JP2006052780A - Ball circulation member and ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a side cap and a ball screw capable of improving precision in a ball circulation passage. <P>SOLUTION: This side cap 17 has the ball circulation passage 27 for scooping up a ball 15 in a ball track passage 8 from one side and returning the scooped up ball 15 to the other side in its inside. The ball circulation passage 27 is composed of a central passage 22 and a pair of guide passages 21 formed continuously at both ends of the central passage 22. In each guide passage 21, an outer face 23a of a peripheral wall forming each guide passage 21 is formed substantially in parallel with ball locus (direction of arrow mark A) in each guide passage 21. Wall thickness TA of the peripheral wall forming each guide passage 21 is substantially the same as the wall thickness TC of a peripheral wall forming the central passage 22 (TA≈TC). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ball screw used in various industrial machines.

  This type of ball screw has, for example, a screw shaft 12 having a spiral ball rolling groove on its outer peripheral surface and extending in the axial direction like a ball screw 100 shown in FIG. A nut 14 having a spiral ball rolling groove corresponding to the ball rolling groove of the screw shaft 12 on the inner peripheral surface is fitted to the screw shaft 12. Here, the ball rolling groove of the nut 14 and the ball rolling groove of the screw shaft 12 are opposed to each other to form a ball raceway 8 between them. A plurality of balls 15 are loaded so as to be able to roll.

  In recent years, in this kind of ball screw, as a ball circulation member for circulating the ball, in order to ensure a smooth circulation of the ball, that is, the ball rolling on the spiral ball raceway is smoothly guided into the ball circulation member, Further, in order to smoothly return the ball moving in the ball circulation member to the ball track, the ball can be picked up in the tangential direction of the ball track and returned to the ball track from the tangential direction of the ball track. It has increased (see, for example, Patent Document 1).

For example, in this type of ball screw, as shown in FIG. 7, the nut 14 has a ball circulation member mounting surface 16 formed of a flat surface on the outer peripheral surface thereof. A pair of ball circulation member mounting holes 20 each having a long hole shape are formed on the ball circulation member mounting surface 16, and the ball circulation member mounting holes 20 communicate with the ball raceway 8 and are drilled. (See, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2003-232421 Japanese Patent Application No. 2003-318123 (unpublished)

Then, for example, a ball circulation member 170 as shown in FIG. 8A is attached to the ball circulation member attachment surface 16.
Here, this kind of ball circulation member 170 is manufactured by resin molding, for example, and is configured by combining a pair of ball circulation member constituting members 230 and 230 as shown in FIG. In this kind of ball circulation member 170, as shown in FIG. 8B, a ball circulation passage 27 is formed in the inside thereof. The ball circulation passage 27 has a pair of guide passages 21 formed continuously at both ends of the central passage 22, and each guide passage 21 has a peripheral wall surrounding each guide passage 21 and a pair of leg portions 190. (See FIG. 2A).

  The pair of leg portions 190 are inclined at predetermined angles with respect to the central passage 21 in different directions so as to correspond to the lead angle of the screw shaft 12 as shown in FIGS. It is formed three-dimensionally with a guide passage 22 formed inside. The pair of legs 190 can be fitted into the ball circulation member mounting hole 20 formed on the ball circulation member mounting surface 16 from the direction perpendicular to the screw shaft 12 with almost no gap. In FIG. 9A, images of the trajectory of the ball 15 moving three-dimensionally in the ball circulation passage 27 are indicated by arrows A to C in the same drawing.

  However, as described above, this type of ball circulation member 170 is configured such that the pair of legs 190 can be fitted into the ball circulation member mounting hole 20 from the direction perpendicular to the screw shaft 12 with almost no gap. Then, in the part shown with the code | symbol D in FIG. 8, the shape of the leg part 190 is comprised by forming a thick part locally. Therefore, in the entire ball circulation member 170, a portion in which the thickness is not uniformly formed is generated. This causes variations in material shrinkage during molding, making it difficult to improve the accuracy of the ball circulation passage formed inside the ball circulation member 170.

In addition, when making the mold, it is necessary to take into account corrections corresponding to uneven thickness, and in addition to prevent the movement of the ball passing through the ball circulation path, There has also been a problem that it is necessary to devise such as adding correction to the mold so as to set the inner diameter of the circulation path large. In addition, if the inner diameter of the ball circulation path becomes too large due to a correction that sets the inner diameter of the ball circulation path in advance, there is a risk of staggering of the balls or the competition between the balls. If it is made of resin, there is a concern about wear inside the ball circulation path.
The present invention has been made paying attention to such problems, and provides a ball circulation member and a ball screw that can improve the accuracy of the ball circulation path in a ball circulation member having a ball circulation path inside. The purpose is that.

  In order to solve the above problems, the invention according to claim 1 is a screw shaft having a ball rolling groove on an outer peripheral surface, and a nut having a ball rolling groove on an inner peripheral surface facing the outer peripheral surface of the screw shaft. And a plurality of balls disposed in a ball raceway formed between both ball rolling grooves of the nut and the screw shaft, and the ball in the ball raceway is moved from one side. A ball circulation member having a ball circulation passage inside for scooping up and returning the scooped ball to the other side, wherein the ball circulation passage is formed continuously at the central passage and at both ends of the central passage. Each guide passage is formed so that the outer surface of the peripheral wall forming each guide passage is substantially parallel to the ball trajectory in each guide passage. And each guide passage is shaped Thickness of the peripheral wall being has characterized that it is substantially the same as the thickness of the peripheral wall forming the central passage.

According to the first aspect of the present invention, the outer surface of the peripheral wall forming each guide passage is formed substantially parallel to the ball trajectory in each guide passage. The wall thickness of the peripheral wall is substantially the same as the wall thickness of the peripheral wall forming the central passage. Thereby, the wall thickness of a surrounding wall is formed substantially the same over the whole ball | bowl circulation channel | path. Therefore, the thickness of the entire ball circulation member is substantially uniform. Therefore, there is almost no variation in material shrinkage during molding, and the accuracy of the ball circulation passage formed inside the ball circulation member can be improved.
Here, “the thickness is substantially the same (substantially uniform)” means that the variation in the thickness of the peripheral wall is within ± 50%. That is, it is preferable that the variation in the thickness of the peripheral wall is within ± 50%, since the material shrinkage during molding is stable throughout. Further, if the variation in the wall thickness of the peripheral wall is within ± 20%, it is more preferable for further stabilizing the material shrinkage during molding.

Further, the invention according to claim 2 is the ball circulation member according to claim 1, wherein the ball circulation passage has an Lw when an inner diameter of the ball circulation passage is Lw and a diameter of the ball is Dw. And Dw satisfy the following expression (1).
Lw−Dw ≦ 0.1Dw (1)
According to the second aspect of the present invention, since it is based on the first aspect of the present invention, the inner diameter of the ball circulation passage can be set within a predetermined range. That is, if the accuracy of the ball circulation path is managed so as to satisfy the expression (1), the inner diameter of the path can be suppressed within a desired allowable value. This further suppresses the possibility of staggering of the balls and the competition between the balls, and particularly when the ball circulation member is made of resin, there is almost no wear inside the path.

  According to a third aspect of the present invention, there is provided a screw shaft having a ball rolling groove on an outer peripheral surface, a nut having a ball rolling groove on an inner peripheral surface facing the outer peripheral surface of the screw shaft, the nut and the screw. A plurality of balls arranged in a ball raceway formed between both ball rolling grooves of the shaft, and scooping up the balls in the ball raceway from one side A ball circulation member having a ball circulation passage for returning the returned ball to the other side, wherein the ball circulation passage includes a central passage and a pair of guide passages formed continuously at both ends of the central passage. Foreign matter for preventing foreign matter from entering from the ball circulation member mounting hole formed on the nut and mounting the ball circulation member on the outer surface of the peripheral wall forming each guide passage. Intrusion prevention lid It is characterized in that arranged through the foreign matter intrusion preventing cap bearing erected on an outer surface of the peripheral wall so as to support the foreign matter intrusion preventing lid.

  According to the third aspect of the present invention, it is possible to prevent foreign matter from entering from the ball circulation member mounting hole for mounting the ball circulation member, and each guide passage forms the guide passage. It is possible to form the outer surface of the peripheral wall substantially parallel to the ball trajectory in each guide passage, and to form the central passage with the thickness of the peripheral wall forming each guide passage. It is possible to form substantially the same thickness as the peripheral wall. Thereby, for example, if the wall thickness of the peripheral wall is formed substantially the same over the entire ball circulation passage, the wall thickness is substantially uniform throughout the ball circulation member. Therefore, variations in material shrinkage during molding can be almost eliminated, and the accuracy of the ball circulation passage formed inside the ball circulation member can be improved.

According to a fourth aspect of the present invention, a ball screw is provided with the ball circulation member according to any one of the first to third aspects.
According to invention of Claim 4, the ball screw which has an effect | action and effect by the ball | bowl circulation member as described in any one of Claims 1-3 can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the ball | bowl screw provided with the ball | bowl circulation member which can improve the precision of a ball | bowl circulation channel | path, and its ball | bowl circulation member can be provided.

Embodiments of the present invention will be described below with reference to the drawings as appropriate. In addition, about the part similar to description with the ball screw mentioned above, the same code | symbol is attached | subjected and demonstrated also in description in each following embodiment.
First, a first embodiment of the present invention will be described.
FIG. 1 is an explanatory view for explaining a side cap type ball screw according to the present invention, and FIG. 2 is a radial sectional view in FIG. 1 for explaining an essential part thereof. 3 and 4 are views in the direction of arrow E in FIG. 2, respectively. FIG. 3 shows a nut before the side cap is attached, and FIG. 4 shows a state where the side cap according to the present invention is attached. Show.

As shown in FIGS. 1 and 2, the ball screw 10 includes a screw shaft 12 and a nut 14.
The screw shaft 12 has a spiral ball rolling groove 11 on the outer peripheral surface. The nut 14 has a spiral ball rolling groove 13 corresponding to the ball rolling groove 11 of the screw shaft 12 on the inner peripheral surface. The nut 14 is fitted to the screw shaft 12, and the ball rolling groove 13 of the nut 14 and the ball rolling groove 11 of the screw shaft 12 face each other, and the ball raceway 8 is configured between the two. Has been. The ball raceway 8 is loaded with a plurality of balls 15 as rolling elements so as to roll.

  Further, as shown in FIG. 3, the nut 14 has a side cap attachment surface 16 formed of a rectangular flat surface on the outer peripheral surface thereof. A pair of ball circulation member mounting holes 20 are formed in the side cap mounting surface 16. The ball circulation member mounting hole 20 is drilled in communication with the ball raceway 8 formed between the ball rolling grooves 11 and 13.

  As shown in FIG. 4, a side cap 17 as a ball circulation member is attached to the side cap attachment surface 16. Here, the side cap 17 has a pair of leg portions 19, and the pair of leg portions 19 is inserted into the ball circulation member mounting hole 20 formed in the side cap mounting surface 16 with respect to the screw shaft 12. Thus, it can be fitted from the vertical direction with almost no gap (see FIG. 1). Then, as shown in FIG. 4, the entire side cap 17 is pressed toward the side cap mounting surface 16 by the lid-shaped side cap cover 26 covering the entire side cap 17, and is attached to the nut 14 by the set screw 18. .

  Here, in the side cap 17, a guide passage 21 is formed in the leg portion 19 as a passage for scooping up the ball from the ball raceway 8 or returning it to the ball raceway 8 (see FIG. 2). . The guide passage 21 is formed by inclining the continuous direction of the passage with respect to the outer peripheral wall surface of the leg portion 19. That is, the ball 15 is formed so as to be inclined in accordance with the direction along the continuous direction of the circulation passage. The guide passage 21 communicates with the central passage 22, and the central passage 22 and the pair of guide passages 21 constitute a ball circulation passage 27. The ball circulation passage 27 and the ball raceway 8 constitute an infinite circulation passage for the ball 15. Note that, for example, an output shaft of a motor (not shown) can be connected to one end of the screw shaft 12 via a coupling, whereby the nut 14 rotates the ball 15 by the rotation of the screw shaft 12. It is movable in the axial direction through movement.

  More specifically, as shown in FIGS. 2 and 4, the side cap 17 forms a ball circulation passage 27 having an integral structure along the continuous direction of the ball circulation passage 27 by the guide passage 21 and the central passage 22. In addition, the ball in the guide passage 21 formed in the leg portion 19 is constructed so that the leg portion 19 can be easily fitted into the ball circulation member mounting hole 20 formed in the side cap mounting surface 16. 15 has a three-dimensional configuration in which the traveling direction of 15 can be scooped up in a direction substantially tangential to the screw shaft 12 and in a direction substantially coincident with the lead angle of both the ball rolling grooves 11 and 13. Therefore, the processing of the nut 14 is simple, and the design freedom of the ball circulation passage 27 (that is, the guide passage 21 and the central passage 22) can be improved. Note that the side cap 17 has a ball scooping portion (portion indicated by reference numeral PU in FIG. 6) at the tip end portion of the guide passage 21 of the side cap 17. The ball scooping portion is a tongue-like shape that can be inserted into the ball rolling groove 11 of the screw shaft 12 in order to smoothly scoop up the ball 15 rolling in the ball raceway 8 from the ball raceway 8 to the guide passage 21. And is formed to protrude from the guide passage 21 toward the ball rolling groove 11.

Next, the peripheral wall forming the side cap 17 and the ball circulation passage formed therein will be described in more detail. 5 is an explanatory perspective view showing the side cap 17. FIG. 5 (a) shows a state in which the side cap constituent members are combined, and FIG. 5 (b) shows one side. A cap component is shown.
The side cap 17 is manufactured by resin molding. As shown in FIG. 5A, for example, side cap constituent members 23 and 23, which are a pair of ball circulation member constituent members formed by molding a resin material, are used. It is configured in combination. Here, the line indicated by the symbol PL in the figure indicates a dividing line that divides the ball circulation member 17 into the side cap constituent members 23. In addition, in the division performed over the entire side cap 17, the dividing line PL is set equally so as to surround the periphery of the ball substantially in accordance with the locus of the center of the ball. , It is divided into two points symmetrically from the set dividing line PL.

In the divided side cap 17, as shown in FIG. 5B, a ball circulation passage 27 including a guide passage 21 and a central passage 22 is formed inside thereof.
That is, the ball circulation passage 27 formed inside the side cap 17 has a pair of guide passages 21 formed continuously at both ends of the central passage 22, and each guide passage 21 includes a guide passage 21. A peripheral wall surrounding each 21 is configured as a pair of leg portions 19 (see FIG. 5A). Here, the pair of leg portions 19 correspond to the lead angle of the screw shaft 12, that is, at a predetermined angle in different directions with respect to the central passage 21 as shown in FIGS. It is inclined and is formed three-dimensionally with a guide passage 22 formed inside. The traveling direction of the three-dimensional ball 15 is shown as an image by arrows A to C in FIG.

Here, as shown in FIG. 5B, in the guide passage 21, the peripheral wall forming the guide passage 21 is formed by a peripheral wall surface 23 a substantially parallel to each guide passage 21. Further, the wall thickness TA of the peripheral wall forming each guide passage 21 is substantially the same as the wall thickness TC of the peripheral wall forming the central passage 22 and the wall thickness TB at the curved portion. Here, “the thickness is substantially the same (substantially uniform)” means that the variation in the thickness of the peripheral wall is within ± 50%. That is, it is preferable that the variation in the thickness of the peripheral wall is within ± 50%, since the material shrinkage during molding is stable throughout. Further, if the variation in the wall thickness of the peripheral wall is within ± 20%, it is more preferable for further stabilizing the material shrinkage during molding. At the same time as defining the thickness of the entire part, it is preferable that the shape in the cross section perpendicular to the ball traveling direction is substantially the same (= the outer peripheral surface is substantially parallel to the inner diameter surface regardless of the shape). In addition, if the overall thickness is reduced in order to make the thickness substantially the same (almost uniform), there is a concern that the parts will become brittle. In such a case, the bending elastic modulus is a molding material. If a material having an Izod impact value of 5 or more is selected that is lower than 40 kg / cm ² , it is suitable as a material that can disperse the impact value of the ball.

Further, the side cap 17 is formed so that the thickness of the peripheral wall is substantially the same (substantially uniform), but the ball circulation path 27 has an inner diameter Lw (FIG. 5). (See (b)), when the diameter of the ball 15 is Dw, the relationship between Lw and Dw is formed to satisfy the following expression (1). In other words, the side cap 17 (the pair of ball circulation member constituting members 23 and 23) is formed so that the variation in the thickness of the peripheral wall is in a range satisfying the following relational expression (1).
Lw−Dw ≦ 0.1Dw (1)

Next, functions and effects of the ball screw 10 and the side cap 17 in the first embodiment of the present invention will be described.
As described above, in the ball screw 10, when the side cap 17 is attached to the side cap attachment surface 16 of the nut 14, the ball 15 rolling between the ball rolling grooves 11, 13 is lifted up by the side cap 17. The portion 24 is lifted up in the lead angle direction of the ball rolling grooves 11 and 13 and smoothly introduced into the central passage 22. Therefore, in this ball screw 10, unlike the tube circulation type ball screw, even if the lead of the ball rolling groove increases, the traveling direction of the ball 15 hardly changes suddenly in the circulating portion of the ball 15. Therefore, when the ball 15 is scooped up, it is possible to suppress the damage of the ball 15 and the generation of noise and the like, and the number of circulation circuits of the ball is limited to the number of threads of the thread groove, for example, like an end cap type ball screw. Since there are no restrictions, the load capacity can be increased without increasing the number of balls (number of turns) per circuit.

Further, in this ball screw 10, the side cap 17 is composed of a pair of ball circulation member constituting members 23, 23 divided into two along the traveling direction of the ball 15. It is possible to easily form the ball circulation passage 27 in the side cap 17 by resin molding or the like by scooping up the ball 15 in the direction coinciding with the lead angle and returning it to the initial position.
Further, the ball screw 10 is formed by combining the side cap 17 with a pair of side cap constituent members 23 and 23 having the same outer shape, so that the side cap constituent members 23 and 23 are molded with a single mold. Thus, the side cap 17 can be more easily manufactured.

  In particular, in this ball screw 10, the outer surface of the peripheral wall 23 a forming each guide passage 21 is formed substantially in parallel with the ball trajectory (reference numeral A shown in FIG. 5) in each guide passage 21. The wall thickness TA of the peripheral wall 23 a is substantially the same as the wall thickness TC of the peripheral wall forming the central passage 22. That is, the wall thickness of the peripheral wall is formed substantially the same (TA≈TC) over the entire ball circulation passage 27. As a result, the thickness of the entire side cap 17 is substantially uniform. For this reason, there is almost no variation in material shrinkage during molding, and the accuracy of the ball circulation passage 27 formed inside the side cap 17 can be improved.

  Further, since the accuracy of the ball circulation passage 27 is managed so as to satisfy the above expression (1), the inner diameter of the ball circulation passage 27 can be suppressed within a desired allowable value. This further suppresses the risk of staggering the balls 15 and causing competition between the balls, and particularly when the side cap 17 is made of resin, wear inside the path can be suitably suppressed.

  Here, the pair of leg portions 19 of the side cap 17 are fitted into the pair of ball circulation member mounting holes 20 each having a long hole shape from the direction perpendicular to the screw shaft 12 with almost no gap. As described above, each leg portion 19 is formed so that the outer surface of the peripheral wall 23a of each guide passage 21 formed therein is formed substantially in parallel with the ball trajectory. Therefore, the outer wall surface 23a is formed obliquely. For this reason, after the side cap 17 is mounted on the nut 14, a recess is formed on the insertion side of each leg 19 of the ball circulation member mounting hole 20. That is, if a recess is formed on the insertion side of each leg 19, the surface of the nut 14 is not closed, and foreign matter may enter from there. It is desirable to close the recess.

Therefore, as a second embodiment of the present invention, a foreign matter intrusion prevention lid portion for suitably preventing foreign matter from entering from the ball circulation member mounting hole 20 is used as a pair of leg portions 19 of the side cap 17. An example of the formation will be described.
That is, according to the second embodiment of the present invention, the peripheral wall is formed with substantially the same wall thickness over the entire ball circulation passage 27, and foreign matter enters from the ball circulation member mounting hole in which the side cap 17 is mounted. There is provided a side cap in which a foreign matter intrusion prevention lid for preventing the above is formed. The second embodiment differs from the side cap 17 in the first embodiment described above only in the foreign matter intrusion prevention lid and the portion that supports the foreign matter intrusion prevention lid. Other than that, the configuration is the same as that of the first embodiment described above. Therefore, here, only the foreign matter intrusion prevention lid portion and the portion that supports the foreign matter intrusion prevention lid portion will be described, and the other description will be omitted.

Specifically, in the side cap 17 of the second embodiment, as shown in FIG. 6, the peripheral wall forming each guide passage 21 is different from the side cap 17 of the first embodiment described above. The outer surface 23 a is provided with a foreign matter intrusion prevention lid portion 24 and a foreign matter intrusion prevention lid support portion 25 for supporting the foreign matter intrusion prevention lid portion 24.
The foreign matter intrusion prevention lid portion 24 has an outer peripheral portion 24a aligned with the inner shape of the ball circulation member mounting hole 20 in order to suitably prevent foreign matter from entering from the ball circulation member mounting hole 20. The concave portion formed on the insertion side is formed so as to cover when it is attached. On the other hand, the foreign matter intrusion prevention lid support portion 25 is erected on the outer surface 23 a of the peripheral wall so as to support the foreign matter intrusion prevention lid portion 24. In other words, the foreign matter intrusion prevention lid portion 24 is disposed on the outer surface 23 a of the peripheral wall via the foreign matter intrusion prevention lid support portion 25.

Therefore, according to the side cap 17 of the second embodiment, it is possible to prevent foreign matter from entering from the ball circulation member mounting hole 20 in which the side cap 17 is mounted, and the first embodiment described above. It is possible to provide the side cap 17 that simultaneously exhibits the same operations and effects.
As described above, according to the ball screw 10 of the present invention, in the side cap 17 having the ball circulation passage 27 inside, it is possible to provide a side cap that can improve the accuracy of the ball circulation passage 27, and A ball screw with a side cap can be provided.

In addition, the ball screw which concerns on this invention is not limited to said each embodiment, A various deformation | transformation is possible unless it deviates from the meaning of this invention.
For example, in each of the above-described embodiments, the side cap 17 is configured by combining a pair of side cap constituent members 23, 23. It is good also as a structure which provides a projection part and a hole as a positioning part, respectively. Further, the side cap 17 may have a structure in which a side cap attachment hole for directly passing the set screw 18 is formed. Further, the side cap 17 is configured by combining the pair of side cap constituent members 23, 23, but is not necessarily divided into two, for example, further divided into four from the center of the central passage. One side cap may be formed from the side cap components. That is, in the pair of guide passages formed continuously at both ends of the central passage, “continuous” is not limited to one in which the constituent members are directly manufactured integrally. Therefore, it is meant to include what is “functionally connected” by combining a plurality of divided members.

Further, in each of the above embodiments, the example in which the dividing line PL over the entire side cap 17 is set equally according to the trajectory of the ball center has been described. However, the present invention is not limited to this, and the position of the dividing line is equally divided. It does not have to be.
Further, for example, in each of the above embodiments, the ball screw 10 has been described with an example in which the side cap 17 (side cap constituent members 23, 23) is formed of a resin. For example, a ball screw may be used even under high temperature conditions that are not suitable for use with a resin, for example, and may be formed by a metal injection molding (MIM). be able to.

It is explanatory drawing explaining the side cap type ball screw which concerns on this invention. It is radial direction sectional drawing in FIG. FIG. 3 is a view taken in the direction of arrow E in FIG. 2, and shows the nut before the side cap is mounted. FIG. 3 is a view taken in the direction of arrow E in FIG. 2, in which the side cap according to the present invention is attached. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the side cap (1st embodiment) which concerns on this invention, and the same figure (a) is an explanatory perspective view explaining the external appearance of a side cap, and the locus | trajectory of the ball center passing through the inside, FIG. 4B is an explanatory perspective view showing an example of a side cap constituent member obtained by dividing the side cap. It is explanatory drawing which shows the side cap (2nd embodiment) which concerns on this invention, the figure (a) is an explanatory perspective view for demonstrating a foreign material penetration | invasion prevention cover part, and the same figure (b) is a foreign material. It is explanatory explanatory drawing which expands and shows the principal part (the leg part in the figure (a)) for demonstrating an intrusion prevention cover part. It is explanatory drawing explaining a side cap type ball screw. It is explanatory explanatory drawing which shows the side cap of a comparative example.

Explanation of symbols

8 Ball track 10, 100 Ball screw 11 Ball rolling groove 12 Screw shaft 13 Ball rolling groove 14 Nut 15 Ball 16 Side cap mounting surface (Ball circulating member mounting surface)
17, 170 Side cap (ball circulation member)
18 Set screw 19, 190 Leg 20 Ball circulation member mounting hole 21 Guide passage 22 Central passage 23, 230 Side cap component (ball circulation member component)
23a (outer wall) outer surface 24 foreign matter intrusion prevention lid portion 25 foreign matter intrusion prevention lid support portion 26 side cap cover 27 ball circulation path PL dividing line

Claims (4)

A screw shaft having a ball rolling groove on the outer peripheral surface, a nut having a ball rolling groove on the inner peripheral surface facing the outer peripheral surface of the screw shaft, and both the ball rolling grooves of the nut and the screw shaft are configured. A ball circulation path used for a ball screw including a plurality of balls disposed in a ball raceway, scooping up the balls in the ball raceway from one side and returning the scooped balls to the other side A ball circulating member having
The ball circulation passage is composed of a central passage and a pair of guide passages formed continuously at both ends of the central passage,
Each of the guide passages has an outer surface of a peripheral wall forming the guide passages formed substantially parallel to a ball trajectory in the guide passages, and the peripheral walls forming the guide passages. The ball circulation member is characterized in that the thickness of the ball is substantially the same as the thickness of the peripheral wall forming the central passage. 2. The ball circulation path according to claim 1, wherein the relationship between Lw and Dw satisfies the following expression (1), where Lw is the inner diameter of the ball circulation path and Dw is the diameter of the ball. The ball circulating member as described.
Lw−Dw ≦ 0.1Dw (1) A screw shaft having a ball rolling groove on the outer peripheral surface, a nut having a ball rolling groove on the inner peripheral surface facing the outer peripheral surface of the screw shaft, and both the ball rolling grooves of the nut and the screw shaft are configured. A ball circulation path used for a ball screw including a plurality of balls disposed in a ball raceway, scooping up the balls in the ball raceway from one side and returning the scooped balls to the other side A ball circulating member having
The ball circulation passage is composed of a central passage and a pair of guide passages formed continuously at both ends of the central passage,
A foreign matter intrusion prevention lid for preventing foreign matter from entering from a ball circulation member mounting hole formed on the nut and mounting the ball circulation member is formed on the outer surface of the peripheral wall forming each guide passage. A ball circulation member, which is disposed through a foreign matter intrusion prevention lid support portion erected on an outer surface of the peripheral wall so as to support a foreign matter intrusion prevention lid portion.   A ball screw comprising the ball circulation member according to claim 1.

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