Ball screw

Abstract

A ball screw (10) is provided with: a screw shaft (20) in which a screw shaft-side raceway groove (21) is formed; a nut (30) in which a nut-side raceway groove (31) is formed and which is provided with a through-hole (32) that connects the outer peripheral surface (33) and the nut-side raceway groove (31); a plurality of balls (26) rolling in the load raceway (25); and a circulation member (40) that is attached to the through-hole (32) and forms a ball return passage (48) through which the balls (26) circulate. A sealing member (50) made of resin or rubber is provided for sealing at least a portion of a gap between the inner peripheral surface of the through-hole (32) of the nut (30) and the outer peripheral surface of the circulation member (40). As a result, it is possible to prevent grease from leaking from the gap between the circulation member and the through-hole formed in the nut or to prevent external foreign matter from entering the gap.

Description

Technical Field

[0001] The present invention relates to a ball screw, and in particular to a ball screw capable of preventing grease from leaking from the inside of a nut and foreign matter from invading from the outside. Background Art

[0002] In recent years, ball screws for high-load drive with large balls of 0.5 to 1 inch have been used as a substitute for hydraulic drive mechanisms. On the other hand, in recent years, especially in the injection axis of injection molding machines, due to the high cycle and high-speed injection molding, there is a strong demand for ball screws to increase the driving speed and heat resistance.

[0003] Until now, the demand for high-speed feeding has been met by a resin circulation component having a three-dimensional ball return channel that can pick up the balls from the tangential direction of the load raceway. However, there are limits in strength and heat resistance in resin circulation components, so in order to solve these problems, circulation components have begun to be made of metal raw materials.

[0004] Patent Documents 1 and 2 describe methods of manufacturing a U-shaped circulation component by stamping. Both ends of the U-shaped circulation component are inserted and fitted into a circular hole provided in a nut to be stably mounted. In particular, in Patent Document 2, an O-ring groove is formed in the circular hole, and the gap between the circulation component and the hole is sealed with an O-ring to prevent grease from leaking from the gap.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-269564

[0008] Patent Document 2: Japanese Patent Application Publication No. 2007-321886 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in Patent Document 2, an O-ring is used to seal the gap between the circulation component and the hole to prevent grease leakage from the gap, but additional processing is required on the nut, such as processing an O-ring groove for installing the O-ring on the nut, which may lead to increased costs.

[0011] In addition, when the lifting portion of the metal circulation component is formed along the tangent direction of the load raceway, the hole of the nut is not circular. In addition, due to the shape restriction, the hole (through hole) of the nut and the circulation component need to have an appropriate gap, and grease may leak from the gap and contaminate the surroundings. In addition, foreign matter may enter from the gap and reduce the service life.

[0012] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a ball screw capable of preventing grease from leaking from a gap between a circulation member and a through hole formed in a nut and preventing external foreign matter from entering from the gap.

[0013] Means for solving problems

[0014] The above object of the present invention is achieved by the following structure.

[0015] [1] A ball screw having:

[0016] A screw shaft having a spiral screw shaft side raceway groove formed on an outer peripheral surface of the screw shaft;

[0017] A nut having a nut side raceway groove formed on an inner peripheral surface thereof and opposed to the screw shaft side raceway groove, and a through hole connecting an outer peripheral surface thereof with the nut side raceway groove;

[0018] a plurality of balls rolling in a load raceway formed by the screw shaft side raceway groove and the nut side raceway groove; and

[0019] a circulation member installed in the through hole and forming a ball return passage for circulating the balls rolling in the load raceway,

[0020] The ball screw includes a sealing member made of resin or rubber that seals at least a portion of a gap between an inner peripheral surface of the through hole of the nut and an outer peripheral surface of the circulation member.

[0021] Effects of the Invention

[0022] According to the ball screw of the present invention, it is possible to prevent grease from leaking from the gap between the circulation member and the through hole formed in the nut, or to prevent external foreign matter from entering from the gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a top view of the ball screw according to the first embodiment of the present invention.

[0024] Figure 2 yes Figure 1 An exploded perspective view of the ball screw is shown.

[0025] Figure 3 yes Figure 2 A perspective view of the sealing component is shown.

[0026] Figure 4 (a) is Figure 3 A top view of the sealing component is shown, Figure 4 (b) is Figure 3The front view of the sealing component is shown, Figure 4 (c) is Figure 3 A bottom view of the sealing component is shown, Figure 4 (d) is Figure 3 A left side view of the sealing component is shown, Figure 4 (e) is Figure 3 A right side view of the sealing component is shown, Figure 4 (f) is Figure 3 Rear view of the sealing component shown.

[0027] Figure 5 It is a cross-sectional view showing the positional relationship among the load raceway where the balls roll, the scooped portion of the circulation member, and the through hole of the nut.

[0028] Figure 6 It is a top view of a ball screw according to a second embodiment of the present invention.

[0029] Figure 7 yes Figure 6 An exploded perspective view of the ball screw is shown.

[0030] Figure 8 yes Figure 7 A perspective view of the sealing component is shown.

[0031] Fig. 9 (a) Yes Figure 8 A top view of the sealing component is shown, Fig. 9 (b) Yes Figure 8 The front view of the sealing component is shown, Fig. 9 (c) Yes Figure 8 A bottom view of the sealing component is shown, Fig. 9 (d) Yes Figure 8 A left side view of the sealing component is shown, Fig. 9 (e) Yes Figure 8 A right side view of the sealing component is shown, Fig. 9 (f) Yes Figure 8 Rear view of the sealing component shown.

[0032] Fig.10 This is a perspective view of a sealing member according to a first modified example of the second embodiment in which a pair of sealing members are formed integrally.

[0033] Fig.11 This is a perspective view of a sealing member according to a second modified example of the second embodiment in which a pair of sealing members are formed of two members each having a connecting portion.

[0034] Fig.12 (a) is a perspective view of a sealing member according to a third modified example of the second embodiment, Fig.12 (b) is a perspective view showing a state where the sealing member is assembled to the through hole of the nut.

[0035] Fig.13 (a) is a perspective view of a sealing member according to a fourth modified example of the second embodiment, Fig.13 (b) is a perspective view showing a state where the sealing member is assembled to the through hole of the nut.

[0036] Fig.14 (a) is a perspective view of a through-hole sealing member of a nut according to a fifth modification of the second embodiment, Fig.13 (b) is a perspective view showing a state where the sealing member is assembled to the through hole of the nut.

[0037] Fig.15 (a) to (c) are perspective views of a sealing member according to a sixth modification example of the second embodiment.

[0038] Fig.16 The sealing member of the modified example of the present invention is formed in a tapered shape with the diameter gradually increasing from the bottom to the top. Figure 4 Figure (b) of .

[0039] Fig.17 is shown with Figure 5 A cross-sectional view showing the positional relationship between the scooping portion, the load raceway and the through hole of the nut of the circulation component in different ways.

[0040] Fig.18 It is shown in Fig.17 This is a perspective view of a modified example in which the shape of the through hole of the nut is changed in the embodiment shown. DETAILED DESCRIPTION

[0041] Hereinafter, each embodiment of the ball screw according to the present invention will be described in detail based on the drawings.

[0042] (First Embodiment)

[0043] First, refer to Figure 1 to Figure 5 The ball screw according to the first embodiment will be described.

[0044] like Figure 1 as well as Figure 2 As shown, the ball screw 10 of this embodiment comprises: a screw shaft 20 having a spiral screw shaft side rolling groove 21 formed on the outer peripheral surface; a nut 30 having a spiral nut side rolling groove 31 on the inner peripheral surface opposite to the screw shaft side rolling groove 21 of the screw shaft 20 (see Figure 5), the nut 30 is provided with a pair of through holes 32 connected to the nut side raceway groove 31 on the outer peripheral surface 33; and a plurality of balls 26 are clamped in a rollable manner on the load raceway 25 formed by the screw shaft side raceway groove 21 of the screw shaft 20 and the nut side raceway groove 31 of the nut 30. The ball screw 10 also includes: a circulation component (return pipe) 40, which is mounted on the through hole 32 of the nut 30 and has a ball return channel 48 for circulating the balls 26 rolling in the load raceway 25; and a sealing component 50, which seals the gap between the through hole 32 of the nut 30 and the circulation component 40.

[0045] The ball screw 10 of the present embodiment is configured to include three circulation members 40 , but the number of the circulation members 40 can be set to any number according to the number of ball circulation passages.

[0046] The nut insertion portions 46 at both ends of the circulation member 40 are respectively inserted into a pair of through holes 32 formed by connecting the outer circumferential surface 33 of the nut 30 with the nut side rolling groove 31. The circulation member 40 is threadedly fixed to the outer circumferential surface 33 of the nut 30 by fixing screws 44 inserted into the threaded holes 43 of the flanged U-shaped fixing member 42.

[0047] The circulation member 40 has: a straight portion formed by bending the pipe member and parallel to the flat surface 33a formed on the outer peripheral surface 33 of the nut 30 when installed on the nut 30; and a nut insertion portion 46, which bends the two ends of the straight portion 45 in a U-shaped manner when viewed from the side and twists them in opposite directions in a Z-shaped manner when viewed from above. A lifting portion 47 is provided at the end of each nut insertion portion 46 (see Figure 5 ).

[0048] Thus, when the circulation member 40 is mounted on the nut 30, each scooping portion 47 is formed in a direction along the tangential direction of the load raceway 25. Thus, the circulation member 40 forms a ball return channel 48, which scoops up the balls 26 rolling in the load raceway 25 from the tangential direction of the load raceway 25 by the scooping portion 47 and returns them to a position on the other side of the load raceway 25.

[0049] In addition, the circulation member 40 can be formed by bending a pipe member, but is not limited thereto, and two members divided along the central axis of the circulation member 40 may be combined to form a pipe shape.

[0050] The sealing member 50 is a member for sealing the gap between the through hole 32 of the nut 30 and the circulation member 40, and is formed of a raw material having elasticity such as resin or rubber. Figure 3 as well as Figure 4As shown, the sealing member 50 has a substantially U-shaped outer peripheral surface 51 along the shape of the inner peripheral surface of the through hole 32 and a substantially C-shaped inner peripheral surface 52 along the shape of the outer peripheral surface of the circulation member 40 .

[0051] In addition, if Figure 4 (b) and Figure 5 As shown, the upper surface 53 and the lower surface 54 of the sealing member 50 are formed in an arc shape along the outer peripheral surface 33 and the inner peripheral surface of the nut 30 when the sealing member 50 is installed in the through hole 32 of the nut 30. Therefore, when the sealing member 50 is installed in the nut 30, it will not protrude from the outer peripheral surface 33 of the nut 30.

[0052] And, if Figure 5 As shown, after the circulation member 40 is inserted into the through hole 32 in the tangential direction of the load raceway 25 at the two nut insertion portions 46, a sealing member 50 is installed from above in the gap between the through hole 32 of the nut 30 and the circulation member 40. Thus, the gap between the through hole 32 and the circulation member 40 is sealed, preventing grease from leaking from the inside of the nut 30 or foreign matter from entering from the outside.

[0053] In particular, the sealing member 50 of the present embodiment is configured such that the side with the larger gap between the through hole 32 and the circulation member 40 ( Figure 5 In order to prevent the leakage of grease and the intrusion of foreign matter from the outside, the gap between the through hole 32 and the sealing member 50 and the gap between the sealing member 50 and the circulation member 40 are preferably 0.1 mm or less. In addition, at least a portion of the sealing member 50 may be formed slightly larger than the circulation member 40 and pressed into the circulation member 40.

[0054] The inner side surface ( Figure 5 As long as the gap between the left side of the nut insertion portion 46 of the circulation member 40 and the side surface of the through hole 32 is a predetermined gap, for example, less than 0.1 mm, it is not necessary to cover it with the sealing member 50, but it is also possible to cover the inner side of the circulation member 40 ( Figure 5 The shape of the sealing component 50 may be changed in a manner such as to reduce the size of the sealing component 50 by adjusting the size of the sealing component 50 so as to reduce the size of the sealing component 50 and to reduce the size of the sealing component 50 by adjusting the size of the sealing component 50 so as to reduce the size of the sealing component 50. Alternatively, other sealing components may be configured.

[0055] In addition, the sealing member 50 is formed of a raw material having elasticity, such as resin or rubber, and thus can easily absorb the processing error of the through hole 32 and the dimensional error of the stamped circulation member 40, and can be installed without a gap in the through hole 32. In addition, when used at high temperatures, the gap between the through hole 32 and the circulation member 40 becomes smaller due to thermal expansion of the resin or rubber.

[0056] Furthermore, since the scooping portion 47 is mounted in the tangential direction of the load raceway 25 , the balls 26 rolling on the load raceway 25 can be smoothly introduced into the ball return passage 48 , and high-speed feeding can be performed by operating at high speed without any hindrance.

[0057] Furthermore, since both the nut 30 and the circulation member 40 are made of metal, heat resistance is improved, and thus the driving speed of the ball screw 10 can be increased.

[0058] (Second Embodiment)

[0059] Next, refer to Figure 6 to Figure 9 A ball screw according to a second embodiment of the present invention will be described.

[0060] The ball screw of this embodiment is different from the first embodiment in that the shape of the sealing component is different from that of the first embodiment, and the sealing component and the circulation component are simultaneously fixed to the nut through the cap component. In addition, the following parts identical to the first embodiment are marked with the same reference numerals or equivalent reference numerals and the description is simplified or omitted.

[0061] like Figure 8 as well as Fig. 9 As shown, the sealing member 50 of the present embodiment is provided with a substantially semicircular convex portion 55 which is formed on the upper surface 53 of the sealing member 50 and further protrudes outward from the main body 70 relative to the through hole 32 of the nut 30, at a position lower than the portion along the upper surface 53 of the sealing member 50. In addition, abutment portions 56a and 56b which abut against the cap member 60 are formed on the side and upper surface of the substantially semicircular convex portion 55, and a concave portion 57 is provided on the back surface of the convex portion 55, and the concave portion 57 covers the curved portion 49 between the straight portion 45 of the circulation member 40 and the nut insertion portion 46.

[0062] The cap member 60 includes a groove (not shown) having a substantially U-shaped cross section covering the straight portion 45 of the circulation member 40 and the curved portions 49 on both sides of the straight portion 45 in the longitudinal direction, and a flange portion 61 having two screw holes 43 formed therein.

[0063] After the two nut insertion portions 46 of the circulation member 40 formed in this way are inserted into the respective through holes 32 in the tangential direction of the load raceway 25, the sealing member 50 is installed from above in the gap between the through hole 32 of the nut 30 and the circulation member 40. At this time, the curved portion 49 of the circulation member 40 is installed in a manner covered by the recessed portion 57 of the sealing member 50.

[0064] Then, if Figure 6 as well as Figure 7As shown, the cap member 60 covers the circulation member 40 and the sealing member 50, and is fixed to the outer peripheral surface 33 of the nut 30 by the fixing screw 44 inserted into the threaded hole 43. At this time, the cap member 60 abuts against the abutment portion 56 formed on the side and upper surface of the sealing member 50 to fix the sealing member 50 and the circulation member 40 together.

[0065] Therefore, the circulation member 40 will not fall off from the through hole 32 of the nut 30. Moreover, it is easy to prevent poor installation of the circulation member 40 and the sealing member 50. In addition, it is also preferred from the appearance that the shape of the recess 57 does not protrude from the outer shape of the cap member 60 when viewed from above.

[0066] The other structures and functions are the same as those of the ball screw in the first embodiment.

[0067] In addition, in this embodiment, if Fig.10 As shown, a sealing member 50A may be used in which a pair of sealing members 50 are formed as a pair of sealing members and are continuously and integrally formed through a connecting portion 59. The outer side surface of the connecting portion 59 is formed in a curved manner in a continuous manner from the abutting portion 56 formed on the upper surface of the pair of sealing members 50, and the lower surface of the connecting portion 59 abuts against the flat surface 33a of the nut 30.

[0068] That is, when the sealing member 50A of this modified example is fixed to the nut 30 via the cap member 60, not only the pair of through holes 32 but also the space between the cap member 60 and the flat surface 33a of the nut 30 is sealed by the connecting portion 59. As a result, on the outside of the nut 30, the portion where metals are in contact with each other disappears, and all of the contact becomes between metal and resin or rubber with a smaller gap.

[0069] Therefore, not only the assembly of the sealing member 50A becomes easy, but also the grease leaking from the circulation member 40 to the inside of the cap member 60 can be effectively suppressed from flowing out to the outside.

[0070] In addition, if Fig.11 As shown, Fig.10 The illustrated shape can also be obtained by dividing the pair of connecting portions 59 and combining a pair of sealing members 50B each having the connecting portion 59 of the same shape.

[0071] In addition, if Fig.12 (a) and Fig.12 As shown in (b), the sealing member 50C makes the end 71a of the upper edge 71 of the protrusion 55 extend outwardly more than the opening edge of the through hole 32, so that the lower surface of the end 71a abuts against the outer peripheral surface 33 of the nut 30. Thus, the contact with the circulation member 40 caused by the excessive entry of the sealing member 50C into the nut 30 can prevent the wear of the sealing member 50C caused by vibration, and can prevent the reduction of the grease leakage resistance performance.

[0072] It should be noted that the shape of the upper edge portion 71 of the sealing member 50C may be such that the lower surface of the end portion 71a is aligned with the cut surface formed around the opening edge of the through hole 32 of the nut 30 (for example, Figure 5 Therefore, in the sealing member 50 as in the first embodiment, the lower surface of the upper edge of the sealing member 50 abuts against the cut surface 32c, thereby preventing the nut 30 from excessively entering.

[0073] In addition, if Fig.13 As shown in (a) of FIG. 5 , the sealing member 50D may also be formed with a cutout 62 at the peripheral edge of the outer peripheral surface 51 and the upper surface 53 that are in contact with the inner surface of the through hole 32 of the nut 30. Thus, as shown in FIG. Fig.13 As shown in (b), when the sealing member 50D is inserted into the through hole 32 of the nut 30, a groove is formed by the inner surface of the through hole 32 and the cutout 62 of the sealing member 50D. Furthermore, by pressing or flowing clay, silicone, caulking material, etc. as a sealing material (not shown) into the groove, the close contact between the sealing member 50D and the through hole 32 can be further improved, and the grease leakage can be further reduced.

[0074] In addition, if Fig.14 (a) and Fig.14 As shown in (b), a cutout portion 32a is formed along the opening edge of the through hole 32 of the nut 30, and a groove is formed between the cutout portion 32a and the outer peripheral surface 51 of the sealing member 50C. In this case, it is also possible to seal by flowing the sealing material into the groove, making it more difficult for the grease to leak.

[0075] In addition, the contact portion 56a of the sealing member 50C that contacts the cap member 60 may also be Fig.15 The combination of the curved surface 56a1 and the flat upper surface 56a2, which match the curved chamfered shape of the inner surface of the cap member 60, shown in (b), increases the contact area with the inner surface of the cap member 60, making it more difficult for grease to leak.

[0076] On the other hand, it is also possible to Fig.15 As shown in FIG. 5( a ), the sealing member 50C1 is formed of a flat upper surface 56a3 and partially contacts the bottom surface of the cap member 60. Alternatively, the shape of the inner surface of the cap member 60 may be matched, such as Fig.15 As in the sealing member 50C2 shown in (c), the contact portion 56a is formed as a combination of a step surface 56a4 and a flat upper surface 56a5, thereby increasing the contact area with the inner surface of the cap member 60.

[0077] In addition, the present invention is not limited to the above-mentioned embodiment and examples, and modifications, improvements, etc. can be made as appropriate.

[0078] For example, Fig.16 As shown, the upper portion of the substantially U-shaped outer peripheral surface 51 of the sealing member 50 is larger than the lower portion. In other words, the side surface 51a of the substantially U-shaped outer peripheral surface 51 is formed in a tapered shape with a gradually increasing diameter from the lower portion toward the upper portion.

[0079] Therefore, when the sealing member 50 is mounted on the through hole 32 of the nut 30, the gap between the through hole 32 and the sealing member 50 becomes smaller as the sealing member 50 is inserted into the through hole 32, and the leakage of grease can be further suppressed. In addition, the displacement of the sealing member 50 can be prevented.

[0080] In addition, if Fig.17 As shown, even if the scooped portion is not oriented in the tangential direction of the load raceway, the sealing member 50 can be inserted into the gap between the through hole 32 of the nut 30 and the circulation member 40 to seal, thereby preventing grease leakage.

[0081] Furthermore, the circulation member 40 of the tangential lifting method is inserted obliquely relative to the through hole 32 of the nut 30, thereby forming a gap to fill the sealing member 50, but Fig.17 In the case of the tubular circulation member shown in FIG. 1 , the shape of the through hole 32 of the corresponding nut 30 may not provide enough space for installing the sealing member. Fig.18 As shown, a space S for embedding the sealing member 50 may be provided in such a through hole 32. Thus, even when the gap between the metal circulation member 40 and the through hole 32 of the nut 30 is large and grease is easily leaked, by providing a space S for embedding the sealing member 50 and locking the leaked grease with the sealing member 50, grease leakage can be reduced.

[0082] The bottom surface of the space S of the through hole 32 constitutes the contact surface 32b of the sealing member 50 and is formed in a stepped shape, thereby preventing the sealing member 50 from excessively entering. The contact surface 32b contacts the sealing member 50, thereby reducing grease leakage.

[0083] Furthermore, in the above-mentioned embodiment, the circulation member is made of metal, but the present invention is not limited thereto and may be made of resin.

[0084] As described above, the following matters are disclosed in this specification.

[0085] (1) A ball screw comprising:

[0086] A screw shaft having a spiral screw shaft side raceway groove formed on an outer peripheral surface;

[0087] A nut having a nut side raceway groove formed on an inner peripheral surface thereof and opposed to the screw shaft side raceway groove, and a through hole connecting an outer peripheral surface thereof with the nut side raceway groove;

[0088] a plurality of balls rolling in a load raceway formed by the screw shaft side raceway groove and the nut side raceway groove; and

[0089] a circulation member installed in the through hole and forming a ball return passage for circulating the balls rolling in the load raceway,

[0090] The ball screw includes a sealing member made of resin or rubber that seals at least a portion of a gap between an inner peripheral surface of the through hole of the nut and an outer peripheral surface of the circulation member.

[0091] According to this structure, it is possible to prevent the grease from leaking from the gap between the circulation member and the through hole formed in the nut, and to prevent external foreign matter from entering from the gap.

[0092] (2) The ball screw according to (1), wherein the sealing member includes a contact portion that contacts a cap member for fixing the circulation member to the nut so as to cover the circulation member.

[0093] According to this configuration, the sealing member can be fixed to the nut together with the circulation member via the cap member, and the sealing member can be prevented from falling out of the through hole.

[0094] (3) The ball screw according to (2), wherein the sealing member includes: a main body portion that is fitted into the through hole of the nut; and a convex portion that protrudes outward from the main body portion and has the contact portion.

[0095] According to this configuration, the sealing member can be fixed to the nut together with the circulation member via the cap member, and the sealing member can be prevented from falling out of the through hole.

[0096] (4) The ball screw according to (3), wherein the convex portion of the seal member has an upper edge portion whose lower surface abuts against an outer peripheral surface of the nut.

[0097] According to this structure, it is possible to suppress the sealing member from excessively entering the nut.

[0098] (5) The ball screw according to (1), wherein the seal member has an upper edge portion whose lower surface abuts against a cut-away surface formed at an opening edge of the through hole of the nut.

[0099] (6) A ball screw according to any one of (1) to (5), wherein the sealing component has a cutout portion formed on the outer peripheral surface and the edge of the upper surface of the through hole embedded in the nut, and a groove is formed by the cutout portion and the inner surface of the through hole.

[0100] According to this structure, the grease can be made less likely to leak by causing the sealant to flow into the groove to seal it.

[0101] (7) The ball screw according to any one of (1) to (5), wherein a cutout portion along an opening edge of the through hole is formed on an outer peripheral surface of the nut, and a groove is formed by the cutout portion and the outer peripheral surface of the sealing member.

[0102] According to this structure, the grease can be made less likely to leak by causing the sealant to flow into the groove and seal it.

[0103] (8) The ball screw according to any one of (1) to (7), wherein the through hole of the nut has a contact surface with which the lower surface of the sealing member contacts, and is formed in a stepped shape.

[0104] According to this structure, it is possible to suppress the sealing member from excessively entering the nut.

[0105] (9) The ball screw according to any one of (1) to (8), wherein when the sealing member is mounted on the nut, a side surface of the sealing member is formed in a tapered shape that gradually increases in diameter from a lower portion toward an upper portion.

[0106] According to this configuration, the gap between the through-hole and the sealing member becomes smaller as the sealing member is pressed into the through-hole, and the leakage of grease can be further suppressed.

[0107] (10) A ball screw according to any one of (1) to (9), wherein the circulation component has scooping portions at both ends thereof for scooping up the balls from the load raceway, and each of the scooping portions is formed along a tangential direction of the load raceway.

[0108] According to this configuration, the scooping portion can more smoothly scoop up the balls rolling on the load rolling path, thereby enabling high-speed operation.

[0109] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-162549) filed on October 7, 2022, and the contents are incorporated herein by reference.

[0110] Description of Reference Numerals

[0111] 10 Ball screw

[0112] 20 Screw shaft

[0113] 21 Screw shaft side raceway groove

[0114] 25 Load raceway

[0115] 26 Ball

[0116] 30 Nut

[0117] 31 Nut side raceway groove

[0118] 32 Through holes

[0119] 33 Outer Surface

[0120] 40 Circulation Parts

[0121] 47 Lifting Section

[0122] 48 Ball return channel

[0123] 50, 50A sealing parts

[0124] 51a Side (side of sealing component)

[0125] 56 abutment

[0126] 60 Cap parts

Claims

1. A ball screw, characterized in that: have: A screw shaft having a spiral screw shaft side raceway groove formed on an outer peripheral surface of the screw shaft; A nut having a nut side raceway groove formed on an inner peripheral surface thereof and opposed to the screw shaft side raceway groove, and a through hole connecting an outer peripheral surface of the nut with the nut side raceway groove; A plurality of balls rolling in a load raceway formed by the screw shaft side raceway groove and the nut side raceway groove; as well as a circulation member installed in the through hole and forming a ball return passage for circulating the balls rolling in the load raceway, The ball screw includes a sealing member made of resin or rubber, and the sealing member seals at least a portion of a gap between an inner peripheral surface of the through hole of the nut and an outer peripheral surface of the circulation member.

2. The ball screw according to claim 1, characterized in that The sealing member includes a contact portion that contacts a cap member, and the cap member is used to fix the circulation member to the nut so as to cover the circulation member.

3. The ball screw according to claim 2, characterized in that: The sealing member includes a main body portion that is fitted into the through hole of the nut, and a convex portion that protrudes outward from the main body portion, the convex portion having the contact portion.

4. The ball screw according to claim 3, characterized in that: The convex portion of the sealing member has an upper edge portion, and a lower surface of the upper edge portion abuts against the outer peripheral surface of the nut or a cut-away surface formed at an opening edge of the through hole of the nut.

5. The ball screw according to claim 1, characterized in that: The sealing member has an upper edge portion, and a lower surface of the upper edge portion abuts against a cut-away surface formed at an opening edge portion of the through hole of the nut.

6. The ball screw according to claim 1, characterized in that: The sealing member has a cutout portion formed on an outer peripheral surface and an edge of an upper surface of the through hole into which the nut is inserted. The cutout portion and the inner surface of the through hole form a groove.

7. The ball screw according to claim 1, characterized in that: A cutout portion is formed on the outer peripheral surface of the nut along the opening edge of the through hole. The cutout portion and the outer peripheral surface of the sealing member form a groove.

8. The ball screw according to claim 1, characterized in that: The through hole of the nut has a contact surface with which the lower surface of the sealing member contacts, and is formed in a stepped shape.

9. The ball screw according to claim 1 or 2, characterized in that: When the sealing member is mounted on the nut, a side surface of the sealing member is formed in a tapered shape with a diameter gradually increasing from a lower portion toward an upper portion.

10. The ball screw according to claim 1, wherein: The circulation member includes scooping portions at both ends thereof for scooping up the balls from the load rolling path, and each of the scooping portions is formed along a tangential direction of the load rolling path.

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