JP2014156020A - Mechanism and method for vibration control of twin-screw extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent vibration generated in a twin-screw extruder.SOLUTION: A vibration control mechanism 1 is provided in a twin-screw extruder 2 which comprises: a pair of mutually rotating kneading screws 4, 4; a long cylindrical barrel 3 capable of accommodating the pair of kneading screws 4, 4; and a drive device 5 supporting one end side of the barrel 3 and giving a rotational driving force to the pair of kneading screws 4, 4. In the vibration control mechanism 1, an upward projecting part 6 which projects upward from the outer peripheral surface of the barrel 3 is provided on the longitudinal other end side of the barrel 3, and the upward projecting part 6 is provided with a vibration control member 13 which generates a frictional force and an impact force to suppress vibration of the barrel 3.

Description

  The present invention relates to a vibration damping mechanism and a vibration damping method for a twin-screw extruder.

When mixing a synthetic resin such as polyethylene or polypropylene, or when mixing a filler or the like with such a synthetic resin, a twin screw extruder is used. This twin-screw extruder is generally provided with a set of long screws having a large shaft length to shaft diameter (L / D), and the barrel is also formed into a long cylindrical shape so as to accommodate this screw. Has been.
In recent years, with respect to such a twin-screw extruder, for the purpose of improving productivity, the kneading screw is rotated at a high speed, and the extrusion amount (production amount) and extrusion pressure (discharge pressure) of the material extruded from the die are increased. There is a growing demand for higher mechanical reliability that does not cause a problem even if the kneading screw is speeded up (high rotation).

Particularly problematic for the needs required for the above-described twin-screw extruder relates to barrel vibration. There are two known vibrations generated in the barrel, one generated by an increased excitation force when the materials are kneaded and one generated by resonance of the barrel during high-speed operation.
For example, as a result of the development of new materials by blending new additives, etc., the materials supplied to the twin screw extruder are more difficult to knead. The excitation force applied to the surface tends to increase. Thus, when the excitation force applied to the barrel during kneading increases, vibration is generated in the barrel. The vibration generated by this excitation force causes the barrel tip to vibrate greatly horizontally as shown in FIG. This is because the twin-screw extruder employs a barrel support structure in which the barrel is fixed to the base with several supports, so the rigidity of the barrel is lower in the horizontal direction than in the front and rear and vertical directions. This is because, since the die mass at the tip is large, the eigenmode in which the barrel tip is vibrated horizontally is generated next.

  On the other hand, when the material is kneaded and extruded in the barrel, the above-described excitation force acts as a reaction force due to the kneading on the entire barrel from the hopper for charging the material to the die for forming the strand. When the operation speed of the kneading screw becomes high, the vibration of the barrel due to the kneading reaction force is amplified by resonance, and vibration different from the large horizontal vibration described above is generated. For example, when the number of kneading blades is two, this vibration mainly consists of a component twice the kneading screw rotation speed. That is, when the kneading screw is operated at a higher speed than the conventional rotation speed and the vibration frequency by kneading is increased, the natural mode of horizontal vibration is excited by a component twice the rotation speed of the kneading screw and causes resonance. This has been confirmed on actual machines.

If the above-described two vibrations appear prominently, it is expected that uniform strand formation will be affected, as well as fatigue life and wear of other machine parts. Therefore, it is desired to develop a technique capable of suppressing vibrations assuming not only barrel resonance during high-speed operation but also an increase in excitation force when mixing new materials.
As means for suppressing the vibration of the barrel, generally means for increasing the rigidity of the barrel support to avoid resonance or providing a dynamic vibration absorber such as a spring or a damper on the barrel support or the like is employed. However, the former requires modification of the entire barrel support, which increases the cost, and considering the further increase in speed in the future, there is a possibility that it may be difficult to handle due to installation space restrictions. The latter can suppress vibrations in a relatively wide frequency range, and is suitable for variable speed twin screw extruders, but has sufficient damping capacity around the barrel heated to about 200 ° C by a heater. There is a problem that it cannot be demonstrated.

  Further, as in Patent Document 1 and Patent Document 2, it is possible to suppress the vibration of the barrel by providing an impact damper as means for reducing the vibration regardless of the frequency. This impact damper dissipates vibration with collision energy, and it has already been disclosed that it is used for a screw of a compressor.

JP 2011-196369 A JP 2011-256773 A

  By the way, although the impact dampers of Patent Document 1 and Patent Document 2 are effective in the natural mode in which the barrel tip described above is largely horizontally oscillated, the frequency exceeds 50 Hz like vibration generated by barrel resonance during high-speed operation. It is not suitable for vibrations, in other words, vibrations that have a small amplitude and are unlikely to cause a collision. However, when aiming at high screw rotation with a twin-screw extruder, vibration with a frequency of 50 Hz or more often occurs, and there is a problem that vibration cannot be sufficiently suppressed.

  The present invention has been made in view of the above-described problems, and a vibration damping mechanism for a twin-screw extruder that can reliably prevent vibrations that occur when the screw rotates at a high speed in the twin-screw extruder. And to provide a vibration control method.

In order to achieve the object, the present invention takes the following technical means.
That is, the vibration damping mechanism of the twin-screw extruder of the present invention supports a pair of kneading screws that rotate with each other, a cylindrical long barrel that can accommodate the pair of kneading screws inside, and one end side of the barrel. And a vibration damping mechanism provided in a twin-screw extruder having a driving device that applies a rotational driving force to the pair of kneading screws, the outer peripheral surface of the barrel at the other end in the longitudinal direction of the barrel An upper projecting portion projecting upward from the upper projecting portion is provided, and the upper projecting portion is provided with a damping member that generates frictional force and impact force to suppress vibration of the barrel. It is a feature.

  Preferably, the damping member is formed by laminating a plurality of mass members having a plate shape and having a predetermined mass, and applying a pressing force downward to the laminated mass members. The mass members may be slid together to generate the frictional force, and the mass member may be configured to generate the impact force when the edge of the mass member collides with a side surface of the upper protruding portion.

Preferably, the barrel includes a plurality of axially protruding vents protruding upward from the outer peripheral surface of the barrel, and is located on the other end side in the longitudinal direction of the barrel among the plurality of vents. The vent may be the upward projecting portion.
Preferably, the mass member surrounds the periphery of the upper projecting portion and is provided with a gap between the side surface of the upper projecting portion.

In addition, Preferably, the said damping member is good to have a press means which can adjust the frictional force which acts between the said mass members by applying downward pressing force with respect to the laminated mass member. .
On the other hand, the vibration damping method of the twin-screw extruder of the present invention supports a pair of kneading screws that rotate with each other, a cylindrical long barrel that can accommodate the pair of kneading screws inside, and one end side of the barrel. In addition, with respect to the twin-screw extruder having a driving device that applies a rotational driving force to the pair of kneading screws, the vibration of the barrel is suppressed by using the vibration damping mechanism described above.

  According to the vibration damping mechanism and vibration damping method of the twin-screw extruder of the present invention, it is possible to reliably prevent vibration that occurs when the screw rotates at a high speed in the twin-screw extruder.

It is front sectional drawing of the twin-screw extruder provided with the damping mechanism of this invention. It is sectional drawing of the BB line of FIG. It is the figure which expanded the A section of FIG. It is a figure which shows the modification of a damping member. It is the figure which showed the horizontal primary vibration mode of the twin-screw extruder.

The vibration damping mechanism 1 of the present invention is provided in the twin screw extruder 2 and suppresses vibrations generated in the barrel 3 of the twin screw extruder 2.
Specifically, as shown in FIGS. 1 and 2, the twin-screw extruder 2 provided with the vibration damping mechanism 1 of the present invention includes a pair of kneading screws 4 and 4 that rotate with each other, and a pair of these kneading screws 4. 4 has a long cylindrical barrel 3 capable of accommodating 4 inside, and a driving device 5 that supports one end of the barrel 3 and applies a rotational driving force to the pair of kneading screws 4, 4. . Further, on the other end side in the longitudinal direction of the barrel 3, there is provided an upper projecting portion 6 projecting upward from the outer peripheral surface of the barrel 3, and the upper projecting portion 6 is provided with the vibration damping mechanism 1 of the present invention. Is provided.

Hereinafter, prior to the description of the vibration damping mechanism 1, the twin-screw extruder 2 provided with the vibration damping mechanism 1 will be described first.
As described above, the twin-screw extruder 2 includes the barrel 3 having a hollow inside and the pair of kneading screws 4 and 4 accommodated in the barrel 3. Both the barrel 3 and the kneading screw 4 are formed in a long shape, and are arranged so that the axis is directed in the horizontal direction.

In the following description, the right side of the paper surface of FIG. 1 is the upstream side when the biaxial extruder 2 is described, and the left side of the paper surface is the downstream side. Moreover, let the left-right direction of the paper surface of FIG. 1 be the axial direction at the time of describing the biaxial extruder 2. FIG.
The barrel 3 is formed in a long cylindrical shape along the horizontal direction. The inside of the barrel 3 is a glasses-shaped cavity whose cross section cut in the direction perpendicular to the axis is formed by connecting two arcs. A kneading screw 4 can be accommodated in the hollow inside the barrel 3, and a material can be supplied between the kneading screw 4 and the inner wall surface of the barrel 3 for kneading.

  A hopper 7 for supplying material into the barrel 3 is provided on the upstream side (one side) of the barrel 3 in the axial direction. Further, a die (not shown) that pushes the kneaded material out of the barrel 3 is provided on the downstream side (the other side) in the axial direction of the barrel 3. In the twin-screw extruder 1, strands and pellets can be processed by cooling or cutting the material extruded from the die.

  Further, on the outer peripheral surface of the barrel 3 located between the die and the hopper 7, in other words, on the outer peripheral surface of the barrel 3 located slightly upstream from the die, extra air generated from the material kneaded in the barrel 3. A vent 9 is provided for exhausting water and moisture to the outside of the barrel 3. The vent 9 is a cylindrical member (upward projecting portion 6) extending upward from the upper surface of the barrel 3 so that the fumes can be exhausted from the inside of the barrel 3. A flange-like flange portion 10 is formed at the upper end of the vent 9 so as to spread outward in the horizontal direction, and a vibration damping mechanism 1 to be described later is attached using the flange portion 10. .

  As shown in FIG. 2, the kneading screw 4 is a member for kneading the material supplied into the barrel 3. The kneading screws 4 are provided in a pair of left and right so as to pass through the inside of the barrel 3 that is hollow as described above, and each kneading screw 4 is disposed so as to be rotatable about a horizontal axis. The material supplied into the barrel 3 can be kneaded by rotating in the cylinder 3. The kneading screws 4 are provided so that the rotation centers of the kneading screws 4 coincide with the centers of the two circles that form the cavity of the barrel 3. The pair of kneading screws 4, 4 includes a plurality of types of kneading flights 11 having different functions in the axial direction.

  The kneading screw 4 has two kneading flights 11 so as to have a phase difference of 180 ° in the circumferential direction with respect to the rotation center, and has a cross-sectional shape in which the cross section along the axis perpendicular direction is elliptical. ing. The pair of kneading screws 4 and 4 rotate in the same direction, and the kneading flight 11 of one kneading screw 4 and the kneading flight 11 of the other kneading screw 4 have a rotational phase of 90. It is configured to rotate with a deviation.

These kneading screws 4 are rotated by a driving device 5 arranged on one end side (upstream side) in the axial direction.
The driving device 5 supports one end side (upstream side) of the barrel 3 and applies a rotational driving force to the kneading screw 4. The drive device 5 is configured to decelerate a rotational drive force generated by a motor (not shown) or the like and transmit it to each of the pair of kneading screws 4, 4.
The kneading screw 4 on the opposite side is not provided with a support mechanism. That is, the kneading screw 4 has a “cantilever structure” in which the downstream end is not supported by a bearing or the like, and the upstream side is also provided with a bearing provided in the vicinity of the speed reducer outlet provided inside the driving device 5. It is supported by.

On the other hand, the other end side (downstream side) of the barrel 3 is supported by a support structure called a barrel support 12. The barrel support 12 is provided to stand on the foundation, and the upper end of the barrel support 12 is connected to the lower surface of the barrel 3 so as to support the barrel 3 from below.
Thus, although the other end of the barrel 3 is supported by the barrel support 12, as explained in detail in “Problems to be Solved by the Invention”, vibration is caused by the cantilever structure of the kneading screw 4. Is likely to occur.

Therefore, in order to suppress the vibration on the other end side of the barrel 3 described above, the biaxial extruder 2 of the present invention is provided with a vibration damping mechanism 1 as shown below.
That is, the vibration damping mechanism 1 according to the present invention includes the vibration damping member 13 that generates frictional force and impact force to suppress the vibration of the barrel 3. The vibration damping mechanism 1 is provided with an upper projecting portion 6 projecting upward from the outer peripheral surface of the barrel 3 on the other end side in the longitudinal direction of the barrel 3 (the existing upper projecting portion 6). It is also possible to suppress the vibration of the barrel 3 by being provided in the upward projecting portion 6.

Next, the configuration of the vibration damping mechanism 1 of the present invention will be described in detail.
As shown in FIG. 3, the damping member 13 includes a plurality of (three in the present embodiment) mass members 14 that have a plate shape and have a predetermined mass. The plurality of mass members 14 are stacked one above the other. The damping member 13 is provided with pressing means 15 that applies a pressing force downward to the stacked mass members 14.

  The mass member 14 is formed so as to have a certain weight using a metal such as stainless steel or steel, and the upper mass member 14 applies a certain pressing force to the lower mass member 14 by being laminated. It can be added. With this structure, when the barrel 3 vibrates, the laminated mass members 14 slide with each other, and a frictional force is generated in a direction opposite to the vibration direction, and the generated frictional force attenuates the vibration. Thus, vibration of the barrel 3 can be suppressed. The attenuation of vibration due to the frictional force is effective even for vibration having a relatively high frequency, such as when resonance occurs. This is because vibration with a high frequency has a small amplitude and cannot be effectively damped by a method of damping by an impact force such as an impact damper. However, the frictional force works effectively between the mass members 14 even if the amplitude is small, and exhibits a sufficient damping effect even for vibrations having a high frequency.

  On the other hand, the mass member 14 is formed in a plate shape (plate shape) with a metal or the like, and an opening 16 is formed at the center so that the above-described upper protrusion 6 (vent 9) can be loosely inserted. The opening 16 has a shape that matches the outer shape of the upper protrusion 6. For example, when the upper protrusion 6 is cylindrical, the opening 16 is formed to open in a circular shape, and the upper protrusion 6 is a square tube. In the case of a shape, it is formed so as to open in a square shape. Further, the opening size of the opening 16 is set larger than the outer size of the upper protruding portion 6, and a gap is formed between the opening 16 and the upper protruding portion 6.

  In this way, if a gap is provided between the opening 16 of the mass member 14 and the upper protrusion 6, the mass member 14 moves by the gap when vibration is applied, and the mass member 14 The impact force is generated in the direction opposite to the vibration direction by colliding with the opening edge of the opening 16, and the vibration of the barrel 3 can be suppressed by attenuating the vibration by the generated impact force. The vibration attenuation due to the impact force is obtained by causing each mass member 14 to act as a so-called “impact damper”, and the frequency is relatively high as in the case where the excitation force applied to the barrel 3 or the like is increased. It exhibits effective vibration damping even for low vibrations.

The pressing means 15 adjusts the friction force generated by the damping member 13 by adjusting the friction force acting between the mass members 14 by applying a pressing force downward to the stacked mass members 14. It is.
Specifically, the pressing means 15 is composed of, for example, a member such as a spring that can exert a biasing force downward, and the mass member 14 stacked on the uppermost side among the stacked mass members 14. The pressing force can be applied from above. If the pressing force is applied by the pressing means 15 in this way, the pressing force of the pressing means 15 in the downward direction is applied in addition to the weight of the mass member 14, and the frictional force generated between the mass members 14 can be freely adjusted. It becomes possible.

  The upward projecting portion 6 to which the damping member 13 is attached is a structure or member that projects upward from the outer peripheral surface of the barrel 3, and is formed to attach the damping member 13 to the barrel 3. Yes. Specifically, the upper projecting portion 6 is formed in order to secure a thickness in a vertical direction so that the damping member 13 can be attached. For example, the damping member 13 is formed on the projecting end side of the upper projecting portion 6. By attaching the lower end of the vibration damping member 13 to the base end side of the upward projecting portion 6, it is possible to easily attach even the thick vibration damping member 13.

  In the case of the present embodiment, a vent 9 provided on the upper surface of the barrel 3 is employed as the upward projecting portion 6. That is, the damping member 13 of the present embodiment includes a plurality of mass members 14 and pressing means 15 between the flange portion 10 of the vent 9 projecting outward and the upper surface of the barrel 3 (outer peripheral surface of the barrel 3). Can be attached as described above.

  In addition, when the some vent 9 is provided in the outer peripheral surface of the barrel 3 along the axial direction, the vent 9 located in the most downstream side of the axial direction, in other words, the die 8 side most, is used as the upper protruding portion 6. Good. Further, for the barrel 3 in which the vent 9 is not provided at all, an upper protruding portion 6 that protrudes upward on the outer peripheral surface on the downstream side of the barrel 3 is newly provided, and the newly provided upper protruding portion 6 On the other hand, the damping member 13 may be attached.

  By the way, in embodiment mentioned above, the example of the annular | circular shaped (annular) mass member 14 which surrounds the circumference | surroundings of the barrel 3 over the perimeter was given. However, for the vent 9, a space is provided to provide piping for removing air and moisture generated during material kneading, wiring to a pump that sucks and removes air and moisture, or instruments. Must-have. Therefore, as shown in FIG. 4A, the circumference of the vent 9 is not surrounded all around, but the shape of the mass member 14 is a shape in which a part in the circumferential direction is cut away (substantially in plan view). C-shaped or U-shaped), and a space for installing wiring around the vent 9 is secured.

Moreover, as shown in FIG. 4B, when the shape of the vent 9 is a square shape, a vibration damping member 13 having a mass member 14 having a square cross section (a mouth shape when viewed from above) can be employed. .
Furthermore, as shown in FIG. 4C, for example, a configuration is adopted in which two mass members 14 having a “U-shape” or “U-shape” in a plan view are combined with each other and connected together with a bolt 17 or the like. You can also. As shown in FIG. 4 (d), the two mass members 14 may be combined with the end of one mass member 14 overlapped with the end of the other mass member 14 and fastened with bolts 17, respectively. The end portions of the mass member 14 may be formed in a stepped shape, and the end portions may be overlapped and fastened with bolts 17 so that the projections and recesses abut each other. If the mass members 14 that can be connected by such bolts 17 are used, each mass member 14 can be easily attached by being sandwiched with respect to the vent 9.

  By attaching the vibration damping mechanism 1 as described above to the vent 9 of the twin screw extruder 2, vibration with a relatively high frequency occurred in the barrel 3 during the kneading operation in the twin screw extruder 2. However, the mass members 14 slide with each other, and a frictional force is generated in a direction opposite to the vibration direction, and the vibration of the barrel 3 can be suppressed by attenuating the vibration with the generated frictional force. . Further, when vibration with a relatively low frequency occurs in the barrel 3 as in the case where the excitation force applied to the barrel 3 or the like is increased, the mass member 14 collides with the vent 9 and is opposite to the vibration direction. Thus, an impact force is generated, and the vibration is attenuated by the generated impact force to suppress the vibration of the barrel 3.

  In summary, if the above-described vibration damping mechanism 1 is used, the impact force effectively suppresses vibration for vibrations having a relatively low frequency, and the friction force vibrates for vibrations having a relatively high frequency. In order to suppress effectively, not only the vibration generated when the new material is kneaded by the twin-screw extruder 2, but also the vibration generated when the twin-screw extruder 2 is operated at a high speed is effectively suppressed. Or can be prevented.

Further, since the vibration damping mechanism 1 uses the frictional force and the impact force generated by the vibration damping member 13 for damping the vibration, the vibration damping effect does not deteriorate even in a high temperature use environment. Therefore, the vibration of the barrel 3 can be reliably suppressed even in a use environment in which a heater is provided nearby like the twin-screw extruder 2.
Further, some twin screw extruders 2 can greatly change the operation speed of the kneading screw 4, and the frequency of vibration generated in the barrel 3 may be in a wide range from a low frequency range to a high frequency range. Even with respect to vibration over such a wide frequency range, with the above-described vibration damping mechanism 1, the frictional force and impact force generated by the vibration damping member 13 suppress vibration over a wide frequency range. Vibration can be effectively suppressed.

Furthermore, the vibration damping mechanism 1 can be attached by using the vent 9 provided in the existing twin-screw extruder 2 as the upward projecting portion 6. Therefore, it is not necessary to make a major modification to the existing twin-screw extruder 2, and vibration of the barrel 3 can be suppressed at a low cost.
By the way, this invention is not limited to said each embodiment, The shape, structure, material, combination, etc. of each member can be suitably changed in the range which does not change the essence of invention. Further, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. However, matters that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Damping mechanism 2 Twin screw extruder 3 Barrel 4 Kneading screw 5 Drive apparatus 6 Upper protrusion 7 Hopper 9 Vent 10 Flange 11 Kneading flight 12 Barrel support 13 Damping member 14 Mass member 15 Pressing means 16 Opening 17 Bolt

Claims (6)

A pair of kneading screws that rotate with each other, a cylindrical long barrel that can accommodate the pair of kneading screws, and a drive that supports one end of the barrel and applies a rotational driving force to the pair of kneading screws. A vibration control mechanism provided in a twin-screw extruder having a device,
On the other end side in the longitudinal direction of the barrel, an upper projecting portion projecting upward from the outer peripheral surface of the barrel is provided,
A vibration damping mechanism for a twin-screw extruder, wherein a vibration damping member that suppresses vibration of the barrel by generating a frictional force and an impact force is provided on the upward projecting portion. The damping member is formed by laminating a plurality of mass members having a plate shape and a predetermined mass,
By applying a downward pressure to the stacked mass members, a plurality of mass members slide with each other to generate the frictional force, and an edge of the mass member is a side surface of the upper protruding portion. The vibration damping mechanism of the twin-screw extruder according to claim 1, wherein the impact force is generated by colliding with the two-screw extruder. The barrel includes a plurality of axially protruding vents protruding upward from the outer peripheral surface of the barrel,
The vent of the two-screw extruder according to claim 1 or 2, wherein a vent located on the other end side in the longitudinal direction of the barrel among the plurality of vents is the upward projecting portion. Shaking mechanism.   4. The twin-screw extruder according to claim 2, wherein the mass member surrounds the periphery of the upper protrusion and is provided with a gap between the mass member and a side surface of the upper protrusion. 5. Vibration control mechanism.   The said damping member has a press means which can adjust the frictional force which acts between the said mass members by applying a pressing force with respect to the laminated mass member below. The vibration control mechanism of the twin-screw extruder in any one of 2-4.   A pair of kneading screws that rotate with each other, a cylindrical long barrel that can accommodate the pair of kneading screws, and a drive that supports one end of the barrel and applies a rotational driving force to the pair of kneading screws. The vibration control of the twin-screw extruder, wherein the vibration of the barrel is suppressed by using the vibration control mechanism according to any one of claims 1 to 5 with respect to the twin-screw extruder having an apparatus. Method.