Patent Publication Number: US-2021187455-A1

Title: Kneading method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a kneading method. 
     BACKGROUND 
     As a kneading method for kneading a mixture, a method using a kneading apparatus that includes a plurality of continuously arranged segments is known. In such a kneading apparatus, each of the plurality of segments includes a cylindrical expanding-contracting body. Also, an operation state of each of the plurality of segments can be switched between a closed state in which the expanding-contracting body is deformed expanding inward to substantially seal an inner side thereof and an open state in which the expanding-contracting body is deformed outward from the closed state. A kneading method using a kneading apparatus configured as described above is described in, for example, PTL 1 set forth below. 
     CITATION LIST 
     Patent Literature 
     PTL 1: WO2018/056378 
     SUMMARY 
     Technical Problem 
     However, the PTL 1 does not disclose a particular method for effectively kneading a mixture. 
     An object of the present disclosure is to propose a kneading method capable of effectively kneading a mixture. 
     Solution to Problem 
     A kneading method according to an aspect of the present disclosure is a kneading method for kneading a mixture using a kneading apparatus, wherein the kneading apparatus includes a plurality of segments continuously arranged, 
     each of the plurality of segments includes a cylindrical expanding-contracting body, 
     an operation state of each of the plurality of segments can be switched between a closed state in which the expanding-contracting body is deformed expanding inward to substantially seal an inner side of the expanding-contracting body and an open state in which the expanding-contracting body is deformed outward from the closed state, and 
     the mixture is kneaded by repetitively forming a compressed space that is formed at least by an expanding-contracting body of a segment in the open state and an expanding-contracting body of a segment in the closed state adjacent to the segment in the open state, substantially sealed, and filled with the mixture in a compressed state pressed by the expanding-contracting body, by changing a combination of the operation state of each of the plurality of segments. 
     According to one embodiment of the present disclosure, the kneading method repetitively forms the compressed space by shifting the compressed space together with at least a portion of the mixture between the plurality of segments. 
     According to one embodiment of the present disclosure, the kneading method repetitively forms the compressed space by reciprocating the compressed space together with at least a portion of the mixture between the plurality of segments. 
     According to one embodiment of the present disclosure, the kneading method forms the compressed space using at least one segment in the open state and segments in the closed state located on either side of the at least one segment. 
     According to one embodiment of the present disclosure, the kneading method forms the compressed space using at least one segment in the open state, a segment in the closed state adjacent to one end of the at least one segment, and a closing wall provided to another end of the at least one segment. 
     According to one embodiment of the present disclosure, the kneading apparatus includes two segments, and the closing wall is provided to either end of the two segments as a whole. 
     According to one embodiment of the present disclosure, an operation state of each of the plurality of segments is switched from the open state to the closed state by the supply of a working fluid to an outside of the expanding-contracting body, or from the closed state to the open state by the discharge of the working fluid from the outside of the expanding-contracting body. 
     According to one embodiment of the present disclosure, each of the plurality of segments is contracted in an axial direction of the expanding-contracting body by switching of the operation state from the open state to the closed state, and expanded in the axial direction by switching of the operation state from the closed state to the open state. 
     According to one embodiment of the present disclosure, the mixture is composed of a liquid and a solid that does not dissolve in the liquid. 
     According to one embodiment of the present disclosure, the solid is a powder. 
     According to one embodiment of the present disclosure, the mixture is an explosive. 
     Advantageous Effect 
     The kneading method according to the present disclosure can effectively knead the mixture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a longitudinal cross-sectional view illustrating a kneading apparatus used by a kneading method according to a first embodiment of the present disclosure; 
         FIG. 2A  is a longitudinal cross-sectional view illustrating one of a plurality of segments constituting the kneading apparatus illustrated in  FIG. 1 ; 
         FIG. 2B  is a perspective view illustrating an inner tube and a ring in the segment illustrated in  FIG. 2A ; 
         FIG. 2C  is a transverse cross-sectional view taken along line AA of  FIG. 2A ; 
         FIG. 3A  is a longitudinal cross-sectional view illustrating another example of one of the plurality of segments constituting the kneading apparatus illustrated in  FIG. 1 ; 
         FIG. 3B  is a transverse cross-sectional view taken along the line BB of  FIG. 3A ; 
         FIG. 3C  is a perspective view of a segment illustrated in  FIG. 3A ; 
         FIG. 4A  is a longitudinal cross-sectional view for explaining the gist of kneading by the kneading method according to the first embodiment of the present disclosure; 
         FIG. 4B  is a longitudinal cross-sectional view illustrating a state in which a compressed space is advanced together with a portion of the mixture by one segment from the state illustrated in  FIG. 4A ; 
         FIG. 4C  is a longitudinal cross-sectional view illustrating a state in which the compressed space is retracted together with a portion of the mixture by one segment from the state illustrated in  FIG. 4B ; 
         FIG. 5A  is a longitudinal cross-sectional view for explaining the gist of kneading by a kneading method according to a second embodiment of the present disclosure; 
         FIG. 5B  is a longitudinal cross-sectional view illustrating a state in which the compressed space is retracted together with a portion of the mixture by one segment from the state illustrated in  FIG. 5A ; 
         FIG. 6A  is a longitudinal cross-sectional view for explaining the gist of kneading by a kneading method according to a third embodiment of the present disclosure; 
         FIG. 6B  is a longitudinal cross-sectional view illustrating a state in which the compressed space is retracted together with a portion of the mixture by one segment from the state illustrated in  FIG. 6A ; 
         FIG. 7A  is a longitudinal cross-sectional view for explaining the gist of kneading by a kneading method according to a fourth embodiment of the present disclosure; 
         FIG. 7B  is a longitudinal cross-sectional view illustrating a state in which the compressed space is retracted together with a portion of the mixture by one segment from the state illustrated in  FIG. 7A ; and 
         FIG. 8  is a graph illustrating a burning rate characteristic of each sample obtained from a strand burner test according to an example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a kneading method according to various embodiments of the present disclosure will be described in detail with reference to the drawings. For convenience of explanation, a shift from left to right in  FIG. 4A  to  FIG. 7B  will be referred to as forwarding, and a shift in an opposite direction will be referred to as retracting. Also, a left end in  FIG. 4A  to  FIG. 7B  will be referred to as one end, and a right end will be referred to as the other end. The respective thicknesses of an expanding-contracting body  4 A and a flange  7  are omitted in  FIG. 4A to 7B . 
     First, a kneading method according to a first embodiment of the present disclosure will be described in detail with reference to  FIG. 1  to  FIG. 4C . The kneading method according to the present embodiment is a method for kneading a mixture  2  using a kneading apparatus  1 A (see  FIG. 4A , etc.). In the present embodiment, the mixture  2  is composed of a liquid and a solid that does not dissolve in the liquid. In particular, the solid is a powder. The mixture  2  may be, for example, an explosive such as a rocket composite propellant. The mixture  2  as a composite propellant can be composed of, for example, a powder serving as an oxidizer, a powder serving as a metal fuel, and a liquid serving as a binder. Further, a plasticizer, a curing agent, or the like may be added in appropriate amounts. The mixture  2  may be cement, dough for noodle making, or the like, and is not limited thereto. The kneading method according to the present embodiment is suitable for kneading a solid-liquid mixture composed of a liquid and a solid that does not dissolve in the liquid. Further, the kneading method according to the present embodiment is particularly suitable for kneading a solid-liquid mixture such as an explosive, because the kneading apparatus used by the kneading method is unlikely to cause a false ignition source such as static electricity. 
     The kneading apparatus  1 A includes a plurality of segments  3 A that are continuously arranged, as illustrated in  FIG. 1 . Each of the plurality of segments  3 A includes a cylindrical expanding-contracting body  4 A. Also, an operation state of each of the plurality of segments  3 A can be switched between a closed state in which an inner side of the expanding-contracting body  4 A is substantially sealed due to an inward expanding deformation of the expanding-contracting body  4 A and an open state in which the expanding-contracting body  4 A is deformed outward from the closed state. The state in which the inner side of the expanding-contracting body  4 A is “substantially closed” means that the inner side is closed to an extent that the mixture  2  is prevented from flowing through a closed portion. Further, the state in which the inner side of the expanding-contracting body  4 A is “substantially sealed” means that a compressed space S, which will be described later, is closed to an extent that the mixture  2  is prevented from flowing through a sealed portion. 
     In the present embodiment, the plurality of segments  3 A are configured such that an operation state of each of the plurality of segments  3 A is switched from the open state to the closed state by the supply of a working fluid  5  (see  FIG. 2A ) to an outer side of the expanding-contracting body  4 A, or from the closed state to the open state by the discharge of the working fluid  5  from the outer side of the expanding-contracting body  4 A. The working fluid  5  may be, for example, a gas such as air or carbon dioxide, or a liquid such as water or oil. 
     In the present embodiment, each of the plurality of segments  3 A has a configuration as illustrated in  FIG. 2A  to  FIG. 2C . In the present embodiment, that is, each of the plurality of segments  3 A includes the expanding-contracting body  4 A, an external cylinder  6 A that has a cylindrical shape arranged outside the expanding-contracting body  4 A, flanges  7  having an annular plate-like shape arranged either axial end of the segment  3 A, and a ring  8  attached to an outer surface of the expanding-contracting body  4 A. In the present embodiment, each of the external cylinder  6 A, the flange  7 , and the ring  8  is formed from a rigid body. An axial direction of the segment  3 A means a direction along a central axis  0  of the expanding-contracting body  4 A (i.e., an axial direction of the expanding-contracting body  4 A). Further, a cross-section including the central axis  0  of the expanding-contracting body  4 A will be referred to as a longitudinal cross-section, and a cross-section orthogonal to the central axis  0  of the expanding-contracting body  4 A will be referred to as a transverse cross-section. 
     Either axial end of the expandable member  4 A is fixed to an inner peripheral edge of the flange  7  by an appropriate joining means in an airtight and liquid-tight manner. Either axial end of the external cylinder  6 A is fixed to an outer peripheral edge of the flange  7  by an appropriate joining means in an airtight and liquid-tight manner. Thus, the expanding-contracting body  4 A, the external cylinder  6 A, and a pair of flanges  7  together define a chamber  9  for the working fluid  5 . 
     A fluid supplying-discharging apparatus  10  included in the kneading apparatus  1 A is connected to the chamber  9 . The fluid supplying-discharging apparatus  10  can supply the working fluid  5  to the chamber  9 . Also, the fluid supplying-discharging apparatus  10  can discharge the working fluid  5  from the chamber  9 . The supplying-discharging apparatus  10  can control the supply and discharge of the working fluid  5  with respect to the chamber  9  of each of the plurality of segment  4 A. The fluid supplying-discharging apparatus  10  may collectively supply or discharge the working fluid  5  with respect to some of the plurality of segments  3 A. The fluid supplying-discharging apparatus  10  can be, for example, an air compressor, a pressure reducing valve, an ON/OFF valve, a processor (a microcomputer, etc.), or the like. 
     The ring  8  has an opening  8   a  having a star-like shape into which the expanding-contracting body  4 A is inserted, as illustrated in  FIG. 2B . The expanding-contracting body  4 A has a cylindrical shape and is formed from an elastic body such as rubber or elastomer. When the expanding-contracting body  4 A is inserted into the opening  8   a  of the ring  8 , the expanding-contracting body  4 A has a longitudinal cross-section having a star-like shape at the portion in contact with a peripheral portion of the opening  8   a  of the ring  8 . As a result, when the working fluid  5  is supplied to the chamber  9 , the expanding-contracting body  4 A can be stably deformed expanding inward from the four directions in the cross-section, as indicated by the chain double-dashed lines in  FIG. 2C . Thus, the expanding-contracting body  4 A can switch the operation state from the open state to the closed state at least when the mixture  2  is not present in the expanding-contracting body  4 A. The shape of the opening  8   a  of the ring  8  is not limited to the star-like shape and may be a non-circular shape including, for example, a triangular shape. In this case also, when the working fluid  5  is supplied to the chamber  9 , the expanding-contracting body  4 A can be stably deformed expanding inward from directions corresponding to the shape of the opening  8   a  in the longitudinal cross-section. Further, the ring  8  can be omitted. In this case, the expanding-contracting body  4 A may be formed in a cylindrical shape or a tubular shape other than the cylindrical shape. When the expanding-contracting body  4 A is formed in a cylindrical shape, for example, grooves extending in the axial direction may be formed at a plurality of circumferential locations, such that the cross-sectional shape of the expanding-contracting body  4 A is stabilized at the time of inward expanding deformation. In this case also, the expanding-contracting body  4 A can switch the operation state from the open state to the closed state, at least when the mixture  2  is not present in the expanding-contracting body  4 A. 
     In the plurality of segments  3 A, the flanges  7  of the segments  3 A adjacent to each other are fixed to each other by an appropriate joining means in an airtight and liquid-tight manner. Thus, an inner space extending over the entire longitudinal length of the plurality of segments  3 A is formed within the expanding-contracting bodies  4 A of the plurality of segments  3 A when all of these segments  3 A are in the open state. In the present embodiment, the inner space is open to the outside at either longitudinal end of the plurality of segments  3 A as a whole. Thus, the mixture  2  can be introduced from one end of the inner space, kneaded while being conveyed toward the other end of the inner space, and then taken out from the other end of the inner space. According to the kneading apparatus  1 A of the present embodiment, as described above, the kneading and conveying of the mixture  2  can be realized simultaneously. 
     The segment  3 A is not limited to have the configuration illustrated in  FIG. 2A  to  FIG. 2C  and may have, for example, a configuration illustrated in  FIG. 3A  to  FIG. 3C . A segment  3 B illustrated in  FIG. 3A  to  FIG. 3C  includes an expanding-contracting body  4 B and a cylindrical external cylinder  6 B arranged on the outer side of the expanding-contracting body  4 B. The external cylinder  6 B is formed from a rigid body in the present embodiment. Either axial end of the expanding-contracting body  4 B is fixed to the external cylinder  6 B by an appropriate joining means in an airtight and liquid-tight manner. A circumferential groove  11  is provided continuously over the entire circumference on the inner surface of the external cylinder  6 B. The circumferential groove  11  is connected to the fluid supplying-discharging apparatus  10 . The fluid supplying-discharging apparatus  10  can supply the working fluid  5  between the outer surface of the expanding-contracting body  4 B and the inner surface of the external cylinder  6 B via the circumferential groove  11 . Also, the fluid supplying-discharging apparatus  10  can discharge the working fluid  5  from between the outer surface of the expanding-contracting body  4 B and the inner surface of the external cylinder  6 B via the circumferential groove  11 . The fluid supplying-discharging apparatus  10  can control the supply and discharge of the working fluid  5  with respect to the plurality of segments  3 B. The fluid supplying-discharging apparatus  10  may collectively control the supply and discharge of the working fluid  5  with respect to some of the plurality of segments  3 B. Further, the circumferential groove  11  can be omitted and the working fluid  5  may be directly supplied to and discharged from between the outer surface of the expanding-contracting body  4 B and the inner surface of the external cylinder  6 B. 
     The external cylinder  6 B has a transverse cross-section having a star-like shape over the axial direction. The expanding-contracting body  4 B is formed from an elastic body such as rubber or elastomer in a cylindrical shape. By fixing or contacting the outer surface of the expandable member  4 B to the inner surface of the external cylinder  6 B having the star-like shape, the expanding-contracting body  4 B has the transverse cross-section having the star-like shape over the axial direction. As a result, the expanding-contracting body  4 B can be deformed expanding inward from four directions in the transverse cross-section when the working fluid  5  is supplied to the circumferential groove  11 , as indicated by the chain double-dashed lines illustrated in  FIG. 3B . The transverse cross-sectional shape of the external cylinder  6 B is not limited to the star-like shape and may be a non-circular shape including, for example, a triangular shape or a circular shape. Further, the expanding-contracting body  4 B may be formed in a tubular shape other than the cylindrical shape. 
     In the plurality of segments  3 B, the external cylinders  6 B and the expanding-contracting bodies  4 B of the segments  3 B adjacent to each other are fixed to each other by an appropriate joining means in an airtight and liquid-tight manner. Thus, an inner space extending along the longitudinal direction throughout the plurality of segments  3 B is formed within the expanding-contracting bodies  4 B of all the plurality of segments  3 B when all the segments  3 B are in the open state. The external cylinders  6 B and/or the expanding-contracting bodies  4 B of the segments  3 B adjacent to each other may be integrally formed. 
     In the present embodiment, the mixture  2  is kneaded by the kneading apparatus  1 A as described above that changes a combination of an operation state of each of the plurality of segments  3 A by repetitively forming the compressed space S (see  FIG. 4A ) that is formed by at least the expanding-contracting body  4 A of the segment  3 A in the open state and the expanding-contracting body  4 A of the segment  3 A in the closed state adjacent to the segment  3 A (in particular, at least one segment  3 A in the open state and the closed segment  3 A located on either side of the at least one segment  3 A), substantially sealed, and filled with the mixture  2  in the compressed state compressed by the expanding-contracting body  4 A. 
     That is, in the kneading method according to the present embodiment, an introducing amount of the mixture  2  (i.e., a ratio of the volume of the mixture  2  to the volume of the inner space) to be introduced into the inner space extending in the longitudinal direction throughout the plurality of segments  3 A can be adjusted to form the compressed space S that is substantially sealed and filled with the mixture  2  in the compressed state compressed by the expanding-contracting body  4 A. In introducing the mixture  2  into the inner space, for example, the liquid component and the powder component may be separately introduced; a slurry obtained by pre-kneading the liquid component and the powder component using any kneading apparatus may be introduced; a slurry and the liquid component may be separately introduced; a slurry and the powder component may be separately introduced; or a slurry of a predetermined component and a slurry of another component may be separately introduced. 
     In the kneading method according to the present embodiment, the compressed space S is repetitively formed by shifting the compressed space S together with at least a portion of the mixture  2  between the plurality of segments  3 A. That is, the kneading method according to the present embodiment includes a step of changing a combination of the operation state of each of the plurality of segments  3 A, in a manner such that the compressed state S is shifted together with at least a portion of the mixture  2  between the plurality of segments  3 A, as illustrated in  FIG. 4B . This step can be performed by, for example, setting one of the segments  3 A in the open state to the closed state and, simultaneously, setting the segment  3 A that is in the closed state and located at the other end of the segment  3 A in the open state to the open state, as illustrated in  FIG. 4A  and  FIG. 4B . That is, the expanding-contracting body  4 A in the open state including the compressed space S of the segment  3 A on one side is deformed to expand inward and press the mixture  2  and, simultaneously, the expanding-contracting body  4 A in the segment  3 A in the closed state on the other side is deformed outward, whereby the mixture  2  is pushed and flows from one side to the other side. In a state in which a space surrounded by the expanding-contracting body  4 A is formed in the segment  3 A on the other side, this space is filled with the mixture  2  in the compressed state. 
     Further, the kneading method according to the present embodiment includes a step of changing a combination of an operation state of each of the plurality of segments  3 A, such that the compressed space S is shifted together with at least a portion of the mixture  2  from one end of the longitudinal direction of the plurality of segments  3 A as a whole to the other end. 
     According to the present embodiment, the compressed space S (see  FIG. 4A ) that is substantially sealed and filled with the mixture  2  in the compressed state is formed at least by the expanding-contracting body  4 A of the segment  3 A in the open state and the expanding-contracting body  4 A of the segment  3 A in the closed state adjacent to the segment  3 A in the open state, whereby both the kneading effect by the flow of the mixture  2  and the kneading effect by the compression of the mixture  2  can be simultaneously obtained. Kneading the mixture  2  not only by flowing but also by compressing enables effective permeation of the liquid constituting the mixture  2  into a dry portion of the solid (the powder) constituting the mixture  2 . According to the kneading method of the present embodiment, thus, even if the mixture  2  has a high proportion of a powder with respect to the liquid, the liquid can be formed into a homogeneous plastic or slurry encapsulating powder particles by the kneading combining the flow and compression of the mixture  2 . According to the kneading method of the present embodiment, further, a shearing force applied to the mixture  2  can be reduced as compared with, for example, a kneading method using a planetary mixer, and thus powder breaking during the kneading is suppressed. This enables stable obtainment of the properties of the mixture  2  that should be expressed by kneading. 
     According to the kneading method of the present embodiment, by shifting the compressed space S together with at least a portion of the mixture  2  between the plurality of segments  3 A, the kneading effect by the flow of the mixture  2  described above can be improved. 
     According to the kneading method of the present embodiment, by shifting the compressed space S together with at least a portion of the mixture  2  from one end of the longitudinal direction of the plurality of segments  3 A as a whole to the other end, the kneading and the conveying of the mixture  2  can be simultaneously performed. 
     In the kneading method according to the present embodiment, the compressed space S may be repetitively formed by reciprocating the compressed space S together with at least a portion of the mixture  2  between the plurality of segments  3 A. That is, the kneading method according to the present embodiment may include a step of changing a combination of an operation state of each of the plurality of segments  3 A, such that the compressed space S is reciprocated together with at least a portion of the mixture  2  between the plurality of segments  3 A, as illustrated in  FIG. 4C . This step can promote the flow of the mixture  2  by a pendulum shift and thus can improve the kneading effect by the flow of the mixture  2 . 
     Next, a kneading method according to a second embodiment of the present disclosure will be described in detail with reference to  FIG. 5A  and  FIG. 5B . A kneading apparatus  1 B used in the present embodiment has the same configuration as the kneading apparatus  1 A used in the first embodiment, except for that a closing wall  12  is provided to the other end of the longitudinal direction of the plurality of segments  3 A as a whole. 
     In the present embodiment, the kneading apparatus  1 B includes a plurality of segments  3 A that are continuously arranged, as illustrated in  FIG. 5A  and  FIG. 5B . A closing wall  12  having a disc-like shape is fixed to the other end of the longitudinal direction of the plurality of segments  3 A as a whole by an appropriate joining means in an airtight and liquid-tight manner. Thus, an inner space formed within the expanding-contracting members  4 A of the plurality of segments  3 A as a whole is closed by the closing wall  12  at the other end of the longitudinal direction. According to the kneading apparatus  1 B configured as described above, the mixture  2  can be introduced from one end of the inner space, kneaded while being shifted in the inner space, and then taken out from the one end of the inner space after the kneading. The configuration of the segments  3 A can be modified in various ways, in a manner similar to the first embodiment. 
     In a kneading method according to the present embodiment using the kneading apparatus  1 B configured as described above, the compressed space S is formed at least by the expanding-contracting body  4 A of the segment  3 A in the open state and the expanding-contracting body  4 A of the segment  3 A in the closed state adjacent to the segment  3 A in the open state (in particular, by at least one segment  3 A in the open state, the segment  3 A in the closed state adjacent to one end of the at least one segment  3 A, and the closing wall  12  provided to the other end of the at least one segment  3 A), as illustrated in  FIG. 5A . 
     The kneading method according to the present embodiment includes a step of changing a combination of an operation state of each of a plurality of segments  3 A, such that the compressed space S is shifted together with at least a portion of the mixture  2  from one end of the longitudinal direction of the plurality of segments  3 A as a whole to the other end and then shifted from the other end to the one end, as illustrated in  FIG. 5B . 
     According to the kneading method of the present embodiment, the kneading effect by the flow of the mixture  2  and the kneading effect by the compression of the mixture  2  can be simultaneously obtained, in a manner similar to the first embodiment. 
     The kneading method according to the present embodiment may include a step of changing a combination of an operation state of each of a plurality of segments  3 A, such that, when the compressed space S is shifted together with at least a portion of the mixture  2  from one end of the longitudinal direction of the plurality of segments  3 A as a whole to the other end, the compressed space S is reciprocated together with at least a portion of the mixture  2  between the plurality of segments  3 A. Further, the kneading method according to the present embodiment may include a step of changing a combination of an operation state of each of a plurality of segments  3 A, such that, when the compressed space S is shifted together with at least a portion of the mixture  2  from the other end of the longitudinal direction of the plurality of segments  3 A as a whole to the one end, the compressed space S is reciprocated together with at least a portion of the mixture  2  between the plurality of segments  3 A. 
     Next, a kneading method according to a third embodiment of the present disclosure will be described in detail with reference to  FIG. 6A  and  FIG. 6B . A kneading apparatus  1 C used in the present embodiment includes two segments  3 A and has the same configuration as the kneading apparatus  1 B used in the second embodiment, except for that the closing wall  12  is provided to either end of the two segments  3 A as a whole. 
     In the present embodiment, the kneading apparatus  1 C includes two segments  3 A that are continuously arranged, as illustrated in  FIG. 6A  and  FIG. 6B . A closing wall  12  having a disc-like shape is fixed to either end of a longitudinal direction of the two segments  3 A by an appropriate joining means in an airtight and liquid-tight manner. Thus, an inner space formed within the extending-contracting body  4 A of the two segments  3 A is closed by the closing walls  12  at either ends of the longitudinal direction. In the present embodiment, an introduction path that can open and close to allow introduction of the mixture  2  into the inner space can be provided to one of the two closing walls  12 , and a discharge path that can be open and close to allow discharge of the mixture  2  from the inner space can be provided to the other one of the two closing walls  12 . Further, the introduction path and/or the discharge path configured as described above may be provided to, for example, the flange  7  illustrated in  FIG. 2A . The introduction path and the discharge path may be controlled to open and close by an ON/OFF valve, a processor (a microcomputer, etc.), or the like. According to the kneading apparatus  1 C configured as described above, the mixture  2  can be introduced into the inner space, kneaded while being shifted within the inner space, and then taken out from the inner space after the kneading. The configuration of the segment  3 A can be modified in various ways, in a manner similar to the first embodiment. 
     As illustrated in  FIG. 6A , the kneading method according to the present embodiment using the kneading apparatus  1 C configured as described above includes the step of changing a combination of an operation state of each of a plurality of segments  3 A, so as to alternately repeat a first step of forming the compressed space S by the segment  3 A in the open state, the segment  3 A in the closed state adjacent to one end of the segment  3 A in the open state, and the closing wall  12  provided to the other end of the segment  3 A in the open state as illustrated in  FIG. 6A , and a second step of forming the compressed space S by the segment  3 A in the open state, the segment  3 A in the closed state adjacent to the other end of the segment  3 A in the open state, and the closing wall  12  provided to one end of the segment  3 A in the open state as illustrated in  FIG. 6B . 
     According to the kneading method of the present embodiment, the kneading effect by the flow of the mixture  2  and the kneading effect by the compression of the mixture  2  can be simultaneously obtained, in a manner similar to the first embodiment. According to the kneading method of the present embodiment, further, the flow of the mixture  2  can be promoted by repeating the pendulum motion, whereby the kneading effect by the flow of the mixture  2  can be improved. 
     Next, a kneading method according to a fourth embodiment of the present disclosure will be described in detail with reference to  FIG. 7A  and  FIG. 7B . A kneading apparatus  1 D used in the present embodiment has a configuration similar to the kneading apparatus  1 C used in the third embodiment, except for that a plurality of (two in the example of the drawing) segments  3 C contract in the axial direction when their operation states are switched from the open state to the closed state and extend in the axial direction when their operation states are switched from the closed state to the open state. 
     In the present embodiment, the kneading apparatus  1 D includes two segments  3 C that are continuously arranged, as illustrated in  FIG. 7A  and  FIG. 7B . A closing wall  12  having a disc-like shape is fixed to either end of the entire longitudinal direction of the two segments  3 C by an appropriate joining means in an airtight and liquid-tight manner. Thus, an inner space formed within the extending-contracting body  4 C of the two segments  3 C as a whole is closed by the closing wall  12  at either end of the longitudinal direction. The configuration of the segment  3 C can be modified in various ways, in a manner similar to the first embodiment. 
     In the present embodiment, each of the two segments  3 C includes an external cylinder  6 C formed by an axially fiber-reinforced type elastic cylindrical body in which a plurality of fiber cords extending in the axial direction are embedded and the expanding-contracting body  4 C formed from an elastic cylindrical body in which fiber cords are not embedded, in a manner similar to the first to third embodiments. However, for example, both the external cylinder  6 C and the expanding-contracting body  4 C may be formed from the respective axially fiber-reinforced type elastic cylindrical bodies. This configuration enables each of the two segments  3 C to contract in the axial direction when its operation state is switched from the open state to the closed state, and to expand in the axial direction when its operation state is switched from the closed state to the open state. The external cylinder  6 C may be formed from a sleeved fiber-reinforced type elastic cylindrical body, such as a so-called Macchiben type artificial muscle, in which the outer surface of the elastic cylindrical body is covered with a fiber cord woven into a sleeve shape, rather than the axially fiber-reinforced type elastic cylindrical body. 
     The kneading method according to the present embodiment using the kneading apparatus  1 D as described above includes a step of changing a combination of an operation state of each of a plurality of segments  3 C to alternately repeat a first step in which the compressed space S is formed by the segment  3 C in the open state, the segment  3 C in the closed state that is adjacent to one end of the segment  3 C in the open state, and the closing wall  12  provided to the other end of the segment  3 C in the open state as illustrated in  FIG. 7A  and a second step in which the compressed space S is formed by the segment  3 C in the open state, the segment  3 C in the closed state adjacent to the other end of the segment  3 C in the open state, and the closing wall  12  provided to one end of the segment  3 C in the open state as illustrated in  FIG. 7B . 
     According to the kneading method of the present embodiment, the kneading effect by the flow of the mixture  2  and the kneading effect by the compression of the mixture  2  can be simultaneously obtained, in a manner similar to the first embodiment. According to the kneading method of the present embodiment, also, the flow of the mixture  2  can be promoted by repeating the pendulum motion, and thus the kneading effect of the flow of the mixture  2  can be improved. According to the kneading method of the present embodiment, further, when the segment  3 C in the open state is switched to the closed state, the expanding-contracting body  4 C of the segment  3 C is deformed expanding inward while contracting in the axial direction, whereby the mixture  2  can be strongly pushed in the axial direction. Thus, the flow of the mixture  2  can be promoted, and the kneading effect can be improved. 
     Note that, also in the first to third embodiments described above, all or some of the plurality of segments  3 A may be contracted in the axial direction by switching operation states from the open state to the closed state and expanded in the axial direction by switching their operation states from the closed state to the open state, in a manner similar to the present embodiment. 
     The descriptions presented above merely illustrate examples of the embodiments of the present disclosure, and various modifications can be made without departing from the gist of the disclosure. 
     For example, an air discharge path for discharging, to the outside of the kneading apparatus, a slight amount of air that gradually escapes to the outside of the mixture from fine gaps between the powders along with the progress of the kneading of the mixture  2  may be provided to the closing wall and/or the flange or the like, in the first to fourth embodiments. 
     EXAMPLE 
     A kneading apparatus having the same configuration as the kneading apparatus  1 D used in the fourth embodiment described above was manufactured as an example of the present disclosure. A composite propellant was kneaded by the kneading apparatus, and the performance of the composite propellant after the kneading was evaluated. 
     A rocket composite propellant was used as the mixture to be kneaded. The rocket composite contained AP powder (ammonium perchlorate) serving as an oxidizer, Al powder (aluminium) serving as a metal fuel, HTPB (Hydroxyl Terminated Polybutadiene) serving as a liquid binder, DOA (dioctyl adipate) serving as a liquid plasticizer, and IPDI (isophorone diisocyanate) serving as a liquid hardener. The compounding ratio (a mass ratio) was set to AP:Al:HTPB:DOA:IPDI=68:18:12:1:1. A mixture having a particle size of 400 μm, 200 μm, or 50 μm manufactured by Nippon Carlit Co., Ltd. was used as the AP powder. TFH-A05P (a median diameter of 5 μm) manufactured by TOYO ALUMINUM K.K. was used as the Al powder. P-41 manufactured by JSR Corporation was used as the HTPB. The Al powder, HTPB, DOA, and IPDI were pre-kneaded using a planetary mixer before mixing the AP powder. 
     In the manufactured kneading apparatus, an expanding-contracting body had an axial length of 90 mm and an inner diameter of φ60 mm. A ring-shaped disc (thickness: 10 mm) made of acrylic resin having an introduction port for a pre-kneaded slurry and an AP powder was placed between two segments. Hot water at 80° C. was poured onto a flange (thickness: 10 mm) of the segment to heat the inner side thereof. To the kneading apparatus, compressed air was supplied to the outside of the expanding-contracting body from a supply port via a regulator and a solenoid valve. 
     Operation states of the two segments were simultaneously switched (that is, the working fluid was supplied to one segment and, simultaneously, discharged from the other segment) at operating intervals of 2 seconds. A pressure of the compressed air was at 60 kPa. Then, to find an optimum amount (an introducing amount) of the mixture with respect to the volume of the inner space of the kneading apparatus to obtain the kneading effect, three levels were set from 500 g in 50 g increments, using the introducing amount as a parameter. For any of the three introducing amounts (500 g, 550 g, 600 g), first, the pre-kneading slurry was put into the kneading apparatus, and the kneading apparatus was operated for 5 minutes to disperse the pre-kneading slurry within the apparatus. Next, the AP powder was added, and the apparatus was operated for a set kneading time (30 minutes, 40 minutes, 60 minutes, or 80 minutes). A propellant slurry thus obtained was casted and defoamed under a reduced pressure for approximately 1 hour, and then left to cure in a thermostatic chamber at an atmospheric pressure of 60° C. for 1 week. 
     A strand combustion test was conducted after the inner side of the cured propellant was confirmed by performing an X-ray nondestructive inspection. In the strand combustion test, the cured propellant was cut into a prism shape of 7 mm×7 mm×40 mm, the surface of which was subjected to a restrictor treatment using an epoxy resin, and the propellant was then burned under a nitrogen gas pressure. A burning rate of the central area in 20 mm of the propellant was calculated from an image analysis. 
     The propellant samples obtained by kneading for 60 minutes were compared to one another using the introducing amount of the sample as a parameter. It was confirmed by the X-ray transmission image that a plurality of voids were present in the propellant sample in the introducing amount of 500 g. There is a possibility that the kneading was insufficient. Insufficient mixing after kneading was visually recognized for the sample propellant in the introducing amount of 600 g. Further, a strand combustion test was conducted in a range of 3 to 7 MPa using 9 samples for each introducing amount. Table 1 shows a pressure index n of a sample burning rate and the correlation coefficient R 2  for each introducing amount used as a parameter. It was confirmed that there was no problem in the pressure index n and the correlation coefficient R 2  in the introducing amount of 550 g. From these results, it can be determined that the introducing amount of 550 g is suitable on the scale of the present apparatus and the introducing amounts of 500 g and 600 g are unsuitable. In the apparatus used in the experiment, it was confirmed by calculation that, when the introducing amount exceeds approximately 540 g, “compressed space filled with the mixture which is substantially blocked and compressed due to the pressure by the expanding-contracting body” is formed, which is consistent with the above experimental results. It is speculated that, when the introducing amount was 500 g, the closed space formed when a segment in the open state is switched to the closed state is not filled with the mixture and thus the compressing effect by the mixture due to the pressure by the expanding-contracting body was not sufficiently obtained because of air intervening between the expanding-contracting body and the mixture. It is also speculated that, when the introducing amount was 600 g, a segment in the open state could not be switched to the closed state, and thus the flow of the mixture was insufficient. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Introducing Amount (g) 
                 Pressure Index n 
                 Correlation Coefficient R 2   
               
               
                   
               
             
            
               
                 500 
                 0.54 
                 0.74 
               
               
                 550 
                 0.44 
                 0.98 
               
               
                 600 
                 0.51 
                 0.97 
               
               
                   
               
            
           
         
       
     
     Next, when the introducing amount was 550 g and the kneading time was used as a parameter, a plurality of voids were observed in an X-ray transmission image of the sample obtained by the kneading time of 30 minutes. Also, it was confirmed that hardening was already progressed after the kneading and a fluidity of the slurry decreased in the sample obtained by the kneading time of 80 minutes.  FIG. 8  illustrates a burning rate characteristic of each sample obtained from the strand burning test. In  FIG. 8 , the solid lines respectively represent approximate straight lines of 30 minutes and 60 minutes, the broken lines respectively represent approximate straight lines of 40 minutes and 80 minutes. Table 2 shows the correlation coefficient R 2  of the approximate straight line of each sample and a converted burning rate at 5 MPa. Both the correlation coefficient R 2  for the kneading time of 40 minutes and that for the kneading time of 60 minutes were close to each other, and the converted burning rate for the kneading time of 40 minutes and that for the kneading time of 60 minutes were close to each other, and thus the samples were kneaded sufficiently. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Kneading Time  
                 Correlation  
                 Converted Burning  
               
               
                 (min) 
                 Coefficient R 2   
                 Rate 
               
               
                   
               
             
            
               
                 30 
                 0.94 
                 6.07 
               
               
                 40 
                 0.98 
                 5.86 
               
               
                 60 
                 0.98 
                 5.83 
               
               
                 80 
                 0.91 
                 6.18 
               
               
                   
               
            
           
         
       
     
     The propellant was kneaded under a usage condition (i.e., introducing amount: 550 g, kneading time: 40 minutes) of the kneading apparatus extracted as described above, and solid rocket motor grains of φ80 mm were produced as a prototype. In the combustion test, it was confirmed that the grains were burnt at an average internal pressure of 5.48 MPa. 
     REFERENCE SIGNS LIST 
       1 A,  1 B,  1 C,  1 D kneading apparatus 
       2  mixture 
       3 A,  3 B,  3 C segment 
       4 A,  4 B,  4 C expanding-contracting body 
       5  working fluid 
       6 A,  6 B,  6 C external cylinder 
       7  flange 
       8  ring 
       8   a  opening 
       9  chamber 
       10  fluid supplying-draining apparatus 
       11  circumferential groove 
       12  closing wall 
     O central axis 
     S compressed space