Matched nut of ball screw

Abstract

The nut of the ball screw is spiral and axially elastic, the screw pitches of the nut and the screw can be inconsistent, the axial elastic deformation force of the assembled nut serves as the pretightening force for pressing a roller, and the pretightening force of the roller on each section of screw pitch is consistent. The roller and the lead screw nut are in uniform contact, accelerated abrasion caused by uneven contact of the roller is relieved, and meanwhile, abrasion of the lead screw nut and the roller is automatically compensated, especially when abrasion of all sections of the lead screw is uneven. And meanwhile, the device has the characteristics of easiness in manufacturing, stable performance and long service life.

Description

Technical Field

[0001] The present invention relates to the field of ball screws, and particularly to a matching nut for a ball screw. Background Art

[0002] Ball screws have a low friction coefficient and are widely used. However, their inherent problem has always been backlash, which needs to be adjusted manually. When applied to numerical control machine tools, the numerical control system will have backlash compensation. After the screw is worn after a period of use, and when the friction on each section of a screw is uneven, the adjustment and system compensation methods fail, and a new screw needs to be replaced. At the same time, due to the error between the screw pitch and the nut pitch, the screw and nut raceways do not contact all the rollers, resulting in few contact points and stress concentration, which will accelerate damage. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a matching nut for a ball screw, which can effectively solve the deficiencies in the prior art.

[0004] The present invention is realized through the following technical solutions: A matching nut for a ball screw, the nut is spiral, axially elastic, and can deform with the screw. The nut has two sets of helical surfaces or helical lines that contact the rollers.

[0005] As a preferred technical solution, when the spiral nut is a concave circular arc that fits evenly with the rollers at the positions where it contacts the rollers on both sides, the two sets of helical surfaces in contact with the rollers are helical surfaces with an arc-shaped cross-section, and the rollers contact the generatrix of the helical surface of the spiral nut.

[0006] As a preferred technical solution, when the spiral nut is a tangent straight line at the positions where it contacts the rollers on both sides, the two sets of helical lines in contact with the rollers are helical lines, and the rollers contact the spiral lines of the spiral nut at a point.

[0007] As a preferred technical solution, the radial position of the rollers in the screw assembly is the center distance D between the two rollers. When the two rollers on both sides of the cross-section of the spiral nut are in contact with the spiral nut when their diameters are D, the axial center distance between the two rollers is t_contact, the pitch of the spiral nut is t_nut, and the pitch of the screw is t_screw. t_contact < t_screw. When t_nut > t_screw, the total compression value is n(t_nut - t_screw) - (t_screw - t_contact), and the outward axial pressure received by each of the two rollers on both sides is F = K(n(t_nut - t_screw) - (t_screw - t_contact)), t_screw > t_contact, and n is the number of elastic deformation turns of the spiral nut.

[0008] As a preferred technical solution, the radial position of the rollers in the screw rod assembly is the center distance D between the two rollers. When the two rollers on both sides of the cross-section of the screw nut are in contact with the screw nut at a diameter of D, the axial center distance between the two rollers is t_contact. The pitch of the screw nut is t_nut, and the pitch of the screw rod is t_screw. t_contact < t_screw. When t_nut is less than t_screw, the total elongation value is n(t_screw - t_nut) - (t_screw - t_contact). The total inward axial pressure on each of the two rollers is F = K(n(t_nut - t_screw) - (t_screw - t_contact)), t_screw > t_contact, and n is the number of elastic deformation turns of the screw nut.

[0009] As a preferred technical solution, the screw nut of the double-row roller ball screw only contacts one side of the rollers and presses the rollers against the screw rod.

[0010] As a preferred technical solution, the screw nut has a connecting portion for driving a moving part.

[0011] As a preferred technical solution, the connecting portion is a flange fixed or welded to the screw nut with screws.

[0012] As a preferred technical solution: the connecting part is a connecting convex block protruding from the outer circle of the screw nut.

[0013] The beneficial effects of the present invention are as follows: A matching nut for a ball screw, the roller screw nut is spiral, and at the same time, it has axial elasticity and can be set to have inconsistent pitches with the screw rod. After assembly, the axial elastic deformation force of the nut serves as the pre-tightening force for pressing the rollers, and the pre-tightening force of the rollers on each pitch is the same, making the contact between the rollers and the screw nut uniform, reducing the accelerated wear caused by uneven roller contact, and at the same time automatically compensating for the wear of the screw nut and the rollers. Especially when the wear of each section of the screw rod is uneven, it is easy to manufacture, has stable performance, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 It is a schematic diagram of the circular cross-section of the screw nut of the present invention;

[0016] Figure 2 It is a schematic diagram of the circular cross-section of the present invention;

[0017] Figure 3 It is a two-sided concave circular cross-section of the present invention;

[0018] Figure 4 The cross-section of the two sloping sides of the present invention;

[0019] Figure 5 The cross-section of the two parallel sides of the present invention;

[0020] Figure 6 The schematic diagram of the lead of the screw rod of the present invention;

[0021] Figure 7 The schematic diagram of the lead when the spiral nut of the present invention is in the relaxed state;

[0022] Figure 8 The schematic diagram of the assembly cross-section of the t-nut larger than the t-screw rod of the present invention;

[0023] Figure 9 The schematic diagram of the assembly cross-section of the t-nut smaller than the t-screw rod of the present invention;

[0024] Figure 10 The schematic diagram of the spiral spring with double-row rollers and ball screw in circular cross-section of the present invention;

[0025] Figure 11 The schematic diagram of the two parallel sides of the spiral spring with double-row rollers and ball screw in circular cross-section of the present invention;

[0026] Figure 12 The schematic diagram of the double concave circular cross-section of the spiral spring with double-row rollers and ball screw with double concave circles on both sides of the present invention;

[0027] Figure 13 The schematic diagram of the flange welding of the present invention;

[0028] Figure 14 The schematic diagram of the flange screw connection of the present invention;

[0029] Figure 15 The schematic diagram of the ordinary nut of the present invention;

[0030] Figure 16 The schematic diagram of the ordinary nut of the present invention after removing a part to form a spiral nut part;

[0031] Figure 17 The schematic diagram of the ordinary nut of the present invention after removing the spiral groove part to form a spiral nut;

[0032] Figure 18 The schematic diagram of the ordinary nut of the present invention after removing the outer circle to form a spiral nut;

[0033] Figure 19 The axial schematic diagram of the through nut of the present invention after removing the outer circle to form a spiral nut;

[0034] Figure 20 The schematic diagram of adding a driving lug to the end face of the spiral-formed spiral nut of the present invention; Description of the drawings:

[0036] 1. Lead screw; 102. Open type double row ball screw with groove; 103. Flat open double row ball screw; 2. Roller; 3. Spiral nut; 301. Spiral nut with circular cross-section; 302. Spiral nut with concave circular cross-section on both sides; 303. Spiral nut with bevel on both sides; 304. Spiral nut with parallel sides on both sides; 3021. t of nut is greater than t of lead screw; 3022. t of nut is less than t of lead screw; 3031. Double row roller spiral nut with double-sided concave circular cross-section; 3032. Double row roller spiral nut with double-sided circular cross-section; 3033. Double row roller spiral nut with double-sided parallel cross-section on both sides; 4. Flange; 5. Welding joint; 6. Screw; 7. Ordinary nut; 8. Removed part of outer circle; 9. Removed part of spiral groove; 10. Connecting convex block for driving Detailed implementation mode

[0037] All features disclosed in this specification, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way

[0038] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless specifically stated, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically stated, each feature is only an example in a series of equivalent or similar features

[0039] Embodiment 1

[0040] As Figure 3 、 Figures 6 - 8 shown Figure 3 As shown, the spiral nut 302 with concave circular cross-section on both sides has a concave circular nut cross-section on both sides, and the two concave circular arcs form two space spiral surfaces with circular cross-sections. The roller is in line contact with this space spiral surface. When the diameter of the roller 2 is D, the axial center distance between the two rollers against the nut is t against Figure 6 It is a schematic diagram of the lead screw pitch Figure 7 It is a schematic diagram of the spiral nut pitch Figure 8 It is a schematic diagram of the assembly cross-section where t of nut is greater than t of lead screw Figure 8 When t of nut is greater than t of lead screw 3021 and it is a concave circular arc cross-section on both sides, the pitch is greater than that of the lead screw. When t of nut is greater than t of lead screw 3021, the spiral nut is compressed in the length direction, causing the concave circular arcs at both ends of the nut to press the corresponding rollers outward against the lead screw Figure 8The middle roller 2 is in the raceway groove of the lead screw 1. The helical elastic nut is larger than the lead screw. Since the nut is larger than the lead screw, the nut is axially compressed. The total compression value is n(t_nut - t_lead screw) - (t_lead screw - t_contact). The outward axial pressures received by the rollers on both sides are F = K(n(t_nut - t_lead screw) - (t_lead screw - t_contact)), where t_lead screw > t_contact, and n is the number of elastic deformation turns of the helical nut. The manufacturing of the helical nut is described in Embodiment 7 and Embodiment 8.

[0041] Embodiment 2

[0042] Different from Embodiment 1, the pitch t_nut of the helical nut is smaller than the pitch t_lead screw of the lead screw. The assembly schematic diagram is as Figure 9 shown. Figure 9 In [reference] where t_nut < t_lead screw, 3022 represents the helical nut with t_nut < t_lead screw. Since the nut of each pitch is lengthened, the circular groove of the helical nut presses the roller 2 inward and presses the roller 2 against one side of the lead screw groove. Figure 3 In [reference], t_contact < t_lead screw. The total elongation value is n(t_lead screw - t_nut) - (t_lead screw - t_contact). The total inward axial pressures received by the rollers on both sides are F = K(n(t_nut - t_lead screw) - (t_lead screw - t_contact)), where t_lead screw > t_contact, and n is the number of elastic deformation turns of the helical nut.

[0043] Embodiment 3

[0044] Different from the above embodiments, helical nuts with different cross-sections are used, such as Figure 2 , Figure 4 , Figure 5 shown. The circular cross-section helical nut 301, the two-sided bevel helical nut 303, and the two-sided parallel helical nut 304 with two parallel sides on both sides in the above embodiments are used to replace the helical nut with circular grooves on both sides. Because the structure is simpler, the contact position between the helical nut and the roller is spiral, and the contact position with the roller is a point on the spiral line, which can reduce costs.

[0045] Embodiment 4

[0046] Different from the above embodiments, as Figure 10 shown, there are two rows of rollers 2 on both sides of the spiral groove of the flat open double-row ball lead screw 103. The double-sided circular cross-section 3032 of the double-row roller helical nut presses on one row of rollers 2 on both sides respectively.

[0047] Embodiment 5

[0048] Different from the above embodiments, as Figure 11 shown, the double-sided two-parallel cross-section 3033 of the double-row roller helical nut is used to replace the double-sided circular cross-section 3032 of the double-row roller helical nut.

[0049] Embodiment 6

[0050] Different from Embodiment 4, as Figure 12 shown, on both sides of the spiral groove of the open type grooved double row ball screw 102, the two rows of rollers 2 are respectively in contact with the grooves on both sides. On both sides of the double row roller spiral nut double-sided concave circular section 3031, there are circular grooves respectively. Under the action of the variable pitch elastic force, both ends of the double row roller spiral nut double-sided concave circular section 3031 respectively press on one of the rollers 2 on both sides, pressing the roller 2, the spiral spring double row roller spiral nut double-sided concave circular section 3031 and the groove of the open type grooved double row ball screw 102 tightly, forming backlash elimination. And because the contact line between the roller 2 and the screw groove (spiral nut groove) is long and the axial force is in the middle of the contact line, the rigidity is very good.

[0051] Embodiment 7

[0052] Different from the above embodiments, the manufacturing process of the spiral nut is introduced. First step, a common nut 7 is processed with spring steel, as Figure 15 shown. Second step, the outer circle cutting part 8 (the blackened part in the figure) is removed, and the remaining spiral nut 3 is obtained, as Figure 16 shown. Then, the flange 4 is installed and welded on the nut or fixed on the nut with screws 6, as Figures 13 - 14 shown. Or a spiral groove is cut off, such as the spiral groove cutting part 9 (the blackened part in the figure) in Figure 17 shown, and the remaining spiral nut 3 is obtained.

[0053] Embodiment 8

[0054] Different from Embodiment 7, Figure 2 the spiral nut with a circular cross-section, Figure 3 the spiral nut with a double-sided concave circular cross-section, Figure 4 the spiral nut with double-sided bevel edges, Figure 5 the spiral nut with double-sided parallel edges, etc., various cross-section spiral nuts are drawn out with a wire drawing die to the corresponding shapes, and then a spring with a pitch of t for the nut is wound on a spring coiling machine. When the spring diameter meets the requirement of t being abutted at the position D in the diameter direction of the center distance between the two rollers on both sides in the figure, after forming, heat treatment is carried out, and then the flange welding part 5 or screws 6 are fixed on the spiral nut 3.

[0055] Embodiment 9

[0056] Different from the above embodiments, as Figure 18 and Figure 19 shown, first a common nut with a pitch of t for the nut is processed, and then the outer circle cutting part 8 is removed to leave the driving connection convex block 10, Figure 18 which is a cross-sectional view, Figure 19 and

[0057] is an axial view.

[0058] Different from the above embodiments, as Figure 20 shown, the spiral nut 3 is directly wound by a spring winding machine and a driving connection block 10 is bent at one end, and the driving connection block 10 is used for driving.

[0059] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any change or replacement that can be thought of without creative work should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims

1. A matching nut for a ball screw, characterized in that: The nut is spiral and axially elastic, capable of deforming with the lead screw. There are two sets of helical surfaces or helical lines inside the nut that contact the rollers. When the concave arc that matches the rollers is at the contact positions of the helical nut with the two side rollers, the surfaces in contact with the rollers are two sets of helical surfaces with an arc-shaped cross-section, and the rollers are in line contact with the helical surfaces of the helical nut.

2. The mating nut of the ball screw according to claim 1, characterized in that: When the contact positions of the helical nut with the two side rollers are tangent lines, the surfaces in contact with the rollers are two sets of helical lines, and the rollers are in point contact with the helical lines of the helical nut.

3. The mating nut of the ball screw according to claim 1, characterized in that: The radial position of the rollers in the lead screw assembly is the center distance D between the two rollers. When the two side rollers on the cross-section of the helical nut are in contact with the helical nut at a diameter D, the axial center distance between the two rollers is t_contact when they are in contact. The pitch of the helical nut is t_nut, the pitch of the lead screw is t_screw, and t_contact < t_screw. When t_nut > t_screw, the total compression value is n(t_nut - t_screw) - (t_screw - t_contact), and the outward axial pressure on each of the two side rollers is F = K(n(t_nut - t_screw) - (t_screw - t_contact)), where t_screw > t_contact and n is the number of elastic deformation turns of the helical nut.

4. The mating nut of the ball screw according to claim 1, characterized in that: The radial position of the rollers in the lead screw assembly is the center distance D between the two rollers. When the two side rollers on the cross-section of the helical nut are in contact with the helical nut at a diameter D, the axial center distance between the two rollers is t_contact when they are in contact. The pitch of the helical nut is t_nut, the pitch of the lead screw is t_screw, and t_contact < t_screw. When t_nut < t_screw, the total elongation value is n(t_screw - t_nut) - (t_screw - t_contact), and the inward axial total pressure on each of the two side rollers is F = K(n(t_nut - t_screw) - (t_screw - t_contact)), where t_screw > t_contact and n is the number of elastic deformation turns of the helical nut.

5. The mating nut of the ball screw according to claim 1, characterized in that: The helical nut of the double-row roller ball screw only contacts one side roller and presses the roller against the lead screw.

6. The mating nut of the ball screw according to claim 1, characterized in that: There is a connecting part on the helical nut for driving the moving part.

7. The mating nut of the ball screw according to claim 6, characterized in that: The connecting part is a flange fixed or welded to the helical nut with screws.

8. The mating nut of the ball screw according to claim 6, characterized in that: The connecting part is a connecting convex block protruding from the outer circle of the helical nut at the connecting position.

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