Agitating – Rubber or heavy plastic working – Stirrer is through-pass screw conveyor
Reexamination Certificate
2000-04-28
2001-05-29
Cooley, Charles E. (Department: 1723)
Agitating
Rubber or heavy plastic working
Stirrer is through-pass screw conveyor
C366S084000, C366S090000
Reexamination Certificate
active
06238079
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to a kneading degree adjusting device for a twin extruder.
2. Related Art
FIGS. 6A-6C
show one example of kneading degree adjusting devices in a conventional twin extruder. This kneading degree adjusting device in the twin extruder comprises a cylinder
101
and two screws
102
which are rotatably provided in the cylinder
101
. A pair of gate valves
103
a
,
103
b
provided at a downstream side of a kneading part B so as to be movable perpendicularly to an axial direction (upward and downward in the drawings) are brought closer to or separated from each other by means of hydraulic cylinders
106
a
,
106
b
, whereby gaps formed between faces
102
a
at the root of a flight of the screws
102
and semicircular faces
104
a
,
104
b
formed at the tip ends of the gate valves
103
a
,
103
b
are changed in size, thereby to vary the kneading degree (Examined Japanese Utility Model Publication Hei. 7-56185).
In the above described conventional art, due to the structure that a pair of the gate valves are moved perpendicularly to the axial direction in order to change the gaps (hereinafter referred to as “opening degree variable channels”) formed between the faces of the screws at the root of the flight and the semicircular faces formed at the tip ends of the gate valves, there have been such problems as described below.
A sectional shape of the opening degree variable channel varies from a substantially annular shape to a substantially oval shape, and the gaps between the semicircular faces of a pair of the gate valves and the faces of the screws at the root of the flight are subjected to a greater change in a vertical direction than in a lateral direction. As the result, an unmolten material having high viscosity is allowed to short-pass the larger gaps in an upper and lower parts, and thus a filling degree of the material in the kneading part upstream of the gate valves will become unstable. Therefore, a uniform kneading efficiency cannot be obtained.
Further, because the opening degree of the opening degree variable channel is changed by moving a pair of the gate valves perpendicularly to the axial direction of the cylinder, not only opening and closing times of the channels will be longer but also the structure will become complicated.
SUMMARY OF INVENTION
The invention has been made in view of the above described problems that the conventional art has had, and aims to realize a kneading degree adjusting device for a twin extruder in which the filling degree of the material can be stabilized and the opening and closing motions of the channels can be rapidly conducted.
In order to attain the above described object, there is provided, according to the invention, a kneading degree adjusting device for a twin extruder which comprises a cylinder and two screws rotatably provided in the cylinder, wherein at least a feeding part, a kneading part, a gate part and a discharging part are provided in order from an upstream side to a down stream side, characterized in that the device includes an opening degree variable channel forming part respectively provided in the screws at a position corresponding to the gate part, each of the opening degree variable channel forming parts having an outer diameter which is equal to or slightly larger than a diameter of the screw at the root of a flight thereof, an upper guide bore and a lower guide bore provided in the cylinder above and below the screws at a position corresponding to the gate part so as to extend in a radial direction, gate rods rotatably contained in the upper guide bore and the lower guide bore respectively, each of the gate rods being provided with opening degree changing recesses in a form of an opencut adjacent to each other in an axial direction of the gate rod so as to constitute opening degree variable channels in an annular shape in combination with outer peripheral faces of the opening degree variable channel forming parts, and that each of the opening degree changing recesses includes a first semicircular face having an inner diameter which is equal to or slightly larger than an inner wall face of the cylinder and a second semicircular face having such a shape that an upstream side end or a downstream side end of the first semicircular face is diagonally cut and outwardly slanted from the first semicircular face, the second semicircular face having an inner diameter which is equal to or slightly larger than the outer peripheral face of the opening degree variable channel forming part.
In addition, it is preferable that a boundary part between the first semicircular face and the second semicircular face may include a curved face.
REFERENCES:
patent: 3360824 (1968-01-01), Schippers
patent: 3419250 (1968-12-01), Brennan, Jr.
patent: 3870285 (1975-03-01), Bausch et al.
patent: 3981658 (1976-09-01), Briggs
patent: 4299499 (1981-11-01), Buchheit
patent: 4332481 (1982-06-01), Inoue et al.
patent: 4462691 (1984-07-01), Boguslawski
patent: 4678339 (1987-07-01), Peiffer et al.
patent: 5335991 (1994-08-01), Wobbe
patent: 5909958 (1999-06-01), Rauwendaal
patent: 513431 (1992-11-01), None
patent: 2-89606 (1990-03-01), None
patent: 2-99305 (1990-04-01), None
patent: 4-14412 (1992-01-01), None
patent: 4-22606 (1992-01-01), None
patent: 4-22607 (1992-01-01), None
patent: 94/15769 (1994-07-01), None
Patent Abstracts of Japan, Publication No. 02092516, Apr. 3, 1990, Application No. 63243925, Sep. 30, 1988.
Naitou Katuyuki
Watada Satoru
Cooley Charles E.
Sughrue Mion Zinn Macpeak & Seas, PLLC
The Japan Steel Works Ltd.
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