CN113586590B

CN113586590B - High-locking crack-preventing mandrel and closing method thereof

Info

Publication number: CN113586590B
Application number: CN202110881835.2A
Authority: CN
Inventors: 郭双双; 魏亮亮; 刘玉生; 齐增星; 单垄垄
Original assignee: Aerospace Precision Products Co Ltd
Current assignee: Aerospace Precision Products Co Ltd
Priority date: 2021-08-02
Filing date: 2021-08-02
Publication date: 2023-04-25
Anticipated expiration: 2041-08-02
Also published as: WO2023010770A1; CN113586590A

Abstract

The invention provides a high-locking crack-preventing mandrel and a closing method thereof, which comprises the following steps: s1: penetrating a mandrel into the nut, wherein the penetrating position of the mandrel comprises a position to be closed on the nut; s2: and (3) closing the nut by using a closing die, extruding the internal thread at the closing position of the nut by the closing die and the mandrel, and controlling the shape of the thread teeth of the internal thread. The mandrel with high locking and crack prevention functions and the closing method thereof can be carried out at normal temperature, can generate higher locking moment and can prevent cracks.

Description

High-locking crack-preventing mandrel and closing method thereof

Technical Field

The invention belongs to the technical field of fastener manufacturing, and particularly relates to a high-locking crack-preventing mandrel and a closing method thereof.

Background

The all-metal self-locking nut is a nut with a self-locking effect, and has a huge application range and application amount. The locking structure of the nut is of various kinds and can be divided into a mechanically fixed locking structure and a locking structure for increasing friction force according to the working principle, wherein the locking structure for increasing friction force can be divided into an effective moment type locking structure and a free rotation type locking structure according to the locking principle. The effective torque refers to the rotational torque measured by the threaded connection pair when the nut is smoothly rotated without bearing an axial load. The moment has the locking function of resisting relative rotation between the threaded connection pairs. The locking performance of such nuts is not entirely dependent on the pretension of the threaded connection pair. Such as: and (5) self-locking the nut. The effective torque type self-locking nut can be divided into an all-metal self-locking nut and a non-metal insert self-locking nut. The working principle of the all-metal self-locking nut is as follows: the locking structure of the self-locking nut is subjected to compression deformation, and when the screw thread at the locking part of the self-locking nut is screwed with the bolt, the self-locking nut is extruded by the screw thread of the bolt to restore the original state, so that the nut generates elastic deformation and elastic deformation force, and friction moment for preventing rotation, namely the locking moment of the self-locking nut, is generated due to the interference action of the elastic deformation force on the screw thread of the bolt.

Generally, in order to generate higher locking torque, a larger amount of necking deformation is required, but as the amount of necking deformation increases, the risk of cracking on the internal thread increases. The internal thread is guaranteed to have no crack when enough locking moment is guaranteed, and the difficulty is very high. A common modification is to heat the neck-in, by heating the nut to increase the plasticity, thus reducing the risk of cracking. But the heating brings a series of difficulties such as heating mode, heating transfer, temperature control, heating influence of nut materials, heating influence of nut surfaces, thermal expansion and contraction dimensional change of the closing die, heating service life of the closing die, heating protection and the like.

Disclosure of Invention

Therefore, the invention aims to provide a high-locking crack-preventing mandrel and a necking method thereof, and the method is carried out at normal temperature, can generate higher locking moment and can prevent cracks.

In order to achieve the above purpose, the technical scheme of the invention is realized as follows:

the utility model provides a dabber for nut binding off is equipped with the external screw thread on the outer wall of dabber, the tooth angle, pitch diameter, path and the pitch of external screw thread are equal to the tooth angle, pitch diameter, path and the pitch of the external screw thread of the bolt that the nut internal screw thread corresponds, the big footpath of external screw thread is less than the big footpath of the external screw thread of the bolt that the nut internal screw thread corresponds.

The large diameter range of the external thread of the mandrel is as follows: d2- (d 1-d 3)/4.ltoreq.d2+ (d 1-d 3)/4;

the large diameter of the external screw thread of the bolt corresponding to the internal screw thread of the nut is d1;

the pitch diameter of the external screw thread of the bolt corresponding to the internal screw thread of the nut is d2;

the minor diameter of the external screw thread of the bolt corresponding to the internal screw thread of the nut is d3;

the major diameter of the external thread of the mandrel is d.

Further, the large diameter part of the internal thread of the mandrel is a plane or a curved surface.

Further, the shaft core is of a fixed solid structure.

Further, the axle core is scalable split structure, the axle core includes fixed axle, screw mandrel inner core, a plurality of screw mandrel multi-lobe shell, screw mandrel inner core sets up in the fixed axle, a plurality of screw mandrel multi-lobe shell sets up the one end at the fixed axle along the circumference, the inside wall of a plurality of screw mandrel multi-lobe shell sets up on the circumference in gap, the external screw thread on the outer wall of dabber is located the outer wall of screw mandrel multi-lobe shell, be equipped with on the fixed axle with the coaxial through-hole in gap, the diameter of through-hole is the diameter of screw mandrel inner core at least, the diameter of gap is less than the diameter of through-hole.

Furthermore, one end of the threaded mandrel inner core is conical, and a reducing transition section is arranged at the joint of the through hole and the gap of the fixed shaft.

Furthermore, the shaft core is made of flexible materials or elastic materials, such as beryllium copper, nickel-titanium alloy, spring steel, rubber, latex and the threaded mandrel multi-piece shell are made of metal materials.

A high locking crack-proof mandrel and a closing method thereof comprise the following steps:

s1: penetrating a mandrel into the nut, wherein the penetrating position of the mandrel comprises a position to be closed on the nut;

s2: and (3) closing the nut by using a closing die, extruding the internal thread at the closing position of the nut by the closing die and the mandrel, and controlling the shape of the thread teeth of the internal thread.

Furthermore, the shaft core is of a fixed solid structure, and the shaft core directly penetrates into and discharges the nut through screw threads in S1 and the process of discharging the mandrel.

Furthermore, the shaft core is of an expandable split structure, the shaft core is directly threaded in the S1 and the shaft core is discharged, the inner core of the threaded shaft is inserted into a gap of the multi-lobe shell of the threaded shaft in the S1, and after the inner core of the threaded shaft is pulled out from the multi-lobe shell of the threaded shaft, the middle diameter and the small diameter of the external thread of the multi-lobe shell of the threaded shaft can be reduced.

Furthermore, the number of the petals of the mandrel multi-petal shell is equal to the number of the necking dies in the step S2, and the necking dies in the step S2 are positioned at the middle positions of the threaded mandrel multi-petal shell, cannot be positioned at the edge positions of the necking dies on the threaded mandrel multi-petal shell and cannot be positioned at gaps between the threaded mandrel multi-petal shells.

Compared with the prior art, the mandrel with high locking and crack prevention and the closing method thereof have the following beneficial effects:

the high-locking crack-preventing mandrel and the closing method thereof can generate larger locking moment with smaller closing deformation at normal temperature, and have no defects such as cracks, and the like.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute an undue limitation on the invention. In the drawings:

FIG. 1 is a schematic illustration of a self-locking nut that has not yet been subjected to a crimping deformation;

FIG. 2 is a schematic view of the closing-in effect obtained by closing-in the nut of FIG. 1 in a conventional manner;

FIG. 3 is a photomicrograph of the internal thread at the neck-in portion of FIG. 2 showing the occurrence of a crack;

FIG. 4 is a schematic illustration of a mandrel of the present invention securing a solid structure;

FIG. 5 is a schematic view of the threads of the mandrel of the present invention after threading into a nut;

FIG. 6 is a schematic view showing the effect of the nut of FIG. 1 after being tightened by the method of the present invention;

FIG. 7 is a photomicrograph of the internal threads of the necked-in region of FIG. 6;

FIG. 8 is a schematic illustration of the core of the collapsible split structure of the present invention in an extracted position;

fig. 9 is a schematic view of the core insertion state of the core shaft of the collapsible split structure of the present invention.

Drawings

1-position one; 2-position two; 3-void; 4-position three; 5-a threaded mandrel multi-lobed housing; 6-slit.

Detailed Description

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

In the description of the invention, it should be understood that the terms "center," "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships that are based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the invention and simplify the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be configured and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. In the description of the invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art in a specific case.

The invention will be described in detail below with reference to the drawings in connection with embodiments.

A high locking crack-proof closing method comprises three steps: step one, penetrating a mandrel into a nut, wherein the penetrating position of the mandrel comprises a position to be closed on the nut; step two, closing the nut by using a closing die, wherein the internal thread of the closing part of the nut is extruded by the closing die and the mandrel, and the form of the thread is controlled to change; and step three, discharging the mandrel. Wherein step three is optionally not performed.

The nut refers to a self-locking nut which is to be subjected to closing deformation but is not subjected to closing deformation yet and comprises an internal thread structure.

The mandrel is a mandrel with special external threads, and can be screwed in and out by freely screwing the special external threads of the mandrel and a nut which is not yet closed. The special external thread is obtained by modifying the external thread of the bolt corresponding to the internal thread of the nut. The tooth angle, pitch diameter, minor diameter and pitch of the special external thread are equal to those of the external thread of the bolt corresponding to the internal thread of the nut. The large diameter of the special external thread is smaller than that of the external thread of the bolt corresponding to the internal thread of the nut and is approximately equal to the medium diameter of the external thread of the bolt corresponding to the internal thread of the nut, and the large diameter of the special external thread can be flat or have certain warpage. The special external thread is designed in such a way that after the mandrel is screwed into the nut, a space with a specific shape and a specific volume is formed between the external thread major diameter of the mandrel and the internal thread major diameter of the nut. The space is used for allowing the deformation of the internal thread subjected to extrusion to flow into the specific space in the second step, so that the shape of the internal thread is changed specifically. After the form of the internal thread at the closing position of the nut is changed into the specific change, the thread pair between the nut and the bolt is changed from integral clearance fit into local interference fit, and enough locking moment can be generated when the closing amount is smaller by the method. In the second step, after the nut is extruded, the deformation space is controlled, and cracks are not easy to generate.

The structure of the threaded portion of the mandrel is divided into two types. The first is a thread for fixing a solid structure, namely, a special external thread is manufactured on a solid cylinder. The threaded mandrel of the first structure directly penetrates into and discharges the nut through threaded screwing in the step one and the step three of closing. The second type is the thread of the collapsible split structure, the split structure thread mainly comprises two parts of structures, namely a threaded mandrel multi-lobe shell and a threaded mandrel inner core, the threaded mandrel inner core is plugged into the threaded mandrel multi-lobe shell, the threaded mandrel multi-lobe shell can expand, the expanded thread pitch diameter and the expanded thread pitch diameter are equal to the pitch diameter and the thread pitch diameter of the external thread corresponding to the internal thread of the nut, and the pitch diameter and the thread pitch diameter of the threaded mandrel multi-lobe shell can be reduced after the threaded mandrel inner core is pulled out from the threaded mandrel multi-lobe shell. In the first and third closing steps, the threaded mandrel with the second structure can obtain more convenience through the expansion and contraction of the medium diameter and the small diameter of the multi-piece shell of the threaded mandrel during the process of screwing in and out the nut. The number of the petals of the multi-petal shell of the threaded mandrel is equal to the number of the necking heads in the second step, and when the second step is performed, the crimping position of the necking head is at the middle position of the multi-petal shell entity of the threaded mandrel, but cannot be crimped at the edge position of the shell, and cannot be crimped at the gap between the shells.

Example 1

Fig. 4 is a schematic diagram of a mandrel with a solid fixed structure according to the present invention. The mandrel is provided with a special external thread, and the thread type of the special external thread is obtained after modification on the basis of the external thread of the bolt corresponding to the internal thread of the nut. The tooth angle, pitch diameter, minor diameter and pitch of the special external thread are equal to those of the external thread of the bolt corresponding to the internal thread of the nut. The large diameter of the special external thread is smaller than that of the external thread of the bolt corresponding to the internal thread of the nut and is approximately equal to the medium diameter of the external thread of the bolt corresponding to the internal thread of the nut. The dotted line in fig. 4 shows the difference between the external thread of the spindle and the external thread of the bolt corresponding to the nut.

The nut shown in fig. 1 is closed using the three steps of the present invention: step one, penetrating a mandrel shown in fig. 4 into the nut shown in fig. 5 through screwing, wherein the penetrating position of the mandrel already comprises the position to be closed on the nut, and a gap 3 with a specific shape and a specific volume appears between the external thread major diameter of the mandrel and the internal thread major diameter of the nut; step two, using a closing die to close the nut, wherein the closing amount of the nut is only one third of that of the nut in the traditional method, and when the nut is closed, the internal thread at the closing position of the nut is extruded by the closing die and the mandrel, so that the metal entity of the internal thread deforms and flows into the gap 3, as shown in a position III 4 in fig. 6; and thirdly, rotating and discharging the mandrel to obtain the self-locking nut with the locking moment required by the product standard and without cracks. A photomicrograph of the internal thread at the constriction is shown in fig. 7.

Example two

Fig. 8 is a schematic diagram of a mandrel core in an expanded and contracted split structure according to the present invention, and fig. 9 is a schematic diagram of a mandrel core in an expanded and contracted split structure according to the present invention, wherein the number of segments of the multi-segment shell of the threaded mandrel is three. The mandrel is used for closing up the nut in three steps: step one, penetrating a mandrel shown in fig. 8 into a nut, wherein the penetrating position of the mandrel comprises the position to be closed on the nut, and then plugging the inner core into the mandrel to enable the mandrel to be in a state shown in fig. 9, or screwing the mandrel into the nut after the mandrel is firstly in the state shown in fig. 9; step two, a closing die is used for closing the nut, the closing position corresponds to the middle position of the threaded mandrel multi-piece shell 5 of the mandrel, but cannot correspond to the edge position of the threaded mandrel multi-piece shell 5 and cannot correspond to the gap 6, the internal thread of the closing position of the nut is extruded by the closing die and the mandrel, and the form of a thread is controlled to change; and thirdly, pulling the inner core out of the mandrel, so that the mandrel is in the state shown in fig. 8, and then, discharging the mandrel from the nut.

Comparative example 1

Fig. 1 is a self-locking nut which has not yet been subjected to necking deformation, the necking effect obtained after three-point necking is shown in fig. 2 in a traditional mode, an outer surface indentation left by necking is shown in a first position 1 in the drawing, the internal thread is deformed in a second position 2 corresponding to the first position, and the necking deformation is required to be large enough to meet the locking moment required by product standards.

Table 1 example 1, example 2, comparative example 1, closing amount and locking moment

	Example 1	Example 2	Comparative example 1
				Closing-up amount	0.1mm	0.1mm	0.3mm
Locking moment	3.2Nm	3.1Nm	3Nm

As can be seen from table 1, the closing amount of example 1 and example 2 was 0.1, the closing amount of comparative example 1 was 0.3, the locking torque of example 1 was 3.2Nm, the locking torque of example 2 was 3.1Nm, and the locking torque of comparative example 1 was 3Nm, so that a large locking torque was generated with a small closing deformation amount at normal temperature, and the deformation of the female screw in comparative example 2 was seen at position two 2 in fig. 2, and the deformation of the female screw in example 1 was seen to be small from fig. 6.

The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A closing-in method of a high-locking crack-resistant mandrel is characterized by comprising the following steps of: the method comprises the following steps:

s2: the nut is closed by using a closing die, the internal thread of the closing part of the nut is extruded by the closing die and the mandrel, and the form of the thread tooth of the internal thread is controlled to change;

the outer wall of the mandrel in the step S1 is provided with external threads, the tooth angle, the pitch diameter, the small diameter and the thread pitch of the external threads are equal to those of the external threads of the bolts corresponding to the internal threads of the nuts, and the large diameter of the external threads is smaller than that of the external threads of the bolts corresponding to the internal threads of the nuts;

the utility model provides a multi-lobe shell of screw mandrel, including the dabber, the dabber is the components of a whole that can function independently structure of scalable, the dabber includes fixed axle, screw mandrel inner core, a plurality of screw mandrel multi-lobe shell, screw mandrel inner core sets up in the fixed axle, a plurality of screw mandrel multi-lobe shell sets up the circumference at the one end of fixed axle along the circumference, the inside wall of a plurality of screw mandrel multi-lobe shell sets up on the circumference in gap, the external screw thread of the outer wall of dabber is located the outer wall of screw mandrel multi-lobe shell, be equipped with on the fixed axle with the coaxial through-hole in gap, the diameter of through-hole is the diameter of screw mandrel inner core at least, the diameter of gap is less than the diameter of through-hole.

2. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: the large diameter range of the external thread of the mandrel is as follows: d2- (d 1-d 3)/4.ltoreq.d2+ (d 1-d 3)/4;

the major diameter of the external thread of the mandrel is d.

3. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: the large diameter of the external thread of the mandrel is a plane or a curved surface.

4. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: one end of the threaded mandrel inner core is conical, and a reducing transition section is arranged at the joint of the through hole of the fixed shaft and the gap.

5. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: the fixed shaft is made of flexible materials or elastic materials, and the threaded mandrel multi-piece shell is made of metal materials.

6. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: the mandrel is of an expandable split structure, and is directly threaded into and out of the mandrel in a screwing mode in S1 and in the process of discharging the mandrel.

7. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: in S1, the inner core of the threaded mandrel is inserted into a gap of the multi-lobe shell of the threaded mandrel, and after the inner core of the threaded mandrel is pulled out of the multi-lobe shell of the threaded mandrel in the process of unloading the mandrel, the pitch diameter and the small diameter of the external thread of the multi-lobe shell of the threaded mandrel are reduced.

8. The method for closing up a high-locking crack-resistant mandrel as recited in claim 1, wherein: the number of the petals of the mandrel multi-petal shell is equal to the number of the necking dies in S2, and the crimping position of the necking dies in S2 is at the middle position of the threaded mandrel multi-petal shell, cannot be positioned at the edge position of the threaded mandrel multi-petal shell and cannot be positioned in a gap crimped between the threaded mandrel multi-petal shells.