JPS58202028A - Twin-shaft type continuous kneader - Google Patents

Abstract

PURPOSE:To provide the titled kneader extremely reduced in bending stress exerting on each rotor and to enhance durability thereof, by providing a groove enlarging the opposed interval of the top part of a kneading blade and the inner surface of a chamber to a predetermined place in an axial direction corresponding to the connecting part of the feeding blade part and a return blade part in the chamber. CONSTITUTION:A material to be kneaded and continuously supplied into a chamber 1 from a hopper 11 is fed to a kneading part 22 through a feed part 21 with the rotation of rotors 2, 2 and, while stirred and kneaded in the kneading part 22 by a kneading blade 24, shearing action is imparted to said material to be kneaded between the top part of the blade 24 and the inner surface of the chamber 1 as well as in the mutual space between both rotors to gradually plasticize and melt the same. In this case, in the side of the central space between both rotors 2, 2, the pressure of the material to be kneaded and the repelling force to the rotors 2 corresponding to said pressure are released. On the other hand, because the material to be kneaded in the forward side in the rotary direction of the blade 24 escapes to a circumferential side through a groove 25 even at the positions in opposite sides with respect to said central space 14, the pressure exerting on the material and the repelling force corresponding thereto are made sufficiently small and the imbalance of the pressure and the repelling force is reduced thereby to reduce the bending stress of each rotor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-screw continuous kneader that continuously mixes and melts polymeric materials such as synthetic resins. It is possible to cross-wire and melt polymer materials efficiently, especially in 2
Continuous shaft kneading machines have advantages over single-shaft kneading machines, such as being superior in mass productivity, transferring the material between both rotors, and improving kneading performance due to the stirring action.

Conventionally, such two-screw continuous kneading machines have structures as shown in FIGS. 6 and 7.

This mixer has two rotors B, which are arranged parallel to each other in a chamber A, and a feed section C1, a kneading section, and a discharge section E, respectively, in order from the material supply side.
is arranged, and the feeding blade part F1 has a twist in the direction of feeding the material to be mixed to the material discharge side as the rotor B rotates, and a feeding blade part F1 having a twist in the direction of sending the material to be mixed to the material supply side as the rotor B rotates. A kneading blade F that continuously includes a twisted return blade portion F2 is provided. The above-mentioned feed wing part F1 and return wing part F
2 serves to enhance the crosstalk effect through a remixing effect or the like.

However, in such a conventional mixer, in the cross section shown in FIG. Here, the material to be mixed H fills the wedge-shaped space between the front side surface of the kneading blade F in the rotational direction and the inner surface of the chamber A.
, a reaction force acts on the rotor B, whereas on the center side, the material H is pushed out into the central space G, and the reaction force is released.
Bending stress is applied to the rotor B due to this unbalanced reaction force. This bending stress is maximum at the joint between the wing parts P and F2. In particular, when mixing ultra-high molecular weight high-density polyethylene, etc. as the material to be mixed, and when mixing a large amount of inorganic substances such as calcium carbonate, Merck, and gypsum as fillers, even in a molten state, Excessive stress is applied to rotor B due to its high viscosity. Therefore, if used for a long period of time, there is a risk that the rotor will be damaged due to bending fatigue, resulting in a problem of reduced durability.

In addition, in order to solve this problem, at a predetermined location in the axial direction corresponding to the joint part between the feed blade part and the return blade part in the kneading section,
A proposed structure is proposed in which by closing the central space between both rotors with an insert member inserted into a chamber, a reaction force is exerted on the rotor on the central side between both rotors, balancing the reaction force and reducing bending stress. has been done. However, according to this structure, the amount of material passing through this part is restricted by the insert member, which reduces the production volume and causes a temperature rise in this part, which increases the material temperature at the kneader outlet. Depending on the type of material to be crossed, there is a possibility that the temperature will exceed the permissible temperature. In addition, in relation to such temperature rise, etc., the length of the rotor's kneading section (ratio of the length of the rotor to the rotor diameter)
cannot be made too long, and there is little freedom in design. Due to these points, there have been drawbacks such as restrictions on the types of crosstalk materials that can be used.

In view of these circumstances, the present invention has been developed to significantly reduce the bending stress applied to each rotor in a two-axis continuous mixer, thereby increasing durability, and reducing production costs even compared to the structure using the above-mentioned insert members. There is no decrease in volume, there is a lot of freedom in design, and it can be applied to various materials, including high viscosity materials,
Can be applied to materials that require low viscosity and sufficient crosstalk2
The present invention provides a continuous shaft kneading machine.

That is, in the present invention, two kneading rotors are arranged parallel to each other in a chamber having a material supply port at one end and a material discharge port at the other end. A feeding blade section having a twist in the direction of sending the material to the material discharge port side as the rotor rotates, and a direction that follows the feeding blade section and returns the mixed material to the material supply port side as the rotor rotates. In a two-shaft continuous kneading machine equipped with a kneading blade having a return blade with a twist, the outer periphery of the rotor and the chamber The present invention is characterized in that a groove is provided on one or both of the inner surfaces of the chamber, at least at a position opposite to the central space between the two rotors, to increase the facing distance between the top of the mixing blade and the inner surface of the chamber.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. In these figures, 1 is a chamber, and 2I2 are two rotors arranged in parallel with each other in the chamber 1. FIG. The chamber 1 is made up of two substantially cylindrical chambers surrounding each of the rotors 2, 2, which are in communication with each other, and one end of the chamber 1 has a pothole as a material supply port.
1, and the other end has an orifice 1 whose opening degree can be adjusted.
A material outlet 12 with 5 is provided.

Both rotors 2, 2 are interlocked and connected to an external drive device 5 so as to rotate synchronously in opposite directions as shown by arrows in FIG. Each rotor 2.2 has a screw-shaped feed section 21 that feeds the material to be mixed, which is supplied from the hopper 11 into the chamber 1, forward in the axial direction, in order from the material supply port side, and A kneading section 22 for kneading and melting the mixed materials and a discharge section 25 are provided. In the crosstalk section 22,
For example, by making the rotor 2 oval in cross section, kneading blades 24 are provided that protrude on both sides in the diametrical direction. In a predetermined range on the front half side of the kneading section 22, a feeding blade section 24a is formed in which the kneading blades 24 are twisted in a direction that feeds the material to be mixed to the material discharge port side as the rotor 2 rotates. In a predetermined range on the rear half side of the kneading section 22, a return wing section 24b is formed in which the kneading wing 24 continues in a twisted state in a direction in which the material to be mixed is returned to the material supply port side as the rotor 2 rotates. . The top of the kneading blade 24 and the inner surface of the chamber 1 are close to each other to the extent that a sufficient shearing action can be obtained on the material to be mixed, and the cha/
A central space 14 exists between the two rotors 2.2 in the bar 1.

A chamber 1 is provided at the top of the kneading blade 24 at a location corresponding to the joint between the sending blade 24a and the return blade 24b.
A groove 25 is provided to increase the distance from the inner surface. The groove 25 is formed by notching the top of the kneading blade 24 at the above-mentioned location along the circumferential direction to an appropriate depth and width.

The action of the kneading machine will be explained next.

The material to be mixed is continuously supplied from the hopper 11 into the chamber 1 by a feeder (not shown), etc., and is sent to the mixing section 22 through the feed section 21 as the rotors 2, 2 rotate. While being stirred and kneaded by the kneading blades 24, the kneading 1 mixture is mixed between the top of the blades 24 and the inner surface of the chamber 1 and the inner rotor 2.
, and undergoes a shearing action between the two, gradually becoming plasticized and melting. In this case, as the rotor 2 rotates, pressure is applied to the mixed material 30 in the wedge-shaped space between the front side surface of the kneading blade 24 in the rotational direction and the inner surface of the chamber 1, and nine reaction forces are generated accordingly. It acts on the rotor 2, but the sending blade part 24a and the return blade part 2
4b, the top of one end of the kneading blades 24 protruding on both sides in the diametrical direction of the rotor 2 connects to the central space 14 between both rotors.
Even when the rotor 2 reaches the position facing the rotor 2, the pressure imbalance is significantly reduced compared to conventional machines, and the bending stress on the rotor 2 is reduced. That is, on the side of the central space 14, the pressure of the material to be mixed 50 and the corresponding reaction force on the rotor 2 are almost completely cancelled, and on the other hand, even on the opposite side, the kneading blades 24
Since the material 30 to be mixed on the front side in the direction of rotation is released through the groove 25 in the circumferential direction, the pressure and corresponding reaction force applied to this material 60 are sufficiently small. The unbalance of the rotor 2 is reduced, and the bending stress of the rotor 2 is reduced.

FIG. 5 shows the axial distribution of the material p pressure to be kneaded (the pressure applied to the material by the kneading blades 24 at a position other than the central space 14) in the chamber 1, where the vertical axis is the material pressure and the horizontal axis is the axial direction. In the figure, L indicates the range of the kneading section 22, and l indicates the range in which the grooves 25 are formed. As shown in the figure, because the kneading section 22 has a sending wing section 24a and a return wing section 24b, the material pressure is low at both the front and rear ends of the kneading section 22, and the material pressure increases as it approaches the joint between the two wing sections. In contrast, in the conventional machine, the material pressure is at its maximum at the joint portion as shown by the two black rust points, whereas in this kneading machine, the material pressure in this portion is significantly reduced. Bending stress corresponding to the material pressure shown in this pressure distribution is periodically applied to the rotor at each position in the axial direction, but since the material pressure in areas other than the joints of both wings is relatively small, the bending stress as a whole is sufficient. will be reduced.

In addition, the bending stress at the joint portion of both wings can be reduced by using the groove 25.
Since the space area is not restricted, the passage of material is restricted and unnecessary temperature rises do not occur as in the case of inserting the insert member described above.

As is clear from FIG. 6, if the width of the groove 25 is increased, the bending stress is further reduced, but if the width of the groove is increased too much, the shearing action is reduced, so the The groove width may be appropriately determined in advance.

FIG. 4 shows a second embodiment of the invention, in which:
A cut-shaped groove 26 is formed on the inner surface of the chamber 1 at a location corresponding to the joint portion between the sending wing section 241L and the return wing section 24b.

This groove 26 is formed in a circular arc shape at a position opposite to the central space 14 between the two rotors over an area at least equivalent to the central space 14 .

Also with the structure shown in the embodiment, the top of one end of the kneading blades 24 protruding on both sides in the diametrical direction of the rotor 2 is connected to the central space between the two rotors at a location corresponding to the joint between the sending blade part and the return blade part. 14, the top of the kneading blade 24 on the other end side reaches the position corresponding to the groove 26, and the material to be mixed 60
is allowed to escape in the circumferential direction through the groove 26, so that the pressure and reaction stress in this portion are reduced, as in the first embodiment.

FIG. 5 shows a sixth embodiment of the present invention, in which:
Grooves 25' and 26' are provided on both the top of the kneading blades 24 of the rotor 2 and the inner surface of the chamber 1 at locations corresponding to the joints between the sending blades 24a and the return blades 24b. Groove 2 provided on the inner surface of chamber 1
The position and formation range of 6' are the same as in the second embodiment.

According to this embodiment, both of the grooves 25' and 26' increase the distance between the kneading blade top of the rotor 2 and the inner surface of the chamber 1 at a position opposite to the central space 14 between the two rotors. It acts to release the material to be mixed in the circumferential direction, and thereby, the first. The same functions and effects as in each of the second embodiments can be obtained.

As explained above, the two-shaft continuous kneading machine of the present invention has the following features: At a predetermined axial location corresponding to the joint between the feed blade section and the return vane section in the kneading section, the rotor outer periphery, the chatuba inner surface, or both. At least at a position opposite to the central space between both rotors, a groove is provided to increase the facing distance between the top of the kneading blade and the inner surface of the chamber, so that at this point, the top of one end of the kneading blade is connected to the central space between the two rotors. It is possible to prevent a large pressure imbalance from occurring even when the rotor is reached, thereby reducing the bending stress on the rotor and significantly increasing the durability of the rotor. Moreover, compared to the case of inserting the insert member mentioned above, the material passage space in the chamber is not restricted, so the production volume does not decrease.
In addition, it is possible to lower the temperature of the discharged material without causing a temperature rise at the joint of both wings, making it suitable for high-viscosity materials such as high-density polyethylene that do not require much mixing. The part can be made longer,
As a result, it can be applied to materials that require low viscosity and sufficient crosstalk, and has great effects such as excellent design freedom and applicability to various materials.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the crosstalk machine of the present invention, FIG. 2 is a cross-sectional view taken along the line 1-( in FIG. Figure 4 shows the second embodiment of the crosstalk machine of the present invention.
・Rotor, 24...Kneading blade, 242L...Feeding blade part, 241)...Returning blade part, 25° 26.25', 26
'···groove. Patent applicant Kobe Steel, Ltd. Representative Patent attorney Etsushi Kotani, BA1'''゛2, i',':・. "5J-・)" Figure 4 Figure 5 Figure 9 Figure 6Lz1 Figure 7

Claims (1)

[Claims] 1. Two kneading rotors are arranged parallel to each other in a chamber having a material supply port at one end and a material discharge port at the other end, and the mixed wires are arranged in a predetermined range in the axial direction of each rotor. A feeding blade section with a twist in the direction of feeding the material to the material discharge port side as the rotor rotates, and a direction following the feeding blade section and returning the mixed material to the material supply port side as the rotor rotates. In a two-shaft continuous mixer equipped with a kneading blade having a return blade with a twist, the outer periphery of the rotor is and the inner surface of the chamber, at least at a position opposite to the central space between the two rotors, a groove is provided to increase the facing distance between the top of the kneading blade and the inner surface of the chamber. Continuous kneading machine. 2. Claim 1, characterized in that the kneading blade top of each rotor is cut out in the circumferential direction to form a groove that increases the facing distance between the kneading blade top and the inner surface of the chamber. In the two-axis continuous type 6 described in Section 6, on the inner surface of the chamber at the outer side of each loaf on the opposite side from the central space between both rotors,
Claim 1 or 2, characterized in that the groove is formed by providing a substantially arc-shaped cut over a predetermined range in the circumferential direction, thereby increasing the facing distance between the top of the kneading blade and the inner surface of the chamber. Two-shaft continuous kneading machine.