CN107498365B - Double-nut precise ball screw pair - Google Patents
Double-nut precise ball screw pair Download PDFInfo
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- CN107498365B CN107498365B CN201710912666.8A CN201710912666A CN107498365B CN 107498365 B CN107498365 B CN 107498365B CN 201710912666 A CN201710912666 A CN 201710912666A CN 107498365 B CN107498365 B CN 107498365B
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- ball screw
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- 238000005096 rolling process Methods 0.000 claims abstract 2
- 230000007246 mechanism Effects 0.000 description 11
- 230000005540 biological transmission Effects 0.000 description 7
- 230000008878 coupling Effects 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 4
- 238000005859 coupling reaction Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q5/00—Driving or feeding mechanisms; Control arrangements therefor
- B23Q5/22—Feeding members carrying tools or work
- B23Q5/34—Feeding other members supporting tools or work, e.g. saddles, tool-slides, through mechanical transmission
- B23Q5/38—Feeding other members supporting tools or work, e.g. saddles, tool-slides, through mechanical transmission feeding continuously
- B23Q5/40—Feeding other members supporting tools or work, e.g. saddles, tool-slides, through mechanical transmission feeding continuously by feed shaft, e.g. lead screw
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q5/00—Driving or feeding mechanisms; Control arrangements therefor
- B23Q5/54—Arrangements or details not restricted to group B23Q5/02 or group B23Q5/22 respectively, e.g. control handles
- B23Q5/56—Preventing backlash
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Transmission Devices (AREA)
Abstract
The invention discloses a double-nut precise ball screw pair, which comprises a ball nut and a ball screw which is supported by an upper supporting part and a lower supporting part and is driven by the ball nut to rotate and can only axially feed, wherein the ball nut consists of a main ball nut and an auxiliary ball nut which are limited relatively in the circumferential direction and can axially move relatively, the diameter of a ball in the ball nut is slightly smaller than that of an upper rolling way of the ball nut and the ball screw, and a clearance eliminating nut which can spirally rotate relative to the lower supporting part is sleeved on the lower supporting part and axially contacts with the auxiliary ball nut; the main ball nut and the anti-backlash nut are respectively driven to rotate by a driving device. The invention can ensure that the ball screw can realize high-precision and high-rigidity axial movement along the main design reference shaft of the machine tool.
Description
Technical Field
The invention belongs to a screw pair, and particularly relates to a double-nut precise ball screw pair.
Background
The ball screw pair works in such a way that the screw is driven to axially feed by the rotation of the nut (the screw does not rotate). The large-diameter ball screw (see figure 1) has an outer diameter of more than or equal to phi 120mm, is of a hollow structure and comprises a set of independent rotary spindle mechanisms (not shown in the figure). Because the diameter of the screw rod is large, the outer cylindrical surface of the screw rod is a sliding guide rail, so that the requirement on the axial feeding movement precision of the cylindrical surface of the screw rod is very high. The axial cutting force F of the screw fluctuates greatly with factors such as wear of a cutter (grinder), variation of feeding amounts of the cutter and a workpiece, and variation of the area of a cutting area. Under such a working condition, to ensure high accuracy of geometric tolerances (thickness, parallelism, flatness) in the thickness direction of the workpiece, the ball screw pair is required to have high axial rigidity in both directions.
There is a ball screw pair of a single nut structure. In order to ensure the axial zero clearance between the ball nut and the ball screw in the working process, a ball nut raceway displacement technology or a method that the diameter of a ball is slightly larger than the circular arc diameter of a raceway is generally adopted, so that the nut ball generates a certain precompression on the screw raceway. Therefore, the ball nut is tightly matched with the steel ball and the rollaway nest of the screw rod, so that relative deflection movement is difficult to generate between the screw rod and the nut in the working process, and the screw rod and the nut are similar to an integral part (only relatively axially move and cannot deflect). The use of the screw pair with such a structure in the above application context causes the following significant problems:
1. as shown in fig. 2 (i), there is a perpendicularity deviation e due to the fact that the installation reference surface B of the main ball nut ab in the main bearing direction is opposite to the axial feeding reference shaft a of the ball screw (determined by two sliding bearings respectively positioned at the upper and lower ends of the ball screw) 1 In order to ensure the axial rigidity of the ball screw pair in this way, a large pretension mounting force F is applied to the axial direction of the ball nut Anan (safety) At F Anan (safety) The screw cd will be relative to the theoretical position c under the action / d / A deflection e occurs 2 =e 1 X H/W, wherein W represents the diameter of the ball nut and H represents the spacing between the upper and lower bearings. Due to such ball nut pairs H>>W, therefore, a small manufacturing error e 1 Will generate larger deviation e 2 。
2. As shown in FIG. 2 (ii), the ball screw is vertically deflected by an amount e relative to the ball nut due to manufacturing and assembly reasons 3 Then at e above 2 、e 3 Under the common influence of the two, the axial feeding of the single-nut ball screw is ensured to be smooth, and the radial clearance E between the inner holes of the upper sliding bearing and the lower sliding bearing relative to the outer cylindrical matching surface of the screw is required to be more than or equal to 2× (E) 2 +e 3 ）=2×（e 1 ×H/W+e 3 ). It follows that in this case, the screw feed is difficult to precisely feed along the original design reference axis a, but is subject to the perpendicularity error e of the main ball nut mounting reference plane B with respect to the feed reference axis a 1 Perpendicularity error e of nut screw rod 3 The comprehensive influence ensures that the fit clearance between the screw rod and the sliding bearing is relatively large, thus having serious influence on the feeding precision and rigidity of the ball screw pair.
Due to the characteristics of the structure of the single-nut ball screw pair, the pretension between the nut screw pairs can only be set by factories before delivery, and once abrasion and gaps are generated between ball raceways along with the extension of service time, the equipment users can hardly adjust and pretension again.
Therefore, such a single-nut ball screw pair has various problems in terms of accuracy, rigidity retention, and the like.
In order to overcome the defects of the single-nut ball screw pair, a double-nut ball screw structure is adopted by many manufacturers. However, most of the nuts are provided with elastic devices such as spring pieces and the like between the two nuts, so that the two nuts generate a mutually-opening force. Chinese patent (patent number: CN201320318571.0 ball screw nut pair) discloses a double-nut ball screw pair structure pre-tightened by a spring piece structure, wherein the mechanism is characterized in that two nuts are relatively folded by a spring piece pre-tightening device. The double-nut screw rod mechanism has a simple structure, can play a certain role in eliminating gaps and automatically compensating abrasion gaps under the action of the elastic device, and has various applications under the working condition that a plurality of screw rods are not stressed in two directions, but has a great disadvantage that the rigidity of the screw rods in one feeding direction depends on the rigidity of the elastic device. In applications where the axial cutting force is large or the amplitude of the fluctuation is large in this direction, the axial rigidity becomes poor.
Chinese patent (patent number: CN 201220411637.6) discloses a device for adjusting the direction of the side gap of the screw drive pair. However, the patent describes a double-nut trapezoidal screw rod, and the gap eliminating mode of the screw rod adopted by the screw rod is that relative rotation is generated between two nuts until two end faces are mutually tightly attached, similar to double-nut tightening. However, this anti-backlash method is not suitable for an accurate and reliable nut rotation driving screw feeding working mode in terms of structural form.
Disclosure of Invention
The invention aims to provide a double-nut precise ball screw pair, which aims to ensure that a ball screw can realize high-precision and high-rigidity axial movement along a main design reference shaft of a machine tool.
In order to achieve the purpose of the invention, the technical scheme provided by the invention is as follows:
the double-nut precise ball screw pair comprises a ball nut and a ball screw which is supported by an upper supporting part and a lower supporting part and is driven by the ball nut to rotate and can only axially feed, wherein the ball nut consists of a main ball nut and an auxiliary ball nut which are limited relatively in the circumferential direction and can axially move relatively, the diameter of a ball in the ball nut is slightly smaller than that of an upper raceway of the ball nut and the ball screw, and an anti-backlash nut which can rotate spirally relative to the lower supporting part is sleeved on the lower supporting part and axially contacts with the auxiliary ball nut; the main ball nut and the anti-backlash nut are respectively driven to rotate by a driving device.
And a thrust bearing is respectively arranged between the main ball nut and the upper supporting part and between the auxiliary ball nut and the clearance eliminating nut.
And a certain gap is kept between the main ball nut and the auxiliary ball nut, and the main ball nut and the auxiliary ball nut are connected through a guide pin.
The upper support part and the lower support part are respectively an upper sliding bearing and a lower sliding bearing, and two symmetrical flat keys are arranged between the upper sliding bearing and the ball screw.
The parts of the screw rod, which are matched with the upper sliding bearing and the lower sliding bearing, are an upper positioning journal and a lower positioning journal, and the screw rod realizes accurate positioning through the upper positioning journal and the lower positioning journal.
The upper and lower locating journals may be the same or different in size.
The invention has the beneficial effects that:
1. because the ball nut is of a double-nut structure, the diameter of the ball is slightly smaller than that of the roller path, so that slight swinging can be generated between the nut and the ball screw. So as to eliminate the perpendicularity error e of the ball nut axial installation surface B relative to the screw rod feeding shaft A to a certain extent 1 Perpendicularity error e between nut and screw rods 3 The ball screw and the upper and lower sliding bearings can ensure a small fit clearance, thereby ensuring that the ball screw realizes high-precision and high-rigidity axial movement along the main design reference A of the machine tool.
2. The auxiliary ball nut is pushed by a set of anti-backlash nuts which are subjected to constant axial thrust. Thereby ensuring zero clearance and reliable axial preload between the ball nut and the screw rod, and ensuring that the ball screw pair has high axial rigidity.
3. The gap eliminating mechanism is a combined mechanism of a worm bevel gear pair and a screw thread screw transmission pair, so that the transmission of the gap eliminating mechanism has self-locking property; and is a rigid coupling rather than an elastic coupling, so that the axial rigidity and reliability of the anti-backlash mechanism are high.
The technical scheme of the invention is further described below with reference to the accompanying drawings.
Drawings
Fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a diagram of single nut ball screw pair reference errors.
Detailed Description
Referring to fig. 1, the double-nut precision ball screw pair provided by the invention comprises a ball nut and a ball screw 1 which is driven by the ball nut to rotate and can only axially feed, wherein the ball screw 1 axially feeds on a common reference shaft A formed by a cylindrical hole of an upper sliding bearing 2 and a cylindrical hole of a lower sliding bearing 8, the upper sliding bearing 2 and the lower sliding bearing 8 are fixedly connected with a box body 9, and two symmetrical flat keys (not shown) are arranged between the upper sliding bearing 2 and the ball screw 1 so as to prevent the ball screw 1 from rotating relative to the sliding bearings 2 and 8 when moving up and down; the ball nut consists of a main ball nut 4 and an auxiliary ball nut 6, the diameter of a ball 10 in the ball nut is slightly smaller than the diameters of the ball nut and the upper rollaway nest of the ball screw 1, a certain gap is kept between the main ball nut 4 and the auxiliary ball nut 6, and the main ball nut 4 and the auxiliary ball nut 6 are connected by a plurality of guide pins 5, so that the main ball nut 4 and the auxiliary ball nut 6 are limited relatively in the circumferential direction but can move relatively in the axial direction; the lower sliding bearing 8 is sleeved with an anti-backlash nut 7 which can rotate spirally relative to the lower sliding bearing 8, and a thrust bearing 3 is respectively arranged between the main ball nut 4 and the upper sliding bearing 2 and between the auxiliary ball nut 6 and the anti-backlash nut 7; the main ball nut 4 and the gap eliminating nut 7 are respectively driven to rotate by a driving device, the driving device adopts a worm driving device, the main ball nut 4 and the worm form a worm-gear pair, the main ball nut 4 is driven to rotate by the worm, and the gap eliminating nut 7 and the wormThe rod forms a worm bevel gear pair, and the anti-backlash nut 7 is driven to rotate by a worm; in the worm bevel gear pair, the outer circular surface of the anti-backlash nut 7 is in a bevel gear form and is driven to rotate relative to the lower sliding bearing 8 by a worm, so that an axial anti-backlash effect is generated; in the figure, W represents the diameter of a ball nut, H represents the distance between an upper sliding bearing and a lower sliding bearing, the part of the screw rod 1 matched with the upper sliding bearing 2 and the lower sliding bearing 8 is an upper positioning journal and a lower positioning journal, the screw rod 1 realizes accurate positioning through the upper positioning journal and the lower positioning journal, and the sizes of the upper positioning journal and the lower positioning journal can be the same or different. D (D) 1 And D 2 Represents the diameter of the cylindrical hole of the upper sliding bearing and the diameter of the cylindrical hole of the lower sliding bearing respectively, d 1 And d 2 And F represents the axial cutting force born by the ball screw.
In the invention, the driving device can also adopt a rack driving device, the main ball nut 4 and the anti-backlash nut 7 respectively form a gear-rack pair with a rack, and the main ball nut 4 and the anti-backlash nut 7 are driven by the rack to rotate.
In the invention, the main ball nut 4 mainly plays a role in bearing load, and the auxiliary ball nut 6 mainly plays a role in eliminating the clearance between the ball nut and the ball screw pair; because the diameter of the ball 10 is slightly smaller than the diameters of the ball nut 4 and the upper roller path of the ball screw 1, the ball nut and the ball screw 1 can slightly swing, so that the perpendicularity error e of the axial installation datum plane B of the ball nut relative to the feeding datum axis A of the ball screw 1 (namely the common axis A of the upper sliding bearing hole and the lower sliding bearing hole and the main design datum axis of a machine tool) can be eliminated to a certain extent 1 Perpendicularity error e between ball nut and ball screw 1 3 The ball screw 1 and the upper and lower sliding bearings 2 and 8 can ensure small fit clearance, thereby ensuring that the ball screw 1 realizes high-precision and high-rigidity axial movement along the main design reference A of the machine tool; a certain gap is kept between the main ball nut 4 and the auxiliary ball nut 6, and the main ball nut 4 and the auxiliary ball nut 6 are connected by a plurality of guide pins 5, so that the main ball nut 4 and the auxiliary ball nut 6 can only axially move and can not relatively rotate; anti-backlash nut 7 and downslideThe movable bearing 8 forms a screw thread transmission mechanism, the gap eliminating nut 7 pushes the auxiliary ball nut 6 to the main ball nut 4 to draw close by screw rotation under the action of a worm, and the gap between the ball nut and the screw rod 1 is eliminated, so that the axial gap eliminating effect is generated.
The screw thread transmission mechanism and the worm bevel gear pair form a better gap eliminating device. The worm in the worm bevel gear pair can be manually rotated and adjusted, and can also generate continuous pre-torque effect under the action of a hydraulic cylinder or an air cylinder or a spring device, so that the clearance eliminating nut is ensured to continuously eliminate the clearance between the ball screw 1 and the ball nut with a certain axial force. The gap eliminating device is a combined mechanism of a worm bevel gear pair and a threaded screw transmission mechanism, so that the transmission of the gap eliminating device has self-locking property; and is a rigid coupling rather than an elastic coupling, the axial rigidity and reliability of the anti-backlash device is high.
The specific action mode of the gap eliminating device is as follows: the main ball nut 4 is driven to rotate by a worm and gear pair so as to drive the screw rod 1 to move up and down. The main ball nut 4 rotates and simultaneously drives the auxiliary ball nut 6 to rotate together through the guide pin 5. On the other hand, the anti-backlash nut 7 continuously generates a constant pre-torque through the spiral transmission action of the worm bevel gear pair and the opposite lower sliding bearing 8, so that a constant axial thrust force is generated to push the auxiliary ball nut 6 to close the main ball nut 4 with a constant axial force, and the constant axial pre-stress on the ball screw 1 is maintained while the clearance between the ball nut and the ball screw 1 is eliminated.
Claims (6)
1. The double-nut precise ball screw pair is characterized by comprising a ball nut and a ball screw which is supported by an upper supporting part and a lower supporting part and is driven by the ball nut to rotate and can only axially feed, wherein the ball nut consists of a main ball nut and an auxiliary ball nut which are limited in a circumferential direction and can axially and relatively move, the diameter of a ball in the ball nut is slightly smaller than that of an upper rolling way of the ball nut and the ball screw, and a clearance eliminating nut which can spirally rotate relative to the lower supporting part is sleeved on the lower supporting part and axially contacts with the auxiliary ball nut; the main ball nut and the anti-backlash nut are respectively driven to rotate by a driving device.
2. The double-nut precision ball screw pair according to claim 1, wherein a thrust bearing is provided between the main ball nut and the upper support member and between the sub ball nut and the anti-backlash nut, respectively.
3. The double nut precision ball screw pair according to claim 1 or 2, wherein a certain gap is maintained between the main ball nut and the auxiliary ball nut, and the main ball nut and the auxiliary ball nut are connected by a guide pin.
4. The double-nut precise ball screw pair according to claim 3, wherein the upper and lower supporting parts are an upper sliding bearing and a lower sliding bearing, respectively, and two symmetrical flat keys are arranged between the upper sliding bearing and the ball screw.
5. The double-nut precise ball screw pair according to claim 4, wherein the parts of the ball screw, which are matched with the upper sliding bearing and the lower sliding bearing, are upper and lower positioning journals, and the ball screw is precisely positioned through the upper and lower positioning journals.
6. The double nut precision ball screw assembly of claim 5, wherein the upper and lower locating journals may be the same or different in size.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710912666.8A CN107498365B (en) | 2017-09-30 | 2017-09-30 | Double-nut precise ball screw pair |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710912666.8A CN107498365B (en) | 2017-09-30 | 2017-09-30 | Double-nut precise ball screw pair |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107498365A CN107498365A (en) | 2017-12-22 |
| CN107498365B true CN107498365B (en) | 2024-03-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710912666.8A Active CN107498365B (en) | 2017-09-30 | 2017-09-30 | Double-nut precise ball screw pair |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109262339B (en) * | 2018-12-10 | 2023-06-23 | 北京博鲁斯潘精密机床有限公司 | Radial floating compression structure of ball screw pair nut |
| CN112510369B (en) * | 2020-11-24 | 2023-05-09 | 武汉滨湖电子有限责任公司 | Antenna every single move transmission with early warning protection |
| CN112756655A (en) * | 2020-12-30 | 2021-05-07 | 遵义金惠机械制造有限责任公司 | Brake drum special clamp capable of improving product yield and using method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3498153A (en) * | 1967-02-10 | 1970-03-03 | Zahnradfabrik Friedrichshafen | Steering gear with rotary ball nut |
| CN201055955Y (en) * | 2006-09-20 | 2008-05-07 | 南通西马特机器制造有限公司 | Long stroke numerically controlled drilling machine feed gear of drill miller |
| CN101698284A (en) * | 2009-10-27 | 2010-04-28 | 李慎旺 | Device for automatically eliminating clearances of screw drive pair |
| CN202877995U (en) * | 2012-09-14 | 2013-04-17 | 山东大学 | Double nut driven type ball screw assembly feeding mechanism |
| CN105090412A (en) * | 2015-07-06 | 2015-11-25 | 广东技术师范学院 | Automatic pre-tightening device for ball screws |
| CN207710405U (en) * | 2017-09-30 | 2018-08-10 | 宇环数控机床股份有限公司 | A kind of double nut precise ball screw pair |
-
2017
- 2017-09-30 CN CN201710912666.8A patent/CN107498365B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3498153A (en) * | 1967-02-10 | 1970-03-03 | Zahnradfabrik Friedrichshafen | Steering gear with rotary ball nut |
| CN201055955Y (en) * | 2006-09-20 | 2008-05-07 | 南通西马特机器制造有限公司 | Long stroke numerically controlled drilling machine feed gear of drill miller |
| CN101698284A (en) * | 2009-10-27 | 2010-04-28 | 李慎旺 | Device for automatically eliminating clearances of screw drive pair |
| CN202877995U (en) * | 2012-09-14 | 2013-04-17 | 山东大学 | Double nut driven type ball screw assembly feeding mechanism |
| CN105090412A (en) * | 2015-07-06 | 2015-11-25 | 广东技术师范学院 | Automatic pre-tightening device for ball screws |
| CN207710405U (en) * | 2017-09-30 | 2018-08-10 | 宇环数控机床股份有限公司 | A kind of double nut precise ball screw pair |
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| CN107498365A (en) | 2017-12-22 |
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