Abstract:
Setting position, direction and magnitude of compressive force applied to a crossing part. A joint with: crossing part in which first and second channels bored in casings cross on an XY plane; and pressure device holds casings from both sides with crossing part between the direction of the Z-axis perpendicular to the XY plane by a pressure member and applies compressive force to the crossing part, the pressure device with: a bored part h is formed in the casings, into which the pressure device is fitted and supports pressure; adjusting the compressive force, the pressure member is in position including an intersection of a peripheral wall of the first and second channels in the z-axis direction, an abutting part of the pressure member and bottom of the bored part presses intersection of peripheral walls; a noncontact part provided to the center preventing the center of the crossing part from pressing.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a joint, especially relates to a joint having a crossing part where two channels cross. 
     2. Description of the Related Art 
     Heretofore, a high pressure joint such as an elbow joint, a T-connection and a cruciform joint is a member which is provided with a crossing part where two channels cross and which supplies high-pressure fluid to a desired location, bending the high-pressure fluid supplied from a high pressure pump, joining it and branching it respectively in the crossing part, and the high pressure joint is widely used in various high-pressure fluid injection systems. As in the crossing part in the high pressure joint, pressure (internal pressure) by high-pressure fluid flowing in the channel repeatedly acts and varies, it is known that a crack caused by the internal pressure has an important effect upon the life of the joint (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-510937 (claim 1, claim 2, Paragraphs 0018 to 0020, FIGS. 7, 8A, 8B, 8C, and 13)). 
     A high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937 makes compressive energizing force concentrate over and under a location (a crossing part) where a channel 128 in a direction of the X-axis and a channel 130 in a direction of the Y-axis respectively formed on a common plane (an XY plane) in a main body 122 cross and negates separating power (internal stress) in a direction of the Z-axis which acts perpendicularly to the common plane and which tries to separate in the direction of the Z-axis by the compressive energizing force so as to prevent a crack caused on the common plane (the XY plane). 
     Concretely, the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937 clamps first and second compressive members 132 in which a compressive protrusion 134 that applies compressive force with the main body 122 between is formed by a clamp 138 and applies compressive energizing force to the crossing part. 
     However, first, as a position of the compressive protrusion 134 and a position of the clamp that applies compressive force are different in the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937, the high pressure joint has a problem that a position, a direction and the magnitude of compressive force applied to the crossing part where the channels cross cannot necessarily be properly set. 
     Besides, secondly, as various internal pressure acts on the crossing part where the channels cross by high-pressure fluid, the high pressure joint has a problem that unexpected various deformation occurs in the crossing part by compressive force (uniaxial lateral compression) when the compressive force in the direction of the z-axis is applied to the center of the crossing part as in the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937, internal stress newly caused by the deformation is superimposed on internal pressure of the high-pressure fluid and new damage may be caused. It is also an indeterminate factor that a direction and a position of compressive force applied to the crossing part are not necessarily properly managed. 
     Unexpected various internal stress (for example, internal stress in a direction along the XY plane) newly caused by compressive force applied to the center of the crossing part will be described, referring to  FIGS. 1, 2A, 2B, 2C, 3A, 3B and 3C  below. 
     Referred  FIG. 1  is a perspective view showing internal pressure that acts on the crossing part where the channel in the direction of the X-axis and the channel in the direction of the Y-axis cross.  FIGS. 2A, 2B, 2C  are drawings for explaining internal stress by the internal pressure that acts on the crossing part, wherein  FIG. 2A  is a front view viewed from the direction of the X-axis,  FIG. 2B  is a side view viewed from the direction of the Y-axis, and  FIG. 2C  is a plan view viewed from the direction of the Z-axis and showing a state in which a crack occurs on the XY plane.  FIGS. 3A, 3B, 3C  show relation between the internal stress by the internal pressure and compressive force, wherein  FIG. 3A  is a front view viewed from the direction of the X-axis,  FIG. 3B  is a side view viewed from the direction of the Y-axis, and  FIG. 3C  is a front view showing a state in which internal stress in the direction along the XY plane is caused by compressive force P. 
     In the following description, as shown in  FIG. 1 , for the convenience of the description, a virtual plane on which a first channel  110  and a second channel  120  pass is called an XY plane, a direction of the first channel  110  is called a direction of the X-axis, a direction of the second channel  120  is called a direction of the Y-axis, and a direction perpendicular to the XY plane is called a direction of the Z-axis. Besides, a plane including the Y-axis and the Z-axis is called a YZ plane and a plane including the X-axis and the Z-axis is called an XZ plane. 
     &lt;Internal Stress by Internal Pressure&gt; 
     As shown in  FIG. 1 , in a cruciform joint  100 , the first channel  110  in the direction of the X-axis and the second channel  120  in the direction of the Y-axis respectively formed in a casing  100   a  join in a crossing part  130  on the XY plane. An intersection  140  in the crossing part  130  is an interface on the XY plane of a peripheral wall  110   a  of the first channel  110  and a peripheral wall  120   a  of the second channel  120  (see  FIG. 2C ). That is, the intersection  140  is an intersection of the peripheral wall  110   a  of the first channel  110  and the peripheral wall  120   a  of the second channel  120  when the crossing part  130  is viewed from the direction of the Z-axis as shown in  FIG. 2C . 
     At this intersection  140 , as shown in  FIG. 2A , internal stress Q 1  by internal pressure q 1  of pressure fluid flowing in the first channel  110  acts in the direction of the Z-axis. Besides, as shown in  FIG. 2B , internal stress Q 2  by internal pressure q 2  of pressure fluid flowing in the second channel  120  acts in the direction of the Z-axis. Therefore, stress concentration occurs at the intersection  140  by the internal stress Q 1  and the internal stress Q 2 , a crack CR 1  is apt to be caused, and as shown in  FIG. 2C , the crack CR 1  extends on the XY plane. 
     To prevent the crack CR 1  caused on the XY plane, as shown in  FIG. 1 , the internal stress Q 1  and the internal stress Q 2  are negated by compressive force P (P 1 , P 2 )(see  FIGS. 2A, 2B ) by pressing the casing  100   a  so that the compressive force P (P 1 , P 2 ) is applied to the center  150  (see  FIG. 2C ) of the crossing part  130  from both sides in the direction of the Z-axis as shown in  FIG. 1 , and the occurrence of the crack CR 1  (see  FIG. 2C ) can be inhibited. 
     Concretely, as shown in  FIG. 3A , the internal stress Q 1  by the internal pressure q 1  of the pressure fluid flowing the first channel  110  is negated by the compressive force P (P 1 ) and as shown in  FIG. 3B , the internal stress Q 2  by the internal pressure q 2  of the pressure fluid flowing in the second channel  120  is negated by the compressive force P (P 2 ). 
     For the convenience of description, the compressive force P is conceptually assorted into the compressive force P 1  and the compressive force P 2  to correlate with the internal stress Q 1  and the internal stress Q 2 , however, the compressive force P may be also considered resultant force of the compressive force P 1  and the compressive force P 2 . 
     &lt;New Internal Stress by Applied Compressive Force&gt; 
     However, it is supposed that new various internal stress by unexpected deformation occurs in the crossing part  130  by applying the compressive force P to the center  150  of the crossing part  130  from the direction of the Z-axis. 
     For example, as shown in  FIG. 3C , in view of an intersection  160  (see  FIG. 1 ) on the YZ plane (a plane including the Y-axis and the Z-axis and perpendicular to the X-axis) where the peripheral wall  110   a  of the first channel  110  and the peripheral wall  120   a  of the second channel  120  cross, internal stress Q 4  in the direction of the X-axis perpendicular to the YZ plane occurs because deformation that a diameter of the second channel  120  is extended in the direction of the X-axis and the diameter is reduced in the direction of the Z-axis occurs (see a reference sign E) by applying the compressive force P. 
     Further, at the intersection  160  (see  FIG. 1 ) on the YZ plane, as internal stress Q 3  by the internal pressure q 2  of the pressure fluid flowing in the second channel  120  acts in the direction of the X-axis, resultant force of the internal stress Q 4  by the compressive force P and the internal stress Q 3  in the direction of the X-axis by the internal pressure q 2  of the pressure fluid causes a crack CR 2  in a direction along the YZ plane. 
     Accordingly, a new harmful effect by the internal stress Q 4  in the direction of the X-axis perpendicular to the YZ plane which is caused by the compressive force P in the direction of the Z-axis applied to the center  150  (see  FIGS. 1, 2C ) of the crossing part  130  where the plural first channel  110  and second channel  120  cross is required to be inhibited. 
     The present invention is made in view of such a background and provides a joint in which a position, a direction and the magnitude of compressive force applied to a crossing part where two channels cross are properly set, the occurrence of new internal stress by compressive force that pressurizes the crossing part is inhibited and the durability can be enhanced. 
     SUMMARY 
     In order to address the problem, a first feature of the present invention provides a joint having: the first channel and the second channel respectively bored in a casing; the crossing part where the first channel and the second channel cross on an XY plane; and pressure means that applies compressive force to the crossing part with the casing between by a pressure member from both sides with the crossing part between in a direction of the Z-axis perpendicular to the XY plane. The pressure means is provided with: a bored part which is formed in the casing, into which the pressure means is fitted and which supports the pressure means; and adjusting means that adjusts the compressive force. The pressure member is arranged in a position including an intersection of a peripheral wall of the first channel and a peripheral wall of the second channel in the direction of the Z-axis. An abutting part of the pressure member and the bottom of the bored part presses a position matched with the intersection of the peripheral walls, and a noncontact part is provided to the center not to press a position matched with the center of the crossing part. 
     In the present invention, first, the pressure member is arranged in a position suitable for the crossing part by being provided with the bored part into which the pressure means is fitted and which supports it and can be stably supported. Besides, compressive force of suitable magnitude can be applied to the crossing part via the pressure member by being provided with the adjusting means that adjusts the compressive force. 
     As described above, the present invention effectively negates internal stress in the direction of the Z-axis by suitably applying compressive force of the suitable magnitude to a proper position of the crossing part via the pressure member, inhibits the occurrence of a crack, and can enhance the durability of the joint. 
     In the present invention, secondly, the abutting part of the pressure member and the bottom of the bored part presses the position matched with the intersection of the peripheral wall and compressive force can be applied to the intersection of the peripheral wall of the first channel and the peripheral wall of the second channel precisely from the direction of the Z-axis without applying compressive force to an intersection of a center line (the center of the crossing part) of the first channel and the second channel in the crossing part by being provided with the noncontact part in the center so that the position matched with the center of the crossing part is not pressed. 
     Therefore, internal stress in the direction of the Z-axis caused in the crossing part is effectively negated, inhibiting the deformation of the crossing part and the occurrence of a crack can be prevented. 
     As described above, the present invention effectively prevents new internal stress caused by deformation from being superimposed on internal stress by internal pressure of high-pressure fluid flowing in the first channel and the second channel and from causing new fatigue and damage by inhibiting the deformation of the crossing part and others by applied compressive force and avoiding the occurrence of new internal stress caused by the deformation, and can enhance the durability of the joint. 
     In accordance with a second feature, in addition to the joint described in the first feature, the abutting part of the pressure member and the bored part is point contact. 
     According to such configuration, as the abutting part is point contact, a point of application of compressive force can be precisely set, a location where stress concentrates is concentratively pressed, and the occurrence of a crack can be effectively inhibited. 
     In accordance with a third feature, in addition to the joint described in the first feature, an abutting part of the pressure member and the bottom of the bored part is annular plane contact. 
     According to such configuration, as the abutting part is plane contact, compressive force can be uniformly applied to the crossing part in a planar area in the abutting part. Therefore, a location where stress concentrates is securely pressed by widely pressing the location where stress concentrates and its circumference and the occurrence of a crack can be effectively inhibited. 
     In accordance with a fourth feature, in addition to the joint described in the first feature, the adjusting means is provided with a tapped hole formed in the casing coaxially with the bored part and a threaded portion formed in the pressure member, the pressure member is screwed to the tapped hole by the threaded portion and the compressive force is adjusted by screw torque of the pressure member. 
     According to such configuration, compressive force can be precisely applied to the crossing part from the direction of the Z-axis owing to the threaded portion formed on the pressure member by screwing the pressure member to the tapped hole formed coaxially with the bored part into which the pressure member is inserted. Besides, as the magnitude of compressive force can be optimally set by adjusting the compressive force by screw torque of the pressure member, internal stress in the direction of the Z-axis is more effectively negated, the occurrence of a crack is inhibited, and the durability of the joint can be enhanced. 
     In accordance with a fifth feature, in addition to the joint described in the fourth feature, the pressure member is provided with a screw on which the threaded portion is formed and a pressure piece which abuts on an end of the screw and in which a abutting part is formed and a diameter of the abutting part of the pressure piece is smaller than that of the screw. 
     According to such configuration, as the diameter of the screw is increased and the diameter of the pressure piece can be reduced by being provided with the pressure piece the diameter of which is smaller than the diameter of the screw, damage is prevented, securely applying screw torque to the screw and compressive force can be properly applied to the crossing part. 
     In accordance with a sixth feature, in addition to the joint described in the second feature, an abutting part having the casing between the abutting parts of the pressure member is spherical and the abutting part is made to abut on a position matched with the intersection of the peripheral wall of the first channel and the peripheral wall of the second channel in the direction of the Z-axis. 
     According to such configuration, as the abutting part of the pressure member and the preceding part is point contact because the abutting part is spherical and a point of application of compressive force can be precisely set, compressive force can be precisely applied to the position matched with the intersection of the peripheral wall of the first channel and the peripheral wall of the second channel in the direction of the Z-axis. 
     Besides, internal stress in the direction of the Z-axis which is concentratively caused at the intersection of the peripheral walls is effectively negated by applying compressive force to the intersection of the peripheral walls, the occurrence of a crack is more securely inhibited, and the durability of the joint can be enhanced. 
     In the joint according to the present invention, a position, a direction and the magnitude of compressive force applied to the crossing part where the two channels cross can be properly set. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will be described in detail based on the following drawings, in which: 
         FIG. 1  is a perspective view showing internal pressure that acts on a crossing part and applied compressive force; 
         FIGS. 2A, 2B, and 2C  are schematic diagrams for explaining internal stress by the internal pressure that acts on the crossing part, wherein  FIG. 2A  is a front sectional view showing the crossing part viewed from a direction of the X-axis,  FIG. 2B  is a side sectional view viewed from a direction of the Y-axis, and  FIG. 2C  is a plan view showing a state in which a crack is caused on an XY plane and viewed from the direction of the Z-axis; 
         FIGS. 3A, 3B, and 3C  are schematic diagrams showing relation between internal stress by internal pressure and compressive force, wherein  FIG. 3A  is a front sectional view showing the crossing part viewed from a direction of the X-axis,  FIG. 3B  is a side sectional view viewed from a direction of the Y-axis, and  FIG. 3C  is a front view showing a state in which internal stress in a direction along an XY plane is caused by compressive force 
         FIGS. 4A and 4B  are sectional views showing the configuration of a joint equivalent to a first embodiment of the present invention, wherein  FIG. 4A  is a front view viewed from a direction of the X-axis, and  FIG. 4B  is a plan view viewed from a direction of the Z-axis and viewed along a line A-A in  FIG. 4A ; 
         FIGS. 5A and 5B  are sectional views showing a modification of the joint equivalent to the first embodiment of the present invention, wherein  FIG. 5A  is a front view viewed from a direction of the X-axis, and  FIG. 5B  is a plan view viewed from a direction of the Z-axis and viewed along a line A-A in  FIG. 5A ; 
         FIG. 6  is a perspective view showing internal pressure which acts on a crossing part of the joint equivalent to the first embodiment of the present invention and applied compressive force; 
         FIGS. 7A, 7B, and 7C  are schematic diagrams for explaining internal stress by internal pressure which acts on the crossing part of the joint equivalent to the first embodiment of the present invention, wherein  FIG. 7A  is a front sectional view showing the crossing part viewed from a direction of the X-axis,  FIG. 7B  is a side sectional view viewed from a direction of the Y-axis, and  FIG. 7C  is a plan view showing a state in which a crack is caused on an XY plane and viewed from a direction of the Z-axis; 
         FIG. 8  is a perspective view showing relation between internal pressure which acts on a crossing part of a joint equivalent to a second embodiment of the present invention and applied compressive force; 
         FIGS. 9A and 9B  are sectional views showing the configuration of the joint equivalent to the second embodiment of the present invention, wherein  FIG. 9A  is a front view viewed from a direction of the X-axis, and  FIG. 93  is a plan view viewed from a direction of the Z-axis and viewed along a line A-A in  FIG. 9A ; 
         FIGS. 10A, 10B, and 10C  are schematic diagrams showing the operation of the joint equivalent to the second embodiment of the present invention, wherein  FIG. 10A  is a front sectional view viewed from a direction of the X-axis,  FIG. 10B  is a plan view viewed from a direction of the Z-axis, and  FIG. 10C  is a front sectional view showing another embodiment of pressure means and viewed from the direction of the X-axis; and 
         FIGS. 11A and 11B  are sectional views showing a modification of the joint equivalent to the second embodiment of the present invention, wherein  FIG. 11A  is a front view viewed from a direction of the X-axis, and  FIG. 11B  is a plan view viewed from a direction of the Z-axis and viewed along a line B-B in  FIG. 11A . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 4A, 4B, 5A, 5B, 6, 7A, 7B, and 7C  suitably, a cruciform high pressure joint  1 A which is a joint equivalent to a first embodiment of the present invention will be described in detail below. 
     A high pressure joint  1  is provided with a first casing  2 , a first channel  3  and a second channel  4  respectively bored in the first casing  2 , a crossing part  5  where the first channel  3  and the second channel  4  cross on an XY plane, a second casing  6  fitted to the outside of the first casing  2  with the second casing covering the first casing  2 , and pressure means  8 A that annularly applies compressive force P (see  FIG. 6 ) to the first casing  2  with the crossing part  5  between the pressure means  8 A as shown in  FIGS. 4A, 4B . 
     In the following description, as shown in  FIG. 6 , a virtual plane which the first channel  3  and the second channel  4  pass is called the XY plane, a direction of the first channel  3  shall be a direction of the X-axis, a direction of the second channel  4  shall be a direction of the Y-axis, and a direction perpendicular to the XY plane shall be a direction of the Z-axis. Besides, a plane including the Y-axis and the Z-axis is called a YZ plane and a plane including the X-axis and the Z-axis is called an XZ plane. 
     The first casing  2  is configured by a square bar-shaped member the section of which is rectangular as shown in  FIG. 4A  and its corners are chamfered so that the first casing  2  is easily inserted into the second casing  6 . As shown in  FIG. 4B , in the first casing  2 , the first channel  3  is bored in the direction of the X-axis and the second channel  4  is bored in the direction of the Y-axis. The first channel  3  and the second channel  4  are perpendicular in the crossing part  5 , and the first channel  3  and the second channel  4  can make high-pressure fluid (not shown) flowing in the first channel  3  and high-pressure fluid (not shown) flowing in the second channel  4  join or separate. 
     The second casing  6  is a toroidal member in the center of which a rectangular through hole where the first casing  2  is inserted is formed as shown in  FIG. 4A  and is provided with a coupling part  61  that is a tapped hole in which a high pressure pipe (not shown) that supplies high-pressure fluid to the second channel  4  is coupled. In the second casing  6 , a pressure part that configures the pressure means  8 A that applies the annular compressive force P (see  FIG. 6 ) to the first casing  2  with the crossing part  5  between the pressure means  8 A is installed. 
     In this embodiment, in consideration of the diversity and the workability of combination, a casing is divided into the first casing  2  and the second casing  6 , however, the present invention is not limited to this, and the first casing  2  and the second casing  6  may be also integrated. 
     The first channel  3  is an annular passage formed along a longitudinal direction (the direction of the X-axis) of the first casing  2  on the XY plane as shown in  FIG. 4B  and at both ends of the first channel  3 , a coupling part  31  to which a high pressure pipe (not shown) where high-pressure fluid flows is coupled is formed. The second channel  4  is an annular passage formed along a shorter direction (the direction of the Y-axis) of the first casing  2  on the XY plane. 
     As for the first channel  3  and the second channel  4 , various shapes can be suitably adopted depending upon applications and others of the high pressure joint  1 A and in the embodiment, a diameter of the second channel  4  is set to be smaller than that of the first channel  3 , however, the present invention is not limited to this, and the first channel  3  and the second channel  4  may also have the same diameter. 
     The crossing part  5  is a part in which the first channel  3  and the second channel  4  on the XY plane join or separate. As internal pressure varies by high-pressure fluid supplied from the first channel  3  and the second channel  4  in the crossing part  5  and a repeated load is applied, the crossing part is in a heavy working condition. 
     In the crossing part  5 , an interface on the XY plane of a peripheral wall  3   a  of the first channel  3  and a peripheral wall  4   a  of the second channel  4  is called an intersection  55  as shown in  FIGS. 4B and 6 . 
     Concretely, as shown in  FIG. 6 , the first channel  3  in the direction of the X-axis formed in the casing  2  and the second channel  4  in the direction of the Y-axis similarly formed in the casing  2  join in the crossing part  5  on the XY plane. The intersection  55  in the crossing part  5  is the interface on the XY plane of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  (see  FIG. 7C ). That is, the intersection  55  is an intersection of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  when the crossing part  5  is viewed from the direction of the Z-axis as shown in  FIG. 7C . 
     The high pressure joint  1 A in this embodiment of the present invention is configured so that the first casing  2  is held from both sides with the crossing part  5  between the pressure means  8 A in the direction of the Z-axis as shown in  FIGS. 4A and 6  and the annular compressive force P including uniform distributed loads is applied to the crossing part  5  by the pressure means  8 A. 
     The pressure means  8 A is provided with a bored part  82 A formed in the first casing  2 , a tapped hole  85 A formed coaxially with the bored part  82 A in the second casing  6 , and a screw  86 A which is screwed to the tapped hole  85 A and which is a pressure member that presses the first casing  2  as shown in  FIG. 4A . 
     As the pressure means  8 A is arranged with a pair opposite so that the first casing  2  is held from both sides with the crossing part  5  between the pair of pressure means  8 A in the direction of the Z-axis and the pair of pressure means  8 A have the similar configuration, the left pressure means  8 A in  FIG. 4A  will be described below and the detailed description of the right pressure means  8 A will be omitted. 
     The bored part  82 A is bored from a surface of the first casing  2  to the vicinity of the crossing part  5  in the direction of the Z-axis, its bottom  82 A 1  is flat, and an and of the screw  86 A reaches the bottom  82 A 1 . The screw  86 A is inserted and supported so that the end of the screw  86 A is fitted to the bored part  82 A. 
     The tapped hole  85 A is formed coaxially with the bored part  82 A in the direction of the Z-axis from a surface of the second casing  6 . 
     As for the screw  86 A, an external thread  88 A which is a threaded portion screwed to the tapped hole  85 A is formed on its periphery, its end that abuts on the first casing  2  is flat, a recess  89 A which is a noncontact part and the section of which is circular is formed in the center, and a hexagon socket  87 A for rotating the screw  86 A is formed at its rear end. 
     Owing to such configuration, as the end of the screw  86 A which functions as the pressure member is flat, the end of the screw  86 A and the bottom of the bored part  82 A formed in the first casing  2  abut each other. 
     Therefore, the annular compressive force P (see  FIG. 6 ) including the uniform distributed loads is applied roughly to the first casing  2  from both sides with the crossing part  5  between in the direction of the Z-axis, detailedly to circumferences of the intersections including the four intersections  55  of the peripheral wall of the first channel  3  and the peripheral wall of the second channel  4 . 
     Besides, as the recess  89 A which is a noncontact part is formed at the end of the screw  86 A as the pressure means  8 A, an intersection  50  (see  FIGS. 6, 7C  and it is merely called the center  50  of the crossing part  5 ) of center lines of the first channel  3  and the second channel  4  in the crossing part  5  is not pressed. 
     That is, the pressure means  8 A can precisely apply the uniform distributed loads to the circumferences of the four intersections  55  by applying the annular compressive force P (see  FIG. 6 ) including compressive force to the four intersections  55  of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  without applying compressive force to the center  50  of the crossing part  5 . 
     In addition, as the pressure means  8 A can adjust the compressive force P (see  FIG. 6 ) by screw torque by screwing the screw  86 A to the tapped hole  85 A, the compressive force P can be simply and suitably set (means for adjusting compressive force). 
     &lt;Modification of Pressure Member&gt; 
     In the above-mentioned pressure means  8 A, the pressure member is configured by the screw  86 A, however, the present invention is not limited to this, and as follows, the pressure member may be also changed to a pressure member.  FIGS. 5A and 5B  are sectional views showing a modification of the pressure member, wherein  FIG. 5A  is a front view viewed from a direction of the X-axis, and  FIG. 5B  is a plan view viewed from a direction of the Z-axis and viewed along a line A-A in  FIG. 5A . In  FIGS. 5A, 5B , the same reference numeral is allocated to the similar configuration to that in  FIGS. 4A, 4B  and the detailed description of the similar configuration in the modification is omitted. 
     Pressure means  8 A′ in the modification of the first embodiment is provided with a bored part  82 A′ formed in a first casing  2 , a tapped hole  85 A′ formed in a second casing  6  to have a larger diameter than the diameter of the bored part  82 A′ and a pressure member  86 A′ that presses the first casing  2  as shown in  FIG. 5A . 
     The pressure member  86 A′ has an external thread  88 A′ and the external thread  88 A′ is provided with a screw  861 A′ screwed to a tapped hole  85 A′ and a cylindrical pressure piece  862 A′ which abuts on an end of the screw  861 A′ and which is fitted into the bored part  82 A′. 
     An end that abuts on the first casing  2  of the pressure piece  862 A′ is flat, and in the center of the end, a recess  89 A′ which is a noncontact part and the section of which is circular is formed. A diameter of the pressure piece  862 A′ is formed to be smaller than a diameter of the screw  861 A′. As for the screw  861 A′, a hexagon socket  87 A′ for rotating the screw  861 A′ is formed at its rear end and is equivalent to means for adjusting compressive force that adjusts the compressive force P (see  FIG. 6 ). 
     In the modification, the screw  861 A′ and the pressure piece  862 A′ are separately configured, however, they may be also integrated. 
     Owing to such configuration, as in the pressure means  8 A′ in the modification of the first embodiment, the diameter of the screw  861 A′ is made longer and the pressure piece  862 A′ can be reduced by reducing the diameter of the pressure piece  862 A′ more than the diameter of the screw  861 A′, damage can be prevented, securely applying screw torque to the screw  861 A′ and compressive force can be suitably applied to intersections  55  (see  FIG. 5B ). 
     In the above-mentioned modification, compressive force adjusting means in the pressure means adjusts compressive force by screw torque when the screw  861 A′ is screwed to the tapped hole  85 A′, however, the present invention is not limited to this, a through hole is formed in place of the tapped hole  85 A′, a pin is inserted into the through hole in a state in which the pressure piece  862 A′ is fitted into the bored part  82 A′, a fixing member is fixed to the second casing  6  by a fixture, the pin is pressed by the fixing member, and compressive force may be also applied to the pressure piece  862 A′. Screw torque that fastens the fixing member is also adjusted by such configuration and the compressive force can be adjusted. 
     The action and the effect of the high pressure joints  1 A, IA′ configured as described above in the first embodiment of the present invention will be described mainly referring to  FIGS. 6, 7A, 7B, and 7C  below. 
     &lt;Occurrence of Internal Stress by Internal Pressure&gt; 
     As shown in  FIG. 6 , in the high pressure joint  1 A, at the intersection  55  of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  when the crossing part  5  is viewed from the direction of the Z-axis, internal stress Q 1  by the internal pressure q 1  of pressure fluid flowing in the first channel  3  acts in the direction of the Z-axis (see  FIGS. 4A and 4B ) as shown in  FIG. 7A . Besides, as shown in  FIG. 7B , internal stress Q 2  by the internal pressure q 2  of pressure fluid flowing in the second channel  4  acts in the direction of the Z-axis (see  FIG. 6 ). 
     Therefore, stress concentration is caused at the intersection  55  by the internal stress Q 1  and the internal stress Q 2 , a crack CR 1  is apt to be made, and when a crack CR 1  is made at the intersection  55 , the crack CR 1  extends on an XY plane as shown in  FIG. 7C . 
     &lt;Negation of Internal Stress&gt; 
     To prevent a crack CR 1  from being made on the XY plane, the high pressure joint  1 A negates the internal stress Q 1  by the compressive force P (P 1 )(see  FIG. 7A ), negates the internal stress Q 2  by the compressive force P (P 2 )(see  FIG. 7B ) by not applying the annular compressive force P (P 1 , P 2 ) including the uniform distributed loads to the center  50  (see  FIGS. 6, 7C ) of the crossing part  5  with the center between both sides in the direction of the Z-axis as shown in  FIG. 6  but applying the compressive force P (P 1 , P 2 ) to the circumferences of the four intersections  55  of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  with the circumferences between both sides in the direction of the Z-axis as shown in  FIG. 6 , and the high pressure joint can inhibit the occurrence of the crack CR 1  (see  FIG. 7C ). 
     In the meantime, the occurrence of unexpected various internal stress (see the internal stress Q 4  in  FIG. 3C ) newly caused by compressive force applied to the center of the crossing part  5  can be avoided by not pressing the center  50  (see  FIGS. 6, 7C ) of the crossing part  5  by the annular compressive force P (P 1 , P 2 ). 
     As described above, the high pressure joint  1 A effectively negates the internal stress in the direction of the Z-axis caused in the crossing part  5 , inhibiting the deformation of the crossing part  5  and can prevent the occurrence of a crack. 
     The compressive force P (P 1 , P 2 ) has been conceptually described in a state in which the compressive force is assorted into the compressive force P 1  and the compressive force P 2  to correlate them with the internal stress Q 1  and the internal stress Q 2  for the convenience of explanation, however, the compressive force P may be also considered resultant force of the compressive force P 1  and the compressive force P 2 . 
     Next, a cruciform high pressure joint  1 B which is a joint equivalent to a second embodiment of the present invention will be described in detail, suitably referring to  FIGS. 8, 9A, 9B, 10A, 10B, and 10C . 
     The high pressure joint  1 B equivalent to the embodiment of the present invention is configured so that a first casing  2  is held between four spheres  81 B (see  FIG. 10A ) that configure a pressure member from both sides with a crossing part  5  between in a direction of the Z-axis as shown in  FIGS. 8, 9A  and compressive force P is applied to four intersections  55  (see  FIG. 9B ) in the crossing part  5  by pressure means  8 B. 
     Therefore, in the following description, the same reference numeral is allocated to the similar component to that of the high pressure joint  1 A in the above-mentioned first embodiment and repeated description is omitted. 
     The pressure means  8 B is provided with: a bored part  82 B formed in the first casing  2 ; a holding groove  83 B (see  FIG. 10A ) which is formed at the bottom of the bored part  82 B and which holds the four spheres  81 B in respective predetermined positions; an intermediate sphere  84 B installed in the bored part  82 B so as to abut on each four sphere  81 B; a tapped hole  85 B formed in a second casing  6  coaxially with the bored part  82 B; and a screw  86 B which is screwed to this tapped hole  85 B and which is adjusting means for adjusting compressive force that presses the four spheres  81 B on the first casing  2  as shown in  FIG. 9A . 
     In the high pressure joint  1 B in the second embodiment, a pressure member in the pressure means BB is configured by the screw  86 B, the intermediate sphere  84 B and the four spheres  81 B. 
     The four spheres  81 B is arranged in predetermined positions (hereinafter merely called predetermined positions) matched with intersections  55  of a peripheral wall  3   a  of a first channel  3  and a peripheral wall  4   a  of a second channel  4  when they are viewed from the direction of the Z-axis as shown in  FIG. 10B . 
     Owing to such configuration, the compressive force P (see  FIG. 10A ) is applied with the intersections  55  between both sides in the direction of the Z-axis via the first casing  2 . Besides, as a point of application of the compressive force P can be precisely set by making a part that abuts on the first casing  2  spherical, the compressive force P can be precisely applied to the positions matched with the intersections  55  from the direction of the Z-axis. 
     In this embodiment, the first casing  2  is pressed by the four spheres  81 B so as to apply compressive force, however, the present invention is not limited to this, and only an end that abuts on the first casing  2  can be also made spherically convex. Besides, the present invention is not limited to the spherical shape and a plane shape acquired by reducing a contact area can be also adopted. 
     The bored part  82 B is bored up to the vicinity of the crossing part  5  in the direction of the Z-axis from a surface of the first casing  2  and the holding groove  83 B that holds the four spheres  81 B in the respective predetermined positions is formed at the bottom. 
     The holding groove  83 B is a hollow groove fitted to a shape of the sphere  81 B as shown in  FIG. 10A  and can hold the sphere  81 B without making the sphere move from the predetermined position. 
     The intermediate sphere  84 B is interposed between the screw  86 B and the four spheres  81 B as shown in  FIG. 9A . The intermediate sphere  84 B is a member for uniformly transmitting the pressure of the screw  86 B to the four spheres  81 B. The intermediate sphere  84 B is installed in the bored part  82 B so that the intermediate sphere  84 B has a larger diameter than each four sphere  81 B and abuts on the four spheres  81 B arranged in the predetermined positions. 
     The tapped hole  85 B is formed coaxially with the bored part  82 B in the direction of the Z-axis from a surface of the second casing  6 . 
     On a periphery of the screw  86 B, an external thread  88 B which is a threaded portion screwed to the tapped hole  85 B is formed, a conical keep hole fitted to the intermediate sphere  84 B is formed at its end that abuts on the intermediate sphere  84 B, and a hexagon socket  87 B for rotating the screw  86 B is formed at a rear end. 
     Owing to such configuration, as the pressure means  8 B presses the four spheres  81 B by screw torque by screwing the screw  863  to the tapped hole  85 B and can adjust the compressive force P (see  FIG. 8 ), the compressive force P can be simply and suitably set (means for adjusting compressive force). 
     The pressure means  8 B simultaneously presses the four spheres  81 B via each intermediate sphere  84 B and applies the compressive force P, however, the present invention is not limited to this, and the compressive force P applied to the four spheres  81 B may be also independently adjusted (independent adjustment type pressure means). 
     An independent adjustment type pressure means  800  is provided with: a bored part  820  which is formed in the first casing  2  and which houses the sphere  81 B at the bottom; a tapped hole (not shown because the tapped hole is similar to the tapped hole  85 B) formed in the first casing  2  coaxially with the bored part  820 ; and a screw (not shown because the screw is similar to the screw  86 B) which is screwed to the tapped hole and which presses the sphere  81 B on the first casing  2  as shown in  FIG. 10C . 
     That is, in the pressure means  800 , the four bored parts  820  that hold the four spheres  81 B in respective predetermined positions without providing an intermediate sphere  84 B are independently provided and the screws (not shown) that press the four spheres  81 B are also separately provided corresponding to each sphere  81 B. 
     Owing to such configuration, as the pressure means  800  can separately adjust compressive force P by each of the four spheres  813 , the compressive force P can be uniformly adjusted in a well-balanced state. 
     The action and the effect of the high pressure joint  1 B equivalent to the above-mentioned second embodiment will be described mainly referring to  FIGS. 8, 10A, 10B, 10C  below. 
     The high pressure joint  1 B in this embodiment can precisely apply the compressive force P (see  FIG. 8 ) to a position of the intersection  55  via the first casing  2  by the four spheres  81 B by arranging the four spheres  81 B in the positions matched with the intersections  55  of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  when the four spheres  81 B are viewed from the direction of the Z-axis. 
     That is, the high pressure joint  1 B in the second embodiment effectively negates internal stress Q in the direction of the Z-axis caused in the crossing part  5 , inhibiting the deformation of the crossing part  5  by not uniformly applying the compressive force P (see  FIG. 6 ) including distributed loads around the center  50  (see  FIGS. 6, 7C ) of the crossing part  5  but precisely applying the compressive force P (see  FIG. 8 ) to the intersections  55  of the peripheral wall  3   a  of the first channel  3  and the peripheral wall  4   a  of the second channel  4  from the direction of the Z-axis, and can prevent the occurrence of a crack (see  FIGS. 10A, 10C ). 
     The embodiments of the present invention have been described, however, the present invention is not limited to the embodiments, and the present invention can be suitably modified. 
     For example, in the above-mentioned embodiments, the cruciform high pressure joint  1  has been described, however, the present invention is not limited to this, and can be similarly applied to various-shaped joints such as an elbow joint, a T-connection and a cruciform joint. 
     Besides, in the above-mentioned embodiments, the crossing part  5  is formed by fitting the second casing  6  to the first casing  2 , however, the present invention is not limited to this, and as shown in  FIGS. 11A, 11B , a high pressure joint  10  acquired by extending a first casing  200 , sharing a first channel  300 , fitting a third casing  600  different in a direction to the first casing  200  and further, adding a crossing part  500  may be also configured.