JP2013076422A - Rotary joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary joint with a simple configuration that can effectively prevent a failure arising from the accumulation and solidification of foreign matters which penetrate a sliding gap between a fixed shaft part and a fitting hole.SOLUTION: In the rotary joint, configured with a rotary seal having an axial rotation flow channel and a fixed seal part having an axial fixed flow channel disposed coaxially to form a face seal part by making a first seal face of the rotary seal part and a second seal face of the fixed seal part adhere to each other, the sliding gap g, in which the fixed shaft part 8a of a floating seat 8 is fitted into the fitting hole 7a provided in a housing member 7, is sealed with a gap seal 12 to provide a communication parts 15 that allow a fluid to move from the sliding gap g to the fixed flow passage 8f by making a fixed flow passage 8f installed axially inside the fixed shaft 8a at the upstream side of the gap seal 12 communicate with the sliding gap g.

Description

  The present invention relates to a rotary joint used for feeding fluid to a rotating part.

  As a fluid coupling that connects a fixed fluid feed pipe to the flow path of a rotating part in a fluid feeding mechanism that feeds a coolant or other fluid to a rotating part that is rotating during operation, such as a spindle of a machine tool A rotary joint is used. The rotary joint is a seal of a rotary seal mounted on each facing end face, with a rotating shaft coupled to the rotating part and a fixed shaft connected to the fluid supply pipe arranged coaxially and facing each other in the axial direction. It is the structure which prevents the leakage of a fluid by sticking a surface mutually. With this configuration, the fluid can be continuously supplied from the fluid supply pipe to the rotating part in the rotating state via the rotary joint. In the rotary joint having such a configuration, the fixed shaft side needs to be moved in the axial direction in order to bring the sealing surface into close contact, so that the fixed shaft is slidably fitted into a fitting hole provided in the casing portion or the like. A gap seal member such as an O-ring interposed between the inner periphery of the fitting hole and the fixed shaft prevents fluid leakage from the sliding gap.

  By the way, the fluid to be supplied by the rotary joint often contains foreign matter such as minute cutting waste such as coolant that is circulated and used in machine tools. It is inevitable that these foreign substances enter the sliding gap between the joint holes. If these foreign objects repeatedly enter, they will accumulate and adhere in the sliding gap, and the smooth sliding of the fixed shaft will be hindered. As a result, the rotary joint will not operate normally and a large amount of fluid leakage will occur. Arise. Therefore, for the purpose of preventing such a problem, a rotary joint having a structure for preventing foreign matter from entering the sliding gap between the fixed shaft and the fitting hole has been proposed (see Patent Documents 1 and 2). .

  In the prior art example shown in Patent Document 1, the sliding gap is filled with grease by constantly pushing the grease into the annular groove provided on the inner peripheral surface of the fitting hole, and foreign matter in the sliding gap is obtained. To prevent the intrusion. In the prior art example shown in Patent Document 2, a bendable diaphragm is attached to the upstream end portion of the fixed shaft, and the fluid is sealed so that no fluid flows except through the flow passage hole of the fixed shaft. The intrusion of foreign matter into the gap is prevented.

Japanese Patent No. 4426538 Japanese Patent Laid-Open No. 3-61786

  However, the above-described prior art has the following problems due to the structure of the mechanism that prevents foreign matter from entering. First, in the prior art example shown in Patent Document 1, since the grease filling the sliding gap is gradually dissolved in the fluid and the filling effect is reduced, it is difficult to stably secure the foreign matter intrusion preventing effect. . Moreover, in the prior art example shown in Patent Document 2, since the diaphragm is mounted on the upstream end of the fixed shaft portion, fluid intrusion from the upstream side of the sliding gap is inhibited, but fluid supply starts. It is not possible to prevent fluid leaking from the rotary seal portion that is not yet in close contact from entering from the downstream side of the sliding gap. For this reason, in any of the prior art examples, it has been difficult to effectively prevent problems caused by foreign matter entering into the sliding gap between the fixed shaft portion and the fitting hole to be accumulated and solidified.

  The present invention has been made in view of such a problem, and effectively prevents a problem caused by foreign matter entering into the sliding gap between the fixed shaft portion and the fitting hole to be accumulated and solidified with a simple configuration. An object of the present invention is to provide a rotary joint that can be used.

  The rotary joint of the present invention is formed by coaxially arranging a rotating part provided with an axial rotation flow path and attached to the rotary shaft and a fixed part provided with an axial fixed flow path and fixedly attached to the holding member, A rotary joint that feeds fluid supplied from a fluid supply source to a rotating flow path of the rotating unit that rotates about an axis through the fixed channel, and is provided on the rotating unit and rotates on a side end surface. A rotary seal portion having a first seal surface with an open channel, and the axial direction with the fixed channel formed in the axial direction with a predetermined sliding gap in a fitting hole provided in the holding member A fixed shaft portion that fits in a state in which movement of the fixed shaft portion is allowed, and has a second seal surface with the fixed flow path opened on one side end surface thereof, and the sliding gap is connected to the shaft. Gap seal part that seals while allowing movement in the direction Forming the first seal surface and the second seal surface in close contact with each other by supplying the fluid from the fluid supply source into the fitting hole and pressing the other side of the fixed shaft portion. Provided on the upstream side in the sliding gap of the gap seal portion, and the fluid is transferred from the sliding gap to the fixed flow path by communicating the sliding gap and the fixed flow path. And a communication portion that allows movement.

  According to the present invention, the rotary seal portion provided with the axial rotational flow path and the fixed seal portion provided with the axial fixed flow path are arranged coaxially, and the first seal surface of the rotary seal portion and the fixed seal are arranged. In a rotary joint configured to form a face seal portion by closely contacting the second seal surface of the portion, a sliding gap in which the fixed shaft portion of the fixed seal portion is fitted into the fitting hole provided in the holding member is a gap. Sealing is performed by the seal part, and the fixed flow path provided in the axial direction inside the fixed shaft part and the sliding gap are communicated with each other on the upstream side of the sliding gap of the gap seal part so that the sliding gap is connected to the fixed flow path. By providing a communication part that allows fluid movement, the flow from the sliding gap to the fixed flow path can be induced by the ejector effect caused by the flow velocity of the fluid passing through the fixed flow path, and the fixed shaft part is fitted. In the sliding clearance with the hole There it is possible to effectively prevent the problems caused by depositing solidifying invade a simple configuration.

Sectional drawing of the rotary joint (1st Example) in one embodiment of this invention Partial sectional view of a rotary joint (first example) according to an embodiment of the present invention. Functional explanatory drawing of the rotary joint (1st Example) in one embodiment of this invention Sectional drawing of the rotary joint (2nd Example) in one embodiment of this invention Sectional drawing of the rotary joint (3rd Example) in one embodiment of this invention Sectional drawing of the rotary joint (4th Example) in one embodiment of this invention Sectional drawing of the rotary joint (5th Example) in one embodiment of this invention Sectional drawing of the rotary joint (6th Example) in one embodiment of this invention

  Next, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of the rotary joint 1 (first embodiment) will be described with reference to FIG. The overall configuration of the fluid feeding mechanism will be described. In FIG. 1, a rotary joint 1 is used in a fluid supply mechanism that feeds a cooling fluid to a rotating shaft such as a spindle shaft of a machine tool, and a rotating portion 1a provided with an axial rotating flow path. And the fixing | fixed part 1b provided with the axial fixed flow path is coaxially arranged and comprised.

  The rotating portion 1a is fastened to a flow passage hole 2a of a spindle shaft 2 that is a rotating shaft. The spindle shaft 2 is driven to rotate by a motor built in the spindle and rotates about an axis A, and is also clamped / unfastened. Advancing and retreating in the axial direction is performed by the clamp cylinder. The fixed portion 1b is fixedly mounted in a mounting hole 3a provided in the casing 3 in communication with the flow path hole 3b via a housing member 7 as a holding member, and a frame (not shown) through which the spindle shaft 2 is inserted. ), The fixing portion 1b is arranged coaxially with the rotating portion 1a. A fluid such as a liquid coolant or cooling air is supplied to the flow path hole 3b from a fluid supply source (not shown).

  Next, the detailed structure of each part will be described. The rotating part 1a is mainly composed of a rotor 4 mounted on the spindle shaft 2. The rotor 4 is provided with a flange part 4b having an outer diameter larger than that of the rotating shaft part 4a at one end of the rotating shaft part 4a. It has a shape in which a rotational flow path 4e is provided in the axial direction at the center. A male screw portion 4d is provided on the outer surface of the rotating shaft portion 4a, and a female screw portion 2b is provided on the inner surface of the flow path hole 2a. By screwing the male screw portion 4d into the female screw portion 2b, the rotor 4 is screwed to the spindle shaft 2, and the screw fastening portion is sealed by the O-ring 6. As a result, the rotating flow path 4 e communicates with the flow path hole 2 a of the spindle shaft 2.

  A circular recess 4c is formed on the side end surface of the right side of the rotor 4 (the side facing the fixed portion 1b) so as to surround the opening surface of the rotating flow path 4e. The recess 4c has a first seal. The ring 5 is fixed. The first seal ring 5 is formed by molding a hard material rich in wear resistance such as ceramic into an annular shape having an opening 5a in the center, and the first seal surface 5b finished to be a smooth surface. It fixes to the recessed part 4c in the state made into the outer surface side. In this state, the rotating flow path 4e communicates with the opening 5a and opens to the first seal surface 5b. In the above configuration, the rotor 4 to which the first seal ring 5 is fixed is a rotary seal portion having a first seal surface 5b provided in the rotary portion 1a and having a rotary flow path 4e opened on a side end surface.

  Next, the structure of the fixing portion 1b attached to the casing 3 will be described. The fixed portion 1 b is configured such that the floating sheet 8 is attached to the housing member 7. A mounting hole 3a provided in communication with the flow path hole 3b is opened on the mounting surface 3c of the casing 3, and a cylindrical housing member 7 constituting the main body of the fixed portion 1b is fitted into the mounting hole 3a. To do. The housing member 7 is bolted to a screw hole (not shown) provided in the mounting surface 3 c, and the fitting portion to the mounting hole 3 a is sealed by the O-ring 11.

  The floating sheet 8 is provided with a disk-shaped flange portion 8b on one side (the side facing the rotating portion 1a in the figure), and a fixed shaft portion formed with a fixed flow path 8f penetrating in the axial direction on the other side. The shape has 8a. A second seal ring 9 is fixed in a convex portion 8c provided in a circular bank shape on the left side of the flange portion 8b (an end surface facing the rotating portion 1a). The second seal ring 9 is formed by molding a hard material similar to that of the first seal ring 5 into an annular shape having an opening 9a in the center, and the second seal surface 9b finished to be a smooth surface. It is fixed to the flange portion 8b in the state of being on the outer surface side. In this state, the fixed flow path 8f communicates with the opening 9a and opens to the second seal surface 9b.

  The fixed shaft portion 8a is fitted in a fitting hole 7a provided through the central portion of the housing member 7 in the axial direction in a state where movement in the axial direction is allowed. That is, the sliding gap g (with a predetermined gap dimension) between the inner peripheral surface 7b of the fitting hole 7a and the outer peripheral surface 8d of the fixed shaft portion 8a is determined by setting the shape and dimensions of the fitting hole 7a and the fixed shaft portion 8a. (See FIG. 2). A seal groove 7c is formed in the inner peripheral surface 7b of the fitting hole 7a, and an O-ring 12a and a backup ring 12b which are annular seal members are fitted in the seal groove 7c. In a state where the fixed shaft portion 8a is fitted in the fitting hole 7a, the sliding gap g is sealed by pressing the O-ring 12a against the outer peripheral surface 8d. The O-ring 12a and the backup ring 12b fitted and mounted in the seal groove 7c form a clearance seal portion 12 that seals the sliding clearance g while allowing the fixed shaft portion 8a to move in the axial direction.

  That is, the floating sheet 8 to which the second seal ring 9 is fixed is a state in which the fixed flow path is formed in the axial direction and the axial movement is allowed in the fitting hole 7a provided in the housing member 7 as the holding member. And a fixed seal portion having a second seal surface 9b having a fixed flow path 8f opened on the side end surface. In the present embodiment, the floating sheet 8 is mounted on the casing 3 via the housing member 7 as a holding member. However, the floating sheet 8 may be mounted directly on the casing 3. In this case, the fixed shaft portion 8a is fitted in a fitting hole provided in the casing 3 as a holding member in a state in which movement in the axial direction is allowed.

  Next, the operation of the rotary joint 1 will be described. By supplying the fluid to be supplied into the fitting hole 7a through the flow path hole 3b, this fluid pressure is applied to the side end face on the other side (opposite side of the second seal ring 9) of the fixed shaft portion 8a. Acts on 8e. As a result, the fixed shaft portion 8a slides toward the rotating portion 1a in the fitting hole 7a, and the second seal ring 9 multiplies the projected area of the side end surface 8e by the fluid pressure with respect to the first seal ring 5. It is pressed by a fluid force F of a certain size. The fluid force F causes the second seal surface 9b and the first seal surface 5b to be in close contact with each other, thereby leaking the fluid fed from the fixed channel 8f to the rotating channel 4e in a rotating state around the axis. A face seal portion 10 is formed to prevent this.

  When the floating sheet 8 is slid in the axial direction, the bolt 16 screwed to the flange portion 8 b and the cylindrical collar 17 that encloses the bolt 16 slide in the guide hole 7 d provided in the housing member 7 in the axial direction. As a result, the movement of the floating sheet 8 in the axial direction is guided and the rotation around the axis is prevented.

  In the operating state of the rotary joint 1, the sealing surface of the face seal portion 10 is brought into and out of contact with the advancement of the floating sheet 8 due to the pressure of the supplied fluid and the advancement and retraction operation of the spindle shaft 2. That is, when the floating sheet 8 is retracted and the first seal surface 5b and the second seal surface 9b are separated from each other, the fluid is supplied to the flow path hole 3b, so that the fluid flows in the fitting hole 7a. The physical strength F acts on the side end face 8e of the fixed shaft portion 8a and presses it in the axial direction. As a result, the floating sheet 8 moves forward (in the direction of arrow a), and the first seal surface 5b and the second seal surface 9b come into contact with each other to form a face seal portion 10 that is in close contact with each other. Thereby, the fluid is supplied from the fixed flow path 8f to the rotating flow path 4e in the rotating state.

  When the spindle shaft 2 moves forward (arrow d direction) relative to the fixed portion 1b, the floating seat 8 moves backward (arrow b direction), and the flange portion 8b returns to a position close to the housing member 7. . Then, by relatively retreating the spindle shaft 2 (in the direction of the arrow c) from this state, the first seal surface 5b and the second seal surface 9b are returned to a separated state.

  Next, with reference to FIG. 2, the communication part 15 provided in the fixed shaft part 8a and connecting the sliding gap g and the fixed flow path 8f will be described. FIG. 2A shows a cross section taken along the line BB in FIG. 1, that is, a cross section on the upstream side of the gap seal portion 12 of the fixed shaft portion 8a. A circumferential groove 13 is provided on the entire circumference of the outer peripheral surface 8d in the fixed shaft portion 8a, and a plurality of (four in this case) are formed by connecting the fixed flow path 8f and the circumferential groove 13 in the fixed shaft portion 8a. Through-holes 14 are provided radially.

  As shown in FIG. 2B, the circumferential groove 13 communicates with a sliding gap g between the inner peripheral surface 7b of the fitting hole 7a and the outer peripheral surface 8d of the fixed shaft portion 8a, and further slides. The gap g communicates with the fixed flow path 8 f through the through hole 14. As a result, the fluid that has entered the sliding gap g after being fed to the fitting hole 7 a is allowed to move to the fixed flow path 8 f via the circumferential groove 13 and the through hole 14. Therefore, the circumferential groove 13 and the through-hole 14 are provided on the upstream side of the sliding gap g of the gap seal portion 12, and the fixed gap flows from the sliding gap g by connecting the sliding gap g and the fixed flow path 8 f. A communication portion 15 that allows movement of fluid to the path 8f is configured. In the example shown in FIGS. 1 and 2, the communication portion 15 is formed by connecting the circumferential groove 13 provided on the outer peripheral surface 8d of the fixed shaft portion 8a, and the circumferential groove 13 and the fixed flow path 8f. The through hole 14 is provided.

  Next, the function of the communication portion 15 in the rotary joint 1 having the above configuration will be described with reference to FIG. FIG. 3 (a) shows that the fluid fed through the flow path hole 3b (FIG. 1) and flowing into the fitting hole 7a (arrow e) flows down the fixed flow path 8f of the fixed shaft portion 8a and rotates. The state when flowing toward the 1a side (arrow h) is shown. In many cases, the fluid to be supplied at this time includes foreign matter 18 such as minute cutting waste such as coolant that is circulated and used in the machine tool, and part of these foreign matter 18 is in the sliding gap g. Enters the sliding gap g together with the fluid flowing in (arrow f). If the entry of these foreign matters 18 is repeated and deposited and fixed in the sliding gap g, smooth sliding of the fixed shaft portion 8a is hindered.

  Even in such a case, in the rotary joint 1 shown in the present embodiment, due to the function of the communication portion 15 provided on the upstream side of the gap seal portion 12, the foreign matter 18 is deposited and fixed in the sliding gap g. Can be prevented. That is, in the rotary joint 1, the fluid flows downstream in the fixed flow path 8f at a flow rate corresponding to the flow rate and pressure defined by the use conditions (arrow h). On the other hand, the flow of fluid in the sliding gap g is a gap flow and has a large resistance, and is further blocked by the gap seal portion 12 on the downstream side. There is a difference.

  For this reason, the static pressure of the fluid in the fixed flow path 8f is lower than that in the sliding gap g, and a pressure difference is generated. This pressure difference causes the sliding gap g to pass through the communication portion 15 to the fixed flow path 8f. Flow occurs due to the ejector effect (arrow i). Along with this flow, the foreign matter 18 in the sliding gap g also moves to the fixed flow path 8f and is discharged downstream along with the fluid in the fixed flow path 8f (arrow j). Therefore, troubles caused by the accumulation of the foreign matter 18 in the sliding gap g, for example, smooth sliding of the fixed shaft portion 8a is hindered, and the face seal portion 10 is not formed normally, and a large amount of fluid is generated. Can be prevented from leaking.

  When the backup ring 12b is used in combination with the O-ring 12a as the gap seal portion 12, the gap seal portion 12 exists in the downstream area of the gap seal portion 12 in the seal groove 7c or the sliding gap g as described below. The effect of discharging foreign matter can be obtained. That is, at the start of the operation of the rotary joint 1, in the process where the fluid starts to be fed into the fitting hole 7a, no fluid exists in the sliding gap g and the fluid flows only in the fixed flow path 8f. The ejector effect due to this flow reaches the sliding gap g through the communication portion 15. At this time, the fluid pressure is not yet applied in the sliding gap g, and the backup ring 12b has not yet pressed the O-ring 12a. Therefore, this ejector effect can be achieved in the seal groove 7c and in the sliding gap g. It extends to the downstream side of the section 12. Accordingly, it is possible to obtain a cleaning effect that eliminates the foreign matter 18 existing in these ranges each time the rotary joint 1 is repeatedly operated and stopped.

  In addition, the rotary joint 1 of this Embodiment is not limited to the structure shown in FIG. 1, A various variation is possible. Hereinafter, some examples of these variations will be described with reference to FIGS. First, FIG. 4 shows the rotary joint 1 of the second embodiment. In the second embodiment, a gap seal portion 12A is provided on the outer peripheral surface 8d of the fixed shaft portion 8a in place of the gap seal portion 12 provided on the inner peripheral surface 7b of the fitting hole 7a in the first embodiment. An example is shown. That is, in the second embodiment, the gap seal portion 12A is formed by fitting an O-ring 12a and a backup ring 12b, which are annular seal members, into a seal groove 8g provided on the outer peripheral surface 8d of the fixed shaft portion 8a. .

  Next, FIG. 5 shows the rotary joint 1 of the third embodiment. In the third embodiment, instead of the circumferential groove 13 provided on the outer peripheral surface 8d of the fixed shaft portion 8a in the first embodiment, a circumferential groove 13A is provided on the inner peripheral surface 7b of the fitting hole 7a. An example is shown in which a through hole 14A for connecting the circumferential groove 13A and the fixed flow path 8f is provided in the fixed shaft portion 8a when the rotary joint 1 is operated. That is, in the third embodiment, the gap seal portion 12 is configured by fitting an O-ring 12a and a backup ring 12b, which are annular seal members, into a seal groove 7c provided on the inner peripheral surface 7b of the fitting hole 7a. The communication portion 15A includes a circumferential groove 13A provided on the inner peripheral surface 7b of the fitting hole 7a separately from the seal groove 7c, and a floating seat 8 provided on the fixed shaft portion 8a as a fixed seal portion. In the state in which the face seal portion 10 is formed, the through-hole 14A connects the circumferential groove 13A and the fixed flow path 8f.

  Next, FIG. 6 shows the rotary joint 1 of the fourth embodiment. In the fourth embodiment, the gap seal portion 12B is formed by fitting an O-ring 12a and a backup ring 12b, which are annular seal members, into a seal groove 7f provided on the inner peripheral surface 7b of the fitting hole 7a. . Here, the formation range of the seal groove 7f is set wider than usual, and the dimension is set so that the gap 7f * is secured on the upstream side in a state where the O-ring 12a and the backup ring 12b are fitted and mounted. And the through-hole 14B which connects the space | gap part 7f * and the fixed flow path 8f is provided in the fixed shaft part 8a. That is, in the fourth embodiment, the communication portion 15B is formed in the gap portion 7f of the seal groove 7f in a state where the floating seal 8 provided on the fixed shaft portion 8a is moved and the face seal portion 10 is formed. It consists of a through hole 14B provided by connecting *, the gap 7f * and the fixed flow path 8f.

  Next, FIG. 7 shows the rotary joint 1 of the fifth embodiment. In the fifth embodiment, the gap seal portion 12C is formed by fitting an O-ring 12a and a backup ring 12b, which are annular seal members, into a seal groove 8h provided on the outer peripheral surface 8d of the fixed shaft portion 8a. Here, similarly to the fourth embodiment, the gap 8h * is secured on the upstream side in a state where the formation range of the seal groove 8h is set wider than usual and the O-ring 12a and the backup ring 12b are fitted and mounted. The dimensions are set as follows. The fixed shaft portion 8a is provided with a through hole 14C that connects the gap portion 8h * and the fixed flow path 8f. That is, in the fifth embodiment, the communication portion 15C has a through hole provided by connecting the gap portion 8h * of the seal groove 8h provided in the fixed shaft portion 8a and the gap portion 8h * and the fixed flow path 8f. 14C.

  In the first to fifth embodiments shown in FIGS. 1 to 7, an example in which the fixed flow path 8f is provided in the fixed shaft portion 8a so as to penetrate the axial direction and open to the fitting hole 7a. Although shown, it is good also as a structure which provided the obstruction | occlusion part 8i which closes the side edge part of the fixed flow path 8f in the fixed shaft part 8a like the 6th Example shown in FIG. In this case, in the fitting hole 7a, an enlarged diameter portion 7e having an enlarged inner diameter corresponding to the upstream side end portion of the fixed shaft portion 8a is provided, and the fixed shaft portion 8a is within the range of the enlarged diameter portion 7e. A corresponding portion is provided with a through hole 19 that connects the channel gap s between the enlarged diameter portion 7e and the outer peripheral surface 8d and the fixed channel 8f.

  In this configuration, the fluid fed to the fitting hole 7a causes the fluid force F due to the fluid pressure to act on the closing portion 8i and flows into the fixed flow path 8f via the flow path gap s and the through hole 19 ( Arrow k), thereby supplying the fluid to the rotating flow path 4e. Also in this configuration, as in the examples shown in the first to fifth embodiments, it is possible to obtain the effect of eliminating the foreign matter 18 that adheres and accumulates in the sliding gap g. Although FIG. 8 shows an example in which this configuration is applied to the first embodiment shown in FIG. 1, this configuration can be similarly applied to the second to fifth embodiments. .

  As described above, in the present embodiment, the rotor 4 provided with the axial rotation flow path 4e and the floating sheet 8 provided with the axial fixed flow path 8f are coaxially arranged, and the first of the rotor 4 is arranged. In the rotary joint 1 having a configuration in which the seal surface 5b and the second seal surface 9b of the floating sheet 8 are brought into close contact with each other to form the surface seal portion 10, the floating sheet 8 is inserted into the fitting hole 7a provided in the housing member 7. The sliding gap g into which the fixed shaft portion 8a is fitted is sealed by the gap seal portion 12, and the fixed flow path provided in the axial direction inside the fixed shaft portion 8a on the upstream side of the sliding gap g of the gap seal portion 12 8 f and the sliding gap g are communicated with each other, and a communication portion 15 is provided that allows fluid to move from the sliding gap g to the fixed flow path 8 f.

  Thereby, the flow from the sliding gap g to the fixed flow path 8f can be induced by the ejector effect generated by the flow velocity of the fluid passing through the fixed flow path 8f, and the sliding between the fixed shaft portion 8a and the fitting hole 7a can be induced. It is possible to effectively prevent problems caused by foreign substances entering the moving gap g and solidifying by solidification with a simple configuration.

  The rotary joint of the present invention has a feature that it is possible to effectively prevent problems caused by foreign matter entering into the sliding gap between the fixed shaft portion and the fitting hole and accumulating and solidifying with a simple configuration. In addition, it is useful for applications in which fluid such as liquid coolant or air is fed to a rotating part such as a spindle of a machine tool.

DESCRIPTION OF SYMBOLS 1 Rotary joint 1a Rotating part 1b Fixed part 2 Spindle shaft 3 Casing member 4 Rotor 4e Rotating flow path 5 1st seal ring 5b 1st seal surface 8 Floating sheet 8a Fixed shaft part 8f Fixed flow path 9 2nd seal ring 9b Second seal surface 10 Surface seal portion 12.12A, 12B, 12C Gap seal portion 13, 13A, 13B, 13C Circumferential groove 14, 14A, 14B, 14C Through hole 15, 15A, 15B, 15C Communication portion 18 Foreign matter

Claims (6)

A rotating portion provided with an axial rotation channel and mounted on the rotating shaft and a fixed portion provided with an axial fixed channel and fixedly mounted on the holding member are coaxially arranged and supplied from a fluid supply source. A rotary joint that feeds fluid through a fixed flow path to a rotary flow path of the rotating unit that rotates around an axis;
A rotary seal portion having a first seal surface provided in the rotary portion and having the rotary flow channel open on a side end surface;
The fixed flow path has a fixed shaft portion that is formed in the axial direction and fits in a state in which a predetermined sliding clearance is maintained in a fitting hole provided in the holding member and movement in the axial direction is allowed. A fixed seal portion having a second seal surface in which the fixed flow path is open on one side end surface;
A gap seal portion that seals the sliding gap while allowing movement in the axial direction;
Forming the first seal surface and the second seal surface in close contact with each other by supplying the fluid from the fluid supply source into the fitting hole and pressing the other side of the fixed shaft portion. A sealed surface seal,
A communicating portion that is provided on the upstream side of the sliding gap of the gap seal portion, and that allows the fluid to move from the sliding gap to the fixed flow path by communicating the sliding gap and the fixed flow path; A rotary joint characterized by comprising   2. The communication portion includes a circumferential groove provided on an outer peripheral surface of the fixed shaft portion, and a through hole provided by connecting the circumferential groove and the fixed flow path. The described rotary joint.   The rotary joint according to claim 2, wherein the gap seal portion is formed by fitting an annular seal member into a seal groove provided on an outer peripheral surface of the fixed shaft portion.   In the state in which the communicating portion is formed with a circumferential groove provided on an inner peripheral surface of the fitting hole, and the fixed seal portion is moved to form the face seal portion in the fixed shaft portion. The rotary joint according to claim 1, further comprising a through hole that connects the circumferential groove and the fixed flow path.   The gap seal portion is formed by fitting an annular seal member into a seal groove provided on the inner peripheral surface of the fitting hole, and the communication portion is provided on the inner peripheral surface separately from the seal groove. And a through-hole that connects the circumferential groove and the fixed flow path in a state where the fixed seal portion provided on the fixed shaft portion moves to form the face seal portion. The rotary joint according to claim 4.   The gap seal portion is formed by fitting an annular seal member into a seal groove provided on an outer peripheral surface of the fixed shaft portion, and the communication portion includes the seal groove, the seal groove, and the fixed flow path. The rotary joint according to claim 1, wherein the rotary joint is formed by connecting through holes.

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