JP2753184B2 - T-die of extruder, molding method of molded article and molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a T-die for an extruder, a method of molding a molded product, and a molded product. The present invention relates to a novel improvement for forming a substantially uniform overall thickness by using a raw material melt contained in the above.

[0002]

2. Description of the Related Art Conventionally, there have been various molding methods and apparatuses for this type of thermoplastic resin, and generally, a molding method shown in FIG. 7 has been employed. That is,
7 is an extruder, and the molten thermoplastic resin extruded by the screw 2 of the extruder 1 is injected into a T-die 3, and the lip portion 3a of the T-die 3 It was hung as a sheet-like thermoplastic resin 4. The sheet-shaped thermoplastic resin 4 is pressure-formed by a mold 5 comprising a pair of pressure-molding mold parts 5a and 5b. Each of the mold parts 5a and 5b has a pressure means 6 as shown in FIG. , 6A are connected.

A pressure adjusting means 7 is provided in the mold 5 and a rod 8a of the pressure adjusting means 7 as shown in FIG.
a is pressed from the inside to secure the thickness of the corner portion 8a.

[0004]

The conventional method and apparatus for molding a thermoplastic resin have the following problems because they are configured as described above. That is, since the thickness accuracy of the sheet-like thermoplastic resin hanging from the T-die is deteriorated, a method of extremely lowering the resin temperature and suppressing the drawdown to a minimum range has been adopted.
In addition to making the extrusion molding technology extremely difficult, there were problems in terms of cost, such as the need to increase the capacity of the screw drive motor. Also, for the neck-in, a wide T-die in anticipation of the neck-in had to be used, and it was extremely difficult to avoid an increase in cost.
Also, when a molded article such as an electric shade is formed by pressure molding using the sheet-like thermoplastic resin, the thickness of a corner having a large stretching ratio becomes thin in a sheet having a uniform thickness, and the strength of the product is reduced. Was getting weaker. On the other hand, if the thickness of the entire sheet is increased in order to increase the thickness of the corners, the weight of the product itself increases, resulting in an increase in cost. There has also been a method of changing the sheet thickness in the width direction by a lip adjustment bolt provided on the T-die and locally increasing a portion corresponding to a corner portion. There was a limit to locally changing, and it was not practical. In addition, it is extremely difficult to adjust the thickness of the corners of the molded product using the pressure means shown in FIG. 9, and the molding process becomes complicated, the molding cycle cannot be shortened, It was extremely difficult to achieve cost reduction.

The present invention has been made in order to solve the above-mentioned problems, and particularly has a thin portion and a thick portion integrally obtained through a variable choke means in a T-die passage of an extruder. It is an object of the present invention to provide a T-die of an extruder, a method of molding a molded product, and a molded product, which are formed by using a raw material melt and having a substantially uniform overall thickness.

[0006]

The T of the extruder according to the present invention is described.
The die includes a main body in which a passage of the molten resin is formed, a variable choke means attached to the main body to form a part of the passage, and a choke member of the variable choke means formed in parallel with a width direction of the passage. A semi-cylindrical concave portion having an axis, a thick setting shaft rotatably provided in the concave portion, a driving means for rotating the thin setting shaft, and a cylindrical surface of the thin setting shaft. And a notch.

More specifically, a plurality of choke members and a plurality of setting shafts are provided.

In the method for molding a molded article according to the present invention, a molten resin extruded from an extruder is obtained through a variable choke means provided in a passage of a T-die to obtain a raw material melt having a thin portion and a thick portion integrally. In addition, it is a method of forming the raw material melt by a mold.

[0009] More specifically, a method wherein the mold is for pressure forming.

[0010] More specifically, a method wherein the mold is for vacuum forming.

In the molded article according to the present invention, a molten resin extruded from an extruder is formed by a choke member provided in a passage of a T-die, a half-shape formed in the choke member and having an axis parallel to a width direction of the passage. A cylindrical concave portion, a thin and thick setting shaft rotatably provided in the concave portion, a driving unit for rotating the thick and thin setting shaft, and a notch formed in a cylindrical surface of the thick and thin setting shaft. In addition to using a raw material melt having a thin portion and a thick portion integrally obtained through a variable choke means having the following, the thickness of the flat portion and the bent portion is substantially uniform.

[0012]

In the T-die of the extruder according to the present invention and the molding method and the molded article of the molded article, the variable choke member is provided when the notched portion of the thin and thick setting shaft is opposed to the passage side. The molten resin passing through the passage has a uniform thickness, moves downstream in the passage, and is pushed out from the outlet. In a state where the notch portion of the thick and thin setting shaft faces the passage side, the molten resin passing through the variable choke member is moved to the downstream side in the passage with only the notch portion being thickened and the outlet portion. From the outside. Thus, a thick portion can be integrally formed at a desired position of the sheet-like molten resin which is a raw material melt having a uniform thickness. Therefore, even when using a mold having a cavity shape such that the amount of stretching varies by location by performing pressurized air or vacuum forming using the raw material melt having such a shape, a uniform thickness of the entire material is obtained. A molded article can be formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a T-die of an extruder, a method of forming a molded product and a molded product according to the present invention will be described below in detail with reference to the drawings. First, an embodiment of the present invention shown in FIGS. 1 to 3 will be described. A second body 12 is integrally fixed to the first body 10 with bolts 14.
The passage 16 is formed by the first main body 10 and the second main body 12 constituting the T-die 52. An accumulator 18 is connected to the upper part (upstream side) in FIG. 1 of the first main body 10 and the second main body 12. This accumulator 18
An upper passage 18 a communicates with the passage 16. The accumulator 18 includes an extruder 54 described later (see FIG. 6).
The molten resin extruded from can be accumulated. Further, by pushing down the piston 18b of the accumulator 18 downward in the figure, the molten resin is moved from the upper passage 18a to the first passage 18a.
6 can be extruded. The lip member 20 is fixed to the lower end of the second main body 12.

A lip bar 22 is disposed on the first main body 10 at a position facing the lip member 20. The lip bar 22 is attached to the first main body 10 with bolts 24. The bolt 24 penetrates a bar-shaped variable choke member 38 described later. The lower end of the lip bar 22 is cut out in an L-shaped cross section, thereby forming a thin portion 22a that is easily elastically deformed. The lip bar 22 has concentric screw holes 22b and 22c formed at the lower end thereof, and a bolt 26 with a through screw hole is screwed into the large diameter screw hole 22b. The bolt 26 with a through screw hole is formed with a screw hole 26a penetrating in the axial direction thereof, and a screw member 28 is screwed into the screw hole 26a.

The screw member 28 has a tip end side penetrating through the screw hole 26a and a small diameter screw hole 22c of the lip bar 22.
Screwed into. The screw member 28 is fixed to the lip bar 22 with a set screw 30 so as not to rotate. Bolt with threaded through-hole 26 and screw member 2
8 and the like constitute a differential screw mechanism 32. Although only one differential screw mechanism 32 is shown in the figure, a plurality of differential screw mechanisms 32 are provided with their axes parallel to each other in a depth direction perpendicular to the figure. It is possible to elastically deform the lower right end in a direction approaching the lip member 20 or in a direction away from the lip member 20. As a result, the thickness of the raw material melt 34 extruded from the outlet 16b of the passage 16 in the left-right direction in the drawing can be changed as described later.

At the lower end of the first body 10, a choke member adjusting bolt 36 and a choke member 38 are arranged. The screw portion of the choke member adjusting bolt 36 is screwed into a screw hole of the choke member 38. The choke member 38 is formed with a through-hole which allows the bolt 24 to pass therethrough, and has a semi-cylinder having an axis parallel to a width direction Wd (a direction orthogonal to the drawing) of the passage 16 at a right end thereof. A concave portion 38a is formed.
The recess 38a of the choke member 38 has a thin and thick setting shaft 4
0 is rotatably fitted so that it does not fall off in the radial direction. The thickness setting shaft 40 is formed with two notches 40a in the axial direction as shown in FIG. 3 (note that only one notch 40a is shown in FIG. 3). The above-mentioned choke member adjusting bolt 3
6, the variable choke member 38, the thickness setting shaft 40 and the like constitute the variable choke means 100.

By rotating the choke member adjusting bolt 36, the choke member 38 and the thickness setting shaft 40 are set.
Can be moved in the left-right direction. Thereby, the thickness of the narrowed portion 16a of the passage 16 in the left-right direction in FIG. 1 (that is, equivalent to the thickness of the raw material melt 34) can be adjusted. As shown in FIG. 4, the first main body 10 and the second main body 12 have side plates 44 attached to both side surfaces thereof. As shown in FIG. 3, the thickness setting shaft 40 penetrates the side plate 44, and a flexible coupling 42 is attached to the right end of the thickness setting shaft 40 in the drawing. The sealing device 80 and the bracket 46 are attached to the side plate 44. The sealing device 80 is configured to prevent the molten resin from leaking from a gap between the side plate 44 and the thin / thin setting shaft 40. Driving means 48 composed of a motor with a speed reducer 50 is attached to the bracket 46. The output shaft 50a of the speed reducer 50 is connected to the flexible coupling 42. Therefore, the first main body 10 and the second main body 1
The T-die 52 is constituted by the bolt 14, the lip member 20, the lip bar 22, the differential screw mechanism 32, the choke member 38, the thickness setting shaft 40, and the like.

By driving the driving means 48, the thin / thin setting shaft 40 can be rotated by a desired rotation angle in a desired rotation direction via a speed reducer 50 and a flexible coupling 42. That is, the T-die 52 is configured such that the cutout portion 40a of the thickness setting shaft 40 is arranged to face the passage wall surface of the second main body 12 and the lip member 20, so that the thickness dimension of the throttle portion 16a of the passage 16 is reduced. Notch 4
For example, it is possible to increase the size of each of the two portions corresponding to 0a.
By setting “a” so as not to face the passage wall surface of the second main body 12 and the lip member 20, the thickness of the throttle portion 16a can be made constant over the entire width.

FIG. 6 shows a compressed air forming apparatus incorporating the above-described T die 52 and the like. The accumulator 18 is connected to the extruder 54, and the piston 18 b of the accumulator 18 is connected to a driving device 56. The molten resin extruded from the extruder 54 can be accumulated in the accumulator 18, and the molten resin in the accumulator 18 can be extruded from the outlet 16 b of the T-die 52 as the raw material melt 34 by driving the driving device 56. It is. A molding die 58 is disposed downstream of the T die 52. The molding die 58 has a rectangular container-shaped cavity. A fluid pressure cylinder 60 is attached to a first mold 58a of the molding mold 58.
A hydraulic cylinder 62 is attached to the second mold 58b, and the first and second molds 58a and 58b can be opened and closed with each other by driving the hydraulic cylinders 60 and 62.

Air sources 64 and 66 are connected to the first and second molds 58a and 58b so as to communicate with these cavities. On both sides of the mold 58 in the vertical direction perpendicular to the drawing, two rollers 70 and 72 on one side, and an endless belt 74 wound around these rollers.
And two motors connected to the rollers 72 are arranged at positions facing each other (FIG. 6 shows only two motors on one side). The tentering device 68 is constituted by a total of four sets of belt devices disposed on both sides of the mold 58 in the vertical direction. The tentering device 68 can drive the motor 76 to convey the raw material melt 34 downward in the figure while holding each end of the raw material melt 34 between the belts 74. That is, the tentering device 68 can perform so-called tentering of the raw material melt 34. The air sources 64 and 66 can supply compressed air to the closed first and second molds 58a and 58b with the raw material melt 34 sandwiched therebetween. As a result, the raw material melt 34 in the mold 58 can be pressed against the cavity wall surface and pressure-formed into a predetermined shape.

Next, the operation will be described. The differential screw mechanism 32 is operated in advance and positioned so that the opening thickness of the outlet portion 16b becomes a predetermined size. The turning position of the thickness setting shaft 40 is turned counterclockwise from the position shown in FIG. 1 by about 90 degrees, and the choke member adjusting bolt 36 is operated so that the drawing size of the drawing portion 16a is constant over the entire width. Choke member 3
The thickness setting shaft 40 is positioned via 8. First, the mold 58 is positioned at the mold opening position shown in FIG. Next, the molten resin extruded from the extruder 54 to the accumulator 18 pushes the piston 18b of the accumulator 18 upward in the drawing, and is accumulated inside. When a predetermined amount of the molten resin is accumulated in the accumulator 18, the driving device 56 is driven to supply the molten resin in the accumulator 18 to the T die 52. That is, the molten resin passes through the passage 18 a of the accumulator 18 and the first main body 10.
The sheet is formed into a sheet having a uniform thickness through the passage 16 such as the second main body 12 and the narrowed portion 16a, and is sent to the downstream side.

When a predetermined amount of the molten resin passes through the throttle 16a, the driving means 48 is driven by a predetermined amount in a predetermined rotation direction. As a result, the thick and thin setting shaft 4 is connected via the speed reducer 50 and the flexible coupling 42.
0 rotates clockwise in the figure, and the notch 40a
Is positioned at the position shown in FIG. That is, the passage of the narrowed portion 16a has a large cross-sectional area only at two locations in the width direction. The molten resin that passes through the squeezing section 16a in this state is formed into a sheet having a partially thick portion, and is sent downstream. When a predetermined amount of the molten resin passes through the narrowed portion 16a, the driving means 48 is driven by the same amount in the direction opposite to the above. That is, the thickness setting shaft 40 rotates counterclockwise, and the notch 40a is again located at the initial position. As a result, the molten resin passing through the narrowed portion 16a is again formed into a sheet having a uniform thickness and sent to the downstream side. By repeating the above operation, the sheet-like molten resin is discharged from the outlet 16.
b is extruded as raw material melt 34. That is, as shown in FIG. 4, the raw material melt 34 has a thin portion 34b having a uniform thickness when viewed in the width direction and a portion in which two thick portions 34a are formed when viewed in the width direction, in the longitudinal direction. It is pushed out from the outlet 16b in a state where it is repeated at a predetermined interval. When the raw material melt 34 hangs between the tentering devices 68, the motors 76 of the tentering devices 68 are driven synchronously. As a result, the raw material melt 34 is guided into the mold 58 while both ends of the raw material melt 34 are sandwiched between the belts 74 and supported. That is, the raw material melt 34 is widened by the widening device 68.

In this state, when the fluid pressure cylinders 60 and 62 are driven, the mold 58 is closed. That is, the raw material melt 34 is sandwiched between the molds 58. Next, compressed air is blown into the mold cavity by driving the air sources 64 and 66. As a result, the raw material melt 34 is pressed against the inner surface of the square container-like mold of the mold 58. At this time, the thick portion 34a of the raw material melt 34
Since it is pressed while being stretched toward each corner of the cavity wall surface of the rectangular container, the amount of stretching is larger than other portions. As a result, FIG.
As shown in (1), a molded product 78 having a substantially uniform thickness over the entire plane portion 78a and the bent portion 78b can be formed. Subsequently, the molds are opened by driving the fluid pressure cylinders 60 and 62 in the opposite direction, and the molded product 7 is opened.
8 is taken out. Thus, one cycle of the molding operation is completed.

(Test Results) Next, the present applicant conducted a molding test of a square illumination shade using a compressed air molding apparatus shown in FIG. First, the thickness setting shaft 40 is rotated by rotating the choke member adjusting bolt 36 in the same manner as in the related art in a state where the rotation thereof is locked while the notch portion 40a of the shaft 40 is located at a position not opposed to the passage 16. Pressure forming was performed so that the thick portion 34a was formed in the sheet-shaped raw material melt 34. The test results show that the average thickness of the cap is 2.0 mm, whereas the corner has a thickness of 0.5 mm, which not only has poor wall thickness accuracy but also causes defective products such as holes. And the product yield was not good. In order to compare with the above test, the same mold 58 is used, and the pressure setting is performed by rotating the thickness setting shaft 40 at a predetermined timing so as to form the thick portion 34a in the sheet-shaped raw material melt 34. Was. The test results show that the average thickness of the cap is 2.0 mm and the thickness of the corner is 1.5 to 2.5 mm.
The thickness accuracy was significantly improved. With this, defective products such as holes were hardly generated, and the product yield was remarkably improved.

In the above-described embodiment, one thick setting shaft 40 is provided on the first main body 10. However, a plurality of thick setting shafts 40 are provided, and each thin setting shaft 4 is provided.
The shape or the like of the 0 notch 40a can be changed. In this case, only the thickness setting shaft 40 corresponding to the die 58 to be used is operated at a predetermined timing, and the other thickness setting shafts 40 are rotated at positions where the notches 40a do not face the respective throttle portions 16a. With the
The molding operation is performed by locking these rotations. Thereby, the same molding operation as described above can be performed. next,
When it is necessary to change the shape of the notch 40a due to a change in the mold 58 to be formed, the mold 58 is replaced and only the corresponding thin / thin setting shaft 40 is operated at a predetermined timing. The molding operation is performed in the same manner as described above. Thus, a molding operation using a different mold can be performed without replacing the thickness setting shaft 40.

In the above embodiment, the T-die 52 of the present invention is used for the compressed air forming apparatus. However, the T-die 52 of the present invention can be used for the vacuum forming apparatus.
Further, although the main body is constituted by the first main body 10 and the second main body 12, the main body may be of an integral structure. In the description of the above embodiment, a rectangular container-shaped molded product is molded. However, the present invention is not limited to the rectangular container-shaped molded product, and the amount by which the raw material melt 34 is stretched in the mold 58 is described. May be a molded product having a partially different cavity shape, and the notch shape and the number of notches of the thickness setting shaft 40 are determined accordingly.

[0027]

As described above, according to the present invention, at the time of molding, the thick and thin setting shaft provided in the passage can be arbitrarily rotated to obtain a thick portion and a thin portion integrally with the raw material melt. Therefore, a molded article having a uniform thickness can be formed even in a cavity shape in which the amount of the raw material melt stretched in the mold is partially different.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a T-die of the present invention together with an accumulator.

FIG. 2 is a view showing the appearance of a T-die.

FIG. 3 is a view showing a thickness setting axis.

FIG. 4 is a diagram illustrating the shape of a raw material melt extruded from a T-die.

FIG. 5 is a view showing a molded product.

FIG. 6 is a view showing a compressed air forming apparatus.

FIG. 7 is a configuration diagram showing a conventional molding apparatus.

FIG. 8 is a configuration diagram showing a conventional compressed air forming apparatus.

FIG. 9 is a configuration diagram showing a conventional molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st main body 12 2nd main body 16 Passage Wd Width direction 34 Raw material melt 34a Thick part 34b Thin part 36 Choke member adjusting bolt 38 Choke member 38a Depression 40 Thick and thin setting shaft 48 Drive means 52 T die 54 Extruder 58 Die 78a Flat part 78b bent part 100 variable choke means

Claims (6)

(57) [Claims] A body (1) having a passage (16) for molten resin formed therein.
0,12) and the passage (16) attached to the main body (10,12).
And a semi-cylinder formed in a choke member (38) of the variable choke means (100) and having an axis parallel to a width direction (Wd) of the passage (16). A concave portion (38a), a thick and thin setting shaft (40) rotatably provided in the concave portion (38a), a driving means (48) for rotating the thick and thin setting shaft (40), A T-die for an extruder, comprising: a notch (40a) formed in a cylindrical surface of a thickness setting shaft (40). 2. The choke member (38) and a thin / thin setting shaft (4).
2. The T-die of an extruder according to claim 1, wherein a plurality of (0) are provided. 3. A molten resin extruded from an extruder (54),
A choke member (38) provided in the passage (16) of the T-die (52),
The width direction of the passage (16) formed in the choke member (38)
A semi-cylindrical recess (38a) having an axis parallel to (Wd), and a thick and thin setting shaft (40) rotatably provided in the recess (38a).
Driving means (4) for rotating the thickness setting shaft (40).
8) and a thin portion (34b) and a thick portion (34a) through a variable choke means (100) having a notch (40a) formed in the cylindrical surface of the thick and thin setting shaft (40). A method for molding a molded article, characterized in that a raw material melt (34) having the above (1) is obtained and the raw material melt (34) is molded by a mold (58). 4. The molding method according to claim 3, wherein said mold is for pressure forming. 5. The method according to claim 3, wherein the mold is for vacuum forming. 6. A molten resin extruded from an extruder (54),
A choke member (38) provided in the passage (16) of the T-die (52),
The width direction of the passage (16) formed in the choke member (38)
A semi-cylindrical recess (38a) having an axis parallel to (Wd), and a thick and thin setting shaft (40) rotatably provided in the recess (38a).
Driving means (4) for rotating the thickness setting shaft (40).
8) and a thin part (34b) and a thick part (34a) obtained through a variable choke means (100) having a notch (40a) formed in the cylindrical surface of the thick and thin setting shaft (40). A molded article characterized by using a raw material melt (34) integrally having a flat portion (78a) and a bent portion (78b) having a substantially uniform thickness.