JPH0733018B2 - Screw extruder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw extruder (hereinafter simply referred to as an extruder). More specifically, it relates to a so-called cold feed extruder for kneading rubber that has not yet been heated.

[0002]

2. Description of the Related Art Conventionally, as an extruder having a screw in a housing and rotating the screw to mix rubber, one shown in FIG. 4 is known (Japanese Patent Publication No. 56-53500). See the bulletin). In this extruder 51, the screw 52 has a screw 53 along the longitudinal direction on the outer periphery thereof, and the valley of the screw 53 constitutes a rubber feed passage 54.
And a housing for accommodating the screw 52 concentrically
Inside the 55, a plurality of mixing pins 56 are provided so as to project. The mixing pin 56 is fixed to the housing 55 so as to reach the vicinity of the bottom of the screw 52. That is, it extends into the rubber feed passage 54. With this configuration, the rubber filled in the housing 55 through the supply port is moved through the screw trough 54 while being kneaded as the screw 52 rotates. Then, since the mixing pin 56 is thrust into the rubber, the flow of the rubber is agitated so as to be fragmented, a partial whirlpool is generated, and the kneading is promoted.

[0003]

In the screw extruder, when the rotation of the screw is increased, the amount of rubber extruded increases, and the internal temperature of the rubber increases the temperature of the rubber.

In the conventional extruder 51, the mixing pin 56
Is fixed and does not rotate, the mixing pin 56 cannot exert its effect independently of the rotation of the screw 52.

Therefore, when the number of revolutions of the screw is changed to increase or decrease the amount of rubber extruded, the temperature of the rubber is also changed, so that the quality of the rubber is not stable.

The present invention has been made in order to solve the above-mentioned problems, and the temperature of the rubber can be controlled to be substantially constant, and in addition, the kneading effect of the rubber can be further improved to further An object of the present invention is to provide an extruder capable of extruding rubber having a high quality level with higher efficiency.

[0007]

A screw extruder according to the present invention includes a cylinder and a cylinder that is concentrically housed in the cylinder.
And a screw capable of rotating around its own axis, a mixing pin projecting inside the cylinder and capable of revolving around the axis of the cylinder, and means for revolving the mixing pin around the axis of the cylinder. And the screw has a thread on its outer peripheral surface, the thread of which has a slit in the shaft of the screw through which the screw and / or the mixing pin can pass when the mixing pin rotates. It is characterized in that it is formed in a vertical plane.

The revolving means is composed of a rotating ring housed concentrically within the cylinder and around the screw, the rotating ring rotating around the screw and circumferentially inside thereof. A plurality of the mixing pins may be provided so as to project at equal intervals.

Further, it is preferable that a plurality of rows of mixing pins projecting along the circumference of the rotating ring are arranged at intervals along the axis of the rotating ring.

Further, it is preferable that the rotary ring has external teeth on its outer circumference so that the external teeth can mesh with a gear for transmitting a rotational force.

[0011]

In the extruder of the present invention, the heat generation in the rubber is promoted by the rotation of the mixing pin, so that the heating efficiency is further improved. Since the rubber temperature rises as the rotation speed of the mixing pin increases, it is possible to control the rubber temperature independently of the rotation of the screw by changing the rotation speed. As a result, rubber with stable quality can be obtained.

In addition to mixing the rubber by the screw, the mixing pin is revolved to stir the rubber in the screw feed passage (screw trough) so as to cut it, so that the kneading efficiency is dramatically improved. To do.

Also, when the rubber of the extruder is changed (a new constant amount of rubber is supplied after the continuous extrusion of a constant amount of rubber is completed), the rubber supply is temporarily interrupted, and it is no longer pushed and extruded. Although it may stagnate, by making the revolving direction of the mixing pin reverse to the rotation of the screw (the same as the rubber flow direction around the screw), the effect of feeding the rubber occurs and the stagnation of the rubber is alleviated. As a result, the rubber can be changed quickly.

As described above, the heating efficiency and kneading efficiency of the rubber are remarkably improved, so that the stroke of the rubber in the extruder can be shortened considerably. That is, when the conditions such as the outer diameter of the screw, the pitch of the screw, and the number of revolutions are the same, the L / D of the conventional cold feed machine was 12 to 18, but the L / D of the extruder of the present invention was L / D. Can be reduced to about 5 to 10. Here, L / D is the ratio of the length L of the screw portion of the screw and the outer diameter D of the screw portion of the screw. The numerical value (12 to 18) is generally adopted in the industry as the minimum ratio that satisfies the performance requirement. If the other conditions are the same, naturally, the smaller the L / D, the lower the manufacturing cost of the extruder, and the shorter the time from the feeding of rubber to the completion of extrusion.

[0015]

The extruder of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway front view showing an embodiment of the extruder according to the present invention, FIG. 2 is a sectional view showing the mixing pin and its driving means in the extruder shown in FIG. 1, and FIG. II of 2
It is a sectional view taken along the line I-III.

FIG. 1 schematically shows the whole extruder 1. 2 is a cylinder in which the screw 3
Are housed concentrically. A rotation driving device 4 for rotating the screw 3 is provided at one end of the cylinder 2. The rotation driving device 4 rotates the screw 3 via a transmission gear by an electric motor or an air motor. A hopper 5 for injecting rubber into the cylinder 2 is installed adjacent to the rotary drive device 4.

The screw 3 is rotatably supported around its axis, and a screw 6 is formed on the outer periphery thereof. Although the screw 6 shown in FIGS. 1 and 2 is a right-handed screw, it may be a left-handed screw, and in this case, it is necessary to reverse the rotation direction. 1 and 2, a double thread is shown, but a single thread may be used. In the thread of this screw 6,
A slit 7 is formed in a plane perpendicular to the axis of the screw 3 so that a mixing pin 14 described later can pass through when the screw 3 rotates (see FIG. 2). This slit 7 is
If it is too large, the rubber becomes hard to move and resistance to the feeding is achieved. A proper gap is provided between the top of the thread and the inner surface of the cylinder 2. Therefore, the valley of the screw 6 constitutes the rubber feed passage 8 (see FIG. 2).
reference).

Inside the cylinder 2 and around the screw, a rotary ring 9 is housed so as to rotate concentrically. Then, that portion of the cylinder 2 is divided by a plane perpendicular to the axial center, and a space for accommodating the rotating ring 9 is formed in the divided portion and then connected by a flange 10. External teeth 11 are formed on the outer circumference of the rotating ring 9 at the center in the width direction. On the other hand, a drive shaft 12 is extended from the rotary drive device 4 through a transmission in parallel with the cylinder, and a gear 13 that meshes with the outer teeth 11 is attached to the drive shaft 12. That is, the rotation driving device 4 has a role of driving both the screw 3 and the rotating ring 9. Of course, a separate driving device may be provided only for driving the rotating ring 9. A sliding portion between the rotary ring 9 and the cylinder 2 is provided with a so-called mechanical seal or the like as a sealing means for the rubber inside the cylinder 2.

As shown in FIG. 3, six mixing pins 14 are provided on the inner side of the rotating ring 9 along the circumference and at equal intervals. The mixing pin 14 is fixed by being screwed into a screw hole formed in the rotary ring 9 as shown in FIG. 2, and is projected into the feed passage 6 of the screw 3. The depth of penetration of the mixing pin 14 is adjusted until the tip of the mixing pin 14 reaches the vicinity of the screw bottom of the screw 3. In this embodiment, two rows of mixing pins 14 are arranged on both sides of the outer tooth 11, but the present invention is not limited to two rows, and the width of the rotary ring 9 is preferably selected. For example, the number of rows may be one, or three or more.

The outer diameter d of the mixing pin 14 is usually preferably 1/10 or less of the outer diameter of the screw of the screw. This is because if it exceeds that, the action of hindering the movement of rubber becomes large.

In this embodiment, the portion of the mixing pin 14 projecting into the feed passage has a cylindrical shape, but the present invention is not limited to a cylindrical shape, and for example, a prismatic shape or an elliptical shape. It may be columnar or the like.

The material used for the mixing pin 14 is not particularly limited as long as it is a metal that is excellent in wear resistance and is tough, and nickel chromium steel or the like is preferably used.

The usage of the extruder 1 constructed as above will be described.

While the screw 3 and the rotary ring 9 are rotated by the rotary drive device 4, rubber is filled from the hopper 5. Rotate the screw 3 so that the screw 6 (right screw) rotates counterclockwise (indicated by arrow A in FIGS. 1 and 2).
Then, the filled rubber is sent from the hopper 5 side to the extrusion port 15 through the feed passage. At that time, the surface of the rubber that contacts the inner surface of the cylinder 2 and the surface of the screw 3 constantly changes, and the rubber is mixed. On the other hand, as the rotary ring 9 rotates, the mixing pins stir in the circumferential direction of the screw 3 so as to interrupt the flow of rubber, so that the kneading efficiency of rubber is dramatically improved. The kneading efficiency is improved as the rotation of the rotating ring 9 is increased. In addition, mixed pins as above
Since 14 vigorously stirs the rubber, the rubber heats up due to internal friction and the temperature rises. If the rotation speed of the screw 3 is the same, the faster the rotation of the rotating ring 9, the higher the temperature of the rubber. Therefore, the heating efficiency is improved as compared with the conventional fixed pin type extruder. Since the kneading effect and the temperature raising effect are large as described above, the rubber supplied to the extruder 1 can be quickly taken out. That is, the stroke of the rubber in the extruder 1 can be shortened. Therefore, since the extruder 1 can be made compact, its cost is reduced and the time required for extrusion is also shortened. Especially when the rubber is changed many times in succession, the total man-hours are extremely short. Furthermore, the temperature of the extruded rubber can be controlled by changing the number of rotations of the rotating ring 9 independently of the rotation of the screw 3. as a result,
For example, even if the rotation speed of the screw 3 is changed every time the rubber is changed, the rubber temperature can be kept constant by changing the rotation speed of the mixing pin 14, so that the quality of the rubber is stabilized.

In the extruder 1 shown in FIGS. 1 to 3, there are six mixing pins per revolution of the rotary ring, and two rows are provided along the axis of the cylinder 2 in this arrangement. The number of columns is not limited to two, and may be appropriately selected depending on the outer diameter and the length of the screw 3. Usually, one to eight lines are provided per revolution, and one to four rows are generally provided along the axis.

The rotating direction of the rotating ring is not particularly limited, but it is preferable to rotate the rotating ring in the same direction as the rotation of the screw. Because, if it is rotated in the same direction as the screw 3, the rubber will be mixed against the flow direction,
This is because the kneading efficiency is improved. And the rotation speed of the rotating ring is appropriately selected according to the outer diameter and the number of mixing pins, the outer diameter and the rotation speed of the screw, but is usually 5 to 50.
It is in the rpm range.

[0028]

The extruder of the present invention has extremely high plasticization efficiency of rubber, so that it can be manufactured compactly at a low manufacturing cost and can be replaced quickly. Further, since the temperature of the rubber can be controlled, there is an advantage that the quality of the rubber can be stabilized.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of an extruder of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a mixing pin and its driving means in the extruder of FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view of an essential part showing an example of a conventional extruder.

[Drawing reference number]

 1 Extruder 2 Cylinder 3 Screw 6 Screw 7 Slit 9 Rotating ring 11 External tooth 12 Drive shaft 13 Gear 14 Mixing pin

Claims (4)

[Claims] 1. A cylinder, a screw concentrically housed in the cylinder and rotatable about its own axis, a screw projecting inside the cylinder, and revolving about the axis of the cylinder. The screw comprises a mixing pin and a revolving means for revolving the mixing pin around the axis of the cylinder, and the screw has a screw on its outer peripheral surface, and the screw and / or the mixing pin have a thread on the screw thread. A screw extruder in which a slit for allowing the mixing pin to pass through when rotated is formed in a plane perpendicular to the axis of the screw. 2. The revolving means comprises a rotating ring housed concentrically within the cylinder and around the screw, the rotating ring rotating around the screw and having a circle inside thereof. The screw extruder according to claim 1, wherein a plurality of the mixing pins are provided at equal intervals along the circumference. 3. The screw extruder according to claim 2, wherein a plurality of rows of mixing pins projecting along the circumference of the rotating ring are arranged at intervals along the axis of the rotating ring. 4. The screw extrusion according to claim 2, wherein the rotating ring has external teeth on its outer periphery, and the external teeth are capable of meshing with a gear for transmitting a rotational force. Machine.