CN1079513C - Ball screw return flow path system - Google Patents

Abstract

The present invention provides a designing method of a rolling ball screw returning flow path system of a rolling ball screw, which uses curvature continuity as the basis in order to avoid the power problem of the traditional design of the rolling ball screw caused by curvature discontinuity. The improvement of the present invention is that the entire returning flow path and the curvature of the connecting part with a thread groove are kept to be continuous in order to eliminate the phenomena that a rolling ball enters and exits from the returning flow system from a screw connecting path in high speed movement and the centripetal acceleration is abruptly changed caused in the movement. Thus, the efficiency, the performance and the service life of the rolling ball screw are increased.

Description

Ball screw return flow path system

The present invention is the improvement of (or being called the circulatory system) of a kind of ball screw return flow path system.Ball screw generally is used for converting to rotatablely moving linear motion or does reverse transmission.The ball screw system generally by screw axis with spiral grooves and collocation have one of similar spiral grooves or several nuts, when the screw rod system transmission in order to the ball of bearing load, form with the return-flow system of ball.Return-flow system wherein is a considerable part in the ball screw, makes system's ball screw be carried out the motion of Infinite Cyclic by this; The influence that the performance of ball screw and efficient often are subjected to this composition is very big.Though the kind of known ball screw-bar return-flow system is a lot, generally it can be divided into four classes shown in figure 13 a to d, promptly so-called end cover type, outer circulation type, inner circulation type, and four kinds of guide-plate types etc.Though application category that these four kinds of return-flow systems are had nothing in common with each other and different good and bad points, its performance and efficient mainly be subjected to return-flow system pattern, geometrical shape, influence with its roughness.In these influence factors, geometrical shape undoubtedly be a most important factor.This is because it not only has very big influence to the dynamic response of screw axis and nut, the smooth and easy degree when tool has influence on the screw rod running.

In known ball screw system, consider as the design of the return-flow system of end cover type or other modes, only be conceived to the revolution of ball mostly.Therefore its when design mostly only at connectivity at the tie point rotary path, and the dynamic problem that may derive when reckoning without the thread groove motion of ball in return-flow system and between turnover screw axis-nut block.So return flow path center line 8 generally is made up of institutes such as straightway, arc section or oval segmental arcs, its path as shown in figure 14; Return flow path is close to the curvature in the gateway of thread groove and backflow road itself and discontinuous among the figure.Because the suffered centrifugal force of the radius of curvature of return flow path and ball is inversely proportional to, therefore change the situation generation that has some setbacks when ball has direction when entering or leaving this return-flow system at a high speed, and then produce unusual dynamic load on generation return-flow system structure and the ball.The dynamic load that this type of is unusual comprises great impact force, extra sliding friction, serious vibrations, and the noise of high-decibel, and these phenomenons all may make the return-flow system structure produce and destroy.In addition because the curvature of the thread groove joint of this return-flow system and screw rod-nut combination and discontinuous, when ball also may cause vibration, collision, and the phenomenon of pushing of ball itself and then the efficient of attenuating screw rod by herein the time.The circuit return-flow system is that example illustrates beyond this, and this type of return-flow system is general uses " U " type reflow pipe as Figure 15 to come for reaching rotating purpose; When ball during with circular turning 9 turn direction by this kind " U " type reflow pipe at a high speed, the situation that inevasible generation is collided.This is because ball when entering the circular arc road by the backflow road of straight line, because the rapid change of radius of curvature causes the change rapidly of ball moving direction, produces the centrifugal acceleration that moment uprushes and causes.Similar problem also can take place in the return-flow system of other kinds.Because of aforesaid curve ball that discontinuous problem causes hits power 10 effects to the kind of screw rod return-flow system structure, can represent by Figure 16; This impact force 10 may cause serious damage to screw rod, cause noise and then make energy loss reduce the performance of screw rod.In current and foreseeable future, industries such as automation, toolroom machine, semiconductor are under the very ardent preceding topic of high speed transmission and high performance linear actuators or module demand, ball screw as one of main original paper of linear transmission, if still design, will can't satisfy the demand of industry because of the above-mentioned discontinuous problem of return-flow system curvature with known method.Therefore for a kind of reliable and high performance ball screw of tool is provided, its return-flow system must be to prevent that ball from passing in and out this system and the unexpected conversion of direction and prevent that irrgular movement from being the starting point in return flow path.In other words, must have technology be used for improving return-flow structure itself and with screw rod-nut thread groove engagement problems.Therefore have various different viewpoints to improve return-flow system, a kind of practice wherein is that the special properties in the path of screw rod and nut groove and return-flow system is kept continuously.For example in the screw rod outer circulation return-flow system improvement method of No. the 50638095th, U. S. Patent, the suggestion reflow pipe is formed with the connecting pin section of two-part, main pin segment wherein is parallel to the direction of screw rod, makes less important pin segment then accompany a sharp comer with main pin segment.Therefore this reflow pipe main body is joined with the direction that is parallel to helix angle and the thread groove at two ends, and tangent at thread groove and its place.In this kind design since less important pin only tangent with thread groove connecting place and its place, cause the ball still can be during reflow pipe, thereby still can produce impact force, noise and other problems of deriving because of the discontinuous centrifugal acceleration that is subjected to moment of aforesaid curvature in turnover.Another improves the U. S. Patent 4953419 (Figure 17) of return-flow system, then proposing the mode that a kind of place, gateway that makes ball backflow road is parallel to helix angle designs, so that backflow road and the thread groove that joins with it are tangent, in the hope of avoiding unexpected variation along the ball path direct of travel.Mode to the multiple improvement return-flow system that also has other so far is suggested, and as the return-flow system of the improvement end cover type of No. 5154091, U. S. Patent etc., but these patents are not all considered the curvature continuity of return-flow system itself and end and nut connecting part.Though these designs have its advantage, when using at a high speed, still have its narrow limitation, because of still there is as described the discontinuous problem of curvature in it, therefore limited to the influence that reduces impact force, sliding friction, vibrating noise etc.

Below will be described further at the discontinuous problem of curvature in the preceding patent of quoting and the traditional screw rod return-flow system.Figure 18 is the planimetric map of a typical ball screw outer circulation rotary path center line, the return flow path 1 among the figure by radius by the semi-circle of R, constituted with two straight line paths are tangent.When rolling element 2 when straight line load path 3 enters semi-circle rotary path 1, curvature is uprushed to 1/R by zero on tie point A; And when leaving semi-circle rotary path 1, be back to zero by the 1/R anticlimax again at tie point C.Therefore ball is by this place the time, and centrifugal acceleration and centrifugal force all produce great variation.How the return flow path pattern of most known or improvement is combined with parts such as straightway, arc section, oval segmental arcs as described above, and is had the discontinuous problem of above-mentioned curvature.So the present invention proposes a kind ofly to can be used for guaranteeing that the curvature in backflow road in the ball screw-bar return-flow system can the curvature with appointment change continuously between two-end-point, and can make the continuous method of curvature of itself and thread groove connecting part.Mat the present invention makes the continuous method of curvature not only can reduce the rapid change of centripetal force when ball turnover return-flow system, also can make the more traditional return-flow system of the motion of ball in return flow path smooth and easy.Therefore when ball screw when running up ball to the impact force of return-flow system structure such as reflow pipe or end cap, surface friction drag that sliding friction causes, reach and the reduction of certain degree can be arranged because of vibrating caused noise.

The problem that the present invention is directed to the ball return flow path system of the ball screw of being made up of screw axis, nut, ball and return-flow system proposes, in the hope of improving the performance of traditional ball screw.

Purpose of the present invention is for providing a kind of return-flow system of avoiding known ball screw because of the discontinuous problem that produces of return flow path curvature, and uses the exercise performance that improves its screw rod.Curvature continous curve proposed by the invention can be exerted helical (Clothoid curve), Bei Xier curve (or claiming Bezier curve Bezier curve), B wedge line (B-Spline), non-uniform rational B wedge line (NURBS by section; Non-uniform rational B-Spline) or the combination of above-mentioned curve or the plane or the space curve of the curve that combined of build-up curve and straightway, arc section, oval segmental arc or other smoothed curve sections are formed therewith.Curvature in order to the curve of describing return flow path among the present invention can be by doing continuous variation with specified particular value along return flow path at the return flow path end points.

By the return flow path that method proposed by the invention is designed with the continuous variation characteristic of curvature, can be used for eliminating ball under high-speed motion from screw rod access path turnover return-flow system and when moving therein the phenomenon of the centripetal force utmost point drastic changeization that may cause.Lowered by this return-flow system structure made living intense impact power, extra sliding friction, and serious vibration and high-decibel noise, and more than the caused return-flow system structural damage of various phenomenons problem etc.Not only can make the more traditional design of the motion of ball in return flow path smooth and easy via the present invention, and efficient, performance and the life-span that can improve screw rod.

A kind of ball screw return flow path system of the present invention; The nut that alleged ball screw is matched to several tool thread grooves and screw axis by a screw axis with thread groove,, the ball of one or more backflows, and as the ball return flow path, and the aforementioned return-flow system of joining with aforesaid screw axis and the formed thread groove of nut, form the mechanism that can do the Infinite Cyclic motion; Aforesaid return flow path is made of one or more curves, it is characterized in that, curve wherein be along each point on this curved path and on its two-end-point with adjacent path, its slope and curvature all must keep continuously; Wherein the curvature of this curve may be defined as from the gateway of return-flow system by the particular value of appointment and changes continuously; Wherein helical, Bei Xier curve, B wedge line, non-uniform rational B wedge line are exerted by the curve section of comprising; Wherein curve also comprises with above-mentioned section and exerts curve that helical, Bei Xier curve, B wedge line, non-uniform rational B wedge line the made up curve that combined of build-up curve and straightway, arc section, oval section or other smoothed curve sections therewith; Curve wherein comprises the plane curve and the tridimensional space curve of dual space.

For further specifying feature of the present invention and effect, after being illustrated in below in conjunction with drawings and Examples, wherein:

Figure 1A is for being exerted the return flow path schematic representation of the external circulation type ball bolt that helical constitutes by section;

Figure 1B is the curvature of Figure 1A rotary path and the graph of a relation of relative position;

Fig. 2 A is that rotary path is exerted helical by the section that Fig. 1 improved and formed schematic representation;

Fig. 2 B is the curvature of Fig. 2 A rotary path and the graph of a relation of relative position;

Fig. 3 A is that rotary path is exerted the helical schematic representation by the another kind of section that Figure 1A improved;

Fig. 3 B is the curvature of Fig. 3 A rotary path and the graph of a relation of relative position;

Fig. 4 A is that rotary path is exerted the helical schematic representation by the another kind of section that Figure 1A improved;

Fig. 4 B is the curvature of Fig. 4 A rotary path and the graph of a relation of relative position;

Fig. 5 A is that rotary path is exerted the helical schematic representation by the another kind of section that Figure 1A improved;

Fig. 5 B is the curvature of Fig. 5 A rotary path and the graph of a relation of relative position;

Fig. 6 A is for being exerted the return flow path schematic representation of the external circulation type ball bolt that helical constitutes by section;

Fig. 6 B is the curvature absolute value of Fig. 6 A rotary path and the graph of a relation of relative position;

Fig. 7 is for being mapped to the schematic representation of Fig. 7 B space curve 7 by Fig. 7 A plane curve 6;

Fig. 8 is the 5 shellfish formula curves of spending of a formation rotary path and the schematic representation at control point thereof;

Fig. 9 is the perspective view of the ball screw of an end cover type return-flow system;

Figure 10 is the detail drawing of return-flow system return flow path, curved section R and L among Fig. 9;

Figure 11 is for using the along the line section L that the present invention drew, and the curvature of curved section R and helix H can Butut.

Figure 12 is known curvature distribution figure by the rotary path that circular arc constituted;

Figure 13 is that return-flow system (A) end cover type, (B) outer circulation type, (C) inner circulation type of four kinds of ball screws reaches (D) schematic representation of guide plate type;

Figure 14 is the schematic representation of known ball screw rotary system design concept;

Figure 15 is the sectional drawing with the outer circulation reflow pipe of known method design;

The sectional drawing of the impact force that Figure 16 may be subjected to for the outer circulation reflow pipe with the design of known method;

Figure 17 is the schematic representation of improvement ball screw-bar return-flow system shown in Figure 5 in the U. S. Patent 4953419;

Figure 18 A is that known rotary path is by a schematic representation that semi-circle constituted;

Figure 18 B is the curvature of Figure 18 A rotary path and the graph of a relation of relative position;

Fig. 1 to Figure 11 is the specific embodiment figure of ball screw-bar return-flow of the present invention system, and Figure 12 to Figure 18 B is the schematic representation of known ball screw-bar return-flow system;

The invention provides a kind of various ball screw ball return flow path structure that is applicable to.Different with traditional ball screw is that the present invention is that the starting point of design flows the smooth degree that is in the hope of improving ball screw with curvature, and uses the performance under running up of improving traditional ball screw.The continuous ball screw return flow path of defined curvature among the present invention can use section be exerted helical (Clothoid curve), Bei Xier curve (or claiming Bezier curve Bezier curve), B wedge line (B-Spline), non-uniform rational B wedge line (NURBS; Non-uniform rational B-Spline) or the curve of other similar characteristics reach.Among the present invention the return flow path of indication by the ball center in return-flow system the path of process.The Yin Kenu helical is the function of arc length in these curves, and more easily explanation is so the design example that helical is exerted with section by following elder generation is illustrated as intension of the present invention.

The general standard form of helical is exerted by section, can have following equation to represent: $(X\left(u\right),Y\left(u\right))=({\mathrm{<figure-callout\; id="0"\; label="X"\; filenames="C9810015800231.png"\; state="\{\{state\}\}">X</figure-callout>}}_0,Y_0)+[h{\&Integral;}_0^u\cos \left(f\left(u\right)\right)\mathrm{du},h{\&Integral;}_0^u\sin \left(f\left(u\right)\right)\mathrm{du}]$

Wherein (X (u), Y (u) are on the helical a bit, (and Xo Yo) is the starting point of helical, and h is a proportionality constant, the helical arc length of u for measuring from this helical starting point, and f (u) is a tangent function, it equals helical in (X (u), the angle of contingence on the Y (u).This section exerts function f (u) and generally may be defined as: $f\left(u\right)=\frac{\mathrm{\&pi;}{u}^2}{2}$

Therefore the curvature function of helical can show be $c\left(u\right)=\frac{\mathrm{\&pi;u}}{h}$

The curvature of hence one can see that this helical can be gradually changed to a certain particular value by zero line with arc length.Figure 1A exerts the design example of helical in ball screw outer circulation return-flow system for application of the present invention section.The return flow path 1 of reflow pipe is exerted helical a by the section of two symmetries among the figure, and b forms, and wherein a helical starting point and straight line load path 3 link, and another helical starting point then links to each other with the zero load path 4 of straight line, and each line segment tie point tangential angle keeps continuously.The relation of the curvature of curve of Figure 1A and arc length relative position, shown in Figure 1B, the curvature of the rotary path 1 among the figure from B o'clock by a setting value k _sIncrease gradually, exert helical interface point place to two sections and diminish gradually again to loop terminal point B one-tenth k _sWherein, can avoid acceleration situation jumpy in the Known designs because of rotary path curvature changes continuously.

Fig. 2 A to Fig. 5 B exerts helical other application examples in return flow path for application of the present invention section, and helical a is exerted by four sections in the loop among Fig. 2 A, b, and c, d forms, and rotary path is then exerted helical a by four sections among Fig. 3 A, b, d, an e and a straightway c constitute; Two above application examples, it is continuous that each contact tangential angle and curvature all can keep.In the above rotary path design, its curvature is all with the linear variation of arc length, and so except that linear change, the variation of this curvature also can be by positive complement of an arc function, or the above multinomial of secondary is stipulated it.With the quadratic polynomial is example, and the change curve of establishing curvature is

C(u)＝6πu(1-u)

Then the available following equation of curve (X (u) and Y (u)) is expressed $X\left(u\right)={\&Integral;}_0^u\cos \left(6\mathrm{\&pi;}(\frac{u^2}{2}-\frac{{\mathrm{<figure-callout\; id="3"\; label="u"\; filenames="C9810015800141.png,C9810015800151.png"\; state="\{\{state\}\}">u</figure-callout>}}^3}{3})\right)\mathrm{du}$ $Y\left(u\right)={\&Integral;}_0^u\sin \left(6\mathrm{\&pi;}(\frac{u^2}{2}-\frac{u^3}{3})\right)\mathrm{du}$

If the upper limit of integral of arc length u is 1, then this section exert helical and curvature thereof along the variation of arc length shown in Fig. 4 A and Fig. 4 B.If with the sine function is the curvature changing function

C(u)＝πsin(2u)

Then the available following equation of curve (X (u) and Y (u)) is expressed $X\left(u\right)={\&Integral;}_0^u\cos \left(\mathrm{\&pi;}\sin {\left(u\right)}^2\right)\mathrm{du}$ $Y\left(u\right)={\&Integral;}_0^u\sin \left(\mathrm{\&pi;}\sin {\left(u\right)}^2\right)\mathrm{du}$

If the upper limit of integral of arc length u is a pi/2, then this section exert helical and curvature thereof along the variation of arc length shown in Fig. 5 A and Fig. 5 B.

As the suitable curvature function of choosing, undergraduate course is exerted the design that helical also can be used for internal circulation system return flow path (lid refluxes).Be decided to be as curvature function

C(u)＝πsin(2u)/2

Then the available following equation of curve (X (u) and Y (u)) is expressed $X\left(u\right)={\&Integral;}_0^u\cos (\mathrm{\&pi;}\sin {\left(u\right)}^2/2)\mathrm{du}$ $Y\left(u\right)={\&Integral;}_0^u\sin (\mathrm{\&pi;}\sin {\left(u\right)}^2/2)\mathrm{du}$ If the upper limit of integral of arc length u is π, then this section exert helical and curvature thereof along the variation of arc length shown in Fig. 6 A and Fig. 6 B.This curve is as changing through three-dimensional space as described below, applicable to the return flow path of actual ball screw internal circulation system.

Though the return flow path in the above example is exerted helical for plane section, as it also can be used for tridimensional return flow path design through appropriate modification.The three-dimensional space return flow path of for example a kind of inner circulating reflux system can get it via the mapping process as Fig. 7; Planar system X-Y among the figure (Fig. 7 A) can map to the cylinder that radius is R (Fig. 7 B) via following formula:

X＝Y

Q＝Y/R

The back curve of this mapping (x (u), y (u), z (u)) can be expressed as by rectangular coordinate system x-y-z $x\left(u\right)=X=\cos \left({\&Integral;}_0^u\cos \left(f\left(u\right)\right)\mathrm{du}\right)$ $y\left(u\right)=R\sin (Y/R)=R\sin \left(\frac{{\&Integral;}_0^u\sin \left(f\right(u\left)\right)\mathrm{du}}{R}\right)$ $z\left(u\right)=R\cos (Y/R)=R\cos \left(\frac{{\&Integral;}_0^u\sin \left(f\right(u\left)\right)\mathrm{du}}{R}\right)$

Its arc length of amended curve is u, and its curvature function becomes $C\left(u\right)=\sqrt{{\left(\frac{d^{2}x}{{\mathrm{du}}^2}\right)}^2+{\left(\frac{d^{2}y}{{\mathrm{du}}^2}\right)}^2+{\left(\frac{d^{2}z}{{\mathrm{du}}^2}\right)}^2}=\sqrt{{\left(\frac{\mathrm{df}\left(u\right)}{\mathrm{du}}\right)}^2+{\left(\frac{{\sin }^2\left(f\left(u\right)\right)}{R}\right)}^2}$

Helical is exerted by the section of drawing along the cylndrical surface as can be seen from following formula, and the curvature that helical is exerted by the more original plane section of its curvature slightly changes, but this new curvature function, and provable its still kept curvature from zero continually varying characteristic.Though last example only designs with the cylindrical and restrictive condition of simplifying for purposes of illustration, method provided by the present invention also can be revised slightly to be applied to the screw rod return-flow system of various different restrictive conditions and geometrical shape.

Except extra curvature is exerted by section, other curve such as Bezier curve, B wedge line or non-uniform rational wedge lines that are widely used in CAD (computer aided design) also can have curvature continually varying characteristic.Exert curve ratio with section, this type of curve can directly design tridimensional return-flow system, and does not need to exert the mapping of curve or other switch process through plane section as described above.Because exerting helical, Bezier curve, B wedge line or non-uniform rational wedge line and part section all can be expressed as reasonable Bezier curve through suitable conversion, and this curve can be done one to the geometrical property of reality of the present invention and explain more clearly, therefore followingly with reasonable Bezier curve the method that designs the return flow path with curvature continuation property with this type of curve (Bezier curve, B wedge line or non-uniform rational wedge line) is described.

If a return flow path of being made up of the reasonable Bezier curve of n dimension can be used C (t)=(x (t), y (t), z (t)) expression, then its parameter type can by $C\left(t\right)=\frac{\underset{t=0}{\overset{n}{\mathrm{\&Sigma;}}}{W}_i{P}_i{B}_i^n\left(t\right)}{\underset{t=0}{\overset{n}{\mathrm{\&Sigma;}}}{W}_i{B}_i^n\left(t\right)}$

Try to achieve function wherein $B_i^n\left(t\right)=\left(\stackrel{n}{i}\right)t^i{(l-t)}^{n-i}$

Be called Bernstein polynomial (Bemstein polynomial), pi is the control point, and wi is the weighted value that pi is ordered.If the two-end-point of this curve is p0 and pn, then the tangent direction of ordering at p0 is the direction of along the line section p0 and p1.In the same manner, some pn and pn-1 can be used for determining the tangent direction at pn point place, and as shown in Figure 8, the reasonable Bezier curve line of one 5 dimensions and 6 control points thereof can be in order to produce the return flow path in a space among the figure.The curvature k of ordering at end points p0 can be tried to achieve by following formula $k=2\frac{n-1}{n}\frac{w_0{w}_2}{{{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="C9810015800151.png,C9810015800171.png"\; state="\{\{state\}\}">w</figure-callout>}}_1}^2}\frac{\mathrm{\&Delta;}{P}_0{P}_1{P}_2}{\left|P_0{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="C9810015800151.png,C9810015800171.png"\; state="\{\{state\}\}">P</figure-callout>}}_1\right|}$

N=5 wherein, △ p0 p1p2 is the area of triangle p0 p1 p2, | p0 p1| is the length of line segment p0 and p1.Curvature k is the inverse of osculating circle (osculatingcircle) radius r, and this osculating circle is one to be positioned at by p0, p1, and the formed plane of p2 point and reasonable Bezier curve are at the tangent circle of a p0.Below with as the ball screw-bar return-flow system of a circle end cover type of 9 be that example is to being described in detail.Return flow path among Fig. 9, curved section R and L part can be known clearly and be painted as shown in figure 10, and the curved section R among the figure is tangent at p0 and p5 respectively along the spiral path H and the straightway L of screw motion with the ball center respectively, and osculating circle O wherein is r in the radius of curvature of a p0.For guarantee slope and curvature continuously, the control point p0 to p5 of this Bezier curve should by each following step standard it:

1, makes that p0 and p5 are the two-end-point of Bezier curve R.

2, make p1 be positioned at return flow path and spiral path H on the tangent tangent line of p0.

3, the equation of the above-mentioned curvature k of mat will be put p2 and be positioned on the osculating plane 0, so radius of curvature is r at the p0 point.

4, control point p3 and p4 are positioned on the line segment L, because curvature is zero at its p5.

Figure 11 is section L along the line, the curvature distribution figure of R and section H; Figure can learn that slope and curvature at next-door neighbour tie point p0 and p5 are continuously thus, has therefore been overcome the discontinuous problem of known return-flow system curve as Figure 12, therefore can reduce rapid centripetal acceleration variation, sliding friction, reach noise etc.In addition, originally has the advantage that bigger degrees of freedom is arranged on setting control point and the weighting parameters.Because these design parameters can be drawn up generally during as use this method proposal plan, make itself and the curvature of return flow path become the continuous state of preliminary summary at the tie point place, and then use suitable optimization rule, adjust repeatedly design parameter with meet as the smooth-going distribution of curvature, shape, manufacturability, with condition such as end cap assembling difficulty or ease.Though more than illustrate respectively that with diverse ways and example the return-flow system of outer circulation, interior circulation and end cover type does specification, when practical application, if these methods are through slightly revising, and all can be used for designing above-mentioned arbitrary return-flow system or other kinds return-flow system as guide plate type.

In the concrete application of product specification, design of the present invention can also be with straightway, arc section, oval segmental arc or other curved sections, be connected and change with the revolution curve, need with size on the realistic product or external form, only its characteristics are at the left and right side of contact that links to each other, identical curvature must be arranged, to keep the continuity of curvature.Main purpose of the present invention, be to keep the curvature of whole ball screw return flow path continuous, and on actual product is used, can be because of reasons such as processing or assemblings, to some fraction correct, as making lead angle or circular arc etc., or, all belong to the application of invention because of assembling needs to increase counter sink etc. at the return flow path two ends.

Above-mentioned specific embodiment, be to be used for describing in detail purpose of the present invention, feature and effect, for being familiar with this type of technology personage, may do part change and modification to this specific embodiment according to the above description, do not raise and do not detach spiritual model of the present invention, so claim of the present invention is limited by claim.

Claims (4)

1, a kind of ball screw return flow path system; The nut that alleged ball screw is matched to several tool thread grooves and screw axis by a screw axis with thread groove,, the ball of one or more backflows, and as the ball return flow path, and the aforementioned return-flow system of joining with aforesaid screw axis and the formed thread groove of nut, form the mechanism that can do the Infinite Cyclic motion; Aforesaid return flow path is made of one or more curves, it is characterized in that, curve wherein be along each point on this curved path and on its two-end-point with adjacent path, its slope and curvature all must keep continuously.

2, ball screw return flow path system according to claim 1 is characterized in that, wherein the curvature of this curve may be defined as from the gateway of return-flow system by the particular value of appointment and changes continuously.

3, ball screw return flow path system according to claim 1 is characterized in that wherein helical, Bei Xier curve, B wedge line, non-uniform rational B wedge line are exerted by the curve section of comprising.

4, ball screw return flow path system according to claim 1 is characterized in that curve wherein comprises the plane curve and the tridimensional space curve of dual space.

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