JP5719706B2

JP5719706B2 - Ball screw

Info

Publication number: JP5719706B2
Application number: JP2011150252A
Authority: JP
Inventors: 喜実岩崎
Original assignee: Kuroda Precision Industries Ltd
Current assignee: Kuroda Precision Industries Ltd
Priority date: 2011-07-06
Filing date: 2011-07-06
Publication date: 2015-05-20
Anticipated expiration: 2031-07-06
Also published as: TW201312024A; TWI565890B; JP2013015213A

Description

本発明は、ボール喪失時にナットを自動的に制動するボールねじに係り、詳しくは、制動に供される制動ピースをリードの異なるボールねじ間で共用化させる技術に関する。 The present invention relates to a ball screw that automatically brakes a nut when a ball is lost, and more particularly to a technique for sharing a brake piece used for braking between ball screws having different leads.

ボールねじは、産業機械やロボット等に用いられる機械要素であり、外周面に雄ねじ溝を有するねじ軸と、内周に雌ねじ溝を有するナットと、雄ねじ溝と雌ねじ溝とによって画成された転走路に収容された多数のボール（通常は鋼球）とを備え、高い動力伝達効率と位置精度とをもって回転運動の直線運動への変換（あるいは、直線運動の回転運動への変換）を行う。ボールねじではボールを循環させる循環通路を設ける必要があり、この循環通路を形成するために循環パイプやデフレクタ等の循環部品が採用されている。ところで、循環部品は、ねじ止めや圧入によってナットに一体化されているが、外力が加わること等によって脱落する可能性がある。そして、循環部品が脱落してボールが一度に失われると、ねじ軸とナットとの係合が解かれてボールねじを組み込んだ装置が予期しない作動（被駆動体の落下等）を起こす虞があった。 A ball screw is a machine element used in industrial machines, robots, and the like. A ball screw is defined by a screw shaft having a male screw groove on the outer peripheral surface, a nut having a female screw groove on the inner periphery, and a male screw groove and a female screw groove. It is equipped with a large number of balls (usually steel balls) accommodated in the runway, and performs conversion of rotational motion to linear motion (or conversion of linear motion to rotational motion) with high power transmission efficiency and positional accuracy. In the ball screw, it is necessary to provide a circulation passage for circulating the ball, and circulation parts such as a circulation pipe and a deflector are employed to form the circulation passage. By the way, the circulating component is integrated with the nut by screwing or press-fitting. However, the circulating component may fall off due to an external force applied. If the circulating parts drop off and the ball is lost at once, the screw shaft and nut are disengaged, and the device incorporating the ball screw may cause unexpected operation (such as falling of the driven body). there were.

そこで、ボールの喪失時にナットを自動的に制動するボールねじとして、雌ねじ山を有する安全ナットをナットの端部に取り付け、ボールの喪失時に安全ナットの雌ねじ山がねじ軸の雌ねじ溝に衝合することにより、ねじ軸に対してナットが自動的に制動されるもの（特許文献１，２参照）や、雌ねじ山の代わりとなるコイル状のストッパリングをナットの雌ねじ溝の端部に固着させたもの（特許文献３参照）、特許文献１，２と同様の雌ねじ山をナット自体に形成したもの（特許文献４参照）、複数のスリットを有する円筒状の制動ハウジングと、この制動ハウジングを縮径方向に付勢するばねリングとをナットの一端に取り付けたもの（特許文献５参照）等が提案されている。 Therefore, as a ball screw that automatically brakes the nut when the ball is lost, a safety nut having an internal thread is attached to the end of the nut, and when the ball is lost, the internal thread of the safety nut abuts the internal thread groove of the screw shaft. As a result, the nut is automatically braked with respect to the screw shaft (see Patent Documents 1 and 2), and a coiled stopper ring instead of the female thread is fixed to the end of the female thread groove of the nut. (Refer to Patent Document 3), the same female screw thread as in Patent Documents 1 and 2 formed on the nut itself (refer to Patent Document 4), a cylindrical brake housing having a plurality of slits, and a diameter reduction of the brake housing. A structure in which a spring ring biased in the direction is attached to one end of a nut (see Patent Document 5) has been proposed.

特開平１１−８２６６５号公報Japanese Patent Laid-Open No. 11-82665 実用新案登録第３０７４７２０号公報Utility Model Registration No. 3074720 特開２０００−１８３６１号公報JP 2000-18361 A 特開平１１−１７３３９４号公報Japanese Patent Laid-Open No. 11-173394 特開２００４−３５３７２５号公報JP 2004-353725 A

上述した特許文献１〜３のボールねじでは、安全ナットの雌ねじ山やストッパリングとしてねじ軸の雄ねじ溝に対応するもの（すなわち、同一のリードを有するもの）が必要となることで、以下に述べる問題が生じていた。一般に、ボールねじでは、同一径でありながら、要求仕様の相違によってリードの異なる多種のねじ軸が用いられるが、この場合にボールねじ間で安全ナットやストッパリングを共用することができなくなる。特許文献１，２の安全ナットは、ボールねじの付随部品であるため、ＭＩＭ（Metal Injection Molding：金属粉末射出成形）法やロストワックス法等によって安価に製造することが望ましいが、リードの相違に対応するものがそれぞれ必要になると、安全ナット用の成形型の製作コストが非常に高くなる。また、特許文献３のストッパリングについても、リードが異なるナット間では安全ナットと同様に共用できないため、その製造や管理が煩雑になる。 In the ball screw described in Patent Documents 1 to 3 described above, since a female screw thread of a safety nut and a stopper ring corresponding to the male screw groove of the screw shaft are required (that is, one having the same lead), it will be described below. There was a problem. In general, a ball screw uses a variety of screw shafts having the same diameter but different leads due to differences in required specifications. In this case, a safety nut or a stopper ring cannot be shared between the ball screws. Since the safety nuts of Patent Documents 1 and 2 are an accessory part of a ball screw, it is desirable to manufacture them at low cost by the MIM (Metal Injection Molding) method or the lost wax method. If each corresponding one is required, the manufacturing cost of the mold for the safety nut becomes very high. In addition, the stopper ring of Patent Document 3 cannot be shared between nuts with different leads in the same manner as a safety nut, so that its manufacture and management become complicated.

一方、特許文献４のボールねじでは、単一のナットに雌ねじ溝と雌ねじ山とを同軸に形成するが、このような加工を行うことは現実的には難しく、例え可能であったとしても段取り等が非常に煩雑となる。また、特許文献５のボールねじでは、端部に制動ハウジングが付加されることでナットの全長が長くなり、ボールねじが組み込まれる装置の体格が大きくなること等が避けられない。 On the other hand, in the ball screw of Patent Document 4, the female screw groove and the female screw thread are formed coaxially in a single nut. However, it is actually difficult to perform such processing, and even if it is possible, the setup is possible. Etc. becomes very complicated. In addition, in the ball screw disclosed in Patent Document 5, it is inevitable that the addition of a braking housing to the end portion increases the overall length of the nut and increases the size of the device in which the ball screw is incorporated.

本発明は、このような背景に鑑みなされたもので、ボール喪失時にナットを制動する制動ピースをリードの異なるボールねじ間で共用できるボールねじを提供することを目的とする。 The present invention has been made in view of such a background, and an object of the present invention is to provide a ball screw that can share a braking piece that brakes a nut when a ball is lost between ball screws having different leads.

本発明の第１の側面では、外周面に雄ねじ溝（２）が形成されたねじ軸（４）と、内周に当該雄ねじ溝に対向する雌ねじ溝（５）が形成されたナット（７）と、前記雄ねじ溝と前記雌ねじ溝とからなる転走路（８）に収容された複数のボール（１１）と、前記ナットに固着され、前記ボールの喪失時における前記ねじ軸と当該ナットとの相対動を抑制する制動ピース（３０）とを備えたボールねじ（１）であって、前記制動ピースは、その先端（３２ａ）が前記雄ねじ溝に進入するとともに当該先端が当該雄ねじ溝に所定の間隙をもって対峙する係止ポール（３２）と、前記係止ポールとは異なる位置で前記ねじ軸のランド（３）に所定の間隙をもって対峙する係止面（３４）とを有し、前記係止ポールの先端は、当該係止ポールの軸心を回動中心として、単体では前記雄ねじ溝内で所定角度をもって回動可能な形状に形成された。 In the first aspect of the present invention, a screw shaft (4) having a male screw groove (2) formed on the outer peripheral surface and a nut (7) having a female screw groove (5) opposed to the male screw groove formed on the inner periphery. And a plurality of balls (11) accommodated in a rolling path (8) comprising the male screw groove and the female screw groove, and a relative relationship between the screw shaft and the nut when the ball is lost and fixed to the nut. A ball screw (1) having a braking piece (30) for suppressing movement, wherein the tip of the braking piece (32a) enters the male screw groove and the tip is in a predetermined gap in the male screw groove. And a locking surface (34) that faces the land (3) of the screw shaft at a position different from that of the locking pole with a predetermined gap. The tip of the shaft rotates around the axis of the locking pole. Mainly, in itself formed in rotatable configuration at a predetermined angle within the male screw groove.

また、本発明の第２の側面では、前記係止ポールの先端は、前記雄ねじ溝の円弧径（Ｒｓ）よりも小さい半径（Ｒｐ）を有する半球状に形成された。 In the second aspect of the present invention, the end of the locking pole is formed in a hemispherical shape having a radius (Rp) smaller than the arc diameter (Rs) of the male screw groove.

また、本発明の第３の側面では、前記制動ピースが前記ナットに締結される円環状の本体部（３１）を有し、前記係止ポールが前記本体部の内周に突設され、前記係止面が前記本体部の内周に形成された。 In the third aspect of the present invention, the braking piece has an annular main body (31) fastened to the nut, and the locking pole protrudes from the inner periphery of the main body, A locking surface was formed on the inner periphery of the main body.

また、本発明の第４の側面では、前記本体部の内周には前記ねじ軸の軸方向視で円弧状を呈する円弧状凸部（３３）が少なくとも１つ突設され、前記係止面が当該円弧状凸部に形成された。 In the fourth aspect of the present invention, at least one arc-shaped convex portion (33) having an arc shape when viewed from the axial direction of the screw shaft protrudes from the inner periphery of the main body portion, and the locking surface Was formed on the arcuate convex portion.

本発明の第１の側面によれば、ボールの喪失が生じた場合、係止ポールの先端が雄ねじ溝に係合する一方、係止面がランドに当接することによりねじ軸とナットとの相対動が抑制される。また、係止ポールの先端が係止ポールの軸心を回動中心として、単体では雄ねじ溝内で回動可能な形状に形成されているため、リードが異なっていても、外径や雄ねじ溝の幅が同一であるねじ軸に対しては、同一の制動ピースを用いることができる。また、第２の側面によれば、ねじ軸のリードが異なっていても、ボール喪失時に係止ポールと雄ねじ溝とが同一かつ強固な係合状態をもって係合する。また、第３の側面によれば、大きな荷重が掛かっても係止ポールと係止面との開きが起こりにくくなり、確実な制動が実現される。また、第４の側面によれば、本体部における円弧状凸部が形成されていない部位がグリース溜まりとして機能し、ボールねじの良好な潤滑を長期間にわたって維持できる。 According to the first aspect of the present invention, when the ball is lost, the tip of the locking pole engages with the male screw groove, while the locking surface comes into contact with the land, so that the screw shaft and the nut are relative to each other. The movement is suppressed. In addition, since the tip of the locking pole is formed in a shape that can rotate within the male thread groove with the axis of the locking pole as the center of rotation, the outer diameter and male thread groove can be different even if the lead is different. The same braking piece can be used for screw shafts having the same width. According to the second aspect, even if the lead of the screw shaft is different, the locking pole and the male screw groove engage with the same and strong engagement state when the ball is lost. Further, according to the third aspect, even when a large load is applied, the locking pole and the locking surface are not easily opened, and reliable braking is realized. Moreover, according to the 4th side surface, the site | part in which the circular-arc-shaped convex part in a main-body part functions as a grease pool, and it can maintain favorable lubrication of a ball screw over a long period of time.

実施形態に係るボールねじの要部斜視図である。It is a principal part perspective view of the ball screw which concerns on embodiment. 実施形態に係るボールねじの分解斜視図である。It is a disassembled perspective view of the ball screw which concerns on embodiment. 実施形態に係るボールねじの要部縦断面図である。It is a principal part longitudinal cross-sectional view of the ball screw which concerns on embodiment. 実施形態に係る制動リングの斜視図である。It is a perspective view of the brake ring which concerns on embodiment. 実施形態に係るボールねじの通常時における作動を示す縦断面図である。It is a longitudinal cross-sectional view which shows the action | operation at the normal time of the ball screw which concerns on embodiment. 実施形態に係るボールねじのボール喪失時における作動を示す縦断面図である。It is a longitudinal section showing operation at the time of ball loss of a ball screw concerning an embodiment. 実施形態に係る制動リングをリードの異なるねじ軸を有するボールねじに用いた状態を示す縦断面図である。It is a longitudinal cross-sectional view which shows the state which used the brake ring which concerns on embodiment for the ball screw which has a screw shaft from which a lead differs. 制動リングの一部変形例を示す斜視図である。It is a perspective view which shows the partial modification of a brake ring. 制動リングの一部変形例を示す斜視図である。It is a perspective view which shows the partial modification of a brake ring.

以下、図面を参照して、本発明を適用したボールねじの一実施形態を詳細に説明する。なお、実施形態の説明にあたっては、図１中に前後を矢印で示し、位置や方向をこれらに沿って表記する。 Hereinafter, an embodiment of a ball screw to which the present invention is applied will be described in detail with reference to the drawings. In the description of the embodiment, front and rear are indicated by arrows in FIG. 1, and the position and direction are indicated along these.

≪実施形態の構成≫
図１〜図３に示すように、本実施形態のボールねじ１は、雄ねじ溝２およびランド３が外周に形成されたねじ軸４と、雄ねじ溝２に対応する雌ねじ溝５が内周に形成されるとともに軸方向中央の外周にフランジ６を有するナット７と、雄ねじ溝２と雌ねじ溝５とによって画成された転走路８に収容された多数個のボール１１と、ナット７の前後端にスクリュー１２によって締結された一対のデフレクタ１３と、ナット７の前端面にスクリュー１２によって締結された制動リング３０（制動ピース）と、ナット７の後端面および制動リング３０の前端面にスクリュー１５によって締結された一対のグリース保持器１６とから構成されている。 << Configuration of Embodiment >>
As shown in FIGS. 1 to 3, the ball screw 1 of the present embodiment has a screw shaft 4 having a male screw groove 2 and a land 3 formed on the outer periphery, and a female screw groove 5 corresponding to the male screw groove 2 formed on the inner periphery. And a plurality of balls 11 accommodated in a rolling path 8 defined by the male thread groove 2 and the female thread groove 5, and the front and rear ends of the nut 7. A pair of deflectors 13 fastened by the screw 12, a brake ring 30 (brake piece) fastened by the screw 12 to the front end face of the nut 7, and a screw 15 fastened to the rear end face of the nut 7 and the front end face of the brake ring 30 And a pair of grease holders 16.

図２，図３に示すように、グリース保持器１６は、薄鋼板プレス成型品のインナカバー１７およびアウタカバー１８内に樹脂製のリップシール１９を２枚内装したものであり、リップシール１９の内周端がねじ軸４の雄ねじ溝２やランド３に摺接することにより、ボールねじ１に封入されたグリース２０の漏出を防止する。 As shown in FIGS. 2 and 3, the grease retainer 16 includes two lip seals 19 made of resin in an inner cover 17 and an outer cover 18 which are press-formed products of thin steel plates. Since the peripheral end is in sliding contact with the male screw groove 2 and the land 3 of the screw shaft 4, leakage of the grease 20 enclosed in the ball screw 1 is prevented.

制動リング３０は、ＭＩＭ法やロストワックス法によって製造されており、図４に示すように、円環状を呈する本体部３１と、本体部３１の内周に突設された円柱状の係止ポール３２と、係止ポール３２と対向する位置（回転位相が１８０°ずれた位置）で本体部３１の内周に突設された円弧状凸部３３とを有しており、円弧状凸部３３の内周が係止面３４となっている。係止ポール３２の先端３２ａは、その半径Ｒｐが雄ねじ溝２の円弧径Ｒｓよりも若干小さい半球状を呈しており、ボールねじ１の組立状態において、図３に示すように、ねじ軸４の雄ねじ溝２にごく小さい間隙Ｓ１（例えば、０．２ｍｍ程度）をもって対峙している。一方、係止面３４も、ボールねじ１の組立状態において、図３に示すように、ごく小さい間隙Ｓ２（例えば、０．２ｍｍ程度）をもって、ねじ軸４のランド３に対峙している。係止ポール３２の先端３２ａは、その半径Ｒｐが雄ねじ溝２の円弧径Ｒｓよりも若干小さい半球状を呈していることから、係止ポール３２の軸心Ｃｐを回動中心として、単体では雄ねじ溝２内で３６０°の角度範囲で回動可能となっている。 The brake ring 30 is manufactured by the MIM method or the lost wax method. As shown in FIG. 4, the brake ring 30 has an annular main body 31 and a cylindrical locking pole protruding from the inner periphery of the main body 31. 32 and an arcuate convex portion 33 projecting from the inner periphery of the main body 31 at a position facing the locking pole 32 (a position where the rotational phase is shifted by 180 °). The inner periphery is a locking surface 34. The tip 32a of the locking pole 32 has a hemispherical shape with a radius Rp slightly smaller than the arc diameter Rs of the male screw groove 2, and in the assembled state of the ball screw 1, as shown in FIG. The male screw groove 2 is opposed with a very small gap S1 (for example, about 0.2 mm). On the other hand, the locking surface 34 faces the land 3 of the screw shaft 4 with a very small gap S2 (for example, about 0.2 mm) as shown in FIG. Since the tip 32a of the locking pole 32 has a hemispherical shape with a radius Rp slightly smaller than the arc diameter Rs of the male screw groove 2, a single male screw is used with the axis Cp of the locking pole 32 as the center of rotation. The groove 2 can be rotated within an angle range of 360 °.

≪実施形態の作用≫
ボールねじ１は、産業機械やロボット等に直線駆動機構の要素として組み込まれ、図５に示すように、ナット７のフランジ６が被駆動部材４１の端面に締結され、ねじ軸４がモータや減速器等からなる図示しない回転駆動装置に連結される。そして、回転駆動装置によってねじ軸４が回転駆動されると、雄ねじ溝２と雌ねじ溝５とがボール１１を介して螺合していることにより、ナット７の螺進に伴って図５中で上方あるいは下方に被駆動部材４１が直進駆動される。この際、図３に示すように、係止ポール３２の先端３２ａと雄ねじ溝２との間に間隙Ｓ１が存在し、係止面３４とランド３との間に間隙Ｓ２が存在するため、ボールねじ１の作動が制動リング３０によって阻害されることがない。なお、本実施形態では、制動リング３０における本体部３１の内周に１つの円弧状凸部３３が突設されているが、内周の残部がグリース溜まり３５となることにより、制動リング３０を持たないものに較べて封入されるグリース２０の量が多くなってボールねじ１の耐久性が向上する。
<< Operation of Embodiment >>
The ball screw 1 is incorporated in an industrial machine, a robot, or the like as an element of a linear drive mechanism. As shown in FIG. 5, the flange 6 of the nut 7 is fastened to the end surface of the driven member 41, and the screw shaft 4 is a motor or a speed reducer. It connects with the rotary drive device which is not illustrated which consists of a container etc. Then, when the screw shaft 4 is rotationally driven by the rotation driving device, the male screw groove 2 and the female screw groove 5 are screwed together via the ball 11, and accordingly, in FIG. The driven member 41 is linearly driven upward or downward. At this time, as shown in FIG. 3 , there is a gap S1 between the tip 32a of the locking pole 32 and the male screw groove 2, and there is a gap S2 between the locking surface 34 and the land 3. The operation of the screw 1 is not hindered by the brake ring 30. In the present embodiment, one arc-shaped convex portion 33 protrudes from the inner periphery of the main body 31 of the brake ring 30, but the remaining portion of the inner periphery becomes a grease reservoir 35, so that the brake ring 30 is The amount of grease 20 to be enclosed is increased as compared with those not having, and the durability of the ball screw 1 is improved.

（ボール喪失時）
さて、ボールねじ１では、デフレクタ１３の脱落等によってボール１１の喪失が生じた場合、図６に示すように、ねじ軸４の雄ねじ溝２とナット７の雌ねじ溝５との係合が断たれ、ナット７および被駆動部材４１が重力によって落下しようとする。ところが、本実施形態の場合、ナット７が下方に若干量移動すると、係止ポール３２の先端３２ａが間隙Ｓ１をもって対峙していた雄ねじ溝２に衝合し、先端３２ａに沿って雄ねじ溝２の内周が滑ることでねじ軸４が図中左方に移動する。すると、ねじ軸４のランド３が間隙Ｓ２をもって対峙していた円弧状凸部３３の係止面３４に当接して係止され、制動リング３０とねじ軸４との相対動が係止ポール３２によって阻止される。これにより、ねじ軸４に対するナット７の軸方向移動が起こらなくなり、ナット７および被駆動部材４１が確実に制動される（すなわち、落下が防止される）。
(When the ball is lost)
In the ball screw 1, when the ball 11 is lost due to the dropping of the deflector 13 or the like, the engagement between the male screw groove 2 of the screw shaft 4 and the female screw groove 5 of the nut 7 is cut off as shown in FIG. 6. The nut 7 and the driven member 41 are about to fall due to gravity. However, in the case of the present embodiment, when the nut 7 moves slightly downward, the tip 32a of the locking pole 32 abuts on the male screw groove 2 facing the gap S1, and the male screw groove 2 along the tip 32a. As the inner circumference slides, the screw shaft 4 moves to the left in the figure. Then, the land 3 of the screw shaft 4 is brought into contact with and locked with the locking surface 34 of the arc-shaped convex portion 33 facing each other with the gap S2, and the relative movement between the brake ring 30 and the screw shaft 4 is stopped. Is prevented by. Thereby, the axial movement of the nut 7 with respect to the screw shaft 4 does not occur, and the nut 7 and the driven member 41 are reliably braked (that is, the fall is prevented).

一方、本実施形態の制動リング３０は、係止ポール３２の先端３２ａが半球状に形成されている（すなわち、係止ポール３２の軸心Ｃｐを回動中心として、単体では雄ねじ溝２内で３６０°の角度範囲で回動可能となっている）ため、雄ねじ溝２の円弧径が略同一であれば、図７（ａ）に示すように、ねじ軸４の雄ねじ溝２のリードが比較的小さいボールねじ１にも採用可能であるし、図７（ｂ）に示すように、ねじ軸４の雄ねじ溝２のリードが比較的大きいボールねじ１にも採用可能である。そして、どちらの場合も、ボール１１の喪失時においては、係止ポール３２の先端３２ａと円弧状凸部３３の係止面３４（図７（ａ），（ｂ）には示さず）とを介して制動リング３０とねじ軸４とが係合し、ナット７および被駆動部材４１が確実に制動される。本実施形態では、このように、ねじ軸４のリードに応じて多数の制動リング３０を用意する必要が無くなるため、成形金型の削減等による製造コストの低減が図れる他、在庫や製造における管理も容易となる。 On the other hand, in the brake ring 30 of the present embodiment, the tip 32a of the locking pole 32 is formed in a hemispherical shape (that is, in the male screw groove 2 as a single unit with the axis Cp of the locking pole 32 as the rotation center). Therefore, if the circular diameter of the male screw groove 2 is substantially the same, as shown in FIG. 7A, the lead of the male screw groove 2 of the screw shaft 4 is compared. The present invention can also be used for a small ball screw 1 and can also be used for a ball screw 1 in which the lead of the male screw groove 2 of the screw shaft 4 is relatively large as shown in FIG. In either case, when the ball 11 is lost, the tip 32a of the locking pole 32 and the locking surface 34 (not shown in FIGS. 7A and 7B) of the arc-shaped convex portion 33 are provided. Thus, the brake ring 30 and the screw shaft 4 are engaged, and the nut 7 and the driven member 41 are reliably braked. In this embodiment, it is not necessary to prepare a large number of brake rings 30 in accordance with the leads of the screw shaft 4 as described above, so that the manufacturing cost can be reduced by reducing the number of molding dies, etc. Will also be easier.

（制動リングの一部変形例）
図８に示す一部変形例の制動リング３０は、本体部３１の内周に一対の円弧状凸部３３を有し、これら円弧状凸部３３の内周が係止面３４となっている。この一部変形例では、ボール１１の喪失時において、３箇所（係止ポール３２の先端３２ａおよび２つの円弧状凸部３３の係止面３４）で制動リング３０とねじ軸４とが係合するため、ナット７がねじ軸４に対して傾斜しにくくなって安定した制動が実現される。また、実施形態と同様に、本体部３１の内周における円弧状凸部３３が設けられていない部位がグリース溜まり３５，３６となるため、制動リング３０を持たないものに較べて封入されるグリース２０の量が多くなってボールねじ１の耐久性が向上する。 (Partial modification of brake ring)
8 has a pair of arc-shaped protrusions 33 on the inner periphery of the main body 31, and the inner periphery of these arc-shaped protrusions 33 is a locking surface 34. . In this partially modified example, when the ball 11 is lost, the brake ring 30 and the screw shaft 4 are engaged at three locations (the tip 32a of the locking pole 32 and the locking surface 34 of the two arc-shaped convex portions 33). Therefore, the nut 7 is not easily inclined with respect to the screw shaft 4, and stable braking is realized. Similarly to the embodiment, since the portions where the arc-shaped convex portions 33 on the inner periphery of the main body 31 are not provided are the grease reservoirs 35 and 36, the grease to be enclosed is compared with the case where the brake ring 30 is not provided. The amount of 20 increases and the durability of the ball screw 1 is improved.

図９に示す一部変形例の制動リング３０は、円弧状凸部を有しておらず、本体部３１の内周全体が係止面３４となっている。この一部変形例では、実施形態や上述の一部変形例に較べて本体部３１の強度や剛性が高くなるため、被駆動部材の重量が大きい場合にも制動リング３０の変形等が起こりにくくなる。 The brake ring 30 of the partial modification shown in FIG. 9 does not have an arcuate convex portion, and the entire inner periphery of the main body 31 is a locking surface 34. In this partial modification, since the strength and rigidity of the main body 31 are higher than those in the embodiment and the above-described partial modifications, the deformation or the like of the brake ring 30 hardly occurs even when the weight of the driven member is large. Become.

以上で具体的実施形態の説明を終えるが、本発明は上記実施形態に限定されることなく幅広く変形実施することができる。例えば、上記実施形態や一部変形例ではボールねじの一端にのみ制動リングを取り付けるようにしたが、両端に制動リングを取り付けるようにしてもよい。また、上記実施形態や一部変形例では本体部の内周に円弧状凸部を１つあるいは２つ設けるようにしたが、３つ以上の円弧状凸部を設けるようにしてもよい。また、上記実施形態や一部変形例では係止ポールの先端を半球状としたが、係止ポールの軸心を回動中心として、単体では雄ねじ溝に対して所定角度（例えば、９０°）をもって回動可能であれば、係止ポールの先端は、半楕円体状や長円体状等としてもよいし、直方体状や六角柱状等としてもよい。その他、ボールねじの具体的構造や各構成部材の具体的形状等についても、本発明の主旨を逸脱しない範囲であれば適宜変更可能である。 Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the brake ring is attached only to one end of the ball screw in the above-described embodiment and some modified examples, but the brake ring may be attached to both ends. Further, in the above-described embodiment and some modified examples, one or two arc-shaped convex portions are provided on the inner periphery of the main body, but three or more arc-shaped convex portions may be provided. Moreover, although the tip of the locking pole is hemispherical in the above-described embodiment and some modified examples, the axis of the locking pole is the center of rotation, and the single unit has a predetermined angle (for example, 90 °) with respect to the male screw groove. The tip of the locking pole may have a semi-ellipsoidal shape, an oval shape, or a rectangular parallelepiped shape, a hexagonal column shape, or the like. In addition, the specific structure of the ball screw, the specific shape of each component, and the like can be changed as appropriate without departing from the spirit of the present invention.

１ボールねじ
２雄ねじ溝
３ランド
４ねじ軸
５雌ねじ溝
７ナット
８転走路
１１ボール
３０制動リング
３１本体部
３２係止ポール
３２ａ先端
３３円弧状凸部
３４係止面
Ｃｐ係止ポールの軸心
Ｒｐ係止ポール先端部の半径
Ｒｓ雄ねじ溝の円弧径
Ｓ１係止ポールの先端と雄ねじ溝との間隙
Ｓ２係止面とねじ軸のランドとの間隙 DESCRIPTION OF SYMBOLS 1 Ball screw 2 Male thread groove 3 Land 4 Screw shaft 5 Female thread groove 7 Nut 8 Rolling path 11 Ball 30 Brake ring 31 Main body part 32 Locking pole 32a Tip 33 Arc-shaped convex part 34 Locking surface Cp Shaft pole axis Rp Radius of locking pole tip Rs Arc diameter of male thread groove S1 Clearance between locking pole tip and male thread groove S2 Clearance between locking surface and screw shaft land

Claims

A screw shaft having a male screw groove formed on the outer peripheral surface;
A nut in which an internal thread groove facing the external thread groove is formed on the inner periphery;
A plurality of balls accommodated in a rolling path composed of the male screw groove and the female screw groove;
A ball screw fixed to the nut and provided with a braking piece that suppresses relative movement between the screw shaft and the nut when the ball is lost;
The braking piece is
A locking pole whose tip enters the male screw groove and whose tip faces the male screw groove with a predetermined gap;
A locking surface facing the land of the screw shaft at a position different from the locking pole with a predetermined gap;
The ball screw characterized in that the tip of the locking pole is formed in a shape that can be rotated at an angle of 360 degrees in the male screw groove with the axis of the locking pole as a rotation center.

The tip of the locking pole is formed in one shape selected from the group consisting of a hemispherical shape, a semi-ellipsoidal shape, an oval shape, a rectangular parallelepiped shape, and a hexagonal column shape. Ball screw described in 1.

The brake piece has an annular main body portion fastened to the nut;
3. The ball screw according to claim 1, wherein the locking pole protrudes from an inner periphery of the main body, and the locking surface is formed on the inner periphery of the main body. 4. .

A screw shaft having a male screw groove formed on the outer peripheral surface;
A nut in which an internal thread groove facing the external thread groove is formed on the inner periphery;
A plurality of balls accommodated in a rolling path composed of the male screw groove and the female screw groove;
A ball screw fixed to the nut and provided with a braking piece that suppresses relative movement between the screw shaft and the nut when the ball is lost;
The braking piece is
A locking pole whose tip enters the male screw groove and whose tip faces the male screw groove with a predetermined gap;
A locking surface facing the land of the screw shaft at a position different from the locking pole with a predetermined gap;
The tip of the locking pole is formed in a shape that can rotate at a predetermined angle within the male thread groove as a single unit, with the axis of the locking pole as the rotation center,
The brake piece has an annular main body portion fastened to the nut;
The locking pole protrudes from the inner periphery of the main body, and the locking surface is formed on the inner periphery of the main body .
At least one arc-shaped convex portion that has an arc shape when viewed from the axial direction of the screw shaft protrudes from the inner periphery of the main body portion, and the locking surface is formed on the arc-shaped convex portion. be Rubo Lumpur screws.