CN111219405A

CN111219405A - Lock nut assembly and method of assembling a lock nut assembly

Info

Publication number: CN111219405A
Application number: CN201811403742.3A
Authority: CN
Inventors: 戴兵; 马求山; 夏曙华
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2018-11-23
Filing date: 2018-11-23
Publication date: 2020-06-02

Abstract

The invention relates to a lock nut assembly for a rotating shaft (6) and a method of assembling a lock nut assembly, the lock nut assembly having an axis of rotation, wherein the centre of mass of the lock nut assembly is on the axis of rotation and the lock nut assembly comprises two lock nuts (1, 2) abutting against each other, wherein the centre of mass of the lock nuts (1, 2) is offset from the axis of rotation and the position of the centre of mass is such that when the lock nuts (1, 2) rotate with the rotating shaft (6), the centrifugal force of the lock nuts (1, 2) generates a moment capable of pressing the lock nuts (1, 2) against the rotating shaft (6).

Description

Lock nut assembly and method of assembling a lock nut assembly

Technical Field

The present invention relates to a lock nut assembly, and more particularly, to a lock nut assembly for a spindle bearing. The invention relates to a method for assembling a cage nut assembly.

Background

The lock nut can be used for positioning and fixing a fixed member such as a bearing attached to a shaft, and has a lock mechanism so that loosening does not occur even if a gap is generated between the lock nut and a fastening surface due to vibration or impact.

In the prior art, the nut is prevented from loosening by various measures. For example, two identical nuts are screwed onto the same bolt, with an additional tightening torque between the two nuts, so that the bolt is securely connected. Alternatively, a locknut can be used in conjunction with the lockwasher. Another solution is to make the lock nut of two parts, for example, in patent document US 6,609,867B 2, which teaches a lock nut in which each part has alternating cams, and since the internal wedge design has a slope with an angle greater than the nut angle of the bolt, the combination is tightly engaged as a whole, and when vibrations occur, the convex parts of the lock nut are dislocated with each other, creating a lifting tension, and thus achieving the anti-loosening effect. However, the three lock nuts are less suitable for use with shafts rotating at high speeds and may damage the external threads of the shaft due to their locking mechanism.

There is also a measure in which a through threaded hole is bored from the outer peripheral surface to the inner peripheral thread surface of the nut for screwing in a countersunk screw of a small diameter in order to apply a force in a centripetal direction to the thread to prevent loosening of the locknut which can be used for locking shaft ends of rotary motion type parts, particularly shaft ends of high-precision bearings such as ball screw mounting end bearings. However, especially when the lock nut is mounted on the spindle, the lock torque of the lock nut provides an axial force to the spindle bearing to maintain a proper play of the spindle bearing, but the lock nut is often loosened by centrifugal force after a period of operation, resulting in a failure of the spindle bearing, which may cause serious damage to the spindle system. Such failures occur frequently and the time cost and economic cost required for maintenance are high.

Disclosure of Invention

Therefore, the technical problem to be solved by the present invention is to provide a locknut with anti-loosening effect, which is easy to install and can be used for rotating shafts rotating at high speed, especially for main shafts equipped with high precision bearings.

The technical problem is solved by a lock nut assembly for a rotating shaft, having a rotation axis, wherein the center of mass of the lock nut assembly is on the rotation axis and the lock nut assembly comprises two lock nuts abutting against each other, wherein the center of mass of each lock nut is offset from the rotation axis and the position of the center of mass is such that when the lock nuts rotate with the rotating shaft, the centrifugal force of the lock nuts generates a moment capable of pressing the lock nuts against the rotating shaft.

It is within the scope of the present invention for the rotating shaft and the jam nut assembly fitted on the rotating shaft to have a common axis of rotation. That is, the two lock nuts have a common rotation axis, and the two lock nuts have concentric through holes in which internal threads are provided to match the external threads of the rotation shaft. Since the center of mass of the lock nut is radially offset from the rotational axis of the lock nut assembly, the lock nut is subjected to centrifugal forces as it rotates with the rotational axis. By reasonably setting the axial position of the center of mass of the lock nut, the centrifugal force can be made to generate a moment that can press the lock nut against the rotating shaft. On the whole, due to the generation of such moment, the internal thread of the lock nut is more closely matched with the tooth surface of the external thread of the rotating shaft, thereby realizing a good locking effect.

In one possible embodiment of the union nut, the union nut is of homogeneous material and is rotationally asymmetrical in shape, i.e. the union nut is not of solid-of-revolution construction, so that the centre of mass of the union nut is not located on the axis of rotation of the union nut. In this case, the lock nut is cut by a plane composed of the center of mass and the rotation axis, and the planar shape of the lock nut in the cut section is non-axisymmetric, so that the centrifugal force can generate a moment to press the lock nut against the rotation axis. In the case of a non-homogeneous structure of the locking nut, the structure of the locking nut can be designed reasonably by calculation so that its centre of mass is not on its axis of rotation and centrifugal forces can generate a moment that presses the locking nut against the axis of rotation.

In addition, through setting up two lock nuts and leaning on each other and make lock nut assembly's barycenter design on the rotation axis through two lock nut's of rational arrangement relative position, lock nut assembly's resultant moment is zero from this, consequently even when lock nut assembly rotates along with the rotation axis at a high speed, lock nut assembly also can keep rotational balance. In addition, since the higher the rotation speed of the rotary shaft, the greater the centrifugal force of the locknut, and the greater the moment, the faster the rotation, the better the locking effect of the locknut. Therefore, the lock nut can be used in the spindle bearing widely used in the high-speed rotation field, particularly in the machine tool industry, the motor manufacturing industry and new energy automobiles.

In a preferred embodiment, the mass of the two lock nuts is equal and the centrifugal forces of the two lock nuts generate the same amount of torque as the lock nut assembly rotates with the rotating shaft. Thereby each part of the locking nut component can realize stable matching. In this case, for example, two homogeneous and identically shaped union nuts can be used, which both have a rotationally asymmetrical design. The two union nuts are arranged such that they lie axially against one another on the rotational axis and the respective center of mass lies opposite the rotational axis of the union nut assembly, so that the overall center of mass of the union nut assembly lies on the rotational axis of the union nut assembly, that is to say forms a rotationally symmetrical shape of the union nut assembly.

In another preferred embodiment, the axial end face of the cage nut assembly is perpendicular to the axis of rotation. So that the axial end face can be used as a force acting surface for providing the bearing with an axial force that maintains the bearing play. The cage nut assembly according to the invention can therefore be used in particular with a spindle bearing.

In this case, it is advantageous to provide the union nut assembly with rotational symmetry, and to provide that the two union nuts bear completely against one another, and that the bearing surfaces of the two union nuts are not perpendicular to the axis of rotation. That is to say, the contact surfaces of the two nut halves extend in a plane which is inclined relative to the central axis of the union nut. This makes it possible to achieve a rotationally symmetrical and offset center of mass construction of the union nut in the simplest possible manner and facilitates manufacture.

Preferably, the abutment surface of the union nut can be a smooth flat surface. For example, the abutment surfaces of both lock nuts can be ground so that the two lock nuts can abut closely and do not move relative to each other, thereby affecting the rotational balance of the lock nut assembly.

Alternatively, the contact surface can also be designed as a wave, or a tooth-shaped projection and a recess can be provided on the contact surface.

In another preferred embodiment, the locking nuts have a structure for mutual positioning and connection. Wherein the connection structure should be detachable.

Advantageously, the lock nut has an axially extending positioning hole and a connecting member, the lock nut assembly further comprising a connecting member inserted in the positioning hole and a connecting member tightened in the coupling hole. For example, a correspondingly provided positioning bore for receiving a positioning pin can be provided on an axial end face of the union nut, the two union nuts being positioned relative to one another, in particular in the radial direction, by the positioning pin, so that the relative position of the two union nuts can be reliably ensured. Alternatively, the relative position of the individual union nuts can also be determined by means of an external tool. Furthermore, corresponding threaded bores are provided on the axial end faces of the two union nuts. The bolt of the lock nut assembly penetrates through the threaded hole of one lock nut and extends towards the other lock nut. After the lock nut assembly is assembled to the rotating shaft, the bolt is removed. Alternatively, the individual union nuts can also be positioned and/or connected by means of an external tool and removed after the assembly has been completed.

In another preferred embodiment, the outer peripheral surface of the cage nut assembly has a groove. Thereby facilitating threading of the cage nut assembly onto the external threads of the rotating shaft.

In another preferred embodiment, the internal thread of the lock nut assembly for screwing to the rotary shaft is continuous. Therefore, the locknut can be accurately screwed on the rotating shaft, and the locking nut can be particularly used for a high-precision bearing. For example, the internal thread can be produced in a step after the fixed connection of the respective locking nut.

The above technical problem is also solved by a method for assembling the above-mentioned cage nut assembly, wherein the following steps are carried out in sequence:

aligning the positioning holes of the two locking nuts and inserting the positioning element into the positioning holes;

-screwing the connecting piece into the connecting holes of the two locking nuts;

-screwing the lock nut assembly as a whole to a given position on the rotating shaft; and

-removing the positioning element and the connecting element.

Drawings

Preferred embodiments of the present invention are schematically illustrated in the following with reference to the accompanying drawings. The attached drawings are as follows:

figure 1 is a side view of a cage nut assembly according to a preferred embodiment of the present invention,

figure 2 is a side view of the cage nut assembly according to figure 1 from another angle,

FIG. 3 is a cross-sectional view of the cage nut assembly according to FIG. 1, an

Figure 4 is a schematic view of the cage nut assembly according to figure 1 under stress during operation.

Detailed Description

FIG. 1 shows a side view of a cage nut assembly according to a preferred embodiment of the present invention. The lock nut assembly comprises two lock nuts, namely a first lock nut 1 and a second lock nut 2, which are attached to each other along the axial direction. The first locking nut 1 and the second locking nut 2 together form a substantially circular locking nut assembly. As shown in fig. 1, the first lock nut 1 and the second lock nut 2 have the same shape and are both of a non-rotationally symmetrical structure. The first and

second lock nuts

1 and 2 have coaxial and equal diameter central bores with internal threads (not shown) disposed within each central bore, the central through bore internal threads of the lock nut assembly being uniform and continuous. The axial end face of the second lock nut 2 can be clearly seen in fig. 1. Fig. 2 shows a side view of the union nut according to fig. 1 from another angle, i.e. the axial end face of the first union nut 1. Fig. 3 shows a sectional view of the union nut according to fig. 1, taken along the axis of rotation of the union nut assembly. With reference to fig. 1, 2 and 3, it can be seen that the first and

second lock nuts

1 and 2 are both non-rotationally symmetrical structures, with the opposite arrangement being such that the lock nut assembly is a substantially rotationally symmetrical structure. The abutment surfaces of the first and

second lock nuts

1, 2 extend in a plane inclined to the axis of rotation of the lock nut assembly and are shown as being perpendicular to the plane of the paper. The two

union nuts

1, 2 each have opposite axially extending positioning holes for receiving positioning pins 4 as positioning elements. At the same time, the two

union nuts

1, 2 each have oppositely disposed, axially extending threaded bores for receiving a screw 3 as a connecting element. As shown in fig. 1 and 2, the circumferential positions of the threaded holes and the positioning holes are determined such that the threaded holes and the positioning holes are uniformly distributed in the circumferential direction of the lock nut, and a pair of the threaded holes or a pair of the positioning holes are arranged at positions where the axial dimension of the lock nut is the largest and smallest, thereby ensuring the rotational balance of the lock nut assembly. Furthermore, the outer circumferential surface of the

lock nut

1, 2 is provided with a groove 5 which facilitates the clamping of the lock nut assembly by the clamp during assembly.

In the process of manufacturing and assembling the lock nut assembly, the

respective lock nuts

1, 2 having only a central hole are first positioned with respect to each other by means of the positioning pin 4, then the two

lock nuts

1, 2 are connected by means of the bolt 3, then the central hole of the lock nut assembly is tapped in one process, then the lock nut assembly is screwed onto the rotary shaft 6, and finally the positioning pin 4 and the bolt 3 are removed.

Fig. 4 shows a schematic view of the stress situation of two lock nuts of the above-described preferred embodiment lock nut. The figures show a cross section through the lock nut assembly along a plane consisting of the centre of mass of the first lock nut 1, the centre of mass of the second lock nut 2 and the axis of rotation of the lock nut assembly. As shown, the lock nut assembly is tightened on the rotating shaft 6 and rotates with the rotating shaft 6 at a high speed, in which case the first lock nut 1 is subjected to a centrifugal force F₁And in which section the first lock nut 1 is under centrifugal force F₁And arm of force L₁Produce bending moment T under the action of₁. Bending moment T₁The first lock nut 1 is pressed against the rotating shaft 6. In the same way, the second lock nut 2 is subjected to a centrifugal force F₂And in cross section the second lock nut 2 is under centrifugal force F₂And arm of force L₂Produce bending moment T under the action of₂. Bending moment T₂The second lock nut 2 is pressed against the rotary shaft 6. Since the first and

second lock nuts

1, 2 are identically designed, the respective centrifugal forces F₁，F₂The same size and opposite direction, the force armsL₁，L₂Equal in length, and therefore, a bending moment T is generated₁And T₂The sizes are the same and act in the same direction. Thereby, the locknut assembly is rotationally balanced by the first and

second locknuts

1, 2 abutting against each other and is reliably pressed against the rotary shaft 6. Centrifugal force F₁，F₂The larger the bending moment T is₁And T₂The larger this facilitates clamping of the cage nut assembly to the rotating shaft.

Although possible embodiments have been described by way of example in the above description, it should be understood that numerous embodiment variations exist, still by way of combination of all technical features and embodiments that are known and that are obvious to a person skilled in the art. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. From the foregoing description, one of ordinary skill in the art will more particularly provide a technical guide to convert at least one exemplary embodiment, wherein various changes may be made, particularly in matters of function and structure of the components described, without departing from the scope of the following claims.

List of reference numerals

1 first locknut

2 second lock nut

3 bolt

4 positioning pin

5 groove

6 rotating shaft

Claims

1. A lock nut assembly for a rotating shaft (6), the lock nut assembly having an axis of rotation, characterized in that the centre of mass of the lock nut assembly is on the axis of rotation and that the lock nut assembly comprises two lock nuts (1, 2) abutting against each other, wherein the centre of mass of the lock nuts (1, 2) is offset from the axis of rotation and the position of the centre of mass is such that when the lock nuts (1, 2) rotate with the rotating shaft (6), the centrifugal force of the lock nuts (1, 2) generates a moment capable of pressing the lock nuts (1, 2) against the rotating shaft (6).

2. Lock nut assembly according to claim 1, characterized in that the mass of both lock nuts (1, 2) is equal and that the centrifugal forces of the two lock nuts (1, 2) generate a moment of the same magnitude when the lock nut assembly is rotated with the rotating shaft (6).

3. The lock nut assembly of claim 1 wherein an axial end face of the lock nut assembly is perpendicular to the axis of rotation.

4. The lock nut assembly according to claim 3, characterized in that it is rotationally symmetrical and that the two lock nuts (1, 2) bear completely against each other and that the bearing surfaces of the two lock nuts (1, 2) are not perpendicular to the axis of rotation.

5. The cage nut assembly of claim 4 wherein the abutment surface is planar.

6. Lock nut assembly according to claim 1, characterized in that the lock nuts (1, 2) have structures for mutual positioning and mutual connection.

7. The lock nut assembly according to claim 6, characterized in that the lock nut (1, 2) has an axially extending positioning hole and a coupling hole, and that the lock nut assembly further comprises a positioning element (4) inserted in the positioning hole and a coupling element (3) screwed in the coupling hole.

8. The cage nut assembly of claim 1 wherein the outer peripheral surface of the cage nut assembly has a groove (5).

9. The lock nut assembly according to claim 1, characterized in that the internal thread of the lock nut assembly for screwing to the rotary shaft (6) is continuous.

10. A method for assembling the cage nut assembly of claim 7, characterized by the sequential steps of:

-aligning the positioning holes of the two locking nuts (1, 2), inserting the positioning element (4) therein;

-screwing the connecting piece (3) into the connecting holes of the two lock nuts (1, 2);

-screwing the lock nut assembly as a whole to a given position on the rotating shaft (6); and

-removing the positioning element (4) and the connecting element (3).