die body 1 connected to a molten resin pumping device not shown. It has a manifold 2 of molten synthetic resin extending in one direction, and further has a planar passage 3 extending below the manifold 2.

A pair of lips 4 and 5 are fixed and supported by bolts 6 and a differential bolt 7 on both sides of the lower side of the die body 1 in order to adjust the interval (thickness) of the lip lands 8. There is.

Reference numeral 10 is a cooling roll provided below the die body 1, and 11 is a press roll.

As shown in FIG. 4, a pair of forming plates 12 are movably provided at both ends of the planar passage 3 in order to adjust the width of a film or sheet (hereinafter referred to as a film) to be formed. An operating rod 13 made of an iron rod having a diameter of about 4 mm is connected to the outer surface of the forming plate 12, the operating rod 13 is extended to the outside of the die body 1, and the protruding end is operated to move the forming plate 12 to the left and right. The width of the planar passage 3 through which the molten resin passes is adjusted by moving the molten resin.

The seal rods 14 arranged at both ends of the lip land portion 8 are made of, for example, a piano wire, and move left and right together with the forming plate 12 to move the lip land portion 8.
It regulates the width of.

In this apparatus, the molten resin diffuses laterally in the manifold 2 from the molten resin supply pipe 15 and is extruded as a film or the like from the lip land portion 8 through the lower planar passage 3. The flow of the molten resin at both ends of the manifold 2 and the planar passage 3 becomes more complicated as it approaches the ends as shown by the thick arrow in FIG.

This complicated flow is likely to cause unevenness in thickness in the width direction of the extruded film or the like. Therefore, in order to improve this problem, the applicant of the present invention has shown in FIGS. As shown in (C-C cross section of FIG. 5), a T-die provided with double manifolds was proposed.

This T-die has a lipland portion 29 formed on the outer side below the die body 21 by lips 27 and 28, which is the same as the conventional example, but from the molten resin supply pipe 22 to the lip land portion 29. The molten resin passage includes a first manifold 23, a first planar passage 24, a second manifold 25, and a second planar passage 26.

At both ends of this second manifold 25,
The forming plate 33 fixed to the tip of the first seal rod 31 that slides through the seal plates 30 provided at both ends of the die body 21 has the second planar passage 26.
It is located inside.

As a result, the flow of the molten resin at both end portions of the second planar passage 26 into which the forming plate 33 is inserted is improved so as to approach the vertical direction as shown in FIG. 8, and as a result, the extruded film. The thickness and the like of both end portions of the etc. 40 are improved.

[0012]

However, since the extruded film or the like 40 is in a molten state immediately after passing through the lip lands 8 and 29, as shown in FIGS. It causes a neck-in phenomenon that shrinks in the direction. The neck-in phenomenon is such that both ends of the neck-in phenomenon shrink due to the condensing force of the molten resin until the position P at which the molten film extruded from the lip land portion solidifies, and the width becomes narrower, and the thickness increases accordingly. It is a phenomenon.

In the neck-in phenomenon, the neck-in width (a and b in the figure) increases as the flow of the molten resin at both ends becomes more complicated. For this reason, both ends of the film or the like 40 become thick as shown in FIG. 9, and since this part is cut off and wound up, waste of material and extra steps are required. In the figure, (a) shows a case where the thickness is hardly increased, and it is not necessary to cut off this part. (B) shows that the neck-in part is thick, so this part is cut off after extrusion.

This neck-in phenomenon is caused by the forming plates 12, 3 inserted at both ends of the planar passages 3, 26.
It is difficult to find the optimum shape because it is greatly influenced by the shape of No. 3. In order to find the optimum shape, it is necessary to make trial forms of forming plates of various shapes and replace them. However, this replacement operation is complicated because the flow of the molten resin is stopped and the seal plate 30 is removed and replaced. Work is required.

An object of the present invention is to solve the above problems and to provide an apparatus capable of obtaining an optimum forming plate shape without stopping the flow of molten resin and continuing the extrusion operation as it is. To do.

[0016]

In order to solve the above-mentioned problems, in a T die of a synthetic resin molding device, a die body 2 for receiving the molten resin pumped from the molten resin pumping device.
1, a manifold 25 extending in one direction at the front end side of the molten resin supply pipe 22, a planar passage 26 continuously connected to the entire width of the lower side of the manifold 25, and the planar passage 26. From the outside by slidingly penetrating a lip land portion 29 provided at the lower end of the die main body 21 and formed by the lips 27, 28 on both sides of the die body 21 and seal plates 30 provided at both ends of the planar passage 26. In the T-die provided with the position adjusting seal rod 34 which is fixed in the planar passage and the position adjusting seal rod 32, the forming plate 35 includes the sealing rod 34. Fixed parallel to the lower side of the seal rod 3
One fixed forming bar 3 matching the tip of 4
5a and a plurality of movable forming bars 35b having the same thickness and the same length as the fixed forming bar 35a below the fixed forming bar 35a are closely arranged on one plane to form the forming plate 35, The sliding through portion of the seal plate 30 is hermetically sealed by an elastic member, and a regulation plate that regulates the tip shape of the movable forming bar group from the outside along the same plane as the movable forming bar group including the plurality of movable forming bars 35b. And 36.

[0017]

As described above, by pressing the regulation plate against the outer ends of the plurality of movable forming bars arranged in a line in a row in the vertical direction, the inner end has the same shape as the regulation plate. So without stopping the flow of molten resin,
It is possible to form a forming plate having an optimum shape.

[0018]

1 is a sectional view of the T-die of the present invention taken along the flow direction of the molten resin, and FIG. 2 is a sectional view taken along line AA of FIG. This T-die is of the improved dual manifold type shown in FIGS. 5 and 6, and the same parts use the same reference numerals.

The difference from the T-die shown in FIGS. 5 and 6 is the forming plate. The forming plate 33 in the case of FIGS. 5 and 6 is one plate fixed to the lower side of the first seal rod 31, but in the case of the present application, it is parallel to the lower side of the first seal rod 34. And one fixed forming bar 35a fixed so that its tip matches the tip of the first seal rod 34, and below this fixed forming bar 35a, the same thickness and length as the fixed forming bar 35a. A plurality of movable forming bars 35b are closely arranged on one plane to form a forming plate 35, and a sliding through portion of the seal plate 30 is sealed by an elastic member (not shown) to form the one fixed forming. The forming plate 35 includes a movable forming bar group including a bar 35a and a plurality of movable forming bars 35b.
And a regulating plate 36 for regulating the tip shape of the movable forming bar group from the outside along the same plane as the forming plate 35.

Next, a method of operating the above-mentioned forming plate 35 will be described. Forming plate 35
The optimum shape of the inner end portion of is determined empirically depending on the type of resin, the melting temperature, the extrusion speed, and the like. Therefore, the end face shape of the regulation plate 36 is tentatively determined, and the first seal rod 34 is
When pressed against the group of fixed forming bars 35a and the group of movable forming bars 35b along, the tip shape of the forming plate 35 composed of the group of fixed forming bars 35a and the group of movable forming bars 35b becomes the same as the end surface shape of the regulation plate 36.

In this state, the molten resin is extruded to form a film 40 and the neck-in width is measured. From this measurement result, if necessary, the end face shape of the regulation plate 36 is changed, the neck-in width is measured by the same operation as described above, and if it is good, the regulation plate 36 is fixed to the first seal rod 34 as it is and the extrusion work is performed. To continue.

[0022]

As described above, it is easy to easily change the shape of the forming plate for minimizing the neck-in width of the extruded film or the like to obtain the best shape, and the type of resin. The shape can be easily changed according to changes in conditions such as temperature, extrusion speed and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a T-die of the present invention taken along the flow direction of molten resin.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a sectional view of a conventional T-die.

FIG. 4 is a sectional view taken along the line BB in FIG. 3, which is also a flow chart of molten resin.

FIG. 5 is a cross-sectional view of a T-die provided with a dual manifold.

6 is a cross section taken along line CC of FIG.

FIG. 7 is a flow chart of molten resin in a T die provided with a dual manifold.

8A and 8B are explanatory diagrams of a neck-in phenomenon, in which FIG. 8A is a minimum neck-in state diagram, and FIG. 8B is an excessive neck-in state diagram.

9A and 9B are explanatory diagrams of the influence of neck-in, where FIG. 9A is a minimum neck-in state diagram, and FIG. 9B is an excessive neck-in state diagram.

[Explanation of symbols]

 21 die main body 23 first manifold 24 first planar passage 25 second manifold 26 second planar passage 29 lip land portion 30 seal plate 34 first seal rod 35 forming plate 35a fixed forming bar 35b movable forming Bar 36 Control plate 40 Film, etc.

Claims (1)

[Claims] 1. A T-die of a synthetic resin molding apparatus, a manifold extending in one direction at a tip side of a molten resin supply pipe provided in a central portion of a die body for receiving molten resin pressure-fed from a molten resin pressure-feeding apparatus. A sheet-like passage continuously formed over the entire width of the lower side of the manifold, a lip land portion formed at the lower end of the sheet-like passage and formed by lips on both sides of the die body, and the sheet-like passage. Forming plates which are fixed in the planar passage to seal rods whose positions can be adjusted from the outside by sliding through seal plates provided on both end sides of the plate, and seal rods whose positions can be adjusted from the outside are also provided. In the T die, the forming plate is fixed in parallel to the lower side of the seal rod, and the tip of the forming plate is aligned with the tip of the seal rod. The fixed forming bar and a plurality of movable forming bars having the same thickness and the same length as the fixed forming bar are arranged under the fixed forming bar so as to be closely arranged on one plane to form a forming plate. The sliding through part of the plate is sealed with an elastic member,
A T-die comprising a movable forming bar group including the plurality of movable forming bars, and a regulation plate that regulates the tip shape of the movable forming bar group from the outside along the same plane.