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WO1997003309A1 - Systeme d'ecrou a billes - Google Patents

Systeme d'ecrou a billes Download PDF

Info

Publication number
WO1997003309A1
WO1997003309A1 PCT/SE1996/000864 SE9600864W WO9703309A1 WO 1997003309 A1 WO1997003309 A1 WO 1997003309A1 SE 9600864 W SE9600864 W SE 9600864W WO 9703309 A1 WO9703309 A1 WO 9703309A1
Authority
WO
WIPO (PCT)
Prior art keywords
ball
nut
ofthe
screw
balls
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE1996/000864
Other languages
English (en)
Inventor
Bo Granbom
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to AU63734/96A priority Critical patent/AU6373496A/en
Publication of WO1997003309A1 publication Critical patent/WO1997003309A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls

Definitions

  • the present invention relates to a new type of ball-nuts.
  • Ball-nuts are used in those cases, where a high precision is desirable.
  • the ball-nut provides further advantages such as a low initial resistance and a minimal need for greasing.
  • the ball- nut has several drawbacks, ofwhich the largest drawback in most applications is a limited speed, i.e. the rotational speed ofthe screw. Moreover, there is a risk for the nut to fasten at the end position.
  • the Swedish patent 8702982-3 describes a ball-nut which can operate at a substantially higher speed and the ball-nut is allowed to rotate at up to 1.000 rpm. In designing the nut the power, with which the nut risks to fasten in an end position, might be reduced considerably in comparison with the type of a ball-nut known in the art.
  • the present invention presented in the characterizing parts ofthe claims, provides a ball-nut provided with the advantages ofthe above mentioned ball-nut , the ball-nut ofthe present invention at the same time operating with a low friction and with an efficiency of about 96 percent. Any risk for an overheating ofthe ball-nut is eliminated.
  • Figure 1 schematically shows a section of a nut half with a screw half
  • Figure 2 schematically shows a part ofthe ball-nut according to the invention in a larger scale.
  • the ball-nut consists of a screw 1 with threads 2, possibly provided with one or several entrances.
  • the threads are only schematically shown in the figures.
  • the ball-nut consists of a nut 3, coaxially circumsizing the screw 1.
  • the nut 3 comprises a sleeve 4 and two gable parts 5 each provided with an opening for the screw 1 and a ball tread 6 on the inward side, respectively.
  • Ball races 8 are provided rotatively suspended in the nut by means of bearing balls 7, running in the ball treads 6.
  • Each ball race 8 comprises a ball tread 9 cooperating with the bearing balls 7, as well as a ball tread 10.
  • the present invention has the obejct to solve the problems for this type of ball-nuts with a large friction resulting in a heavy heat release and the undefined movements ofthe balls in the ball treads.
  • the ball-nut is provided with only one line of balls, the balls 11, running in the nut threads 2 cooperating with two ball races 8 freely rotatable in the nut and that the thread profile and the profile ofthe ball treads 10 ofthe corresponding ball races are provided with dimensions in relation to the balls 11 , that these during the operation ofthe ball-nut comprise three contact or rolling points, on one hand a point 15 on the side ofthe screw thread and on the other hand a point 16 on each ball tread 10 of the ball races 8.
  • a certain gap has to exist between the ball and the thread sides, i.e. the thread groove should be somewhat larger than is required for the ball. This gap can be about 0.02 mm.
  • the ball rolling point in the thread thus will be displaced radially outwards, as seen from the shaft 12 ofthe screw 1, i.e. the rolling point is placed longer outwards on the thread side.
  • the balls are forced radially outwards and thereby a good contact is provided with the ball races 8, see figure 2, in which the nut 3 possibly is actuated by an axial force from the right, being understood that the illustrated gaps are largely schematic.
  • a well defined contact between the ball, the thread side and the ball races is established in three rolling points.
  • the contact or rolling point ofthe ball 11 on the corrsponding ball race 8 should be situated at a point, where the ball radius declines with an angle ⁇ towards the shaft 12 ofthe screw.
  • the angle ⁇ should then be equal or less than the angle a, being the declination ofthe contact or rolling point towards the shaft 12 of the screw.
  • the balls 11 will operate in the steadily provided plane, defined by the three contact or rolling points 15 and 16, i.e.
  • the balls 11 are rolling in a common plane without any friction losses in the screw 1 and in the ball races 8.
  • the ball races 8 freely rotating in the nut, the races 8 thus will turn in opposite directions, when the balls are rolling in the screw threads on its thread side along the rolling line generated by the rolling points 15.
  • the efficiency for a ball nut is calculated as an example, the angle ⁇ being 45 degrees and the angle ⁇ 30 degrees.
  • the ball-nut has a diameter of 25 mm, a pitch of of 36 mm and eight thread entrances (i.e. eight balls).
  • the gap between the balls and the both screw thread sides is about 0.02 mm.
  • L is the length ofthe distance the ball will roll when the screw rotates one turn and C is the pressure ofthe screw against the ball retainer for a certain load and ⁇ is the coefficient of friction between the ball and the ball retainer.
  • angles ⁇ and ⁇ might of course possibly have other values than said above, but ⁇ should always be less than a.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)

Abstract

L'invention concerne un système d'écrou à billes comprenant une vis (1) dotée de filets (2) et de billes (11) retenues dans un écrou, coopérant avec ces éléments. Les billes se déplacent entre deux cages à billes (8) suspendues perpendiculairement par rapport à l'axe de la vis (1) et roulant dans l'écrou. L'écrou à billes est caractérisé en ce que chaque bille (11) a un rayon inférieur au rayon du profil de filetage de la vis (1), d'une part, et à celui des chemins de roulement des billes (6) dans les cages à billes (8), d'autre part, dans des proportions telles que, d'une part, le point de contact (15) entre la bille (11) et le filet (2) correspondant à une charge donnée sur l'écrou à billes est situé sur une tangente à cet écrou à partir de laquelle on abaisse un angle α inférieur à 90 degrés et supérieur à zéro par rapport à l'axe (12) de la vis et que, d'autre part, le point de contact (16) du chemin de roulement des billes (6) de la cage à billes correspondante (8) est situé sur une tangente à partir de laquelle on abaisse un angle β supérieur à zéro mais inférieur ou égal à l'angle α par rapport à l'axe (12) de la vis.
PCT/SE1996/000864 1995-07-11 1996-06-28 Systeme d'ecrou a billes Ceased WO1997003309A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU63734/96A AU6373496A (en) 1995-07-11 1996-06-28 Ball-nut

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9502562A SE503473C2 (sv) 1995-07-11 1995-07-11 Kulskruv
SE9502562-3 1995-07-11

Publications (1)

Publication Number Publication Date
WO1997003309A1 true WO1997003309A1 (fr) 1997-01-30

Family

ID=20398958

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1996/000864 Ceased WO1997003309A1 (fr) 1995-07-11 1996-06-28 Systeme d'ecrou a billes

Country Status (3)

Country Link
AU (1) AU6373496A (fr)
SE (1) SE503473C2 (fr)
WO (1) WO1997003309A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107725709A (zh) * 2017-11-20 2018-02-23 北京精密机电控制设备研究所 一种重载滚珠丝杠双曲率圆弧曲面滚道结构

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2091374A (en) * 1980-12-22 1982-07-28 Beaver Machine Tool Sales Ltd Improvements in ball screws
GB2160948A (en) * 1984-06-13 1986-01-02 Hiroshi Teramachi Feeding apparatus employing a ball screw
SE458229B (sv) * 1987-07-28 1989-03-06 Bo Granbom Kulskruv
SE458878B (sv) * 1987-02-10 1989-05-16 Bo Granbom Kulskruv

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2091374A (en) * 1980-12-22 1982-07-28 Beaver Machine Tool Sales Ltd Improvements in ball screws
GB2160948A (en) * 1984-06-13 1986-01-02 Hiroshi Teramachi Feeding apparatus employing a ball screw
SE458878B (sv) * 1987-02-10 1989-05-16 Bo Granbom Kulskruv
SE458229B (sv) * 1987-07-28 1989-03-06 Bo Granbom Kulskruv

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107725709A (zh) * 2017-11-20 2018-02-23 北京精密机电控制设备研究所 一种重载滚珠丝杠双曲率圆弧曲面滚道结构
CN107725709B (zh) * 2017-11-20 2019-06-18 北京精密机电控制设备研究所 一种重载滚珠丝杠双曲率圆弧曲面滚道结构

Also Published As

Publication number Publication date
SE9502562D0 (sv) 1995-07-11
AU6373496A (en) 1997-02-10
SE9502562L (sv) 1996-06-24
SE503473C2 (sv) 1996-06-24

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