JP2008064274A - Rotation sealing mechanism for fluid feeding mechanism, and rotary joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation sealing mechanism for a fluid feeding mechanism capable of reasonably adjusting bearing pressure, and to provide a rotary joint to be used for the same. <P>SOLUTION: The rotary joint is used for the fluid feeding mechanism which feeds a plurality of types of fluid supplied from fluid supply sources 7a, 7b to a rotation part 2a rotating around the axis via a fixed part 2b. Herein, a stepped part 15g is provided on the outer peripheral face of a fixed shaft part 15b which is fitted to a fitting hole 13a of a housing member 13 and moved in the axial direction. When fluid of a type requiring a low sealing bearing pressure value is supplied, bearing pressure adjusting fluid introduced via a pressure opening hole 20 is operated on the stepped part 15g to give force to a fixed sealing part 15 in the opposite direction to the thrust of fluid pressure, thus reducing the sealing bearing pressure of a face sealing part 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotary seal mechanism in a fluid feeding mechanism for feeding fluid to a rotating portion, and a rotary joint used in the rotary seal mechanism.

  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.

  Incidentally, in recent years, air may be used as a cooling medium in addition to the water-based liquid coolant that has been conventionally used. By using air, there are advantages such that an appropriate cooling characteristic corresponding to the object to be cooled can be obtained, and that environmental measures such as waste liquid treatment after use are unnecessary and the environmental load can be reduced. When it is necessary to use liquid coolant and air separately with the same device, the rotary joint used as a fluid coupling is considered to be usable for both liquid and gas with different characteristics as fluid. In the past, a rotary joint of a type assuming such an application has been proposed (see, for example, Patent Document 1).

In the example shown in Patent Document 1, a rotary seal provided on the rotary shaft side is slidably contacted with a fixed seal to form a face seal portion that prevents fluid leakage, and a floating sheet that holds the fixed seal is rotated by fluid pressure. In the configuration in which the seal surface pressure is generated by pressing against the shaft side, a step portion is provided on the outer peripheral surface of the floating sheet, and fluid pressure is applied to the step portion. When the fluid to be used is a liquid coolant, a fluid pressure corresponding to the pressure of the liquid coolant acts on the stepped portion, and when the fluid is air, an air pressure corresponding to the air pressure acts. Thereby, the seal surface pressure can be changed according to the type of the target fluid, and the liquid coolant and the air can be selectively used by the same device.
Japanese Patent No. 3037900

  However, in the prior art shown in the above-mentioned patent document examples, due to the above-described configuration, there are the following problems in the configuration for changing the seal surface pressure. That is, in this prior art example, when a liquid coolant requiring a higher seal surface pressure value is targeted, the liquid coolant is introduced to the outer peripheral surface of the floating sheet in order to adjust the seal surface pressure. . For this reason, foreign matters such as sludge in the liquid coolant are likely to be caught in the sliding gap between the housing and the floating sheet, causing malfunction. In addition, since it is necessary to separately guide the liquid coolant for adjusting the surface pressure, there is a problem that piping work when the rotary joint is mounted is complicated and it is difficult to install simply and easily. As described above, in the rotary seal mechanism using the rotary joint that can be used for a plurality of types of fluids having different seal surface pressure values, the structure of the surface pressure adjustment mechanism is not necessarily rational, and operation failure or mounting is difficult. There were difficulties in workability.

  The present invention has been made in view of such problems, and provides a rotary seal mechanism in a fluid feed mechanism capable of rationally adjusting the surface pressure and a rotary joint used in the rotary seal mechanism. Objective.

  The rotary seal mechanism in the fluid feeding mechanism of the present invention comprises a rotating part provided with an axial rotational flow path and a fixed part provided with an axial fixed flow path arranged coaxially, and a plurality of fluid supply sources A rotary seal mechanism in a fluid feed mechanism that selectively feeds a plurality of types of fluids supplied from a rotary flow channel of the rotating unit that rotates about an axis via the fixed flow channel, A rotary seal portion having a first seal surface provided on the side end surface of the rotary flow channel and a fixed shaft portion formed by penetrating the fixed flow channel in the axial direction. A fixed seal portion having a second seal surface with the fixed flow path opened on a side end surface thereof, and a housing member constituting the main body of the fixed portion, and the fixed shaft portion is allowed to move in the axial direction. The fitting hole to be fitted in a state, and the fixed shaft portion, A step portion that is divided into a large-diameter portion that is provided with a shaft diameter that fits into the joint hole, and a small-diameter portion that is provided close to the second seal surface side with a shaft diameter smaller than the large-diameter portion; A first shaft seal portion and a second shaft for sealing a gap between the inner peripheral surface of the fitting hole and the small diameter portion and the large diameter portion in a state where the fixed shaft portion is fitted in the fitting hole, respectively. Between the seal portion and the first shaft seal portion and the second shaft seal portion, a gap is formed between the small diameter portion and the inner peripheral surface of the fitting hole, and the surface pressure is adjusted in the gap. A pressure opening for feeding a fluid, and selectively supplying any one of the plurality of types of fluid from the plurality of fluid supply sources into the fitting hole, and the rotation through the fixed flow path. A fluid supply means for feeding a fluid for adjusting the surface pressure to the pressure opening, The fixed seal portion is pressed against the rotary seal portion by applying a fluid pressure of the supplied fluid to the side end surface on the side, so that the first seal surface and the second seal surface are mutually connected. The surface sealing portion is formed in close contact with the surface, and the surface pressure adjusting fluid is fed into the gap through the pressure opening to cause the surface pressure adjusting fluid pressure to act on the stepped portion. A force in the direction opposite to the pressing force due to the fluid pressure is applied to the seal portion to reduce the seal surface pressure of the face seal portion.

  The rotary according to the present invention is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and a fixed portion provided with an axial fixed flow path, and a fluid supplied from a fluid supply source is axially centered. A rotary joint used in a fluid feed mechanism that feeds through a fixed flow path to a rotary flow path of the rotary section that rotates around, wherein the rotary flow path is provided at a side end surface of the rotary section. A rotary seal portion having a first seal surface, a fixed shaft portion formed so that the fixed flow path penetrates in the axial direction, and the fixed flow path is opened on a side end surface on one side. A fixed seal portion having a sealing surface, a fitting hole provided in a housing member constituting a main body of the fixed portion and fitting the fixed shaft portion in a state in which movement in the axial direction is allowed, and the fixed shaft The large portion provided with a shaft diameter that fits into the fitting hole. In a state where the fixed shaft portion is fitted in the fitting hole and a step portion that is divided into a small diameter portion that is provided close to the second seal surface side with a smaller shaft diameter than the large diameter portion The first shaft seal portion and the second shaft seal portion that seal the gap between the inner peripheral surface of the fitting hole and the small diameter portion and the large diameter portion, respectively, and the first shaft seal portion and the second shaft seal portion. A pressure opening that opens a gap between the small diameter portion and the inner peripheral surface of the fitting hole between the shaft seal portions, and supplies a surface pressure adjusting fluid into the gap. By supplying the fluid from the fluid supply source into the fitting hole, applying fluid pressure to the other side end surface of the fixed shaft portion, and pressing the fixed seal portion against the rotary seal portion The first seal surface and the second seal surface are brought into close contact with each other to form a surface seal portion, and the pressurization By supplying the surface pressure adjusting fluid into the gap through the hole and causing the surface pressure adjusting fluid pressure to act on the stepped portion, a force in a direction opposite to the pressing force by the fluid pressure is applied to the fixed seal portion. It is configured to act and reduce the seal surface pressure of the face seal portion.

  According to the present invention, the stepped portion is provided on the outer peripheral surface of the fixed shaft portion that is fitted in the fitting hole of the housing member and moves in the axial direction, and the surface pressure adjusting fluid introduced through the pressure opening is supplied to the stepped portion. Surface pressure adjustment fluid pressure is applied to the stepped portion, and the force in the direction opposite to the pressing force by the fluid pressure is applied to the fixed seal portion to reduce the seal surface pressure of the surface seal portion, thereby reducing the surface pressure. The adjustment may be performed only for a type of fluid that is required to have a low sealing surface pressure value such as air. These types of fluids are easy to pipe and are less contaminated with foreign matter.Therefore, the surface pressure adjustment is rationally performed, the workability during installation is excellent, and the rotation seal mechanism in the fluid feeding mechanism is less likely to malfunction during use. A rotary joint used in this rotary seal mechanism can be realized.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration explanatory view of a fluid feeding mechanism in one embodiment of the present invention, FIG. 2 is a sectional view of a rotary joint used in a rotary seal mechanism of the fluid feeding mechanism in one embodiment of the present invention, FIG. FIG. 4 is a structural explanatory view of a housing member of a rotary joint in one embodiment of the present invention, FIG. 4 is a structural explanatory view of a floating sheet of a rotary joint in one embodiment of the present invention, and FIGS. It is operation | movement explanatory drawing of the rotary joint in embodiment.

  First, the overall configuration of the fluid feed mechanism 1 will be described with reference to FIG. In FIG. 1, a fluid feeding mechanism 1 has a function of feeding a cooling fluid supplied from a fluid supply unit 7 to a rotating shaft such as a spindle of a machine tool. A rotary joint 2 formed by coaxially arranging a rotating portion 2a provided and a fixed portion 2b provided with an axial fixed flow path is mainly used.

  The rotating portion 2a is fastened to a fastening hole 4a of the spindle shaft 4, and the spindle shaft 4 is rotated around an axis A in an insertion hole 5a provided in the frame 5 by being driven to rotate by a motor built in the spindle. At the same time, the axial movement is performed by the clamp / unclamp cylinder. The fixing portion 2b is fitted and mounted in a mounting hole 3a provided in the cylindrical block-shaped casing 3, and the casing 3 is detachably fastened to the frame 5 by fastening means (not shown) such as bolts. Accordingly, the fixed portion 2b is arranged coaxially with the rotating portion 2a.

  The fluid supply unit 7 includes a first fluid supply source 7a and a second fluid supply source 7b. The first fluid supply source 7a supplies liquid coolant, and the second fluid supply source 7b supplies air. . Here, the air supplied from the second fluid supply source 7b is supplied as general factory air, dry air obtained by treating factory air with a dryer, or oil mist-containing air mixed with a predetermined amount of oil mist. Various forms can be selected according to the object.

  The fluid supplied from the fluid supply unit 7 is selectively supplied by a fluid supply circuit 6 including a first on-off valve 6a, a second on-off valve 6b, and a check valve 6c. That is, the first fluid supply source 7a is connected to the flow passage hole 3b of the casing 3 through the first on-off valve 6a by the coolant pipe 8a made of a pressure-resistant pipe, and opens and closes the first on-off valve 6a. Thus, the supply of the liquid coolant supplied from the first fluid supply source 7a to the fixed portion 2b can be turned on and off.

  The second fluid supply source 7b is connected to the coolant pipe 8a via the second on-off valve 6b and the check valve 6c by an air pipe 8b made of a resin tube or the like, and similarly the second on-off valve 6b. By opening / closing the air supply, it is possible to turn on / off the supply of air supplied from the second fluid supply source 7b to the fixed portion 2b. Here, the check valve 6c is provided in order to prevent the backflow of fluid from the coolant pipe 8a side to the air pipe 8b. Furthermore, the air piping 8c branched on the downstream side of the second opening / closing valve 6b is connected to a pressurization opening 20 (see FIG. 2) provided in the fixed portion 2b, and the fluid to be supplied is air. In this case, as described later, air as a surface pressure adjusting fluid is fed to the fixed portion 2b.

  That is, in the above configuration, by switching the first opening / closing valve 6a and the second opening / closing valve 6b in accordance with the object to be processed in the machine tool, the type of the cooling fluid to be fed can be selected and switched. At the same time, the surface pressure adjusting fluid can be supplied to the fixed portion 2b for the specific fluid. Therefore, the fluid supply circuit 6 shown in FIG. 1 selectively supplies any one of a plurality of types of fluids from a plurality of fluid supply sources into the fitting hole 13a, and rotates the rotation channel via the fixed channel 15d. 10a, and a fluid supply means for supplying the surface pressure adjusting fluid to the pressurizing hole 20. The rotary joint 2 and the fluid supply circuit 6 pass a plurality of types of fluids supplied from a plurality of fluid supply sources to the rotation channel of the rotation unit 2a that rotates about the axis through the fixed channel of the fixing unit 2b. A rotary seal mechanism having a function of selectively feeding is configured.

  Next, the detailed structure of the rotary joint 2 will be described with reference to FIGS. In FIG. 2, the rotating part 2a is mainly composed of a rotor 10 having a rotating flow path 10a penetrating in an axial direction in an axial center part and a fastening screw part 10b provided on an outer surface. By screwing the fastening screw portion 10b into the fastening hole 4a, the rotor 10 is screwed to the spindle shaft 4, and the screw fastening portion is sealed by the O-ring 12. As a result, the rotating flow path 10 a communicates with the flow path hole 4 b of the spindle shaft 4.

  An annular ring-shaped convex portion 10c is formed on the side end surface on the right side (the side facing the fixed portion 2b) of the rotor 10 so as to surround the aperture surface of the rotating flow path 10a. A first seal ring 11 is fixed to a recess formed inside the annular protrusion 10c. The first seal ring 11 is formed by molding a hard material rich in wear resistance such as ceramic into an annular shape having an opening 11a in the center, and the first seal surface 11b finished to be a smooth surface. It fixes to the cyclic | annular convex part 10c in the state made into the outer surface side. In this state, the rotating flow path 10a communicates with the opening 11a and opens to the first seal surface 11b. That is, the rotor 10 to which the first seal ring 11 is fixed is a rotary seal portion having a first seal surface 11a provided in the rotary portion 2a and having a rotary flow path 10a opened on a side end surface.

  Next, the structure of the fixing portion 2b attached to the casing 3 will be described. A mounting hole 3a provided in communication with the flow path hole 3b is opened in the mounting surface 3c of the casing 3, and the mounting hole 3a is provided in a cylindrical housing member 13 constituting the main body of the fixed portion 2b. The mounting convex portion 13b is fitted. Then, as shown in FIG. 3, the housing member 13 is bolted to the casing 3 by being screwed into a screw hole 3 d provided in the mounting surface 3 c by a plurality of equally arranged bolts 14, and is mounted by an O-ring 16. The fitting part of the convex part 13b is sealed. A fitting hole 13a penetrating in the axial direction is provided at the center of the housing member 13, and O-ring grooves 13c and 13d are provided on the inner peripheral surface of the fitting hole 13a.

  In FIG. 2, the floating sheet 15 is provided with a disk-shaped flange portion 15a on one side (the side facing the rotating portion 2a in the figure), and a fixed channel 15d is formed through the other side in the axial direction. The shape has a fixed shaft portion 15b. The fixed shaft portion 15b is fitted in the fitting hole 13a of the housing member 13 in a state where movement in the axial direction is allowed.

  An annular annular convex portion 15c is formed on the side end surface of the left side of the flange portion 15a (the side facing the rotating portion 2a) so as to surround the opening surface of the fixed flow path 15d, and the annular convex portion 15c is formed. A second seal ring 17 is fixed to a recess formed on the inside. The second seal ring 17 is formed by molding a hard material similar to that of the first seal ring 11 into an annular shape having an opening 17a at the center, and the second seal surface 17b finished to be a smooth surface. It fixes to the annular convex part 15c in the state made into the outer surface side. In this state, the fixed flow path 15d communicates with the opening 17a and opens to the second seal surface 17b. That is, the floating sheet 15 to which the second seal ring 17 is fixed has a fixed shaft portion 15b formed with a fixed flow path 15d penetrating in the axial direction, and the second end of the rotary flow path 15d is opened on the side end surface. This is a fixed seal portion having a sealing surface 17b.

  The detailed shape of the floating sheet 15 will be described with reference to FIG. The flange portion 15 a is provided with a notch portion 15 j at an even position corresponding to the position of the bolt 14 shown in FIG. 3, and the flange portion 15 a is attached to the casing 3 of the housing member 13 with the floating sheet 15 being attached to the housing member 13. Bolts can be fastened. A plurality of concave portions 17c for lubricating the seal surface are formed on the second seal surface 17b of the second seal ring 17. In the state where the second seal surface 17b is in close contact with the first seal surface 11b to form a surface seal portion, the recess 17c allows the fluid in the opening 17a to flow through the first seal surface 11b and the second seal surface 17b. It has the function of improving the lubricity by guiding to the mutual sliding surfaces. The concave portion 17c is not essential and may not be provided depending on sliding characteristics such as the characteristics of the target fluid, the seal surface pressure value, and the rotational speed used.

  The fixed shaft portion 15b fits larger than the outer diameter D1 with a small diameter portion 15e having an outer diameter D1 provided at a position close to the second seal ring 17 by a step portion 15g provided at an intermediate portion in the longitudinal direction. It is divided into a large-diameter portion 15f provided with an outer diameter D2 of a size that fits into the joint hole 13a. Here, the side area on the side end face 15h of the large-diameter portion 15f, that is, the side area excluding the portion of the fixed flow path 15d with the inner diameter d from the circle with the outer diameter D2 is A1, and the outer diameter D2 at the step portion 15g. The side area excluding the cross-sectional area of the small diameter portion 15e from the circle is A2.

  As shown in FIG. 2, in a state where the fixed shaft portion 15b is fitted in the fitting hole 13a, the O-ring grooves 13c and 13d (see FIG. 3) are the small diameter portion 15e and the large diameter portion 15f in the fixed shaft portion 15b, respectively. When the O-ring 21a and the O-ring 22a are mounted in the O-ring grooves 13c and 13d, respectively, the first shaft seal portion 21 and the second shaft seal portion 22 are configured. The first shaft seal portion 21 and the second shaft seal portion 22 are configured such that the inner peripheral surface of the fitting hole 13a, the small diameter portion 15e, and the large diameter portion 15f in a state where the fixed shaft portion 15b is fitted in the fitting hole 13a. Seal the gaps between them. In this state, the pressure of the fluid in the fitting hole 13a acts on the side end face 15h whose pressure receiving area is A1.

  The housing member 13 is provided with a pressurizing hole 20 connected to the air pipe 8c shown in FIG. 1. The pressurizing hole 20 includes a first shaft seal portion 21 and a second shaft seal portion 22. In between, it opens to the annular clearance 23 between the small diameter part 15e and the inner peripheral surface of the fitting hole 13a. In this state, air as a surface pressure adjusting fluid is supplied into the annular gap 23 by supplying air from the second fluid supply source 7b via the air pipe 8c. The fluid pressure in the annular gap 23 acts on the step portion 15g having a pressure receiving area A2.

  By supplying the fluid to be supplied into the flow path hole 3b, this fluid pressure acts on the side end face 15h on the other side (opposite side of the second seal ring 17) of the fixed shaft portion 15b. Accordingly, the fixed shaft portion 15b slides toward the rotating portion 2a in the fitting hole 13a, and the second seal ring 17 is pressed against the first seal ring 11. This pressing force causes the second seal surface 17b and the first seal surface 11b to be in close contact with each other, thereby causing leakage of the fluid supplied from the fixed channel 15d to the rotating channel 10a that is rotating around the axis. A face seal portion 18 to prevent is formed. In the sliding of the floating sheet 15, a bolt 24 screwed into the screw hole 15 i (FIG. 4) of the flange portion 15 a and a cylindrical collar 25 that encloses the bolt 24 are provided in the housing member 13 in the axial direction. By sliding inside, the movement of the floating sheet 15 in the axial direction is guided and the rotation around the shaft is prevented.

  In the operating state of the rotary joint 2, the sealing surface of the face seal portion 18 is contacted and separated by the advancement of the floating sheet 15 due to the pressure of the supplied fluid and the advancement and retraction operation of the spindle shaft 4. That is, when the floating sheet 15 is retracted and the first seal surface 11b and the second seal surface 17b are separated from each other, fluid is fed into the fitting hole 13a through the flow path hole 3b. As a result, the floating sheet 15 moves forward (in the direction of arrow a), the first seal surface 11b abuts on the second seal surface 17b, and the surface seal portion 18 is formed.

  When the spindle shaft 4 moves forward (arrow d direction) relative to the fixed portion 2b, the floating sheet 15 moves backward (arrow b direction), and the flange portion 15a returns to a position close to the housing member 13. . Then, by relatively retreating the spindle shaft 4 (in the direction of the arrow c) from this state, the first seal surface 11b and the second seal surface 17b are returned to a separated state.

  Next, with reference to FIG. 5 and FIG. 6, the operation of the rotary joint 2 when a plurality of types of fluids are supplied will be described. 5 and 6 show cases where fluids to be fed are liquid coolant and air, respectively. First, a case where the supplied fluid is a liquid coolant will be described.

  In FIG. 5, the liquid coolant (pressure P1) is supplied from the first fluid supply source 7a into the fitting hole 13a by opening the first on-off valve 6a. The liquid coolant flows to the rotary flow path 10a via the fixed flow path 15d. At this time, the pressure P1 acts on the side end face 15h in the fitting hole 13a, and the pressure receiving area A1 of the side end face 15h (see FIG. 4). The fluid force F (L) corresponding to the above acts on the fixed shaft portion 15b. A pressing force F1 obtained by subtracting the sliding resistances f1 and f2 by the first shaft seal portion 21 and the second shaft seal portion 22 from the fluid force F (L) acts on the face seal portion 18, and this pressing force is applied. A value obtained by dividing F1 by the seal area where the first seal surface 11b and the second seal surface 17b are in contact is the seal surface pressure value of the surface seal portion 18.

  Next, the case where the fluid supplied is air will be described. In FIG. 6, by opening the second opening / closing valve 6b, air (pressure P2) is fed into the fitting hole 13a from the second fluid supply source 7b through the check valve 6c. At the same time, air (pressure P <b> 2) is similarly supplied to the pressure opening 20. The air supplied into the fitting hole 13a flows to the rotary flow path 10a via the fixed flow path 15d. At this time, the pressure P2 acts on the side end face 15h in the fitting hole 13a, and the pressure receiving area A1 ( Fluid force F (G1) commensurate with (see FIG. 4) acts on the fixed shaft portion 15b.

  Further, the air supplied to the pressure opening 20 acts on the step portion 15g in the annular gap 23, and the fluid force F (G2) corresponding to the pressure receiving area A2 (see FIG. 4) becomes the fluid force F (G1). ) Acts in the opposite direction. A pressing force F2 obtained by subtracting the aforementioned sliding resistances f1 and f2 and the fluid force F (G2) from the fluid force F (G1) acts on the face seal portion 18. In this case, a value obtained by dividing the pressing force F2 by the seal area described above becomes the seal surface pressure value.

  Here, the seal surface pressure in the rotary joint will be described. In a rotary seal mechanism that seals a fluid by bringing the rotary sliding surface into close contact, it is necessary to set an appropriate seal surface pressure value according to the characteristics of the target fluid and the supply pressure. For example, as shown in the present embodiment, when a liquid coolant that is often supplied at a relatively high supply pressure (for example, 1 Mpa to 20 Mpa) is a target, the supply pressure is used to prevent leakage from the sealing surface as much as possible. The seal surface pressure value at the same level as the pressure is set.

  On the other hand, when air used at a low supply pressure (for example, 0.1 Mpa to 1 Mpa) is used as a target, the seal surface pressure is made half or less of the supply pressure in order to prevent wear due to sliding of the seal surface as much as possible. Is required. This is because when a liquid is to be supplied, a thin film of liquid that has entered the seal surface acts as a lubricating film that lubricates the sliding surface, whereas in the case of air, lubrication such as oil mist is mixed. This is generally due to the absence of such a lubrication action, unless measures are taken.

  As described above, when fluids having different supply pressures or desired seal surface pressure values are to be supplied, it is necessary to change the ratio of the seal surface pressure value to the supply pressure in accordance with the fluid. Here, since the seal area of the face seal portion is common to all fluids, the pressure receiving area where the fluid pressure acts depends on the type of fluid in order to change the ratio of the seal face pressure value to the supply pressure. Need to be different. In the present embodiment, as shown in FIG. 6, in the case of targeting air for which a low seal surface pressure value is required, the substantial pressure receiving area that generates a pressing force acting on the surface seal portion 18 is (A1- A2), which is different from the pressure receiving area A1 when the liquid coolant is targeted.

  That is, in the case shown in FIG. 6, air as a surface pressure adjusting fluid is fed into the annular gap 23 through the pressure opening 20, and air pressure (surface pressure adjusting fluid pressure) is applied to the step portion 15g. By acting, a fluid force F (G2) in a direction opposite to the pressing force F (G1) due to the fluid pressure acting on the side end surface 15h is applied to the floating sheet 15 that is the fixed seal portion, and the seal of the face seal portion 18 is applied. The surface pressure is reduced.

  In designing the rotary joint 2, the seal surface pressure value of the face seal portion 18 by the pressing force F 1 shown in FIG. 5 is an appropriate value for the liquid coolant at the pressure P 1, and the pressing force F 2 shown in FIG. The size of each part is set so that the seal surface pressure value of the surface seal part 18 by the above becomes an appropriate value for the air of the pressure P2. That is, the diameters of the small-diameter portion 15e and the large-diameter portion 15f are based on the above-mentioned pressures P1, P2, appropriate seal surface pressure values for the respective fluids as given design numerical data, the above-described sliding resistances f1, f2, and the like. The dimensions D1 and D2, the diameter dimension d of the fixed flow path 15d, and the like are determined.

  In actual design, it is most suitable to apply the present invention to liquid coolant and air whose supply pressure is in the range of (1 Mpa to 20 Mpa) and (0.1 Mpa to 1 Mpa), respectively. In this case, the recommended values of the ratio of the seal surface pressure value to the supply pressure are preferably (0.6 to 1.2) and (0.1 to 0.5), respectively.

  In other words, in the rotary joint 2 shown in the present embodiment, the surface pressure adjusting fluid is used only when a fluid that is required to have a low seal surface pressure value among a plurality of types of fluids to be processed. Adjust the surface pressure with. For example, as shown in the present embodiment, when the supplied fluid is liquid coolant and air, when the supplied fluid is a liquid coolant, the surface pressure adjustment is not required, and the supplied fluid is more than the liquid coolant. Only when the air is required to have a low seal surface pressure value, a form in which air is supplied into the pressure opening 20 as the surface pressure adjusting fluid is adopted. And even when air having no lubricity as described above is targeted by this surface pressure adjustment, the rotational sealing function can be performed without supplying lubricant such as oil to the sliding surface of the face seal portion 18 from the outside. Can be secured.

  As described above, in the surface pressure adjustment of the surface seal portion 18 in the rotary joint 2, the surface pressure adjustment by the surface pressure adjustment fluid is performed only when the fluid required to have a low seal surface pressure value is targeted. By adopting, the following effects are obtained.

  A fluid that requires a high seal surface pressure value generally has a high pressure, and a piping system that feeds such a fluid requires pressure-resistant piping. Further, when the coolant liquid of a machine tool is a target, it is difficult to avoid the contamination of foreign matters due to circulation, so that there is a difficulty in using it as a fluid for adjusting the surface pressure. Even when such a fluid is included in the supply target, according to the present invention, it is not necessary to adjust the surface pressure for a fluid having a high seal surface pressure value. There is no occurrence of problems that have occurred in the prior art used.

  That is, in the configuration in which the liquid coolant is introduced to the outer peripheral surface of the floating sheet in order to adjust the seal surface pressure as in the prior art example shown in Patent Document 1, foreign matters such as sludge in the liquid coolant are placed in the sliding gap. It is difficult to bite. In contrast, in the example shown in the present embodiment, it is not necessary to use liquid coolant for surface pressure adjustment, and surface pressure adjustment is performed using air only when air with a low seal surface pressure value is targeted. Therefore, it is possible to prevent malfunction due to biting of foreign matter. Furthermore, by using air as the fluid for adjusting the surface pressure, there is no need for pressure-resistant piping for liquid coolant, and it is only necessary to add air piping that is easy to work and simple, and piping work when installing a rotary joint is easy. Thus, workability can be improved.

  Further, in the configuration shown in the present invention, when the liquid coolant is a target, the operation of the surface pressure adjusting fluid is not required. Therefore, the conventional dedicated rotary for a single fluid is essentially used. There is no difference from the joint. Therefore, even if a malfunction occurs in the surface pressure adjusting fluid piping circuit, etc., there is no effect on the operation for the liquid coolant, stable sealing performance is ensured, and damage to the machine tool body due to liquid leakage Can be prevented. The air pressure adjustment fluid is operated while the air is less affected by the leak from the face seal portion. In this case, even if the above-mentioned problems occur, only the seal parts are quickly worn out. No damage to the machine body.

  As described above, by adopting the configuration shown in the present embodiment, in the conventional rotary seal mechanism using the rotary joint that can be used for a plurality of types of fluids having different seal surface pressure values, It is possible to rationally adjust the surface pressure by eliminating problems caused by the configuration.

  In the present embodiment, the case where the fluid supplied from the fluid supply unit 7 is either liquid coolant or air is shown. Only when air is used as the supplied fluid, the surface pressure adjusting fluid is used. An example in which air is supplied to the pressure opening 20 is shown. Of course, the type of fluid is not limited to only liquid coolant or air, but may be a combination of a plurality of fluids having different ratios between the supply pressure and the appropriate seal surface pressure value required for the face seal portion 18. Thus, the present invention is applicable.

  Examples of such fluid types and combinations include air / pure water, air / vacuum, air / slurry, and slurry / pure water. Even in these combinations, the fluid for which a low seal surface pressure value is required is used as the surface pressure adjusting fluid. Furthermore, a fluid other than the fluid to be supplied may be used as the surface pressure adjusting fluid. That is, when the fluid to be supplied is introduced from the pressurizing hole 20 due to the characteristics of the fluid, for example, the normal operation of the surface pressure adjusting mechanism is hindered, such as the engagement of the slurry component into the sliding gap. It is also possible to use a fluid that is easy to handle, such as water, and has little damage due to leakage as a surface pressure adjusting fluid for the purpose of adjusting the surface pressure only. In this case, the pressure of the surface pressure adjusting fluid is arbitrarily set according to a desired adjustment range.

  The rotary seal mechanism and the rotary joint in the fluid feeding mechanism of the present invention have a feature that the surface pressure can be rationally adjusted, and a plurality of types such as liquid coolant and air are provided on a rotating part such as a spindle of a machine tool. Useful for fluid delivery applications.

Structure explanatory drawing of the fluid feeding mechanism in one embodiment of this invention Sectional drawing of the rotary joint used for the rotation sealing mechanism of the fluid supply mechanism in one embodiment of this invention Structure explanatory drawing of the housing member of the rotary joint in one embodiment of the present invention Structure explanatory drawing of the floating seat of the rotary joint in one embodiment of the present invention Operational explanatory diagram of a rotary joint in an embodiment of the present invention Operational explanatory diagram of a rotary joint in an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid feed mechanism 2 Rotary joint 2a Rotating part 2b Fixed part 4 Spindle shaft 6 Fluid supply means 7 Fluid supply part 7a 1st fluid supply source 7b 2nd fluid supply source 10 Rotor 10a Rotating flow path 11 1st seal | sticker Ring 11b First seal surface 13 Housing member 13b Fitting hole 15 Floating sheet 15a Flange portion 15b Fixed shaft portion 15d Fixed flow path 15e Small diameter portion 15f Large diameter portion 15g Stepped portion 17 Second seal ring 17b Second seal surface 18 Face seal portion 20 Pressure opening 21 First shaft seal portion 22 Second shaft seal portion 23 Annular gap

Claims (3)

The rotating part provided with the axial rotation flow path and the fixed part provided with the axial fixed flow path are coaxially arranged, and a plurality of types of fluids supplied from a plurality of fluid supply sources are arranged around the axis. A rotary seal mechanism in a fluid feed mechanism that selectively feeds through a fixed flow path to a rotary flow path of the rotating part that rotates;
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;
A fixed seal portion having a fixed shaft portion formed by penetrating the fixed flow channel in the axial direction, and having a second seal surface in which the fixed flow channel is opened on one side end surface;
A fitting hole provided in a housing member that constitutes the main body of the fixed portion, and the fixed shaft portion is fitted in a state in which movement in the axial direction is allowed;
A large-diameter portion provided with a shaft diameter that fits the fixed shaft portion into the fitting hole, and a small-diameter portion provided near the second seal surface with a shaft diameter smaller than the large-diameter portion. A step portion to be divided into,
In a state where the fixed shaft portion is fitted in the fitting hole, a first shaft sealing portion and a second shaft sealing each of the gaps between the inner peripheral surface of the fitting hole and the small diameter portion and the large diameter portion. A shaft seal,
An opening is formed in a gap between the first shaft seal portion and the second shaft seal portion between the small diameter portion and the inner peripheral surface of the fitting hole, and a surface pressure adjusting fluid is fed into the gap. Pressurizing apertures,
One of the plurality of types of fluids is selectively supplied from the plurality of fluid supply sources into the fitting hole, and is supplied to the rotating flow path via the fixed flow path, and the pressurization Fluid supply means for feeding the surface pressure adjusting fluid to the opening,
By applying the fluid pressure of the supplied fluid to the other side end surface of the fixed shaft portion to press the fixed seal portion against the rotary seal portion, the first seal surface and the second seal surface The seal surface is brought into close contact with each other to form a surface seal portion,
By feeding the surface pressure adjusting fluid into the gap through the pressure opening and causing the surface pressure adjusting fluid pressure to act on the stepped portion, the fixed seal portion is opposite to the pressing force by the fluid pressure. A rotary seal mechanism in a fluid feed mechanism, wherein a force in a direction is applied to reduce a seal surface pressure of the face seal portion.   The supplied fluid is either liquid coolant or air, and only when air is used as the supplied fluid, air is supplied to the pressurized opening as the surface pressure adjusting fluid. The rotary seal mechanism in the fluid feeding mechanism according to claim 1. The rotating part provided with an axial rotation flow path and the fixed part provided with an axial fixed flow path are arranged coaxially, and rotates the fluid supplied from a fluid supply source around the axis. A rotary joint used in a fluid feeding mechanism that feeds the rotating flow path through the fixed flow path,
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;
A fixed seal portion having a fixed shaft portion formed by penetrating the fixed flow channel in the axial direction, and having a second seal surface in which the fixed flow channel is opened on one side end surface;
A fitting hole provided in a housing member that constitutes the main body of the fixed portion, and the fixed shaft portion is fitted in a state in which movement in the axial direction is allowed;
A large-diameter portion provided with a shaft diameter that fits the fixed shaft portion into the fitting hole, and a small-diameter portion provided near the second seal surface with a shaft diameter smaller than the large-diameter portion. A step portion to be divided into,
In a state where the fixed shaft portion is fitted in the fitting hole, a first shaft sealing portion and a second shaft sealing the gap between the inner peripheral surface of the fitting hole and the small diameter portion and the large diameter portion, respectively. A shaft seal,
An opening is formed in a gap between the first shaft seal portion and the second shaft seal portion between the small diameter portion and the inner peripheral surface of the fitting hole, and a surface pressure adjusting fluid is fed into the gap. A pressure opening to
Supplying the fluid from the fluid supply source into the fitting hole and applying fluid pressure to the other side end surface of the fixed shaft portion to press the fixed seal portion against the rotary seal portion; The first seal surface and the second seal surface are brought into close contact with each other to form a surface seal portion,
By feeding the surface pressure adjusting fluid into the gap through the pressure opening and causing the surface pressure adjusting fluid pressure to act on the stepped portion, the fixed seal portion is opposite to the pressing force by the fluid pressure. A rotary joint characterized in that a force in a direction is applied to reduce a seal surface pressure of the face seal portion.

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