WO2023010770A1

WO2023010770A1 - High-locking, anti-cracking mandrel and crimping method therefor

Info

Publication number: WO2023010770A1
Application number: PCT/CN2021/140794
Authority: WO
Inventors: 郭双双; 魏亮亮; 刘玉生; 齐增星; 单垄垄
Original assignee: 航天精工股份有限公司
Priority date: 2021-08-02
Filing date: 2021-12-23
Publication date: 2023-02-09
Also published as: CN113586590B; CN113586590A

Abstract

Provided are a high-locking, anti-cracking mandrel and a closing method therefor. A major diameter of external threads of the mandrel is smaller than a major diameter of external threads of a bolt corresponding to internal threads of a nut. The method comprises the following steps: S1: inserting a mandrel into a nut, a position where the mandrel is inserted needing to comprise a position where the nut is to be crimped; and S2: crimping the nut using a crimping mold, so that internal threads of the nut are squeezed by the crimping mold and the mandrel, and a morphology of thread teeth of the internal threads thereof produces a controlled deformation. The high-locking, anti-cracking mandrel and the crimping method therefor can be used at normal temperatures, a high locking torque can be generated, and cracks can be prevented.

Description

A high-locking and anti-crack mandrel and its closing method

technical field

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

Background technique

The all-metal self-locking nut is a nut with its own anti-loosening effect, and its application range and application volume are huge. There are many types of locking structures for nuts, which can be divided into mechanically fixed locking structures and friction-increasing locking structures according to their working principles. Among them, the locking structures that increase friction can be divided into effective locking structures according to the locking principle. Torque type locking structure and free rotation type locking structure. The effective torque refers to the rotational torque measured when the threaded connection pair is not under the condition of axial load, when the nut is rotated smoothly. This torque has the locking function of resisting the relative rotation between the threaded connection pairs. The locking performance of this nut does not depend entirely on the pretightening force of the threaded connection pair. Such as: self-locking nut. Effective torque type self-locking nuts can be divided into all-metal self-locking nuts and non-metallic insert self-locking nuts. The working principle of the all-metal self-locking nut is: the locking structure of the self-locking nut is compressed and deformed. When the thread of the locking part is screwed with the bolt, it is squeezed by the thread of the bolt and restored to its original shape, so that the nut is deformed. Elastic deformation and elastic deformation force, due to the interference of the elastic deformation force on the bolt thread, produce a frictional moment that prevents rotation, that is, the locking torque of the self-locking nut.

Generally, in order to generate a higher locking torque, a larger amount of closing deformation is required. However, as the amount of closing deformation increases, the risk of cracks on the internal thread also increases. It is very difficult to ensure sufficient locking torque while ensuring that the internal thread is free from cracks. A commonly used improvement method is to heat the closure and increase the plasticity by heating the nut, thus reducing the risk of cracks. However, heating has brought about a series of problems such as heating method, heating transfer, temperature control, nut material affected by heat, nut surface affected by heat, size change of closing die due to thermal expansion and contraction, heating working life of closing die, and heat protection.

Contents of the invention

In view of this, the present invention aims to propose a high-locking and anti-crack mandrel and its closing method. This method is carried out at normal temperature, which can generate a higher locking torque and prevent cracks.

In order to achieve the above object, the technical solution created by the present invention is achieved in this way:

A mandrel for closing a nut, the outer wall of the mandrel is provided with an external thread, and the profile angle, medium diameter, minor diameter and pitch of the external thread are equal to the profile angle, medium diameter, minor diameter and pitch, the major diameter of the external thread is smaller than the major diameter of the corresponding bolt external thread of the nut internal thread.

The major diameter range of the external thread of the mandrel is: d2-(d1-d3)/4≤d≤d2+(d1-d3)/4;

The major diameter of the bolt external thread corresponding to the internal thread of the nut is d1;

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

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

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

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

Further, the shaft core is a fixed solid structure.

Further, the shaft core is a split structure that can expand and contract. The shaft core includes a fixed shaft, a threaded mandrel inner core, several threaded mandrel multi-lobed shells, and the threaded mandrel inner core is arranged in the fixed shaft. Several The threaded mandrel multi-lobed shell is arranged at one end of the fixed shaft along the circumference, the inner walls of several threaded mandrel multi-lobed shells are arranged on the circumference of the gap, and the external threads on the outer wall of the mandrel are located on the outer wall of the threaded mandrel multi-lobed shell Above, the fixed shaft is provided with a through hole coaxial with the slit, the diameter of the through hole is at least the diameter of the inner core of the threaded mandrel, and the diameter of the slit is smaller than the diameter of the through hole.

Further, one end of the inner core of the threaded mandrel is conical, and a diameter-reducing transition section is provided at the connection between the through hole and the slit of the fixed shaft.

Further, the material of the shaft core is flexible material or elastic material, such as beryllium copper, nickel-titanium alloy, spring steel, rubber, latex, and the material of the multi-lobed shell of the threaded mandrel is metal material.

A high-locking and anti-crack mandrel and a closing method thereof, comprising the following steps:

S1: Insert the mandrel into the nut, the position where the mandrel penetrates should include the position to be closed on the nut;

S2: Use a closing die to close the nut. The internal thread at the closing part of the nut is squeezed by the closing die and the mandrel, and the shape of the thread teeth of the internal thread changes in a controlled manner.

Further, the shaft core is a fixed solid structure, and the shaft core is threaded directly into and out of the nut during S1 and unloading the shaft core.

Further, the shaft core is a split structure that can be expanded and contracted. In S1 and when the mandrel is unloaded, it is directly threaded and threaded. In S1, the inner core of the threaded mandrel is inserted into the multi-lobed threaded mandrel. In the gap of the shell, after the inner core of the threaded mandrel is pulled out from the multi-lobe shell of the threaded mandrel, the middle diameter and the minor diameter of the external threads of the multi-lobe shell of the threaded mandrel will be reduced.

Further, the number of petals of the multi-lobed shell of the mandrel is equal to the number of closing dies in S2, and the pressure position of the closing die in S2 should be in the middle of the multi-lobed shell of the threaded mandrel, and cannot be located at the The edge position of the multi-lobed shell of the threaded mandrel, and cannot be located on the gap between the multi-lobed shells of the threaded mandrel.

Compared with the prior art, the invention creates a high-locking and anti-crack mandrel and its closing method has the following beneficial effects:

A high-locking and anti-crack mandrel and its closing method of the present invention can produce a large locking torque with a small closing deformation at room temperature, without defects such as cracks, and can be expanded and contracted when used. The thread of the split structure can obtain more convenience through the expansion and contraction of the middle and small diameters of the multi-lobed shell of the threaded mandrel when the threads are threaded into and out of the nut, and it is easy to disassemble.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the schematic diagram of a kind of self-locking nut that has not yet been deformed;

Fig. 2 is a schematic diagram of the closing effect obtained after closing the nut shown in Fig. 1 in a traditional way;

Fig. 3 is a photomicrograph of cracks appearing in the inner thread at the closing part of Fig. 2;

Fig. 4 is the schematic diagram of the mandrel of a kind of fixed solid structure of the present invention;

Fig. 5 is a thread schematic diagram after the mandrel of the present invention is penetrated into the nut;

Fig. 6 is the schematic diagram of the effect after the nut shown in Fig. 1 is closed by the method of the present invention;

Fig. 7 is a photomicrograph of the internal thread at the closing part of Fig. 6;

Fig. 8 is a schematic diagram of the pull-out state of the mandrel inner core of an expandable split structure of the present invention;

Fig. 9 is a schematic diagram of an expandable and contractible split structure in which the inner core of the mandrel is inserted. Description of drawings

1-Position 1; 2-Position 2; 3-Gap; 4-Position 3; 5-Threaded mandrel multi-lobed shell; 6-Gap.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention Creation and simplification of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be interpreted in a broad sense, for example, it can be a fixed connection or a flexible connection. Detachable connection, or integral connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

The invention will be described in detail below with reference to the accompanying drawings and examples.

A high-locking and anti-crack closing method, which is divided into three steps: Step 1, penetrate the mandrel in the nut, and the position where the mandrel penetrates should include the position on the nut to be closed; Step 2, use the closing mold to The nut is closed, and the internal thread at the closed part of the nut is squeezed by the closing die and the mandrel, and the shape of the thread teeth changes in a controlled manner; Step 3, unload the mandrel. Step 3 is optional.

The above-mentioned nut refers to a self-locking nut that needs to be deformed but has not been deformed, and includes an internal thread structure.

The above-mentioned mandrel refers to a mandrel with a special external thread, and the mandrel can be screwed in and out through the free rotation of the special external thread and the nut that has not been closed. The profile 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 profile angle, pitch diameter, minor diameter and pitch of the special external thread are equal to the profile angle, pitch diameter, minor diameter and pitch of the bolt external thread corresponding to the nut internal thread. The major diameter of the special external thread is smaller than the major diameter of the corresponding bolt external thread of the nut internal thread, which is approximately equal to the middle diameter of the corresponding bolt external thread of the nut internal thread. The major diameter of the special external thread can be flat or have a A certain warp. The tooth form of 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 appears between the major diameter of the mandrel's external thread and the major diameter of the nut's internal thread. The function of this space is to allow the squeezed internal thread deformation to flow into this specific space in the second step above, so that the shape of the internal thread teeth will produce specific changes. When the shape of the internal thread teeth at the closing position of the nut undergoes the above-mentioned specific changes, the thread pair between the nut and the bolt changes from an overall clearance fit to a local interference fit. Through this method, a large enough gap can be produced when the closing amount is small. Tightening torque. In the second step above, after the nut is squeezed, its deformation space is controlled, and cracks are not easy to occur.

The structure of the threaded part of the above-mentioned mandrel is divided into two types. The first type is the thread for fixing the solid structure, that is, a special external thread is made on the solid cylinder. The threaded mandrel with the first structure is threaded directly into and unloaded from the nut in the

above closing steps

1 and 3. The second type is an expandable split-structure thread. The split-structure thread is mainly composed of two parts, namely the multi-lobed shell of the threaded mandrel and the inner core of the threaded mandrel. The inner core of the threaded mandrel is inserted into the threaded core. In the multi-lobed shell of the shaft, the multi-lobed shell of the threaded mandrel can be expanded. The diameter and minor diameter of the expanded thread are equal to the major diameter and minor diameter of the external thread corresponding to the internal thread of the nut. The pitch and minor diameters of the threaded mandrel multi-lobe casing shrink after being pulled out of the casing. In the threaded mandrel with the second structure, in the

above closing steps

1 and 3, when the thread is screwed in and the nut is unloaded, more can be obtained through the expansion and contraction of the middle diameter and the small diameter of the multi-lobed shell of the threaded mandrel. convenience. The number of petals of the multi-lobed shell of the threaded mandrel is equal to the number of closing indenters in step 2. When closing in step 2, the closing pressure position of the closing indenter should be in the middle of the threaded mandrel multi-lobed shell entity, and cannot be pressed against the shell The edge position of the device cannot be squeezed on the gap between the shells.

Embodiment one

The solid line in FIG. 4 is a schematic diagram of a mandrel for fixing a solid structure of the present invention. The mandrel has a special external thread, and the profile 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 profile angle, pitch diameter, minor diameter and pitch of the special external thread are equal to the profile angle, pitch diameter, minor diameter and pitch of the bolt external thread corresponding to the nut internal thread. The major diameter of the special external thread is smaller than the major diameter of the corresponding bolt external thread of the nut internal thread, approximately equal to the middle diameter of the corresponding bolt external thread of the nut internal thread. Shown in dotted line among Fig. 4 is exactly the difference of the mandrel external thread of the present invention and the corresponding bolt external thread of nut.

Use the three steps of the present invention to close the nut shown in Figure 1: Step 1, thread the mandrel shown in Figure 4 into the nut as shown in Figure 5 by threading, at this time the mandrel penetration position has included Hold the position on the nut to be closed, and a gap 3 with a specific shape and a specific volume appears between the major diameter of the external thread of the mandrel and the major diameter of the internal thread of the nut; step 2, use a closing mold to close the nut, which is used in this embodiment The closing amount of the present invention is only one-third of the closing amount of the traditional method. When closing, the internal thread at the closing part of the nut is squeezed by the closing die and the mandrel, so the metal entity of the internal thread deforms and flows into the above-mentioned gap 3, As shown in

position

3 and 4 in Figure 6; step 3, rotate the mandrel and unload it, and obtain a self-locking nut with the locking torque required by the product standard and no cracks. The metallographic photomicrograph of the internal thread at the closing part is shown in Figure 7.

Embodiment two

Fig. 8 is a schematic diagram of the pull-out state of the mandrel inner core of an expandable split structure of the present invention, and Fig. 9 is a schematic view of the inserted state of the mandrel inner core of an expandable split structure of the present invention Schematic diagram, the number of petals of the multi-lobed shell of the threaded mandrel in this embodiment is three. Using the mandrel to close the nut is divided into three steps: Step 1. Insert the mandrel shown in Figure 8 into the nut. The position of the mandrel penetration should include the position to be closed on the nut, and then insert the inner core into the core. Make the mandrel turn into the state shown in Figure 9, or make the mandrel turn into the state shown in Figure 9 first and then screw the mandrel into the nut; step 2, use the closing mold to close the nut, and the closing position should correspond to the thread of the mandrel The middle position of the multi-lobed shell 5 of the mandrel cannot correspond to the edge position of the multi-lobed shell 5 of the threaded mandrel and cannot correspond to the gap 6. The internal thread at the closing part of the nut is squeezed by the closing die and the mandrel, and the shape of the thread teeth Generate controlled changes; step 3, pull out the inner core from the mandrel, so that the mandrel becomes the state shown in Figure 8, and then unload the mandrel from the nut.

Comparative example 1

Figure 1 is a self-locking nut that has not been deformed. The closing effect obtained after three-point closing in the traditional way is shown in Figure 2. The position 1 in the figure is the pressure on the outer surface left by the closing. The internal thread is also deformed at the

corresponding position

2 and 2. In order to achieve the locking torque required by the product standard, the deformation of the closure needs to be large enough.

Table 1 Closing amount and locking torque of embodiment 1, embodiment 2, comparative example 1

the	实施例1Example 1	实施例2Example 2	对比例1Comparative example 1
收口量Closing amount	0.1mm0.1mm	0.1mm0.1mm	0.3mm0.3mm
锁紧力矩Locking torque	3.2Nm3.2Nm	3.1Nm3.1Nm	3Nm3Nm

It can be seen from Table 1 that the closing amount of Example 1 and Example 2 is 0.1, the closing amount of Comparative Example 1 is 0.3, the locking torque of Example 1 is 3.2Nm, and the locking torque of Example 2 is 3.1Nm , the locking torque of Comparative Example 1 is 3Nm, which can produce a larger locking torque at room temperature with a small closing deformation. From position 2 in Figure 2, it can be seen that the internal thread in Comparative Example 2 Deformation has occurred, and it can be seen from Figure 6 that the internal thread in Example 1 has a small change in shape.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the Within the scope of protection of the present invention.

Claims

A high locking and anti-crack mandrel, characterized in that: the outer wall of the mandrel is provided with an external thread, and the profile angle, middle diameter, minor diameter and pitch of the external thread are equal to the external thread of the bolt corresponding to the internal thread of the nut. Profile angle, middle diameter, minor diameter and pitch, the major diameter of the external thread is smaller than the major diameter of the corresponding bolt external thread of the nut internal thread.
A high-locking crack-proof mandrel according to claim 1, characterized in that: the major diameter range of the external thread of the mandrel is: d2-(d1-d3)/4≤d≤d2+(d1- d3)/4;

The major diameter of the bolt external thread corresponding to the internal thread of the nut is d1;

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

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

The major diameter of the external thread of the mandrel is d.
The high-locking and anti-crack mandrel according to claim 1, characterized in that: the major diameter of the external thread of the mandrel is a plane or a curved surface.
The high-locking and anti-crack mandrel according to claim 1, wherein the mandrel is a fixed solid structure.
A high-locking and anti-crack mandrel according to claim 1, characterized in that: the mandrel is a split structure that can expand and contract, and the mandrel includes a fixed shaft, a threaded mandrel inner core, and several threads The mandrel multi-lobe shell, the inner core of the threaded mandrel is arranged in the fixed shaft, several threaded mandrel multi-lobe shells are arranged on one end of the fixed shaft along the circumference, and the inner side walls of several threaded mandrel multi-lobe shells are set on the circumference of the gap Above, the external thread on the outer wall of the mandrel is located on the outer wall of the multi-lobed shell of the threaded mandrel, and a through hole coaxial with the slit is provided on the fixed shaft, the diameter of the through hole is at least the diameter of the inner core of the threaded mandrel, and the diameter of the slit The diameter is smaller than the diameter of the through hole.
A high-locking and anti-crack mandrel according to claim 4, characterized in that: one end of the inner core of the threaded mandrel is conical, and the connection between the through hole and the gap of the fixed shaft is provided with a variable diameter Transition.
The high-locking and anti-crack mandrel according to claim 5, characterized in that: the material of the fixed shaft is flexible material or elastic material, and the material of the multi-lobed shell of the threaded mandrel is metal material.
A method for closing a high-locking anti-crack mandrel, using the mandrel for closing a nut according to any one of claims 1-6, characterized in that it includes the following steps:

S1: Insert the mandrel into the nut, the position where the mandrel penetrates should include the position to be closed on the nut;

S2: Use a closing die to close the nut. The internal thread at the closing part of the nut is squeezed by the closing die and the mandrel, and the shape of the thread teeth of the internal thread changes in a controlled manner.
A closing method for a high-locking crack-proof mandrel according to claim 8, characterized in that: the mandrel is a fixed solid structure, and the mandrel is directly screwed through during S1 and when the mandrel is unloaded Inserting and unloading the nut, the shaft core is a split structure that can expand and contract. In S1 and unloading the mandrel, it is directly inserted and unloaded by screwing in and out, and in S1 by inserting the inner core of the threaded mandrel Into the gap of the threaded mandrel multi-lobe shell, after the inner core of the threaded mandrel is pulled out from the threaded mandrel multi-lobe shell when the mandrel is unloaded, the diameter and minor diameter of the external thread of the threaded mandrel multi-lobe shell will shrink.
A method for closing a high-locking crack-proof mandrel according to claim 9, characterized in that: the number of petals of the mandrel multi-lobed shell is equal to the number of closing dies in S2, and the number of closing dies in S2 is The compression position should be in the middle of the multi-lobe casing of the threaded mandrel, not at the edge of the multi-lobed casing of the threaded mandrel, and not on the gap between the multi-lobed casings of the threaded mandrel.