JPH0611515B2 - Non-meshing twin-screw extruder for rubber heat input - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In a conventionally known twin-screw extruder for rubber heat input, heat is generated by an extrusion operation of a screw shaft, so that a so-called rubber burning phenomenon occurs because of high pressure and high temperature type. There were drawbacks such as poor degassing action and unstable discharge rate. In the present invention, when a rubber to be heat-heated, for example, a block-shaped rubber is charged, the rubber having a plasticity most suitable for the rubber is heated, and the discharged rubber has a low temperature and a low pressure, and a high rotation rate and a low horsepower give a high discharge amount. The present invention is to complete a twin-screw extruder capable of carrying out the following, and the embodiments of the drawings will be described. The two screw shafts have a non-rotating non-meshing type, and each screw shaft (1) (2) is The ridges (3) and valleys (4) face each other with a double screw, and a gap (5) of about 10% of the diameter is provided between both shafts, and they are arranged side by side without meshing. Next, the screw shafts (1) and (2) are divided into two parts in the longitudinal direction, and the first half is the pressurizing part (6) (6 ') with a low screw angle (α) of about 9 ° and the latter half is the angle. The bite portions (7) and (7 ′) and the heat input portions (8) and (8 ′) having a large (α ₁ ) are used. The screw diameter (D) of the pressurizing part (6) (6 ') is slightly larger than that of the screw (D ₁ ) of the bite part (7) (7') and the heat input part (8) (8 '). The screws (a) and (b) of (6) and (6 ′) are individually fitted into the cylinder (A), respectively, and the screw (c) of the bite (7) (7 ′) and the heat inlet (8) (8 ′) ) (d) are inserted side by side into the cavity (B) with a cross section of eyebrow shape provided in the cylinder (A), and several meters are placed between the wall of the cavity (B) and the screws (c) and (d).
It forms a gap (E) of m. This extruder is also equipped with the same conductive device, cooling device, hopper, and extrusion die as those of known extruders.

In the present invention, for example, a block-shaped kneading rubber is used as a hopper (G).
When it is put in, the biting part (7) (7 ') is automatically bitten and the heat input part
(8) It is sent to (8 '). At this time, because there is a gap (E) of several mm between the screw and the cylinder wall and the screw angle is large, the rubber will go out of the screw groove and be decompressed even if extra block rubber is replenished. Since the dough rise phenomenon does not occur unlike the known machines, there are no defects such as inability to replenish and temperature rise. Next, heat input part (8) (8 ')
The rubber material transferred to the machine moves forward toward the pressing parts (6) and (6 ') while being kneaded with each other by the left and right screws, but the screw shaft (1)
Since (2) is inserted into the cylinder independently, it forms a wall surface (F) at the inlet, and the rubber that is sent hits the wall surface (F), and the screws (c) (d) and the cylinder wall surface ( B)
The rubber is sufficiently plasticized because it is backed from the gap (E) and between the screws (5), that is, it is repeatedly stretched and kneaded, and its repetitive action has the effect of degassing the bubbles in the rubber. Moreover, since the pressure does not rise during the heating operation, the material is transferred to the pressurizing sections (6) and (6 ') with a plasticity and temperature suitable for the material rubber and the purpose of use. Next, the heat-injection-plastified kneaded rubber enters the pressurizing section (6) (6 ') and is pressurized, that is, from the heat-introducing section (8) (8'). The screws (a) and (b) of the pressurizing parts (6) (6 '), which are transferred to the pressurizing part in a state where the discharge pressure is slightly pressurized to about several kg / cm ² , have a screw angle of about 9 °. Since it is a hot-feed type screw, rubber with insufficient plasticity is not ingested. This phenomenon is the greatest feature of the extruder of the present invention, and it is possible to keep the quality constant. This is also proved by the fact that when the shoe sole is press-vulcanized using a rubber sheet extruded by the extruder of the present invention and a rubber sheet cut out from a known heat-in roll, the former has less shrinkage and less defective products. I was able to do it.

The heat-injection plasticization phenomenon by the extruder of the present invention is considered to be a low-temperature low-pressure plasticization phenomenon by a heat-injection roll, unlike the high-temperature high-pressure plasticization phenomenon which reaches 130 ° C. as in the known Banbury mixer.

In the extruder of the present invention, the pressing section (6) (6 ') has only the function of feeding out the rubber having a certain plasticity at the heat input section (8) (8'). It is a revolutionary invention compared to conventional extruders because it can be made shorter in length and can be made compact or low horsepower as a whole, which is advantageous for small and medium-sized factories. .

[Brief description of drawings]

FIG. 1 is a schematic cut front view of the extruder of the present invention, and FIG. 2 is a plan view showing a screw shaft with an upper cylinder removed.
FIG. 3 is a front view in which the cylinder is longitudinally cut from the center portion, and FIG. 4 is a plan view of the cylinder portion, and the lower half has the upper cylinder removed. 5 is a sectional view taken along the line II of FIG. 2, FIG. 6 is a sectional view taken along the line II-II of the same, FIG.
The figure is also a sectional view taken along line III-III. A ... Cylinder, 1, 2 ... Screw shaft, 3 ... Screw crest, 4 ... Screw valley, 5 ... Gap, 6,
6 '... pressurizing part, 7, 7' ... biting part, 8, 8 '... heat input part, E ... space, F ... wall surface.

Claims (1)

[Claims] 1. In a twin-screw extruder with different rotation directions, each screw shaft has a peak and a valley facing each other, and 10% to 10% of the diameter between both shafts.
They are arranged side by side so that there is a gap in the front and back, and the axial direction is divided into two parts in the front and back, the first half is a low-angle pressurizing part consisting of a screw angle of about 9 °, and the latter half is a biting part and heat input part, and pressurizing The screw diameter of the part is slightly larger than the biting part and the heat input part, and the pressurizing part screws are individually fitted into the cylinders. A non-intermeshing twin-screw extruder for heat-inserting rubber, characterized in that it is inserted and formed with a gap of several% of the diameter between the inner wall and the cylinder.