Seal member, seal unit and screw device

Abstract

To improve a seal function, in a seal member used in a screw device.SOLUTION: A seal member 40 of the present disclosure is fixed to an axial end part 33 of a nut member 30 of a screw device 10, and seals a gap S1 between the nut member 30 and a screw shaft 20. The seal member 40 comprises an annular body 41, and a cloth material 43 fixed to the body 41. The cloth material 43 contacts side surfaces 21a, 21b of a thread 21 spirally formed on an outer peripheral surface 20a of the screw shaft 20 in a normal direction of the side surfaces 21a, 21b of the thread 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a seal member, a seal unit, and a screw device. [Background technology]

[0002] A screw device is known as a mechanical element that converts the rotational motion of a motor or the like into linear motion. The screw device includes a screw shaft having a spiral groove on its outer periphery and a nut having a spiral groove on its inner periphery. In the case of a ball screw device, the screw shaft and a nut are further provided with a plurality of balls that roll between the screw shaft and the nut. If foreign matter enters the screw device, there is a risk of deterioration, such as a decrease in the feed accuracy of the screw device or an increase in the torque required for rotation.

[0003] For this reason, sealing members have traditionally been used to prevent foreign matter from entering screw devices. Patent Document 1 discloses an end seal for a ball screw that includes cut piles that protrude toward the groove of the male screw shaft. The cut piles are arranged in a spiral shape around the outer periphery of the male screw shaft, facing the groove over a length of at least one rotation.

[0004] Patent Document 2 discloses a technology in which the inner peripheral surface of a rubber seal member contacts the periphery of a screw shaft. Patent Document 3 discloses a rubber dustproof arc step with an arc of 237 degrees that contacts the external thread groove of the screw shaft in an arc shape. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2020 / 071515 [Patent Document 2] Japanese Patent Application Publication No. 2018-112313 [Patent Document 3] Japanese Patent Application Publication No. 2019-19919 Summary of the Invention [Problem to be solved by the invention]

[0006] There is a demand for improved sealing functions of sealing members used in screw devices, such as preventing the intrusion of foreign matter and removing foreign matter adhering to the screw shaft (these functions are appropriately referred to as "sealing functions"). For example, Patent Document 2 aims to improve the sealing function by increasing the axial thickness of the sealing member and increasing the contact area between the outer circumferential surface of the screw shaft and the sealing member.

[0007] However, if the axial thickness of the seal member is increased, excessive interference may occur between the screw shaft and the seal member, potentially creating a gap between them. For this reason, in the technology of Patent Document 2, the thickness of the portion of the seal member that comes into contact with the screw shaft is set to a predetermined value or less based on the pitch, lead angle, and groove width of the screw shaft, and there is a limit to how much the axial thickness of the seal member can be increased.

[0008] Furthermore, if the axial thickness of the seal member is increased to improve the sealing function, the frictional resistance of the seal member against the rotation of the screw shaft increases, which causes a problem of an increase in the rotational torque of the screw device.When the frictional resistance of the seal member increases, in addition to the increase in rotational torque due to the frictional resistance itself, there is also the problem of the screw shaft and the like expanding due to frictional heat, which further increases the rotational torque of the screw device.

[0009] In view of these problems, the present disclosure aims to solve the problems associated with improving the sealing function of a sealing member used in a screw device. [Means for solving the problem]

[0010] The screw device of the present disclosure is a sealing member that is fixed to the axial end of a nut member of the screw device and seals the gap between the nut member and the screw shaft, and is provided with an annular main body and a cloth material fixed to the main body, and the cloth material is a sealing member that contacts the side of a screw thread that is formed spirally on the outer peripheral surface of the screw shaft in the normal direction to the side of the screw thread. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to solve problems associated with improving the sealing function of a sealing member used in a screw device. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a screw device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the screw device according to the embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the screw device according to the embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a part of FIG. 3. [Figure 5] 3A and 3B are diagrams illustrating a main body of a sealing member according to an embodiment. [Figure 6] 3A and 3B are diagrams illustrating a main body of a sealing member according to an embodiment. [Figure 7] 10A to 10C are diagrams illustrating the effects of the screw device according to the embodiment. [Figure 8] 5A to 5C are diagrams illustrating an example of a method for manufacturing a sealing member according to an embodiment. [Figure 9] 5A to 5C are diagrams illustrating an example of a method for manufacturing a sealing member according to an embodiment. [Figure 10] 10A and 10B are diagrams showing a seal member according to a modified example. [Figure 11] FIG. 10 is a cross-sectional view of a screw device according to a modified example. [Figure 12] 10A to 10C are diagrams illustrating a manufacturing method of a seal unit according to a modified example. [Figure 13] 10A to 10C are diagrams illustrating a manufacturing method of a seal unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described.

[0014] [1. Embodiment] [1.1 Overall configuration of the screw device 10] FIG. 1 is a perspective view showing a screw device 10 according to an embodiment. FIG. 2 is an exploded perspective view of the screw device 10 of FIG. 1, disassembled in the axial direction. FIG. 3 is a cross-sectional view of the screw device 10 taken along an xz plane including the center line C1. FIG. 4 is an enlarged cross-sectional view showing a part of FIG.

[0015] For ease of explanation, an xyz Cartesian coordinate system is shown in the figure. In the following explanation, the x direction is referred to as the "axial direction," the positive side of the x direction is referred to as the "one axial side," and the negative side of the x direction is referred to as the "other axial side." The yz plane is a plane perpendicular to the axial direction.

[0016] The screw device 10 includes a screw shaft 20, a nut member 30, and a plurality of seal members 40 (seal units U1). The screw device 10 is a device that converts rotational motion of one of the screw shaft 20 and the nut member 30 into linear motion in the axial direction of the other of the screw shaft 20 and the nut member 30, and is also called a "feed screw." In the following explanation, the screw device 10 that does not include a ball will be described, but the screw device 10 may also be a ball screw device.

[0017] The screw shaft 20 is a shaft member extending in the axial direction and is provided rotatable around a center line C1. In the following description, the axial end side of the screw shaft 20 is also referred to as the "axial outer side," and the axial inside of the screw shaft 20 is also referred to as the "axial inner side." In Fig. 3, the right side is the axial inner side (one axial side), and the left side is the axial outer side (one axial side).

[0018] The direction perpendicular to the center line C1 is referred to as the "radial direction." The radial direction includes at least one of a y-direction component and a z-direction component. In the radial direction, the side closer to the center line C1 is the inner side, and the side away from the center line C1 is the outer side. The direction in which the screw shaft 20 rotates around the center line C1 is referred to as the "circumferential direction." A screw thread 21 is formed helically on the outer peripheral surface 20a of the screw shaft 20. The screw thread 21 includes a side surface 21a on the other axial side, a side surface 21b on one axial side, and an apex portion 21c located radially outward from the side surfaces 21a and 21b. A screw groove 22 is formed between adjacent screw threads 21 in the axial direction.

[0019] The nut member 30 includes a nut body N1, a housing H1, and a flange F1. A screw groove 31 that faces the screw groove 21 in the radial direction is formed in a spiral shape on an inner peripheral surface 30a of the nut body N1. A screw groove 32 is formed between two screw grooves 31 that are adjacent in the axial direction. The screw groove 32 faces the screw groove 22 in the radial direction. If the screw device 10 is a ball screw device, the screw groove 31 faces the screw groove 22 in the radial direction, and multiple balls are provided between the screw grooves 22 and 31.

[0020] The housing H1 is a member that houses a plurality of seal members 40. In this embodiment, the housing H1 is a member separate from the nut body N1, and the nut body N1 and the plurality of seal members 40 are fixed to the inner circumferential surface H1a of the housing H1. Note that the housing H1 may be a member that is formed integrally with the nut body N1.

[0021] A plurality of (e.g., three) ribs 34 extending in the axial direction are formed on the inner peripheral surface H1a of the housing H1. The ribs 34 are, for example, rod-shaped members extending in the axial direction and are provided as separate members from the housing H1. A recess (not shown) extending in the axial direction is formed on the inner peripheral surface H1a, and the ribs 34 are axially inserted into the recess with a portion of the rib 34 protruding radially inward, for example, after a plurality of seal members 40 are accommodated in the housing H1. In the example of FIG. 2, three ribs 34 are provided at 120-degree intervals in the circumferential direction. The ribs 34 have a shape corresponding to a recess 65 (described below) of the seal member 40, and inserting the rib 34 into the recess 65 fixes the seal member 40 within the housing H1.

[0022] The flange F1 is provided at the other axial end of the housing H1. The diameter of the inner peripheral surface F1a of the flange F1 is smaller than the outer diameter of the seal members 40. Therefore, the flange F1 functions as a lid that prevents the multiple seal members 40 housed in the housing H1 from slipping out to the other axial end.

[0023] One of the screw shaft 20 and the nut member 30 is connected to a rotation mechanism (not shown) such as a motor and a pulley, and is driven to rotate around the center line C1 by the rotation mechanism. As a result, the other of the screw shaft 20 and the nut member 30 moves linearly in the axial direction. In other words, the screw shaft 20 and the nut member 30 rotate relatively around the center line C1.

[0024] The seal unit U1 includes a plurality of (for example, four) seal members 40. The number of seal members 40 included in the seal unit U1 is not particularly limited. Also, the screw device 10 may be provided with a single seal member 40, rather than the seal unit U1. When particularly distinguishing between the four seal members 40, they will be appropriately referred to as seal members 40a, 40b, 40c, and 40d, in order from the other axial side.

[0025] The seal member 40 is fixed to an axial end portion 33 of the nut member 30 and seals a gap S1 between the nut member 30 and the screw shaft 20. The axial end portion 33 is, for example, a region of the nut member 30 that is axially outer (on the other axial side) than the nut body N1. In this case, the gap S1 is the space between the inner circumferential surface H1a of the housing H1 and the outer circumferential surface 20a of the screw shaft 20. The seal member 40 includes an annular main body 41 and a fabric material 43 fixed to the main body 41 with an adhesive 42.

[0026] [1.2 Configuration of the sealing member 40] 5 and 6 are diagrams illustrating the main body 41 of the seal member 40. FIG. 5 is a front view showing the main bodies 41 of four seal members 40 stacked one on top of the other. FIG. 6 is a front view showing the main bodies 41 of four seal members 40 individually. When particularly distinguishing between the main bodies 41 of the four seal members 40, they will be appropriately referred to as main bodies 41a, 41b, 41c, and 41d in order from the other axial side. FIG. 6(a) shows the main body 41a, and similarly FIGS. 6(b) to 6(d) show the main bodies 41b to 41d, respectively. The main body 41 is an integrally molded product made of, for example, rubber or resin. The main body 41 may also be made of metal.

[0027] 6(a), the main body 41 includes a side surface 61 formed along the zy plane, an inclined surface 62 inclined in the axial direction from the side surface 61, an inner peripheral surface 63 formed along the outer peripheral surface 20a of the screw shaft 20, an outer peripheral surface 64 formed along the inner peripheral surface H1a of the housing H1, and a plurality of (e.g., three) recesses 65 recessed radially inward from the outer peripheral surface 64. The inclined surface 62 is inclined along the helix of the screw thread 21.

[0028] The side surface 61 includes a side surface 61a on one axial side (the far side in the plane of the paper in FIG. 6) and a side surface 61b on the other axial side. As shown in FIG. 4, the inclined surface 62 includes an inclined surface 62a inclined toward one axial side and radially inward, and an inclined surface 62b inclined toward the other axial side and radially inward. The arc degree of each of the inclined surfaces 62a, 62b is equal to or greater than 90 degrees and equal to or less than 180 degrees, for example, 120 degrees.

[0029] 5 and 6, the positions where the recesses 65 are formed on the main bodies 41a to 41d are equal in the circumferential direction. As shown in Fig. 3, the seal member 40 is housed in the housing H1 with the screw shaft 20 inserted into the inner periphery of the seal member 40 and the ribs 34 inserted into the recesses 65. In this state, radial movement of the seal member 40 is restricted by the outer periphery 64 of the seal member 40 abutting against the inner periphery H1a of the housing H1.

[0030] Furthermore, the circumferential width of the recesses 65 is slightly (for example, about 5 to 10%) larger than the circumferential width of the ribs 34 of the housing H1. Therefore, circumferential movement of the seal member 40 is permitted only by the difference in circumferential width between the recesses 65 and the ribs 34, and is restricted by the inner surfaces of the recesses 65 abutting against the ribs 34. In other words, the seal member 40 can move slightly (for example, about 1 degree) in the circumferential direction until the inner surfaces of the recesses 65 abut against the ribs 34.

[0031] The ribs 34 function like rails, allowing the seal member 40 to move in the axial direction. The axial movement of the seal member 40 is restricted by the screw shaft 20, the nut body N1, and the flange F1. When the screw shaft 20 rotates in one circumferential direction relative to the nut member 30 and the nut member 30 moves in one axial direction relative to the screw shaft 20, the seal member 40 moves in the other axial direction (toward the flange F1) due to friction with the screw shaft 20. Then, the seal member 40a, which is closest to the flange F1, abuts against the flange F1, restricting the movement of the seal member 40 in the other axial direction.

[0032] When the screw shaft 20 rotates in the other circumferential direction relative to the nut member 30 and the nut member 30 moves in the other axial direction relative to the screw shaft 20, the seal member 40 moves to one axial side (toward the nut body N1) due to friction with the screw shaft 20. Then, the seal member 40d closest to the nut body N1 abuts against the nut body N1, thereby restricting the movement of the seal member 40 to one axial side.

[0033] On the main bodies 41a and 41d, the positions where the inclined surfaces 62 are formed are the same in the circumferential direction. On the other hand, on the main bodies 41a to 41c, the positions where the inclined surfaces 62 are formed are different in the circumferential direction. Specifically, on the main bodies 41a to 41c, the positions where the inclined surfaces 62 are formed are rotated by 120 degrees around the center line C1.

[0034] As shown in Figure 4, the inclined surface 62a (for example, the inclined surface 62a of the sealing member 40b) faces the side surface 21a on the other axial side of the thread 21, and the inclined surface 62b (for example, the inclined surface 62b of the sealing member 40a) faces the side surface 21b on one axial side of the thread 21.

[0035] See Figures 3 and 4. The adhesive 42 that secures the fabric material 43 to the main body 41 is, for example, a hot-melt adhesive, more specifically, a rubber- or polyester-based hot-melt adhesive. By using a hot-melt adhesive, swelling of the adhesive 42 can be suppressed compared to a solvent-based adhesive, even if a liquid such as a coolant seeps into the sealing member 40 during use of the screw device 10. This can prevent peeling of the fabric material 43 due to swelling of the adhesive 42. If swelling during use of the screw device 10 is unlikely, a solvent-based adhesive that exerts its adhesive function by drying an organic solvent may be used as the adhesive 42. Alternatively, a water-based adhesive containing vinyl acetate resin may be used as the adhesive 42. Alternatively, the adhesive 42 may be a double-sided tape.

[0036] The fabric material 43 is, for example, a chemical fiber material, specifically a fiber material made of polyester, PFA (perfluoroalkoxyalkane), or PTFE (polytetrafluoroethylene). The fabric material 43 is, for example, a pile knitted fabric, specifically including cut pile 44 protruding from the surface of the fabric material 43. Note that the fabric material 43 may be, for example, a knitted fabric other than a pile knitted fabric, or may be a woven fabric.

[0037] The fabric material 43 covers the side surfaces 61, inclined surfaces 62, and inner peripheral surface 63 of the main body 41. Specifically, as shown in FIG. 4, the fabric material 43 is attached to the main body 41 with an adhesive 42 so as to conform to the shapes of the inclined surfaces 62 and inner peripheral surface 63. Therefore, the protruding direction of the cut pile 44 protruding from the fabric material 43 attached to the inclined surfaces 62 and inner peripheral surface 63 mainly includes a component normal to the inclined surfaces 62 and inner peripheral surface 63. In other words, the cut pile 44 stands almost perpendicular (for example, within a range of 70 degrees to 90 degrees) on the inclined surfaces 62 and inner peripheral surface 63. Note that the fabric material 43 does not need to cover all of these surfaces 61 to 63; for example, it may cover only the inclined surface 62.

[0038] The fabric material 43 contacts the side surfaces 21a, 21b of the thread 21 in the normal direction to the side surfaces 21a, 21b. Because the normal direction to the side surfaces 21a, 21b mainly includes an axial component, the fabric material 43 can also be expressed as contacting the side surfaces 21a, 21b of the thread 21 in the axial direction. Here, "contact in the axial direction" means that the axial component is greater than the radial component in the contact direction between the fabric material 43 and the side surfaces 21a, 21b. For example, in FIG. 4 , the cut pile 44 protruding from the portion of the fabric material 43 covering the inner circumferential surface 63 "radially" contacts the crest portion 21c of the thread 21 or the thread groove 22. In contrast, the cut pile 44 protruding from the portion of the fabric material 43 covering the inclined surface 62 "axially" contacts the side surfaces 21a, 21b of the thread 21 at an angle of more than 45 degrees from the radial direction.

[0039] More specifically, the tip portions 44a of the cut pile 44 protruding from the portion of the fabric material 43 covering the inclined surface 62a are in contact with the side surface 21a of the thread 21. Similarly, the tip portions 44a of the cut pile 44 protruding from the portion of the fabric material 43 covering the inclined surface 62b are in contact with the side surface 21b of the thread 21. The tip portions 44a are in contact with the side surfaces 21a and 21b in an upright position (i.e., with the normal direction of each of the side surfaces 21a and 21b as the main component). In other words, the contact angle between the cut pile 44 and each of the side surfaces 21a and 21b is greater than 45 degrees, for example.

[0040] That is, the fabric material 43 of the sealing member 40 is in contact with the outer peripheral surface 20a of the screw shaft 20 over the entire circumferential direction. Specifically, the fabric material 43 is in three-dimensional contact with the side surfaces 21a, 21b, the apex portion 21c, and the thread groove 22 over the entire circumferential direction, thereby allowing the sealing member 40 to exhibit its sealing function. The portions of the fabric material 43 that are in contact with the side surfaces 21a, 21b are in contact in the normal direction to the side surfaces 21a, 21b, and the portions of the fabric material 43 that are in contact with the apex portion 21c or the thread groove 22 are in contact in the normal direction to the apex portion 21c or the thread groove 22.

[0041] [1.3 Effects of this embodiment] FIG. 7 is a diagram illustrating the effects of the screw device 10 according to this embodiment. 7(a) shows a conventional seal member 91 (for example, Patent Document 2, etc.). The seal member 91 is, for example, a rubber seal, and is in radial contact with the thread groove 22 of the screw shaft 20. Therefore, the contact length D1 between the seal member 91 and the screw shaft 20 is approximately equal to the thickness W1 (in reality, because the thread groove 22 is curved, the contact length D1 is slightly longer than the axial thickness W1 of the seal member 91).

[0042] In order to improve the sealing function of the sealing member 91, it is conceivable to increase the contact area between the outer peripheral surface 20a of the screw shaft 20 and the sealing member 91 (i.e., increase the contact length D1) by increasing the thickness W1 of the sealing member 91, as proposed in Patent Document 2, for example.

[0043] Also, as shown in Figure 7(b), by bringing the sealing member 91 into contact with the side surface 21a of the screw thread 21, it is possible to make the contact length D2 between the sealing member 91 and the screw shaft 20 longer than the contact length D1 while keeping the thickness W1 of the sealing member 91 the same.

[0044] However, if the contact length D2 between the seal member 91 and the screw shaft 20 becomes longer, the frictional resistance (sliding resistance) of the seal member 91 against the rotation of the screw shaft 20 increases accordingly, which creates the problem of increasing the rotational torque of the screw device 10.

[0045] When the frictional resistance of the seal member 91 increases, not only does the frictional resistance itself increase the rotational torque, but the screw shaft 20 and other components expand due to frictional heat, which further increases the rotational torque of the screw device 10. Also, when the screw shaft 20 expands due to frictional heat, the axial dimension of the screw shaft 20 changes, which causes a problem of a decrease in the feed accuracy of the screw device 10. Furthermore, when the frictional resistance of the seal member 91 is high, scratches are more likely to occur on the contact surface of the seal member 91 with the screw shaft 20, and these scratches may reduce the sealing function.

[0046] Therefore, the sealing member 40 of the embodiment uses a fabric material 43. The fabric material 43 contacts the side surface 21a (or side surface 21b) of the thread 21 in the normal direction of the side surfaces 21a and 21b. When a rubber sealing member 91 is used, the sealing member 91 deforms according to the shape of the side surface 21a, bringing the sealing member 91 and the side surface 21a into close contact, increasing the frictional resistance between the sealing member 91 and the side surface 21a. In contrast, the fabric material 43 has fine irregularities on its surface, which reduces the frictional resistance compared to when a rubber sealing member 91 is used. In this way, the sealing member 40 contacts the side surface 21a in the normal direction, making the contact length D2 longer than the contact length D1 and improving the sealing function, while the use of the fabric material 43 reduces the frictional resistance compared to the rubber sealing member 91.

[0047] Furthermore, the sealing member 40 (for example, sealing member 40a) seals the side surface 21b (or side surface 21a) of the thread 21 by bringing the cut pile 44 into contact with the side surface 21b (or side surface 21a) in the normal direction, and also seals the apex portion 21c of the thread 21 by bringing the cut pile 44 into contact with the apex portion 21c in the normal direction (i.e., radial direction). This allows the thread 21 to be sealed three-dimensionally, further improving the sealing function.

[0048] The cloth material 43 comes into sliding contact with the side surfaces 21a, 21b of the thread 21 when the screw shaft 20 rotates around the center line C1 relative to the nut member 30. At this time, the cloth material 43 removes foreign matter adhering to the side surfaces 21a, 21b, thereby preventing foreign matter from entering the screw device 10 and maintaining the meshing between the screw shaft 20 and the nut member 30.

[0049] The fabric material 43 has cut pile 44 that protrudes in the normal direction of the side surfaces 21a, 21b of the thread 21. The tip portions 44a of the cut pile 44 come into contact with the side surfaces 21a, 21b of the thread 21. This allows the fabric material 43 to come into point contact with the side surfaces 21a, 21b of the thread 21, thereby further reducing frictional resistance with the screw shaft 20.

[0050] The screw device 10 includes a plurality of seal members 40 arranged in the axial direction. By providing a plurality of seal members 40 in multiple stages in the axial direction, the sealing function of the entire screw device 10 can be further improved.

[0051] In particular, the seal members 40a, 40b, 40c have contact positions with the side surfaces 21a, 21b that vary circumferentially within one lead of the screw shaft 20. In this way, foreign matter can be removed at multiple locations within one lead of the screw shaft 20 by the multiple seal members 40, thereby further improving the sealing function.

[0052] Furthermore, for example, if multiple seal members 40 are integrated, the inner circumferential surface of the seal member 40 will include multiple projections and recesses corresponding to the threads 21 and the thread grooves 22. This makes it difficult to secure the fabric material 43 along the projections and recesses, which may result in, for example, poor fixation (poor adhesion) of the fabric material 43 to the main body 41. In contrast, in the present embodiment, by dividing the seal member 40 into multiple seal members 40 in the axial direction, the projections and recesses per seal member 40 are simplified, making it easier to secure the fabric material 43 along the inclined surface 62 and the inner circumferential surface 63. This simplifies the manufacturing process of the seal member 40, reducing manufacturing costs, while preventing the fabric material 43 from peeling off from the main body 41.

[0053] 2. Variations The present disclosure is not limited to the above-described embodiment, and various modifications are possible. In the following modifications, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0054] 2.1 Manufacturing method of the seal member 40 8 is a diagram showing an example of a manufacturing method for the seal member 40. The fabric material 43 may include, for example, two disk-shaped pieces of fabric 43a and 43b. The fabrics 43a and 43b are formed, for example, by punching out pile knitted fabric into a disk shape using a Thompson die. The inner diameter of the fabric 43a is smaller than the inner diameter of the main body 41. The disk-shaped region of the fabric 43a whose inner diameter is smaller than that of the main body 41 is referred to as "region R1."

[0055] The sealing member 40 is manufactured by attaching the fabric 43a from one axial side and the fabric 43b from the other axial side to the main body 41 in a state in which the adhesive 42 has been applied to the side surface 61 and the inclined surface 62. At this time, the fabrics 43a and 43b are bent from the side surface 61 along the inclined surface 62, thereby forming the fabric material 43 that contacts the side surfaces 21a and 21b of the thread 21 in the normal direction.

[0056] Furthermore, region R1 protrudes radially inward from inner circumferential surface 63 of main body 41. In this modification, materials 43a and 43b are not attached to inner circumferential surface 63. Instead, the inner circumferential edge of region R1 comes into radial contact with screw shaft 20, thereby sealing, for example, apex portion 21c of thread 21 and thread groove 22.

[0057] For example, there are cases where it is difficult to apply the adhesive 42 to the inner circumferential surface 63. According to this modification, even in such a case, the step of applying the adhesive 42 to the inner circumferential surface 63 can be omitted, making it easier to manufacture the seal member 40, while the region R1 comes into contact with the screw shaft 20 in the radial direction, thereby maintaining the sealing function of the seal member 40.

[0058] 2.2 Manufacturing method of the seal member 40 9A and 9B are diagrams illustrating an example of a method for manufacturing the seal member 40. As shown in Fig. 9A, the fabric material 43 may be a tubular fabric having an end E1 on one axial side and an end E2 on the other axial side that are open. In this case, the fabric material 43 is, for example, a tubular knitted material.

[0059] 9(a) and 9(b), the fabric material 43 is passed around the inner periphery of the main body 41 with the adhesive 42 applied to the main body 41. Then, both ends E1 and E2 are spread outward in the radial direction and attached to both side surfaces 61a and 61b, respectively, to produce the sealing member 40 as shown in FIG.

[0060] With this configuration, the fabric material 43 can seamlessly cover the side surface 61, the inclined surface 62, and the inner circumferential surface 63. The fabric material 43 tends to peel off easily, for example, from the ends E1 and E2. For example, compared to a case where the side surface 61, the inclined surface 62, and the inner circumferential surface 63 are covered with three pieces of fabric, peeling of the fabric material 43 from the main body 41 can be suppressed. In particular, because the ends E1 and E2 are fixed to the side surface 61, which does not come into contact with the screw shaft 20, peeling of the fabric material 43 can be further suppressed.

[0061] [2.3 Divided seal member 40e] 10A and 10B are diagrams showing a seal member 40e according to a modified example. As shown in Fig. 10A, the seal member 40e is formed by combining an upper member P1 and a lower member P2 that are divided in the vertical direction.

[0062] The upper member P1 is a semi-cylindrical member that is open downward, and has a connecting pin 45a formed on a mating surface P1a with the lower member P2. The connecting pin 45a protrudes downward from the mating surface P1a.

[0063] The lower member P2 is a semi-cylindrical member that is open on the upper side, and has a connecting hole 45b formed in a mating surface P2a with the upper member P1. The connecting hole 45b is recessed downward from the mating surface P2a and has a shape that corresponds to the connecting pin 45a.

[0064] 10(b), with the connecting pin 45a inserted into the connecting hole 45b, the upper member P1 and the lower member P2 are connected by butting the butting surfaces P1a and P1b together, thereby forming the seal member 40e. For example, when attaching the seal member 40 according to the above embodiment to the screw shaft 20, it is necessary to pass the seal member 40 along the spiral of the thread 21 from the axial end of the screw shaft 20 to the position where the seal member 40 is fixed. In contrast, by giving the seal member 40e a split structure, it is possible to attach the seal member 40e from midway in the axial direction of the screw shaft 20, which makes it easier to manufacture the screw device 10.

[0065] [2.4 Hybrid seal made of pile fiber and urethane resin] 11 is a cross-sectional view of a screw device 10a according to a modified example. The screw device 10a differs from the screw device 10 of the above embodiment in that the seal unit U1 further includes an auxiliary seal member 40f, but the other points are the same.

[0066] The auxiliary seal member 40f abuts against the outer peripheral surface 20a of the screw shaft 20 on one axial side (axially inner side) of the multiple seal members 40. That is, the auxiliary seal member 40f is located on one axial side of the seal member 40d. Like the multiple seal members 40, the auxiliary seal member 40f is fixed to the inner peripheral surface H1a of the housing H1.

[0067] The portion of the auxiliary seal member 40f that contacts the outer peripheral surface 20a of the screw shaft 20 is made of polyurethane resin. The entire auxiliary seal member 40f may be made of polyurethane resin. The polyurethane resin may be impregnated with, for example, a lubricant. The polyurethane resin contacts the outer peripheral surface 20a of the screw shaft 20 in a planar manner while elastically deforming (surface contact). While the tip portions 44a of the cut pile 44 are in point contact with the outer peripheral surface 20a of the screw shaft 20, the polyurethane resin provided on the auxiliary seal member 40f has a larger contact area per unit area than the tip portions 44a. This makes it easier for the polyurethane resin to remove foreign matter with a smaller particle size than the cut pile 44.

[0068] Here, the fabric material 43 of the multiple sealing members 40 is pile fiber. By combining a seal made of pile fiber and a seal made of polyurethane resin in this way, for example, large particles of foreign matter can be removed by the sealing members 40, and small particles of foreign matter or cutting oil (e.g., coolant) that cannot be removed by the sealing members 40 can be removed by the auxiliary sealing members 40f.

[0069] In particular, polyurethane resin tends to be easily damaged by large particles, while pile fibers tend to be more rigid and less susceptible to damage than polyurethane resin. Therefore, by providing a seal member 40 containing pile fibers on the axially outer side and an auxiliary seal member 40f containing polyurethane resin on the axially inner side, it is possible to more reliably remove foreign matter while maintaining the life of the polyurethane resin. This improves the sealing function of the screw device 10a.

[0070] [2.5 Divided seal unit U2] 12 and 13 are diagrams showing a manufacturing method for a seal unit U2, which is a modified example of the seal unit U1. The seal unit U2 is formed by combining two divided bodies P3 that are separated in the radial direction. The manufacturing method will be described below.

[0071] First, as shown in Fig. 12(a), a sheet-like fabric material 43c is attached to a semi-cylindrical main body 41g with an adhesive 42a. At this time, the adhesive 42a is attached to the surface of the fabric material 43c facing the main body 41g. The adhesive 42a is, for example, a double-sided tape. The fabric material 43c is, for example, a pile knitted fabric.

[0072] Next, as shown in Fig. 12(b), the ends E3 and E4 of the fabric material 43c are folded toward the side surfaces of the main body 41g, respectively, so that the inner circumferential surface and both side surfaces of the main body 41g are covered with the fabric material 43c, thereby forming the sealing member 40g, as shown in Fig. 12(c).

[0073] Next, as shown in FIG. 13(a), a seal member 40g is fixed to the seal fixing portion 34a. The seal fixing portion 34a is a semi-cylindrical member with grooves G1 and G2 formed on its inner circumferential surface. In the example of FIG. 13, two seal members 40g are fixed to one seal fixing portion 34a. Specifically, with an adhesive (e.g., an oil-resistant water-based adhesive) applied to the grooves G1 and G2, the two seal members 40g are fitted into the grooves G1 and G2, respectively. This forms one divided body P3 as shown in FIG. 13(b).

[0074] At this time, both end portions E3, E4 of the fabric material 43c are fixed to the seal fixing portion 34a in a state where they are sandwiched between the wall surfaces of the groove G1 (or groove G2) of the seal fixing portion 34a. By fixing both end portions E3, E4 in this manner, it is possible to prevent the fabric material 43c from peeling off from both end portions E3, E4 when the seal unit U2 is used in an environment where a liquid such as cutting oil is used.

[0075] 13(c), a cylindrical seal unit U2 is formed by combining two divided bodies P3 so that the two divided bodies P3 sandwich the screw shaft 20. By making the seal unit U2 a divided structure, it becomes possible to attach the seal unit U2 from the middle of the axial direction of the screw shaft 20, which facilitates the manufacture of the screw device 10. As in the above embodiment, the fabric material 43c included in the seal unit U2 is in normal contact with the side surfaces 21a, 21b of the screw thread 21 over the entire circumferential direction, and is in normal contact with the apex portion 21c of the screw thread 21 or the screw groove 22.

[0076] Here, in the divided body P3 shown in FIG. 13(b), the two seal members 40g are provided with a gap between them in the axial direction. However, the two seal members 40g may be provided in contact with each other without a gap in the axial direction. Also, three or more seal members 40g may be provided in one divided body P3, or only one seal member 40g may be provided. Furthermore, one seal member 40g may be provided so as to cover one thread 21, or may be provided so as to cover multiple threads 21. In the latter case, for example, the axial length of the seal member 40g is longer than the lead length of the screw shaft 20.

[0077] 3. Summary of Embodiments and Modifications The gist of the above embodiment and modifications will be described below.

[0078] (1) The sealing member 40, 40e of the present disclosure is a sealing member 40, 40e that is fixed to the axial end 33 of the nut member 30 of the screw device 10, 10a and seals the gap S1 between the nut member 30 and the screw shaft 20, and includes an annular main body 41 and a cloth material 43 fixed to the main body 41, and the cloth material 43 contacts the side surfaces 21a, 21b of the screw thread 21 that are spirally formed on the outer peripheral surface 20a of the screw shaft 20 in the normal direction of the side surfaces 21a, 21b of the screw thread 21.

[0079] The sealing member 40 contacts the side surface 21a in the normal direction, thereby increasing the contact length with the screw shaft 20 and improving the sealing function, while frictional resistance can be reduced by using the fabric material 43. This solves the problem (reducing the increase in frictional resistance) that accompanies the improvement of the sealing function.

[0080] (2) The fabric material 43 may have cut pile 44 protruding in the normal direction. In this case, the tip portions 44a of the cut pile 44 may be in contact with the side surfaces 21a, 21b of the thread 21. With this configuration, the fabric material 43 comes into point contact with the side surfaces 21a, 21b of the thread 21, thereby further reducing frictional resistance with the screw shaft 20 (and the temperature rise of the screw shaft 20 due to friction).

[0081] (3) The fabric material 43 may include a disk-shaped fabric 43a. In this case, the fabric 43a may be fixed to the axial side surface 61 of the main body 41 in a state in which an inner peripheral region R1 of the fabric 43a protrudes radially inward beyond the inner peripheral surface 63 of the main body 41. With this configuration, the process of applying the adhesive 42 to the inner peripheral surface 63 can be omitted, making it easier to manufacture the seal member 40, and the region R1 comes into contact with the screw shaft 20 in the radial direction, thereby maintaining the sealing function of the seal member 40.

[0082] (4) The fabric material 43 may be a tubular fabric having both axial ends E1, E2 open. In this case, both ends E1, E2 may be fixed to the side surface 61 of the main body 41 with the tubular fabric passing through the inner periphery of the main body 41. This configuration can prevent the fabric material 43 from peeling off.

[0083] (5) The seal unit U1 of the present disclosure is a seal unit U1 including a plurality of seal members 40, 40e arranged in the axial direction, the seal members 40, 40e being any one of (1) to (4). By providing the seal members 40, 40e in multiple stages in the axial direction in this manner, the sealing function can be improved.

[0084] (6) The positions at which the multiple seal members 40, 40e come into contact with the side surfaces 21a, 21b of the thread 21 in the normal direction are varied in the circumferential direction. This configuration allows foreign matter to be removed from multiple locations on the screw shaft 20, thereby further improving the sealing function.

[0085] (7) The seal unit U1 may further include an auxiliary seal member 40f that abuts against the outer peripheral surface 20a of the screw shaft 20, axially inward of the nut member 30 relative to the plurality of seal members 40. In this case, the plurality of seal members 40 may include a seal member 40 whose fabric material 43 is pile fiber, and the portion of the auxiliary seal member 40f that abuts against the outer peripheral surface 20a of the screw shaft 20 may be made of polyurethane resin. This configuration allows foreign matter to be removed more reliably while maintaining the life of the polyurethane resin.

[0086] (8) The screw device 10, 10a of the present disclosure is a screw device comprising a screw shaft 20, a nut member 30, and any one of the seal members 40, 40e (1) to (4) or any one of the seal units U1 (5) to (7).

[0087] [4. Other] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0088] 10 screw device 10a screw device 20 screw shaft 20a outer surface 21 thread 21a side surface 21b side surface 21c apex portion 22 screw groove 30 nut member 30a inner peripheral surface 31 thread groove 32 thread 33 axial end 34 rib 40 sealing member 40a sealing member 40b sealing member 40c Seal member 40d Seal member 40e Seal member 40f auxiliary seal member 41 main body 41a main body 41b body 41c body 41d body 42 Adhesive 43 Fabric material 43a Fabric 43b Fabric 44 Cut pile 44a Tip 45a Connecting pin 45b Connecting hole 61 Side 61a Side 61b Side 62 Slope 62a Inclined surface 62b Inclined surface 63 Inner peripheral surface 64 outer peripheral surface 65 recess 91 sealing member C1 Center line N1 Nut body H1 Housing H1a Inner surface F1 Flange F1a Inner surface S1 Gap R1 Area E1 End E2 End P1 Upper part P2 Lower part P1a Mating surface P2a Mating surface U1 Seal unit

Claims

1. A seal member that is fixed to an axial end of a nut member of a screw device and seals a gap between the nut member and the screw shaft, an annular body; a fabric material fixed to the main body; Equipped with The fabric material has cut pile protruding in a normal direction from a side surface of a thread formed spirally on the outer peripheral surface of the screw shaft, The tip portion of the cut pile is in contact with the side surface of the thread. Sealing material.

2. The annular body is composed of a plurality of semi-cylindrical members divided in the radial direction. The seal member according to claim 1 .

3. the fabric material includes a disk-shaped fabric; The fabric is fixed to the axial side surface of the main body in a state where an inner peripheral region of the fabric protrudes radially inward from the inner peripheral surface of the main body, The sealing member according to claim 1 or 2.

4. The fabric material is a tubular fabric having both axial ends open, The two ends are fixed to the side surfaces of the main body with the tubular fabric passing through the inner periphery of the main body. The sealing member according to claim 1 or 2.

5. The seal member according to any one of claims 1 to 4, wherein a plurality of seal members are arranged in an axial direction. A seal unit comprising:

6. The plurality of sealing members are arranged so that positions at which they contact the side surfaces of the threads in the normal direction are different from each other in the circumferential direction. The seal unit according to claim 5 .

7. Further provided is an auxiliary seal member that abuts against the outer circumferential surface of the screw shaft at an axially inner side of the nut member than the plurality of seal members, The plurality of sealing members include a sealing member in which the fabric material is pile fiber, A portion of the auxiliary seal member that contacts the outer peripheral surface of the screw shaft is made of polyurethane resin. The seal unit according to claim 5 or 6.

8. The screw shaft; The nut member; The seal member according to any one of claims 1 to 4 or the seal unit according to any one of claims 5 to 7; A screw device comprising:

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