Rotation device and method for assembling rotation device

Abstract

In this rotation device, one of a rotation member and a support member is provided with an annular groove part for accommodating a packing, and the other of the rotation member and the support member is provided with a projection part which elastically deforms and contacts the packing and annularly extends along the circumferential surface of the packing. The projection part is provided with: a first inclined surface which is provided on an lubricant accommodation space side; a second inclined surface which is provided on the opposite side to the accommodation space side; and a contact end part which contacts the packing. The contact end part has a region in which the contact pressure with the packing becomes maximum, and the region in which the contact pressure becomes maximum is positioned, in the rotational axis direction of the rotation member, on the accommodation space side from the center of the contact end part.

Description

Rotating device and method for assembling the rotating device

[0001] The present invention relates to a rotation device and a method for assembling a rotation device.

[0002] A sealing method utilizing an oil seal is known to prevent leakage of lubricating oil from a rotating shaft (see, for example, Patent Document 1). As shown in FIG. 1A, an oil seal 100 includes an annular seal body 101 fitted to a support member 120 of a rotating shaft 110, on which a seal lip 101A is formed. A spring 102 presses the seal lip 101A against the rotating shaft 110. The seal surface of the seal lip 101A is formed with an inclined surface 103 inclined toward the liquid side, such as the lubricating oil, and an inclined surface 104 inclined toward the atmosphere side. For example, the angle α of the inclined surface 103 relative to the axial direction of the rotating shaft 110 is set larger than the angle β of the inclined surface 104 (α > β). This results in a peak (maximum value) of the pressure distribution where the seal lip 101A presses against the rotating shaft 110 being located on the liquid side, as shown in FIG. 1B. Furthermore, minute irregularities between the seal lip 101A and the rotating shaft 110 facilitate retention of the lubricating oil, forming an oil film 106. 1B, if the pressure distribution peak of the seal lip 101A is on the liquid side, a force (pumping force) is generated that pushes the oil film 106 back toward the liquid side when the rotating shaft 110 rotates. This pumping action can prevent the lubricating oil (liquid) from leaking into the atmosphere.

[0003] Japanese Utility Model Application Laid-Open Publication No. 4-127462

[0004] However, the seal lip 101A of the oil seal 100 is made of rubber and is pressed against the rotating shaft 110 by the spring 102. This results in a relatively low sealing pressure (e.g., approximately 0.03 MPa) to seal the liquid. However, in recent years, when performing cutting processes using rotary tables, coolant (cutting oil) used to remove chips has increasingly been discharged at high pressures (e.g., 1 to 7 MPa). Therefore, when the oil seal 100 is used to seal a rotary table, a problem has arisen in that when coolant is sprayed onto the seal lip 101A, the seal lip 101A is warped, making it impossible to maintain its sealing performance. Meanwhile, a sealing method that uses a packing such as an O-ring between the rotating shaft and the support member instead of an oil seal is known. The packing is typically compressed by approximately 5 to 20% before installation, allowing it to be strongly pressed against the rotating shaft and withstand high-pressure coolant. However, using a packing increases the frictional force (friction torque) compared to using an oil seal. As a result, rotation efficiency decreases, heat generation and wear occur, and positioning accuracy decreases.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a rotating device that reduces the frictional force generated between the rotating member or support member and the packing while maintaining sealing performance against external forces, and a method for assembling a rotating device.

[0006] The primary invention for achieving the above object is a rotating device comprising: a rotating member, a support member supporting the circumferential surface of the rotating member, an accommodation space for accommodating a lubricant, and a gasket disposed between the rotating member and the support member for preventing leakage of the lubricant, wherein one of the rotating member and the support member comprises an annular groove for accommodating the gasket, and the other of the rotating member and the support member comprises a protrusion that contacts the gasket so as to elastically deform the gasket and extends annularly along the circumferential surface of the gasket, the protrusion comprising: a first inclined surface provided on the accommodation space side; a second inclined surface provided on the opposite side from the accommodation space side; and a contact end portion in contact with the gasket, the contact end portion having a portion where the contact pressure with the gasket is maximum, the maximum portion being located closer to the accommodation space than the center of the contact end portion in the direction of the rotation axis of the rotating member. Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] According to the present invention, it is possible to provide a rotating device that reduces frictional forces generated between a rotating member or a support member and a packing while maintaining sealing performance against external forces, and a method for assembling a rotating device.

[0008] FIGS. 1A and 1B are explanatory diagrams of an oil seal 100. FIGS. 2A and 2B are explanatory diagrams of a barrel cam device 1. FIGS. 4A and 4B are explanatory diagrams of a protruding portion 21. FIGS. 5A and 5B are diagrams showing the state before and after the protruding portion 21 is pressed against the packing 40. They are diagrams showing changes in the contact pressure between the packing 40 and the protruding portion 21. They are diagrams showing a state in which the apex of the protruding portion 21 is shifted to the side opposite the accommodation space 30. They are diagrams showing a state in which the apex of the protruding portion 21 is shifted toward the accommodation space 30. FIGS. 9A to 9D are explanatory diagrams of an annular groove portion 13. FIGS. 10A to 10C are explanatory diagrams of a modified annular groove portion 51. FIGS. 11A and 11B are explanatory diagrams of a modified version of the rotating device 1. They are diagrams showing an example of a crushing margin for the packing 40. FIGS. 13A to 13D are explanatory diagrams showing another method of assembling the rotating device 1.

[0009] The present specification and the accompanying drawings make clear at least the following: (Aspect 1) A rotating device comprising: a rotating member, a support member that supports a circumferential surface of the rotating member, an accommodation space that accommodates a lubricant, and a packing that is provided between the rotating member and the support member and that prevents leakage of the lubricant, wherein one of the rotating member and the support member has an annular groove that accommodates the packing, and the other of the rotating member and the support member has a protrusion that contacts the packing so that the packing elastically deforms and extends annularly along the circumferential surface of the packing, the protrusion having a first inclined surface that is provided on the accommodation space side, a second inclined surface that is provided on the opposite side to the accommodation space side, and a contact end that contacts the packing, the contact end having a portion where contact pressure with the packing is maximum, the maximum portion being located closer to the accommodation space than a center of the contact end in a direction of the rotation axis of the rotating member.

[0010] According to the first aspect, the distribution of contact pressure between the packing and the protruding portion can be made similar to that of an oil seal. Therefore, when the rotating member rotates, a pumping action (a pumping force that pushes the lubricant back into the accommodation space) is thought to act on the lubricant between the packing and the protruding portion, improving the sealing performance between the rotating member and the support member. This can prevent the lubricant from leaking outside the rotating device. Furthermore, the contact surface between the packing and the protruding portion is not exposed to the outside and is less susceptible to external forces such as high-pressure coolant, making it easier to maintain sealing performance. Furthermore, the contact width of the packing is smaller than when the packing contacts a flat surface, reducing the frictional force generated between the packing and the protruding portion.

[0011] (Aspect 2) A rotation device according to aspect 1, characterized in that the inclination angle formed by the first inclined surface and a virtual plane passing through the apex of the protrusion and extending along the rotation axis direction is larger than the inclination angle formed by the virtual surface and the second inclined surface.

[0012] According to the second aspect, the packing is easily deformed so that the portion where the contact pressure between the packing and the protrusion is greatest is located on the housing space side in the rotation axis direction.

[0013] (Aspect 3) The rotating device according to Aspect 1 or Aspect 2, wherein the packing is an O-ring, and the contact end of the protrusion is in contact with a central portion of the packing in the direction of the rotation axis.

[0014] According to the third aspect, the first and second inclined surfaces of the protrusion can be brought into stable contact with the packing. Therefore, the packing is easily deformed so that the area where the contact pressure between the packing and the protrusion is greatest is located on the housing space side in the rotation axis direction. Furthermore, by changing the size and hardness of the O-ring, the O-ring can be used in sealing structures for various rotating devices.

[0015] (Aspect 4) A rotating device according to any one of Aspects 1 to 3, wherein the annular groove portion is defined by a first surface and a second surface that face each other in the direction of the rotation axis, and a third surface that connects the first surface and the second surface, the packing is in contact with the first surface, the second surface, and the third surface, and one of the rotating member and the support member comprises a first member having the first surface and the third surface, and a second member that is separate from the first member and has the second surface.

[0016] According to the fourth aspect, the position of the packing in the rotating device (annular groove) can be determined. Therefore, the protrusion can be brought into contact with a desired position (e.g., the center) of the packing in the rotational axis direction, and the protrusion can deform the packing by a desired amount. Furthermore, after the packing is placed on the first and third surfaces (L-shaped grooves), the second surface can be used to cover the packing. This allows the packing to contact the first to third surfaces while preventing localized deformation of the packing.

[0017] (Aspect 5) A method for assembling a rotating device including a rotating member, a support member that supports a circumferential surface of the rotating member, an accommodation space that accommodates a lubricant, and a gasket that is provided between the rotating member and the support member and prevents leakage of the lubricant, the method comprising: a first step of arranging the gasket in an annular groove that one of the rotating member and the support member includes; and a second step of bringing a protruding portion that the other of the rotating member and the support member includes, into contact with the gasket so that the gasket elastically deforms, the protruding portion extending annularly along the circumferential surface of the gasket and having a first inclined surface that faces the accommodation space and a second inclined surface that faces the opposite accommodation space, wherein in the second step, the protruding portion forms a contact end that is a portion that contacts the gasket, and the protruding portion is brought into contact with the gasket so that a portion of the contact end where the contact pressure with the gasket is greatest is located closer to the accommodation space than a center of the contact end in a direction of the rotational axis of the rotating member.

[0018] According to Aspect 5, the distribution of contact pressure between the packing and the protruding portion can be made similar to that of an oil seal. Therefore, when the rotating member rotates, a pumping action is thought to be exerted on the lubricant between the packing and the protruding portion, improving the sealing performance between the rotating member and the support member. This can prevent the lubricant from leaking outside the rotating device. Furthermore, the contact surface between the packing and the protruding portion is not exposed to the outside, making it less susceptible to external forces such as high-pressure coolant, and therefore sealing performance can be easily maintained. Furthermore, the contact width of the packing is smaller than when the packing contacts a flat surface, reducing the frictional force generated between the packing and the protruding portion.

[0019] (Aspect 6) A method for assembling a rotating device according to Aspect 5, wherein the annular groove portion is defined by a first surface and a second surface that face each other in the direction of the rotation axis, and a third surface that connects the first surface and the second surface, and after the packing is placed in a first member having the first surface and the third surface, the packing is covered with a second member that is a separate member from the first member and has the second surface, thereby bringing the packing into contact with the first surface and the second surface.

[0020] According to the sixth aspect, the position of the packing in the rotating device (annular groove portion) can be determined. Therefore, the protrusion can contact the desired position (e.g., the center) of the packing in the rotation axis direction. Furthermore, by placing the packing on the first and third surfaces (L-shaped grooves) and then covering it with the second surface, local deformation of the packing can be prevented, improving sealing performance.

[0021] Regarding the Barrel Cam Device 1: Hereinafter, an embodiment of the rotation device according to the present invention will be described using the barrel cam device 1 as an example. The barrel cam device 1 can be used, for example, in an NC table for a machine tool, a positioner for a robot, or a rotating shaft for a robot.

[0022] 2A and 2B are explanatory diagrams of the barrel cam device 1. Fig. 2A is a schematic plan view of the barrel cam device 1, and Fig. 2B is a schematic side view of the barrel cam device 1. In the drawings relating to this embodiment, including drawings to be described later, appropriate members may be omitted, and oblique lines on cross sections may be omitted in order to make the present invention easier to understand.

[0023] The barrel cam device 1 has an X direction, a Y direction, and a Z direction, and the X direction and the Y direction intersect with each other, and the Z direction intersects with both the X direction and the Y direction. The horizontal direction of the paper in Fig. 2A is the X direction, with the left side of the paper referred to as the left side of the X direction and the opposite side as the right side. The vertical direction of the paper is the Y direction, with the upper side of the paper referred to as the back side in the Y direction and the opposite side as the front side. The vertical direction of the paper in Fig. 2B is the Z direction (vertical direction), with the upper side of the paper referred to as the upper side in the Z direction and the opposite side as the lower side.

[0024] The barrel cam device 1 has a housing 2, which accommodates an input shaft 3, a barrel cam 70, a rotary shaft 4, a cam follower 5, a rotary table 10 (a rotating member), and a support member 20. A motor 6 is attached to the housing 2 as a drive unit.

[0025] The motor 6 is provided with its rotational axis extending along the Y direction and is connected to the input shaft 3 by a coupling 7. The input shaft 3 is provided along the Y direction and is rotatably supported by an input bearing 8. A portion of the input shaft 3 on the front side extends further forward than the input bearing 8, and this extending portion is connected to the rotational shaft of the motor 6 by a coupling 7. The input shaft 3 is provided on both ends of a barrel cam 70 in the Y direction, and the barrel cam 70 and the input shaft 3 rotate integrally.

[0026] The barrel cam 70 also has a barrel cam groove 70a, which is spiral and extends in the direction of the input shaft 3. The rotation of the barrel cam 70 is transmitted to the turntable 10 by engaging the cam follower 5 of the turntable 10 with the barrel cam groove 70a.

[0027] The turntable 10 has a circular shape and is rotatably supported by a support member 20. The support member 20 supports the turntable 10 via bearings 9. In this embodiment, the bearings 9 are large-diameter four-point supported ball bearings. The turntable 10 also includes a plurality of cam followers 5 that engage with barrel cams 70 (barrel cam grooves 70a). Therefore, when the barrel cams 70 rotate around the input shaft 3 that extends in the Y direction, the turntable 10 rotates around a rotation axis that extends in the Z direction.

[0028] The cam followers 5 are components that engage with the barrel cam grooves 70a, and are cylindrical, rotatable rotating bodies that are provided so that the rotation axis direction is along the Z direction. A plurality of cam followers 5 are provided at equal intervals along a circle centered on the rotation center of the turntable 10. In this embodiment, 16 cam followers 5 are provided at equal intervals.

[0029] Furthermore, the cam follower 5 engages with the barrel cam groove 70a of the barrel cam 70 on the underside of the turntable 10, and this engaged cam follower 5 moves while being guided by the barrel cam groove 70a. Specifically, when the barrel cam 70 rotates counterclockwise as viewed from the front side, the engaged cam follower 5 moves from the front side to the rear side along the circumferential direction of the turntable 10 while being guided by the spiral barrel cam groove 70a. In other words, the turntable 10 rotates clockwise as viewed from above.

[0030] The rotating shaft 4 is attached to the center (hollow portion) of the turntable 10 along the Z direction and rotates integrally with the turntable 10. Note that although the rotating shaft 4 in this embodiment is a so-called hollow shaft having a hollow portion, it may also be a solid shaft without a hollow portion.

[0031] ===Sealing Structure 100 of Rotating Device (Barrel Cam Device 1)=== Figure 3 is an explanatory diagram of sealing structure 100 of a rotating device (barrel cam device 1). Figures 4A and 4B are explanatory diagrams of protrusion 21. Figures 5A and 5B are diagrams showing the state before and after protrusion 21 is pressed against packing 40. Figure 6 is a diagram showing the change in contact pressure between packing 40 and protrusion 21.

[0032] As described above, a rotating device such as the barrel cam device 1 includes the rotating table 10, which is a rotating member, the support member 20 that supports the peripheral surface of the rotating table 10, and the bearing 9. The rotating table 10 is rotatably supported by the support member 20 via the bearing 9. In the following description, the barrel cam device 1 will also be referred to as the rotating device 1.

[0033] The rotary table 10 shown in Figure 3 includes an upper table 11 and a lower table 12. The upper surface of the upper table 11 is exposed to the outside. Therefore, when the rotating device 1 is used as, for example, an NC rotary table of a machine tool, a workpiece can be placed on the upper surface of the upper table 11. The lower table 12 supports the upper table 11 from below, and a cam follower 5 is attached to the lower table 12. The movement of the cam follower 5 by the barrel cam 70 rotates the lower table 12, and the upper table 11, which is fixed to the lower table 12, also rotates. The support member 20 supports the peripheral surface facing the lower table 12 via a bearing 9.

[0034] To reduce friction, a lubricant such as lubricating oil or grease is placed between the two sliding surfaces, between the lower table 12 and the bearing 9 and between the bearing 9 and the support member 20. For this purpose, the rotating device 1 is provided with an accommodation space 30 for accommodating the lubricant, at least between the opposing circumferential surfaces of the lower table 12 and the support member 20. To prevent the lubricant in this accommodation space 30 from leaking out of the rotating device 1, the rotating device 1 is provided with a sealing structure 100. The sealing structure 100 is provided between the lower table 12 and the support member 20 and is formed using a packing 40 for preventing leakage of the lubricant, and a protrusion 21 provided on the support member 20.

[0035] The rotary table 10 has an annular groove 13 that accommodates a packing 40. As shown in Fig. 2A, the annular groove 13 is provided continuously along the circumferential direction of the peripheral surface of the lower table 12 that faces the support member 20. Although Fig. 3 shows an O-ring as an example of the packing 40, the packing 40 is not limited to this. The packing 40 may be any annular member formed of an elastic member that can be deformed by pressure contact with the protrusion 21, and may be, for example, a square ring with a square cross section or a D-ring with a D-shaped cross section.

[0036] The protrusion 21 provided on the support member 20 contacts (presses) the packing 40 so that the packing 40 is elastically deformed, and extends in an annular shape along the circumferential surface of the packing 40 as shown in Fig. 2A. In other words, the protrusion 21 is a portion that is processed and molded on the surface 20a of the support member 20 facing the lower table 12 so as to protrude toward the packing 40.

[0037] 4A , the protrusion 21 includes a first inclined surface 211 provided on the storage space 30 side (liquid side) and a second inclined surface 212 provided on the opposite side (atmosphere side) from the storage space 30 side. The first inclined surface 211 is a surface that inclines toward the support member 20 side (right side in the X direction) toward the lower side in the Z direction (liquid side). The second inclined surface 212 is a surface that inclines toward the support member 20 side (right side in the X direction) toward the upper side in the Z direction (atmosphere side).

[0038] In the rotating device 1 (i.e., when the sealing structure 100 is assembled), as shown in Fig. 5B , the protruding portion 21 has a contact end portion 213 (the portion indicated by diagonal lines) that contacts the packing 40. The contact end portion 213 is the portion where the protruding portion 21 elastically deforms the packing 40 and bites into it. As shown in Fig. 6 , the contact end portion 213 has a portion 213x where the contact pressure with the packing 40 is maximum. The maximum portion 213x is located closer to the accommodation space 30 than the center 213c of the contact end portion 213 in the Z direction (rotation axis direction).

[0039] When the protrusion 21 contacts the packing 40 with a certain amount of compression, the packing 40 deforms along the first inclined surface 211 and the second inclined surface 212. The amount of deformation (e.g., d1 to d4 in FIG. 6 ) is considered to be roughly proportional to the contact pressure (e.g., p1 to p4 in FIG. 6 ) between the protrusion 21 and the packing 40. Therefore, the portion of the packing 40 where the amount of deformation in the X direction is greatest (d1 in FIG. 6 ) is the portion 213x where the contact pressure with the packing 40 is greatest. In addition, the portion 213x where the contact pressure is greatest is located closer to the accommodation space 30 than the center 213c of the contact end portion, which can be expressed as the Z-direction length D1 from the bottom end 213l of the contact end portion 213 to the maximum portion 213x is shorter than the Z-direction length D2 from the maximum portion 213x to the top end 213u of the contact end portion 213 (D1 < D2).

[0040] The distribution of contact pressure between the protrusion 21 and the packing 40 as described above reproduces the pressure distribution ( FIG. 1B ) where the seal lip 101A of the oil seal 100 presses against the rotating shaft 110. Therefore, when the turntable 10 rotates, a pumping action (a pump force that pushes the lubricant back toward the accommodation space 30) is exerted on the lubricant film between the packing 40 and the protrusion 21. This improves the sealing performance between the turntable 10 and the support member 20, making it possible to suppress leakage of the lubricant outside the rotating device 1. For example, it is possible to suppress leakage of the lubricant from the gap formed between the lower surface of the upper table 11 and the upper surface of the support member 20 as shown in FIG. 3.

[0041] Furthermore, the protrusion 21 is a hard member (such as a metal member or a hard resin member) that elastically deforms the packing 40. Therefore, as shown in FIG. 5B , the protrusion 21 bites into the packing 40, and the contact surface (sealing surface) between the packing 40 and the protrusion 21 is not exposed to the outside. Therefore, it is less susceptible to external forces such as high-pressure coolant. Therefore, unlike the seal lip 101A of the oil seal 100, it is not turned over by external forces, and its sealing performance is easily maintained. Furthermore, because the protrusion 21 is a hard member, the bottom of the protrusion 21 exposed from the packing 40 is also less likely to deform by external forces, and its sealing performance is easily maintained. Furthermore, the protrusion 21 is less likely to deform due to the rotational force of the turntable 10, and its sealing performance is easily maintained. Therefore, the sealing structure 100 can also prevent foreign matter (such as high-pressure coolant) from entering from the external space.

[0042] Another conventional example is a sealing structure in which a flat surface of the support member 20, which does not have the protrusion 21, abuts against the packing 40. Compared to this conventional example, the sealing structure 100 of this embodiment can reduce the frictional force generated between the support member 20 (protrusion 21) and the packing 40. As a result, it is possible to suppress a decrease in the rotation efficiency of the rotating device 1, as well as heat generation, wear, and a decrease in positioning accuracy.

[0043] Specifically, even if the maximum deformation amount of the packing 40 at the contact surface when the packing 40 is brought into contact with the flat surface of the support member 20 with a predetermined crushing margin and the maximum deformation amount d1 of the packing 40 due to the protrusion 21 of this embodiment are the same, in the conventional example, the entire arc portion of the packing 40 is crushed, whereas in this embodiment, only the portion along the protrusion 21 is crushed. Therefore, the deformation amount of the packing 40 is small, and the contact pressure between the support member 20 and the packing 40 is also small. Furthermore, the contact width between the support member 20 and the packing 40 is also smaller in this embodiment than in the conventional example. Therefore, the frictional force can be reduced in this embodiment compared to the conventional example.

[0044] A verification test was conducted on a 400 mm diameter rotary table 10, in which an 8.4 mm diameter O-ring (packing 40) was compressed 0.5 mm (= d1) in the X direction by the protrusion 21 (the inclination angle α of the first inclined surface 211 = 45 degrees, the inclination angle β of the second inclined surface 212 = 30 degrees). A machine oil with a viscosity of 260 cst was used as the lubricant, and the rotary table 10 was rotated in both directions at 50 RPM for approximately 1,000 hours. As a result, it was confirmed that no lubricant leakage occurred outside the rotary device 1. It was also confirmed that the friction force (friction torque) was approximately 1 / 10 of that of a comparative rotary device under the same conditions except that the support member 20 was a flat surface without the protrusion 21.

[0045] As described above, the rotating device 1 of this embodiment can reduce frictional forces occurring between the support member 20 and the packing 40 while maintaining sealing performance against external forces. Furthermore, the sealing structure 100 using the packing 40 as in this embodiment can reduce the size of the rotating device 1 compared to a case where an oil seal ( FIG. 1A ) is used. Furthermore, various types of packings 40, such as O-rings, are standardized and distributed, differing in size, hardness, material, and the like. Therefore, the sealing structure 100 of this embodiment can be applied to various rotating devices by changing the size, hardness, and the like of the packing 40. Furthermore, when the packing 40 is an O-ring, its cross-sectional shape is symmetrical, making it less likely to be installed incorrectly.

[0046] The protrusion 21 may be a separate member from the support member 20 and may be formed by being fixed to the opposing surface 20a of the support member 20. However, it is preferable that the opposing surface 20a of the support member 20 is processed and formed integrally with the support member 20 using the same material (e.g., a metal material, etc.). This prevents gaps from occurring between the protrusion 21 and the support member 20 and also increases the accuracy of the dimensions and positioning of the protrusion 21, thereby further improving the sealing performance of the rotating device 1.

[0047] 4A illustrates an example in which the corner (top of the protrusion 21) where the first inclined surface 211 and the second inclined surface 212 intersect has a V-shaped cross section, but this is not limiting. For example, as shown in FIG. 4B , the corner of the first inclined surface 211 and the second inclined surface 212 may be rounded, so that the cross section of the corner has a curved shape. In this case, the top 21t of the protrusion 21 contacts the packing 40 more gently, making it less likely for cracks to occur in the packing 40 and extending the life of the packing 40.

[0048] 4A , the inclination angle α of the first inclined surface 211 with respect to a virtual plane Vf that passes through the vertex 21t of the protrusion 21 and is aligned along the Z direction, which is the rotation axis direction, is preferably greater than the inclination angle β of the second inclined surface 212 with respect to the virtual plane Vf (α>β). While the present embodiment illustrates a case where α is 45 degrees and β is 30 degrees, this is not limiting. In other words, the angle α' (= 180-45 degrees) formed between the first inclined surface 211 and the opposing surface 20a of the support member 20 should be smaller than the angle β' (= 180-30 degrees) formed between the second inclined surface 212 and the opposing surface 20a of the support member 20.

[0049] As shown in FIG. 6 , the contact pressure with the packing 40 tends to be greatest at the apex 21t of the protrusion 21. Therefore, by increasing the inclination angle α of the first inclined surface 211, the length D1 in the Z direction over which the first inclined surface 211 contacts the packing 40 tends to be shorter than the length D2 in the Z direction over which the second inclined surface 212 contacts the packing 40. Therefore, the packing 40 tends to deform so that the portion 213x of the contact end 213 of the protrusion 21, where the contact pressure with the packing 40 is greatest, is positioned closer to the accommodation space 30 in the Z direction. Therefore, a pumping action is applied to the lubricant between the packing 40 and the protrusion 21, improving the sealing performance between the turntable 10 and the support member 20.

[0050] However, the present invention is not limited to the above, and the inclination angle α may be the same as or smaller than the inclination angle β. In this case, it is also sufficient that the portion 213x of the contact end 213 where the contact pressure is maximum is located on the accommodation space 30 side by, for example, devising the position where the protrusion 20 abuts on the packing 40 or the shape of the packing 40.

[0051] Fig. 7 is a diagram showing a state in which the apex 21t of the protrusion 21 is shifted to the side opposite to the storage space 30 (toward the atmosphere), and Fig. 8 is a diagram showing a state in which the apex 21t of the protrusion 21 is shifted to the side of the storage space 30 (toward the liquid).

[0052] When the packing 40 is an O-ring, the protrusion 21 preferably contacts the center of the packing 40 in the Z direction. In an O-ring, the surface facing the protrusion 21 is curved. Therefore, when the protrusion 21 contacts the center of the packing 40 in the Z direction, both the first inclined surface 211 and the second inclined surface 212 of the protrusion 21 can be stably contacted with the packing 40. Therefore, the packing 40 can be deformed so that the portion 213x of the contact end 213 where the contact pressure is greatest is positioned on the accommodation space 30 side, thereby sealing the space between the turntable 10 and the support member 20.

[0053] Note that the protrusion 21 contacting the center of the packing 40 in the Z direction does not necessarily mean that the apex 21t of the protrusion 21 and the center of the packing 40 (O-ring) are aligned in the Z direction, as shown in FIG. 6 . The apex 21t of the protrusion 21 may be slightly offset from the center of the packing 40, as shown in FIGS. 7 and 8 . FIGS. 7 and 8 show a state in which the apex 21t of the protrusion 21 is offset from the center of the packing 40 by approximately 0.5 mm when the diameter of the packing 40 is 10 mm. However, if the protrusion 21 is significantly offset from the center of the packing 40 in the Z direction, the area of ​​the protrusion 21 that contacts the packing 40 becomes smaller, and the distribution of contact pressure also changes. Therefore, the protrusion 21 is considered to contact the center of the packing 40 in the Z direction when the pressure distribution is maintained such that the portion 213x of the contact end 213 where the contact pressure is greatest is located on the side of the housing space 30.

[0054] 7 shows a case where the apex 21t of the protrusion 21 is shifted in the Z direction from the center of the packing 40 to the opposite side of the accommodation space 30 (toward the atmosphere). In this case, the portion 213x where the contact pressure is maximum is also located on the accommodation space 30 side, and the length D3 from the bottom end 213l of the contact end 213 to the maximum portion 213x is shorter than the length D4 from the maximum portion 213x to the top end 213u of the contact end 213. Therefore, a pumping action occurs, and the gap between the rotating member 10 and the support member 20 is sealed.

[0055] 8 shows a case where the apex 21t of the protrusion 21 is shifted in the Z direction toward the accommodation space 30 (liquid side) from the center of the packing 40. In this case, the portion 213x where the contact pressure is maximum is also located on the accommodation space 30 side, and the length D5 from the bottom end 213l of the contact end 213 to the maximum portion 213x is shorter than the length D6 from the maximum portion 213x to the top end 213u of the contact end 213. Therefore, a pumping action is generated, and the gap between the rotating member 10 and the support member 20 is sealed.

[0056] 9A to 9D are explanatory diagrams of the annular groove 13. FIGS. 10A to 10C are explanatory diagrams of a modified annular groove 51. The annular groove 13 of the turntable 10 is defined by a first surface S1 and a second surface S2 that face each other in the Z direction, and a third surface S3 that connects the first surface S1 and the second surface S2. In this case, in the rotating device 1 (i.e., when the sealing structure 100 is assembled), it is preferable that the packing 40 be in contact with the first surface S1, the second surface S2, and the third surface S3.

[0057] This eliminates clearance in the Z direction in the annular groove 13 that accommodates the packing 40, and the position of the packing 40 in the Z direction in the rotating device 1 can be determined. Therefore, the protrusion 21 can be brought into contact with the center of the packing 40 in the Z direction (as in any of Figures 6 to 8). Therefore, the packing 40 can be deformed so that the portion 213x of the contact end 213 where the contact pressure is greatest is positioned on the housing space 30 side. The position of the packing 40 in the X direction in the rotating device 1 is also determined. Therefore, the protrusion 21 can be pressed into the packing 40 by the desired amount, achieving the desired contact pressure. Therefore, the sealing performance between the rotary table 10 and the support member 20 can be improved.

[0058] Furthermore, as shown in FIG. 9A, it is preferable that the rotary table 10 includes a lower table 12 (first member) having a first surface S1 and a third surface S3 that form the annular groove portion 13, and an upper table 11 (second member) that is a separate member from the lower table 12 and has a second surface S2.

[0059] The annular groove that accommodates the packing 40 may be a U-shaped groove 51 (horizontal U-shaped groove) provided in an inseparable member 50 (rotating member or support member), as shown in Fig. 10A. In this case, the packing 40 can be installed in contact with three surfaces that define the U-shaped groove 51, as shown in Fig. 10C. However, if the packing 40 is fitted into the U-shaped groove 51 without any clearance, there is a risk that local deformation (dentation) of the packing 40 will occur.

[0060] Therefore, as described above, it is preferable that the annular groove portion 13 be composed of multiple disassembled components (upper table 11 and lower table 12). By doing so, as shown in FIG. 9B, the packing 40 can be placed on the first surface S1 and third surface S3 (L-shaped groove) of the lower table 12, and then the second surface S2 of the upper table 11 can be used to cover the groove, as shown in FIG. 9C. This prevents local deformation (depression due to elongation) of the packing 40 while keeping the packing 40 in contact with the first surface S1 to the third surface S3, thereby preventing a decrease in sealing performance due to local deformation. This also prevents increased friction in the portion of the packing 40 where the diameter increases due to shrinkage caused by local deformation.

[0061] 11A and 11B are explanatory diagrams of a modified example of the rotating device 1. In FIG. 3, the packing 40 is housed in the rotary table 10 (rotating member), but as shown in FIG. 11, an annular groove 22 may be provided in the support member 20, and the packing 40 may be housed in the annular groove 22. In this case, the rotary table 10 (lower table 12) may be provided with a protrusion 14 that extends annularly along the circumferential surface of the packing 40. An example of the protrusion 14 is one that is processed and molded so as to protrude toward the packing 40 on the surface 12a of the lower table 12 facing the support member 20.

[0062] Like the protrusion 21 described above, the protrusion 14 of the turntable 10 also preferably has a first inclined surface 141 provided on the lubricant storage space 30 side and a second inclined surface 142 provided on the opposite side, as shown in Fig. 11B. The contact end 143 of the protrusion 14 where it comes into contact with the packing 40 has a portion where the contact pressure with the packing 40 is maximum, and this maximum portion is preferably located on the storage space 30 side. In this way, the distribution of the contact pressure between the protrusion 14 and the packing 40 becomes similar to the contact pressure distribution of the oil seal 100, which acts as a pumping action and improves the sealing performance between the turntable 10 and the support member 20.

[0063] 11 includes a lower support member 201 that forms an L-shaped groove and an upper support member 202 that covers the L-shaped groove from above. This allows the packing 40 to be placed in the annular groove 22 without local deformation of the packing 40 while being in contact with the three surfaces that define the annular groove 22.

[0064] 11 , the packing 40 is provided on the support member 20 side. Therefore, it is preferable that the frictional force (total value of static frictional forces) generated between the packing 40 and each of the three surfaces of the annular groove 22 is at least twice the rotational force (rotational torque) of the rotating member 10, i.e., the rotational frictional force between the protrusion 14 and the packing 40. This makes it more difficult for the packing 40 to move than when the frictional force between the packing 40 and the annular groove 22 is less than twice the rotational force of the rotating member 10, thereby preventing the packing 40 from rotating due to the rotational force of the rotating member 10. The static frictional force between the packing 40 and the annular groove 22 and the rotational frictional force between the protrusion 14 and the packing 40 can be determined by actual measurements.

[0065] FIG. 12 is a diagram showing an example of the crushing allowance of the packing 40. When the total deformation of the packing 40 due to the three surfaces of the annular groove 22 (the total of the crushed cross-sectional areas a401, a402, and a403) is greater than the deformation of the packing 40 due to the protrusion 14 (the crushed cross-sectional area a14), the packing 40 can be fixed to the annular groove 22 and prevented from rotating. Specifically, when the diameter of the packing 40 (O-ring) is D, the crushing allowances on the upper and lower sandwiching surfaces are each set to 0.06D, and the crushing allowance on the surface along the Z direction is set to 0.04D. Meanwhile, the crushing allowance due to the protrusion 14 is set to 0.06D. In this case, although there is uncertainty due to variations in the roughness and friction coefficient of each surface, the static friction force between the packing 40 and the annular groove 22 is likely to be approximately twice the rotational friction force between the protrusion 14 and the packing 40.

[0066] This also applies to the aforementioned embodiment ( FIG. 3 ) as well as the modified example. In other words, the total amount of deformation of the packing 40 caused by the three surfaces of the annular groove 13 on the rotating member 10 side should be greater than the amount of deformation of the packing 40 caused by the protrusion 21 on the support member 20 side. This secures the packing 40 to the annular groove 13, making it less likely for the packing 40 to shift position relative to the rotating annular groove 13, and allowing the packing 40 to rotate together with the annular groove 13. Preferably, the frictional force generated between the packing 40 and each of the three surfaces of the annular groove 13 is at least twice the rotational frictional force between the protrusion 21 and the packing 40. This more reliably secures the packing 40 to the annular groove 13, allowing the packing 40 to rotate together with the annular groove 13.

[0067] 3 illustrates a four-point support ball bearing as the bearing 9, but the bearing 9 is not limited to this. For example, the bearing 9 may be a cross roller bearing (not shown) or the like.

[0068] ====Method of Assembling Rotating Device 1=== Next, a method of assembling the rotating device 1 including the rotating table 10, the support member 20, the accommodation space 30 for accommodating the lubricant, and the packing 40 will be described.

[0069] The assembly method includes a first step of placing the packing 40 in an annular groove portion (annular groove portion 13 in FIG. 3 or annular groove portion 22 in FIG. 11A) provided on one of the rotating table 10 and the support member 20, and a second step of bringing a protrusion (protrusion 21 in FIG. 3 or protrusion 14 in FIG. 11A) provided on the other of the rotating member 10 and the support member 20 into contact with the packing 40 so that the packing 40 elastically deforms. The protrusion (21 or 14) extends annularly along the circumferential surface of the packing 40 and has a first inclined surface (211 or 141) provided on the storage space 30 side and a second inclined surface (212 or 142) provided on the opposite side.

[0070] In the second step, a contact end portion (213 or 143) is formed at the portion where the protrusion (21 or 14) contacts the packing 40, and the protrusion (21 or 14) is brought into contact with the packing 40 so that the portion of the contact end portion (213 or 143) where the contact pressure with the packing 40 is maximum is located closer to the storage space 30 than the center of the contact end portion (213 or 143) in the Z direction.

[0071] With the rotating device 1 assembled using the above assembly method, the distribution of contact pressure between the protrusion (21 or 14) and the packing 40 is similar to the distribution of contact pressure of the oil seal 100. Therefore, a pumping action is generated, improving the sealing performance between the rotary table 10 and the support member 20.

[0072] Furthermore, the annular groove portion may be an inseparable U-shaped groove 51 (see FIG. 10A ), but as shown in FIG. 9A , it may be formed by a member having a first surface S1 and a third surface S3 that are L-shaped grooves and a separate member having a second surface S2. In this case, as shown in FIG. 9B , the packing 40 may first be placed on the member having the first surface S1 and the third surface S3 that are L-shaped grooves (here, the lower table 12). Then, the packing 40 may be covered with a member having the second surface S2 that is separate from the member having the L-shaped groove (here, the upper table 11), thereby bringing the packing 40 into contact with the first surface S1 and the second surface S2.

[0073] By doing so, the position of the packing 40 in the Z direction is defined, and the protrusion (21 or 14) can be brought into contact with a desired position (for example, the center) of the packing 40 in the Z direction. Therefore, the packing 40 can be deformed so that the portion where the contact pressure between the protrusion (21 or 14) and the packing 40 is greatest is located on the side of the accommodation space 30. Furthermore, compared to when the packing 40 is fitted into an inseparable U-shaped groove 51, local deformation of the packing 40 can be suppressed, and the sealing performance between the turntable 10 and the support member 20 is improved.

[0074] 9D , the packing 40 can be brought into contact with the third surface S3 by bringing the protruding portion (21 or 14) into contact (pressure-contact) with the packing 40. This determines the position of the packing 40 in the X direction, and allows the protruding portion (21 or 14) to bite into the packing 40 by a desired amount of compression, thereby obtaining a desired contact pressure.

[0075] 13A to 13D are explanatory diagrams of another method of assembling the rotating device 1. As shown in Fig. 13B, after a first step of placing the packing 40 in an L-shaped groove having a first surface S1 and a third surface S3, as shown in Fig. 13C, a second step of bringing the protrusion (21 or 14) into contact with the packing 40 may be performed, and finally, a step of covering the packing 40 with the second surface S2 may be performed.

[0076] Even in this case, the protrusion (21 or 14) can be brought into contact with a desired position (e.g., the center) of the packing 40 in the Z direction. Therefore, the packing 40 can be deformed so that the portion of the contact end (213 or 143) where the contact pressure with the packing 40 is maximum is located on the housing space 30 side. Furthermore, according to the above assembly method, unlike when the packing 40 is fitted into a U-shaped groove, local deformation (depression due to elongation) of the packing 40 can be prevented, and a decrease in sealing performance can be prevented. Furthermore, it is also possible to prevent increased friction in the portion of the packing 40 where the diameter has increased due to shrinkage caused by local deformation.

[0077] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0078] For example, although the barrel cam device 1 has been exemplified as a rotating device, the present invention is not limited to this. The rotating device may be, for example, a device in which a rotating member is rotated directly by a motor or indirectly via gears or the like. Furthermore, although the rotating device 1 has been exemplified as being used as an NC table for a machine tool, the rotating device 1 (sealing structure 100) of this embodiment can be used in various machines (vehicles, construction machinery, air conditioning equipment, robots, etc.).

[0079] DESCRIPTION OF SYMBOLS 1 Rotating device (barrel cam device) 2 Housing, 3 Input shaft, 4 Rotating shaft body, 5 Cam follower, 6 Motor, 7 Coupling, 8 Input bearing, 9 Bearing, 10 Rotating table (rotating member), 11 Upper table, 12 Lower table, 13 Annular groove, 14 Protrusion, 20 Support member, 21 Protrusion, 22 Annular groove, 30 Storage space, 40 Packing, 51 U-shaped groove, 70 Barrel cam, 100 Oil seal, 101 Rotating shaft

Claims

1. A rotating device comprising: a rotating member; a support member supporting a peripheral surface of the rotating member; a storage space for storing a lubricant; and a gasket provided between the rotating member and the support member for preventing leakage of the lubricant, wherein one of the rotating member and the support member has an annular groove portion for storing the gasket, and the other of the rotating member and the support member has a protrusion that contacts the gasket so that the gasket elastically deforms and extends in an annular shape along the peripheral surface of the gasket, the protrusion having a first inclined surface provided on the storage space side, a second inclined surface provided on the opposite side to the storage space side, and a contact end in contact with the gasket, the contact end having a portion where the contact pressure with the gasket is maximum, and the maximum portion being located on the storage space side rather than the center of the contact end in the direction of the rotational axis of the rotating member.

2. A rotating device as described in claim 1, characterized in that the inclination angle formed by a virtual plane that passes through the apex of the protrusion and is aligned with the direction of the rotation axis and the first inclined surface is greater than the inclination angle formed by the virtual plane and the second inclined surface.

3. A rotating device according to claim 1 or 2, characterized in that the packing is an O-ring, and the contact end of the protrusion is in contact with the center of the packing in the direction of the rotation axis.

4. A rotating device as claimed in claim 1 or 2, characterized in that the annular groove portion is defined by a first surface and a second surface opposing each other in the direction of the rotation axis, and a third surface connecting the first surface and the second surface, the gasket is in contact with the first surface, the second surface, and the third surface, and one of the rotating member and the support member comprises a first member having the first surface and the third surface, and a second member which is a separate member from the first member and has the second surface.

5. A method for assembling a rotating device comprising: a rotating member; a support member supporting a circumferential surface of the rotating member; a storage space for storing a lubricant; and a gasket provided between the rotating member and the support member for preventing leakage of the lubricant, comprising: a first step of arranging the gasket in an annular groove provided on one of the rotating member and the support member; and a second step of bringing a protruding portion provided on the other of the rotating member and the support member, the protruding portion extending in an annular shape along the circumferential surface of the gasket and having a first inclined surface provided on the storage space side and a second inclined surface provided on the opposite side to the storage space side, into contact with the gasket so as to elastically deform the gasket, wherein in the second step, the protruding portion forms a contact end portion which is a portion where the protruding portion contacts the gasket, and the protruding portion is brought into contact with the gasket so that a portion of the contact end portion where the contact pressure with the gasket is maximum is located closer to the storage space than the center of the contact end portion in the direction of the rotational axis of the rotating member.

6. A method for assembling a rotating device as described in claim 5, wherein the annular groove portion is defined by a first surface and a second surface opposing each other in the direction of the rotation axis, and a third surface connecting the first surface and the second surface, and the method comprises placing the packing in a first member having the first surface and the third surface, and then covering the packing with a second member which is a separate member from the first member and has the second surface, thereby bringing the packing into contact with the first surface and the second surface.

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