JP5221249B2 - Rotary joint - Google Patents

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 (refer patent document 1, 2). As a result, a fluid having a predetermined pressure and a predetermined flow rate is continuously supplied from the fluid supply pipe to the rotating portion in a rotating state via the rotary joint.
Japanese Utility Model Publication No. 62-163685 JP 2004-205037 A

  In the fluid feeding mechanism as described above, the flow rate supplied via the rotary joint may vary greatly depending on the state of the machine side such as a machine tool. In other words, a pump with a sufficient capacity is used as the fluid supply source, so if an unexpected situation such as a fluid injection nozzle dropping off occurs on the supply side, it will be out of the range of pressure and flow rate assumed as the usage range. May flow to the supplied side through the rotary joint. Such large fluctuations in pressure and flow rate are factors that impede normal operation of the coolant supply piping system, and therefore it is required to suppress fluctuations as much as possible. However, the conventional rotary joints including the above-mentioned patent document examples have not been provided with a function for preventing such fluctuations. For this reason, in order to stabilize the flow rate of the entire coolant supply system, it is necessary to arrange a flow rate adjustment valve or the like on the upstream side or the downstream side of the rotary joint, resulting in a complicated configuration of the coolant supply piping system. It was.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a rotary joint that can prevent fluctuations in the flow rate of the coolant supply piping system with a simple configuration.

The rotary joint of the present invention is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds fluid supplied from a supply source to a rotating flow path of the rotating unit that rotates about an axis through the fixed channel, the rotary joint being provided on the rotating unit on the side end surface. A rotary seal portion having a first seal surface with an open passage; flow rate limiting means provided in the rotary seal portion for limiting the flow rate of fluid flowing in the rotary flow path; and provided on the fixed portion on one side. A fixed seal portion having a second seal surface with the fixed flow path opened on a side end surface thereof, and provided in the other side of the fixed seal portion, is moved in the axial direction in a fitting hole provided in the casing member. In an acceptable state And a fixing shank which case, the fixed channel is formed through the fixed shaft portion in the axial direction in a straight tubular shape, the fluid from the fluid source to the fitting hole The first seal surface and the second seal surface are supplied by 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. And the flow rate restricting means is provided at the downstream side of the face seal portion in the rotary seal portion, and the flow rate restricting means further includes the rotary flow path. Even when the downstream side of the rotary seal portion is completely opened, the flow path cross-sectional area of the straight seal pipe is locally reduced to 75% or less of the cross-sectional area of the straight pipe-shaped fixed flow path. In order to suppress the pressure loss to 10% or less of the fluid pressure To limit the amount.

  According to the present invention, in a rotary joint having a configuration in which a rotating portion provided with an axial rotation flow path and a fixed portion provided with an axial fixed flow path are coaxially arranged, the rotary joint is rotated on a side end surface. A coolant supply pipe with a simple structure is provided by providing a flow rate limiting means for limiting the flow rate of the fluid flowing in the rotary flow path by generating a pressure loss in the rotary seal portion having the first seal surface with the flow path opened. Variations in the flow rate of the system can be prevented.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a rotary joint (first example) according to an embodiment of the present invention, FIG. 2 is an operation explanatory view of the rotary joint (first example) according to one embodiment of the present invention, and FIG. 4 is a cross-sectional view of a rotary joint (second example) according to an embodiment of the present invention, FIG. 4 is a cross-sectional view of a rotary joint (third example) according to an embodiment of the present invention, and FIG. FIG. 6 is a cross-sectional view of a rotary joint (fifth example) according to an embodiment of the present invention.

  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 fixing portion 1b is fitted and mounted in a fitting hole 3a provided in the cylindrical block-shaped casing member 3, and the casing (not shown) is inserted into a casing (not shown) through which the spindle shaft 2 is inserted by a fastening means such as a bolt. By fastening the member 3 detachably, the fixed portion 1b is arranged coaxially with the rotating portion 1a. A gas such as a liquid coolant or cooling air is selectively fed from the fluid supply part (not shown) to the fitting hole 3a (arrow a).

  Next, the detailed structure of the rotary joint 1 will be described. In FIG. 1, the rotating part 1 a is mainly composed of a rotor 4 mounted on the spindle shaft 2. The rotor 4 has a shape in which a flange portion 4b having an outer diameter larger than that of the rotation shaft portion 4a is provided at one end of the rotation shaft portion 4a, and a rotation flow path 4e is provided in the axial direction in the axial center portion. Yes. 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.

A throttle portion 4f is provided at the downstream end of the rotation shaft portion 4a. The throttle portion 4f at the downstream end of the rotating shaft portion 4a, has a configuration provided with an orifice hole 4g of the small channel diameter d ₃ than the flow path diameter d ₂ of the channel diameter d ₁ and rotating passage 4e of the fixed passage 7f (See FIG. 2). In the present embodiment, the flow rate of the fluid fed from the upstream side in the rotary flow path 4e is limited by the throttling effect of the throttling portion 4f. 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. The rotary seal portion is provided with a throttle portion 4f as a flow rate limiting means for limiting the flow rate of the fluid flowing in the rotary flow path 4e. Note Figure 1, in the example shown in FIG. 2, but set the channel diameter d ₂ of the rotating passage 4e to be larger than the channel diameter d ₁ of the stationary flowpath 7f, Nagarero径d ₂ and the flow path diameter d ₁ may have the same diameter.

  Next, the structure of the fixing portion 1b attached to the casing member 3 will be described. The fixing portion 1b is mainly composed of a floating sheet 7 fitted and fitted in the fitting hole 3a of the casing member 3. The floating sheet 7 is provided with a disk-shaped flange portion 7b on one side (the side facing the rotating portion 1a in the figure), and a fixed shaft portion formed by penetrating a fixed flow path 7f in the axial direction on the other side. 7a. The fixed shaft portion 7a is fitted in the fitting hole 3a in a state where movement in the axial direction is allowed. An O-ring groove 3b is provided on the inner surface of the fitting hole 3a, and the fitting portion of the fixed shaft portion 7a is sealed by the O-ring 10 attached to the O-ring groove 3b. A non-rotating member 11 is implanted in the casing member 3 in the axial direction. When the floating sheet 7 is mounted on the casing member 3, the non-rotating member 11 extends through the non-rotating hole 7 c provided in the flange portion 7 b in the axial direction. Is inserted.

  A circular concave portion 7e is formed on the convex portion 7d provided on the left side of the flange portion 7b (the end surface facing the rotating portion 1a) so as to surround the opening surface of the fixed flow path 7f. A second seal ring 8 is fixed to the. The second seal ring 8 is formed by molding a hard material similar to that of the first seal ring 5 into an annular shape having an opening 8a at the center, and the second seal surface 8b finished to be a smooth surface. It fixes to the recessed part 7e in the state made into the outer surface side. In this state, the fixed flow path 7f communicates with the opening 8a and opens to the second seal surface 8b. In other words, the floating sheet 7 to which the second seal ring 8 is fixed is in a state in which the fixed flow path is formed in the axial direction so that the fitting hole 3a provided in the casing member 3 is allowed to move in the axial direction. It has a fixed shaft portion 7a to be fitted, and is a fixed seal portion having a second seal surface 8b having a fixed flow path 7f opened on the side end surface.

  Next, the operation of the rotary joint 1 will be described with reference to FIG. When the fluid to be supplied is fed into the fitting hole 3a (arrow a), this fluid pressure acts on the side end face 7g on the other side (opposite side of the second seal ring 8) of the fixed shaft portion 7a. To do. As a result, the fixed shaft portion 7a slides toward the rotating portion 1a in the fitting hole 3a, and the second seal ring 8 applies fluid pressure to the projected area A1 of the side end surface 7g with respect to the first seal ring 5. It is pressed with a pressing force F of the multiplied size. This pressing force F causes the second seal surface 8b and the first seal surface 5b to be in close contact with each other, thereby leaking the fluid fed from the fixed channel 7f to the rotating channel 4e in a rotating state around the axis. A face seal portion 9 is formed to prevent this.

  That is, a fluid is supplied from the fluid supply source into the fitting hole 3a and fluid pressure is applied to the other side end surface 7g of the fixed shaft portion 7a, so that the floating sheet 7 as a fixed seal portion is a rotary seal portion. By pressing against the rotor 4, the first seal surface 5 b and the second seal surface 8 b are brought into close contact with each other to form the surface seal portion 9. In the sliding of the floating sheet 7, the anti-rotation hole 7 c provided in the flange portion 7 b slides along the anti-rotation member 11 to guide the movement of the floating sheet 7 in the axial direction and A detent is made.

  In the operating state of the rotary joint 1, the seal surface of the face seal portion 9 is contacted and separated by the advancement of the floating sheet 7 due to the pressure of the supplied fluid and the advancement / retraction operation of the spindle shaft 2. That is, when the floating sheet 7 is retracted and the first seal surface 5b and the second seal surface 8b are separated from each other, the fluid is fed into the fitting hole 3a, so that the floating sheet 7 moves forward ( Then, the first seal surface 5b comes into contact with the second seal surface 8b to form the surface seal portion 9. Then, when the spindle shaft 2 moves forward (arrow e direction) relative to the fixed portion 1b, the floating sheet 7 moves backward (arrow c direction), and the flange portion 7b returns to a position close to the casing member 3. . Then, by relatively retreating the spindle shaft 2 from this state (in the direction of arrow d), the first seal surface 5b and the second seal surface 8b are returned to a separated state.

  Here, the function of the throttle portion 4f when the rotary joint 1 is operated will be described. As described above, the throttle portion 4f has a function of limiting the flow rate of the fluid flowing in the rotary flow path 4e. The restriction of the flow rate in the rotary joint 1 has the following significance. In the fluid feeding mechanism having the above-described configuration, the flow rate supplied through the rotary joint 1 may vary greatly depending on the state of the downstream supply side. In other words, since the fluid supply source generally has a sufficient capacity, if an unexpected situation such as a fluid ejection nozzle dropping occurs on the supply side, the fluid supply source will deviate from the pressure / flow rate range assumed as the range of use. May flow to the supplied side through the rotary joint.

  Such fluctuations in flow rate and pressure are factors that hinder the normal operation of the coolant supply piping system, and therefore it is required to suppress fluctuations as much as possible. As a means for suppressing such fluctuation, it is conceivable to provide a flow restricting means such as a throttle so that an excessive flow does not flow in the coolant supply piping system. When incorporating such a flow restricting means for the purpose into the coolant supply piping system, the following considerations are necessary in order not to impair the stability of the sealing function of the rotary joint 1.

  In the mechanical seal structure employed in the rotary joint 1, a sealing function is achieved by applying a pressing force F by fluid pressure to the face seal portion 9 as shown in FIG. 2. A stable sealing performance is maintained by maintaining the relative ratio between the sealing pressure generated in the face seal portion 9 by the pressing force F and the internal fluid pressure at a balance ratio appropriately set according to the use conditions. ing. For this reason, when incorporating the above-mentioned flow restricting means into the coolant supply piping system, the relationship between the fluid pressure in the vicinity of the face seal portion 9 and the fluid pressure acting on the side end surface 7g of the fixed shaft portion 7a should not be changed as much as possible. It is necessary to consider the configuration of the flow restriction means and the position where the flow restriction means is inserted.

  That is, when the flow restricting means is provided on the upstream side of the rotary joint 1, the fluid pressure acting on the face seal portion 9 decreases due to the pressure loss in the throttle portion provided to restrict the flow rate, and the seal The stability of performance may be impaired. On the other hand, if it is intended to provide a flow restricting means on the downstream side of the rotary joint 1, it is necessary to incorporate a mechanism for restricting the flow rate into a part that always rotates, such as the spindle shaft 2, which is often difficult due to the device configuration. .

  In consideration of such mechanical seal characteristics, in the rotary joint 1 shown in the present embodiment, the flow rate is limited by providing the throttle portion 4f in the rotor 4 positioned downstream from the face seal portion 9. Yes. By adopting such a configuration, the flow rate flowing from the fixed flow path 7f to the flow path hole 2a via the rotary flow path 4e without causing fluctuations in the fluid pressure acting on the floating sheet 7 and the face seal portion 9 can be obtained. Can be limited. In addition, since this flow restricting means is provided in the rotor 4 constituting the rotary joint 1, there is no need to add any new mechanism to the rotating part such as the spindle shaft 2, and there is absolutely no need to change or modify the equipment. do not do.

In the configuration of the diaphragm portion 4f, passage diameter d ₃ of the orifice holes 4g are those determined in relation to the channel diameter d ₁ of the stationary flowpath 7f. In other words, the degree of restriction necessary for suppressing the fluctuation of the flow rate in the rotary joint 1 within an allowable range is set using the percentage of the channel cross-sectional area of the orifice hole 4g with respect to the channel cross-sectional area of the fixed channel 7f. Is done. In the present embodiment, the flow path cross-sectional area of the orifice hole 4g obtained by locally constricting the rotary flow path 4e is set to 90% or less of the flow path cross-sectional area of the fixed flow path 7f. Here, in order to obtain a more reliable flow restriction effect, it is desirable that the percentage is 75% or less. Further, the position where the throttle portion 4 f is provided in the rotor 4 is not limited to the lower end portion of the rotor 4, and can be provided at any position of the rotary flow path 4 e as long as it is downstream from the face seal portion 9.

  The numerical value of the degree of aperture is set based on the following calculation basis. In order to ensure a stable sealing performance in the rotary joint, it is desirable that the fluctuation of the balance ratio is 10% or less. Since the balance ratio is determined by the fluid pressure and the pressing force F in the face seal portion 9, the pressure loss in the fixed flow path 7 f in the floating seat 7 is suppressed to 10% or less of the fluid pressure on the front side of the rotary joint 1. Is required. Here, an increase in flow rate that causes an increase in pressure loss is caused by the fact that the downstream side of the rotary joint 1 is close to being open, and therefore it is assumed that the rotor 4 is completely open and no static pressure is established. In this state, a condition that the pressure loss is 10% or less may be set. In other words, 10% of the fluid pressure P of the fluid supplied to the rotary joint 1 is expended as a pressure loss in the fixed flow path 7f, and the remaining 90% is moved by the orifice hole 4g provided in the rotor 4. What is necessary is just to find conditions that can be converted into pressure.

That is, the fanning pressure loss calculation formula (1) when the pressure loss ΔP in the fixed flow path 7f is 10% of the fluid pressure P, and the flow rate when the differential pressure around the orifice hole 4g is 90% of the fluid pressure P. formula for calculating the Q and (2), by simultaneous on condition that the flow rate Q is equal, the flow path cross-sectional area S of orifices 4g against the flow path cross-sectional area S ₁ of satisfying stationary flowpath 7f above A ratio of ₃ (S ₃ / S ₁ ) is determined.
(ΔP =) 0.1P = λ (L / d ₁ ) V ² / 2g ·· (1)
Q = α (S ₃ ) √ (2 g × 0.9 P) (2)
Here, λ: pipe friction coefficient L: fixed flow path length d ₁ : fixed flow path diameter V: fixed flow path flow velocity g: gravitational acceleration α: orifice flow coefficient (1) 1P = λ (L / d ₁ ) (Q / S ₁ ) ² / 2g. Then, by substituting Equation (2) into this flow rate Q and using numerical values of λ = 0.03, α = 0.75, L = 40 mm, and d ₁ = 5 mm as examples of numerical conditions, the above condition is satisfied (S _As a limit value of ₃ / S ₁ ), 0.91 is obtained.

That is, if the ratio (S ₃ / S ₁ ) of the flow passage cross-sectional area S ₃ of the orifice hole 4g to the flow passage cross-sectional area S ₁ of the fixed flow passage 7f is set to 90% or less under the above numerical conditions, the rotor 4 Even when the downstream is completely opened, the pressure loss ΔP in the fixed flow path 7f can be suppressed to 10% or less of the fluid pressure P. In a normal rotary joint, there is no extreme difference in the above numerical conditions. Therefore, the above numerical value (90%) is used as a standard value for (S ₃ / S ₁ ) for ensuring stable sealing performance. Can be used. It has been experimentally confirmed that when (S ₃ / S ₁ ) is set to 75% or less, the sealing performance is not affected even when the tip is open.

  Thus, the effect of restricting the flow rate in the rotary joint 1 is particularly remarkable when the fluid flowing through the rotary joint 1 is a gas such as cooling air. That is, when pressure loss increases due to an excessive flow rate of gas flowing through the floating sheet 7, the fluid pressure in the vicinity of the face seal portion 9 decreases with respect to the fluid pressure on the upstream side of the floating sheet 7. This results in an increase in the seal surface pressure acting on the face seal portion 9 without maintaining the balance ratio. Such an increase in the sealing surface pressure has a greater influence on the sealing performance when the fluid is a gas.

  In other words, since gas generally does not have lubricity, a large seal surface pressure acts on a non-lubricated seal surface, which may cause a sealing operation failure such as rough seal surface and increased leakage. is there. On the other hand, in the rotary joint 1 shown in the present embodiment, even when a gas having such characteristics is to be supplied, the flow rate restricting means provided in the rotor 4 allows the flow rate to flow through the rotary joint 1. I am trying to limit it. Thereby, it is possible to prevent an excessively high flow rate of gas from flowing through the floating sheet 7, and it is possible to effectively prevent the sealing operation failure such as the rough surface of the sealing surface and the increase of the leakage amount as described above. .

The flow rate limiting means provided in the rotor 4 is not limited to the throttle portion 4f as shown in the above configuration, and various variations can be assumed. Hereinafter, some of these variations will be described with reference to FIGS. First, FIG. 3 shows a rotary joint 1A of the second embodiment. In this second embodiment, while there is provided a throttle portion 4f that focus rotating passage 4e locally in the first embodiment, securing the passage diameter d ₄ of the rotating passage 4e over the entire length of the rotor 4A it is obtained so as to limit the flow rate to be smaller than the passage diameter d ₁ of the flow passage 7f. In determining the Nagarero径d _4, it is determined based on the percentage of the flow path cross-sectional area of the orifice hole 4g against the flow path cross-sectional area of the first embodiment similarly to the fixed passage 7f.

That is, the rotor 4A shown in FIG. 3 is the same as the rotor 4 shown in the first embodiment in that the cross-sectional area of the rotary flow path 4e provided in the axial center portion is equal to the cross-sectional area of the rotary flow path 4e over the entire length of the rotor 4A. By setting it to 90% or less, the flow rate is limited. Here again, in order to obtain a more reliable flow restricting effect, it is desirable to set the percentage to 75% or less. The first seal ring 5A fixed to the right side end surfaces of the rotor 4A, the opening 5a of the same diameter as the inner diameter d ₄ of the rotating passage 4e is formed. About the structure of those other than this, it is the same as that of the rotary joint 1 shown in FIG. By adopting such a configuration instead of providing the throttle portion 4f, there is an advantage that the processing of the rotor 4A can be simplified.

  FIG. 4 shows a rotary joint 1B of the third embodiment. In the third embodiment, a bending portion that changes the flow direction of the fluid in the radial direction in the rotary flow path 4e is provided in the rotor 4B, thereby generating a pressure loss and limiting the flow rate. That is, in FIG. 4, the rotor 4 </ b> B has a configuration in which a bent portion 14 is provided at the downstream end of the rotor 4 in FIG. 1. The bending part 14 has a form in which one or a plurality of through holes 14a penetrating from the rotating flow path 4e to the outer surface of the rotating shaft part 4a are provided. An angle θ between the flow direction of the rotary flow path 4e (arrow f) and the flow direction of the through hole 14a (arrow g) is set to a right angle or an obtuse angle close to a right angle. That is, in the bending portion 14, the fluid in the rotating flow path 4e flows out to the flow path hole 2a through the through hole 14a, and thereby the flow direction changes in the radial direction. The flow rate is limited by the pressure loss accompanying the change in the flow direction and the flow path diameter.

FIG. 5 shows a rotary joint 1C of the fourth embodiment. In the fourth embodiment, the flow rate is restricted by providing the rotary flow passage 4e with a flow restricting portion in which a plurality of pores penetrates in the axial direction. That is, in FIG. 5, the rotor 4 </ b> C has a configuration in which the flow restriction unit 15 is provided at the downstream end of the rotor 4 in FIG. 1. Flow restriction 15, the closing portion 15b for closing the flow path at the downstream end of the rotating passage 4e formed, it has a plurality form the pores 15a of the inner diameter d ₅ through the occlusion 15b. As shown in the end face 4i on the downstream side of the rotating shaft 4a, the pores 15a are provided in a point-symmetric arrangement with respect to the center of the flow path. The fluid in the rotating flow path 4e flows out to the flow path hole 2a through the pores 15a of the flow rate limiting unit 15, and the flow rate is limited by the pressure loss at this time.

  FIG. 6 shows a rotary joint 1D of the fifth embodiment. In this fifth embodiment, the flow rate is limited by inserting a porous filter member having a plurality of micropores into the rotating flow path 4e. That is, in FIG. 6, the rotor 4 </ b> D has a configuration in which the filter member 17 is inserted in the downstream portion of the rotating flow path 4 e in the rotor 4 of FIG. 1. The filter member 17 is formed by forming a porous material having a plurality of fine holes, such as a ceramic sintered body, into a substantially cylindrical plug shape, and is inserted into the rotary flow path 4e and held in position by the coloring ring 16. . The fluid in the rotating flow path 4e passes through the filter member 17 and flows out into the flow path hole 2a. At this time, foreign matter mixed in the fluid is captured by the filter member 17, and the flow rate is limited by the pressure loss when the fluid passes through the filter member 17. Since the filter member 17 rotates together with the rotor 4D, the foreign matter captured by the filter member 17 is accumulated in the outer peripheral direction due to the centrifugal force accompanying the rotation, and clogging of the filter member 17 is suppressed. It has a great effect.

  The effects of the flow restriction in the third embodiment, the fourth embodiment, and the fifth embodiment are determined based on the magnitude of pressure loss in the bending portion 14, the flow restriction portion 15, and the filter member 17, respectively. That is, the pressure loss is measured while changing the hole diameter and arrangement of the through holes 14a in the bent part 14, the hole diameter / hole length and the number of holes 15a in the flow restriction part 15, the filter thickness in the filter member 17, the mesh, and the like. It is made to be equivalent to the pressure loss of the throttle portion 4f in one embodiment.

  As described above, the present invention relates to a rotary joint having a configuration in which a rotating portion provided with an axial rotation flow path and a fixed portion provided with an axial fixed flow path are arranged coaxially. The rotary seal portion having the first seal surface with the rotary channel opened at the end face is provided with a flow rate limiting means for limiting the flow rate of the fluid flowing in the rotary channel. This flow restriction is performed by generating a pressure loss in the flow path. In the conventional technical common sense in this type of rotary joint, pressure loss in the flow path was supposed to be avoided as much as possible, but in the present invention, by appropriately setting the position where pressure loss occurs, Stabilization of sealing performance is realized. Thereby, the fluctuation | variation of the flow volume of a coolant supply piping system can be prevented with a simple structure, and abnormality of the sealing performance which may generate | occur | produce with the fluctuation | variation of a flow volume can be prevented.

  The rotary joint of the present invention is characterized by being capable of preventing fluctuations in the flow rate of the coolant supply piping system with a simple configuration, and supplying fluid such as liquid coolant and air to a rotating part such as a spindle of a machine tool. It is useful for the application.

Sectional drawing of the rotary joint (1st Example) in one embodiment of this invention Explanatory drawing of operation | movement 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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary joint 1a Rotating part 1b Fixed part 2 Spindle shaft 3 Casing member 4 Rotor 4e Rotating flow path 4f Constriction part 5 1st seal ring 5b 1st sealing surface 7 Floating sheet 7a Fixed shaft part 7f Fixed flow path 8 2nd Seal ring 8b Second seal surface 9 Surface seal portion 14 Bending portion 15 Flow rate limiting portion 17 Filter member

Claims (3)

A fluid supplied from a fluid supply source is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds through the fixed flow path to the rotary flow path of the rotating part that rotates around the 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;
A flow rate limiting means for limiting the flow rate of the fluid flowing in the rotary flow path provided in the rotary seal portion;
A stationary sealing portion having a second sealing surface on which the fixed channel on one side side end face of the provided in the fixing unit is opened,
A fixed shaft portion provided on the other side of the fixed seal portion and fitted in a fitting hole provided in the casing member in a state in which movement in the axial direction is allowed;
The fixed flow path is formed in a straight pipe shape penetrating the fixed shaft portion in the axial direction,
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 ,
The flow rate restricting means is provided at the downstream side of the face seal portion in the rotary seal portion,
Further, the flow rate restricting means restricts the flow passage cross-sectional area of the rotary flow passage locally to 75% or less of the flow passage cross-sectional area of the straight tube-shaped fixed flow passage so that the downstream side of the rotary seal portion is completely closed. A rotary joint that restricts the flow rate in order to suppress a pressure loss in the fixed flow path to 10% or less of a fluid pressure even when it is opened . A fluid supplied from a fluid supply source is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds through the fixed flow path to the rotary flow path of the rotating part that rotates around the 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;
A flow rate limiting means for limiting the flow rate of the fluid flowing in the rotary flow path provided in the rotary seal portion;
A stationary sealing portion having a second sealing surface on which the fixed channel on one side side end face of the provided in the fixing unit is opened,
A fixed shaft portion provided on the other side of the fixed seal portion and fitted in a fitting hole provided in the casing member in a state in which movement in the axial direction is allowed;
The fixed flow path is formed in a straight pipe shape penetrating the fixed shaft portion in the axial direction,
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 ,
The flow rate restricting means is provided at the downstream side of the face seal portion in the rotary seal portion,
Furthermore, the flow rate restricting means sets the rotary seal portion to 75% or less of the flow passage cross-sectional area of the straight fixed channel over the entire length of the rotary seal portion. The rotary joint is characterized in that the flow rate is limited in order to suppress the pressure loss in the fixed flow path to 10% or less of the fluid pressure even when the downstream side of the valve is completely opened .   The rotary joint according to claim 1, wherein the fluid is a gas.

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