JP2004044660A - Construction of toothing for one-way torque transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction of toothing for one-way torque transmission or a screw of a biaxial resin kneading extruder capable of transmitting large torque in spite of being machineable at a relatively low cost. <P>SOLUTION: Toothing 3 for one-way torque transmission or the screw of the biaxial resin kneading extruder is formed in a shape which has an involute curve surface or a curved surface according to an involute curve on a front surface 4 in a side where force acts in turning and has a roughly straight back surface 5 in a side where force does not act. Pressure angles α of the back surface side are larger than pressure angles β of the front surface side. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, the teeth of the rotation driving member and the teeth of the rotation driven member mesh with each other, and the rotational force in one direction of the rotation driving member is transmitted to the rotation driven member via the teeth. The present invention relates to a structure of teeth for transmitting one-way rotational force and a structure of teeth in a biaxial resin kneading extruder.
[0002]
[Prior art]
A biaxial resin kneading extruder is known as one of the devices for transmitting the rotational force in one direction. The twin-screw kneading extruder is composed of two screws as is well known in the art, and a part thereof is shown in the plan view of FIG. The screw 20 includes a screw shaft 22 and a screw segment 30, and a plurality of teeth 23, 23,... For transmitting a rotational force to the screw segment 30 are formed on an outer peripheral portion of the screw shaft 22. An involute spline is used for these teeth 23, 23,.... On the other hand, the screw segment 30 is composed of an operating surface 31 that comes into contact with the resin during rotation and exerts mainly axial thrust on the resin, and a contact surface 32 that comes into contact with the adjacent screw segment 30 during assembly. In the center, teeth having the same tooth shape are formed so as to mesh with the teeth 23 of the screw shaft 22. Therefore, when a plurality of screw segments 30, 30,... Are mounted on the screw shaft 22 having a predetermined length, the screw 20 is formed, and the screw 20 is inserted into the cylinder barrel 35 as shown in FIG. When they are arranged in parallel at predetermined intervals, a biaxial resin kneading extruder is constituted. The other reference numeral 36 in FIG. 3B indicates a kneading disk. When the two screw shafts 22, 22 arranged as described above are rotationally driven in the same direction or in different directions, the rotational force of the screw shafts 22, 22 is transmitted through the teeth 23, 23,. , And the screw segments 30, 30,... Are rotationally driven. When the resin is supplied from one of the cylinder barrels 35, it is melt-kneaded as is well known in the art while being transferred to the other end, and extruded from the end.
[0003]
On the other hand, gears that mainly transmit rotational force in one direction have also been proposed in, for example, JP-A-2001-165280 and JP-A-7-259872. The tooth profile shown in the former Japanese Patent Application Laid-Open No. 2001-165280 has an involute tooth profile on the front side and the rear side of the tooth on which force acts during rotation, and the reference pressure angle on the rear side is larger than the reference pressure angle on the front side. It is getting bigger. Further, the tooth described in the latter Japanese Patent Application Laid-Open No. 7-259872 has a relatively small curvature of the front surface on the side on which a force acts during rotation, and the rear surface has a gentle outward curvature.
[0004]
[Problems to be solved by the invention]
Since the teeth 23 of the screw shaft 22 of the above-described conventional twin-screw kneading extruder have an involute tooth profile, they are characterized by relatively high processing accuracy and uniform meshing of the teeth. However, such a tooth profile that transmits a large rotational torque only in one direction, such as a biaxial resin kneading extruder, is not necessarily a suitable tooth profile. The reason will be further described. FIG. 4A is a diagram schematically showing the above-described involute tooth profile. As can be seen from FIG. 4, the front surface 24 and the rear surface 25 of the tooth on which a force acts during rotation have the same involute curve. Thus, the reference pressure angles a, a on the front side and the back side are also the same. Therefore, there is an advantage that the rotational torque can be transmitted in the same way as the forward and reverse directions. However, when a large force acts on the front face 24, the teeth 23 deform. This is shown in FIG. FIG. 4B is a diagram showing the result of strength calculation performed under a load (the front surface 24 and the back surface 25 are both involute curves and the pressure angle a is 20 degrees) assuming actual use conditions. It can be seen that a large tensile force is acting on portion A and a compressive force is acting on portion B. As a result of the application of such a large stress, the teeth 23 are deformed and broken as shown in FIG.
[0005]
The teeth disclosed in Japanese Patent Application Laid-Open No. 2001-165280 have the advantage of being able to transmit rotational torque in both directions because the front and back surfaces of the teeth are involute teeth. Since the reference pressure angle on the side is larger than the reference pressure angle on the front side, there is also an advantage that a relatively large rotational torque can be transmitted. However, since both surfaces have involute teeth, there is a possibility that machining costs for machining both surfaces into different curved surfaces may increase, and it is not always suitable as a tooth profile that transmits rotational force only in one direction. Further, the tooth profile disclosed in Japanese Patent Application Laid-Open No. 7-259872 is also formed to be asymmetrical, and thus has an advantage that a relatively large rotational torque can be transmitted. However, there is also a problem in processing. Further, as schematically shown in FIG. 5 (a), the tooth profile of the female shaft is formed so that the front surface 26 on which the force acts is formed substantially linearly, and the rear surface 27 is curved so as to be concave inward. And it's getting thinner. Therefore, when a large force acts on the front surface 26, a tensile force acts on a portion indicated by A 'and a compressive force acts on a portion indicated by B' in FIG. As a result, the teeth are easily deformed and broken as shown in FIG.
SUMMARY OF THE INVENTION An object of the present invention is to provide a tooth structure that solves the above-mentioned disadvantages or problems of the conventional tooth profile. It is an object of the present invention to provide a structure of teeth for transmitting unidirectional rotational force capable of transmitting a force and a structure of a tooth of a screw shaft or a screw segment capable of obtaining a high-torque, high-strength biaxial resin kneading extruder. I have.
[0006]
[Means for Solving the Problems]
The present invention achieves the above object by adopting a configuration focusing on the rotation direction. In other words, the teeth that transmit rotational force in only one direction need not have the same or symmetrical configuration on the front side where the force acts during rotation and the opposite back side, and the front side engages with the teeth. In consideration of this, the rear side is achieved by configuring the structure with an emphasis on strength and workability. In consideration of the engagement, the shape of the front surface is desirably an involute curve. However, even a curve similar to the involute curve, for example, a cycloid curve meshes smoothly, and the object of the present invention is achieved. The structure that emphasizes the strength and workability of the teeth has a shape that exhibits a substantially straight line. Straight lines are easier to process than curves. Further, in order to improve the strength of the teeth, the pressure angle on the back side is configured to be larger than the pressure angle on the front side. Increasing the thickness increases the thickness of the root portion of the tooth and allows it to withstand compressive stress.
Thus, according to the first aspect of the present invention, in order to achieve the above object, the teeth of the rotation drive member and the teeth of the rotation follower mesh with each other, and the rotational force in one direction of the rotation drive member is transmitted through the teeth. A structure of a one-way rotational force transmitting tooth configured to be transmitted toward the rotation driven member, wherein the tooth has a front surface on a side on which a force acts during rotation conforms to an involute curve or an involute curve. The back surface on the non-working side is formed in a curved line, and the pressure angle on the back surface is larger than the pressure angle on the front surface.
According to a second aspect of the present invention, there is provided a screw comprising a screw shaft and a screw segment having teeth meshing with teeth formed on an outer peripheral portion of the screw shaft, the screws being arranged in parallel, and in the same direction as the screw shaft. Alternatively, it is a tooth structure in a biaxial resin kneading extruder in which a rotational force in one direction in a different direction is transmitted to the screw segment via the teeth, wherein the teeth are rotated during rotation. The front face on which the force acts is formed in a curved shape according to an involute curve or an involute curve, and the back face on the non-working side is formed substantially linearly, and the pressure angle on the back face is the pressure angle on the front face side. It is configured to be larger than
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example in which the embodiment of the present invention is applied to a biaxial resin kneading extruder will be described with reference to FIGS. As is well known in the art, a twin-screw kneading extruder generally includes a cylinder barrel having a predetermined length in the axial direction and two screws provided at a predetermined interval in the cylinder barrel. Has become. These screws are driven to rotate in the same direction or in different directions by a rotary drive device. An embodiment of the present invention of such a screw 1 is shown in FIG. That is, the screw 1 includes a screw shaft 2 and a plurality of screw segments 10 mounted on the screw shaft 2.
[0008]
A plurality of teeth 3, 3, ... are formed in the outer peripheral portion of the screw shaft 2 in the axial direction. As shown by a solid line in FIG. 1 (b), the teeth 3 have a front surface 4 on which a transmitting force acts directly on the teeth of a screw segment 10 which will be described later in detail during rotation, and an opposite side of the front surface 4. It comprises a back surface 5 on which no transmission force acts and a top surface 6 connecting the front surface 4 and the back surface 5. The shape of the front side surface is a conventionally known involute curve or a curve based on the involute curve. And the back surface 5 is substantially straight according to the present embodiment. The pressure angle α on the back surface 5 side that is linear as described above is larger than the pressure angle β on the front surface 4 side by 0 to 70 degrees. According to this embodiment, since the back surface 5 is linear and the pressure angle is large, the processing of the teeth is easy, the roots of the teeth are thick and the strength is high.
[0009]
As is conventionally known, the outer shape of the screw segment 10 is composed of a flight surface 11 that comes into contact with the resin when driven to rotate, and a contact surface 12 that comes into contact with another adjacent screw segment when assembled. A hole is provided at the center of the screw shaft 2 to be inserted into the screw shaft 2. A plurality of teeth 13, 13, which mesh with the teeth 3, 3,. Are formed. These teeth 13, 13,... Have a similar shape to the teeth 3 of the screw shaft 2, as shown by the dotted line in FIG.
[0010]
When a plurality of screw segments 10, 10,... Are mounted on the screw shaft 2 configured as described above, the screw 1 having a predetermined length in the axial direction is formed. As shown in FIG. 3B, when the two screws 1 and 1 are arranged in the cylinder barrel 35 in parallel at a predetermined interval, a biaxial resin kneading extruder is formed. Therefore, when the two screw shafts 2, 2 are rotationally driven in the same direction or different directions, the rotational force of the screw shafts 2, 2 is transmitted through the teeth 3, 3, ... 13, 13, ... to the screw segments 10, 10,. , And the screw segments 10, 10,... Are rotationally driven. When the resin is supplied from one of the cylinder barrels 35, the resin on the surface of the screw flight surface 11 is transferred to the other end while being scraped off by the screw flight surfaces 11. In the meantime, it is melt-kneaded as is well known in the art and extruded from the end.
[0011]
Example: The results of strength calculation with a load assuming actual use conditions where the front surface 4 is an involute curve, the back surface 5 is a straight line, the front side pressure angle β is 20 degrees, and the back side pressure angle α is 55 degrees, This is schematically shown in FIG. According to the present embodiment, concentration of stress is avoided, and both the tensile force a and the compressive force b are small, which is about 6.3% as compared with the strength of the tooth profile shown in FIG. The strength of the tooth profile shown in (a) was improved by about 20% or more.
[0012]
Although not specifically described, it is apparent that the present invention is not limited to the above-described embodiment, but can be similarly applied to a general spline that transmits a rotational force in one direction.
[0013]
【The invention's effect】
As described above, according to the present invention, the teeth of the rotation driving member and the teeth of the rotation driven member mesh with each other, and the rotational force in one direction of the rotation driving member is transmitted to the rotation driven member via the teeth. The structure of the one-way torque transmitting tooth is such that two screws are arranged in parallel, and the one-way rotational force of the screw shaft in the same direction or different direction is transmitted through the teeth. The tooth structure of the twin-screw kneading extruder that is transmitted to the screw segment is such that the front surface on the side where the force acts during rotation has an involute curve or a curve similar to the involute curve, and no action The back side is formed substantially linearly, and the pressure angle on the back side is configured to be larger than the pressure angle on the front side, that is, the front side has an involute curve or an involute curve. Since the turned accordance curvilinear in volute curve, good machining precision, during driving rotation effect of forces act uniformly on the teeth is obtained. According to the present invention, the back surface on the non-working side is formed in a substantially linear shape, and the pressure angle on the back surface is configured to be larger than the pressure angle on the front surface. The effect unique to the present invention is that it is easy, the thickness at the root of the tooth is increased, and the strength of the tooth is large. Further, since the machining of the teeth is easy and the strength of the teeth is high, an effect that a high-capacity biaxial resin kneading extruder capable of withstanding a high torque can be obtained at low cost can be obtained.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of the present invention, in which (a) is a perspective view showing an embodiment of a screw, and (b) is an enlarged view of a part of an embodiment of a tooth and shows a part thereof. It is a front view.
FIG. 2 is a view showing a structure of a tooth according to an embodiment of the present invention, in which (a) is a developed view schematically showing one tooth, and (b) is a view showing a result of strength calculation thereof. It is.
FIG. 3 is a view showing a conventional example, in which (a) is a perspective view of a screw, and (b) is a plan view showing a part of a biaxial resin kneading extruder.
FIG. 4 is a view showing the structure of the conventional tooth shown in FIG. 3, wherein (a) is a developed view schematically showing one tooth, and (b) is a view showing the result of strength calculation. .
FIG. 5 is a view showing still another conventional tooth structure, in which (a) is a developed view schematically showing one tooth, and (b) is a view showing the result of strength calculation. .
[Explanation of symbols]
Reference Signs List 1 screw 2 screw shaft 3 teeth 4 front 5 back 10 screw segment 13 teeth α pressure angle on the back side β pressure angle on the front side

Claims (2)

The teeth of the rotation driving member and the teeth of the rotation driven member mesh with each other, and the one-way rotation force of the rotation driving member is transmitted to the rotation driven member via the teeth. The structure of the transmitting teeth,
The tooth has a front surface on the side on which a force acts upon rotation in a curved shape in accordance with an involute curve or an involute curve, and a back surface on a non-working side has a substantially linear shape, and the pressure angle on the back side is The one-way power transmission tooth structure is configured to be larger than the pressure angle on the front side. A screw composed of a screw shaft and a screw segment having teeth meshing with teeth formed on an outer peripheral portion of the screw shaft is arranged in parallel, and a rotational force of the screw shaft in one direction or another direction in the same direction. Is a tooth structure in a biaxial resin kneading extruder adapted to be transmitted toward the screw segment via the teeth,
The tooth has a front surface on the side on which a force acts upon rotation in a curved shape in accordance with an involute curve or an involute curve, and a back surface on a non-working side has a substantially linear shape, and the pressure angle on the back side is The one-way power transmission tooth structure is configured to be larger than the pressure angle on the front side.

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