阅读说明：本技术 双头螺柱的装卸装置及装卸双头螺柱的方法 (Stud bolt assembling and disassembling device and method ) 是由 王卫勇 申孝立 马申 崔俊荣 陈岩 赵小梅 马丽娜 牛丽丽 古魁 陈祥伟 于 2020-12-11 设计创作，主要内容包括：本发明公开了一种双头螺柱的装卸装置及装卸双头螺柱的方法,属于双头螺柱的安装领域,包括外套筒、芯轴、方螺母、芯轴驱动组件及方螺母固定件,外套筒内上端开设有中心孔,下端开设有四方孔；芯轴通过中心孔装配于外套筒内上端,芯轴顶部开设有用于转接扳手的四方孔,底部设有用于压紧双头螺柱端面的顶头；方螺母通过四方孔装配于外套筒内下端；芯轴驱动组件连接外套筒与芯轴且当外套筒与芯轴相对旋动时使芯轴相对外套筒向下运动；方螺母固定件对应方螺母设置于外套筒下端侧壁。本发明解决了现有工具使用时应力集中在双螺母与双头螺柱旋合螺纹上而导致一系列问题,具有螺纹不易损伤,双头螺柱不会回松,集装配、拆卸双头螺柱功能于一体的特点。(The invention discloses a device and a method for assembling and disassembling a double-end stud, belonging to the field of installation of double-end studs and comprising an outer sleeve, a mandrel, a square nut, a mandrel driving assembly and a square nut fixing piece, wherein the upper end in the outer sleeve is provided with a central hole, and the lower end is provided with a square hole; the mandrel is assembled at the upper end in the outer sleeve through a central hole, a square hole for a switching wrench is formed in the top of the mandrel, and a top head for compressing the end face of the stud is arranged at the bottom of the mandrel; the square nut is assembled at the inner lower end of the outer sleeve through a square hole; the mandrel driving assembly is connected with the outer sleeve and the mandrel and enables the mandrel to move downwards relative to the outer sleeve when the outer sleeve and the mandrel rotate relatively; the square nut fixing piece is arranged on the side wall of the lower end of the outer sleeve corresponding to the square nut. The invention solves a series of problems caused by stress concentration on the screwing threads of the double nuts and the double-end studs when the existing tool is used, and has the characteristics that the threads are not easy to damage, the double-end studs cannot be loosened, and the double-end studs are assembled and disassembled into a whole.)

1. A handling device of stud, its characterized in that: comprises that

The upper end in the outer sleeve is provided with a central hole, and the lower end in the outer sleeve is provided with a square hole;

the mandrel is assembled at the upper end in the outer sleeve through the central hole, a square hole for switching a wrench is formed in the top of the mandrel, and a top for pressing the end face of the stud is arranged at the bottom of the mandrel;

the square nut is assembled at the inner lower end of the outer sleeve through the square hole;

a mandrel driving assembly which is connected with the outer sleeve and the mandrel and enables the mandrel to move downwards relative to the outer sleeve when the outer sleeve and the mandrel rotate relatively;

and the square nut fixing piece is arranged on the side wall of the lower end of the outer sleeve corresponding to the square nut.

2. The stud handling device of claim 1, wherein: the mandrel drive assembly further comprises:

the pair of V-shaped guide grooves are symmetrically formed in the cylindrical surface of the outer sleeve;

the through hole is formed in the mandrel and is perpendicular to the central line of the mandrel;

and the positioning pin penetrates through the through hole, and two ends of the positioning pin are embedded in the V-shaped guide groove.

3. The stud handling device of claim 2, wherein: the angle of the V-shaped guide groove is larger than the lead angle of the double-ended stud.

4. The stud handling device of claim 3, wherein: the square nut fixing member includes:

the fastening piece is arranged in a first positioning hole in the side wall of the lower end of the outer sleeve;

and the elastic fixing piece is arranged in a second positioning hole on the side wall of the lower end of the outer sleeve corresponding to the fastening piece.

5. The stud handling device of claim 4, wherein: the elastic fixing component comprises

The steel ball is abutted against the side face of the square nut;

the spring is abutted with the steel ball;

and the blocking cover is arranged outside the spring and blocks the second positioning hole.

6. The stud handling device of claim 4, wherein: the tightening piece is a tightening pin.

7. The stud handling device of claim 1, wherein: the square nut is a component family with the same external dimension and different specifications of threaded holes in the center.

8. A method of assembling a stud using the stud handling apparatus of any of claims 1-7, wherein: the method comprises the following steps:

a matched square nut assembling step, namely loosening the square nut fixing piece, installing the square nut matched with the double-end stud in the square hole of the outer sleeve in a threaded manner, and fastening the square nut fixing piece;

assembling a double-ended stud, namely, after the double-ended stud is preassembled on a machine body, installing the square nut on the thread at the exposed end of the double-ended stud, and installing a torque wrench in the square hole of the mandrel; to screwing up the direction rotating torque spanner, the dabber downstream, the top is tight stud terminal surface, stud handling device with the stud lock becomes a whole, the torque effect that torque spanner applied is in stud with on the screw thread of organism, screw up stud reaches predetermined torque value.

9. A method of disassembling a stud using the stud handling apparatus of any one of claims 1 to 7, wherein: the method comprises the following steps:

a matched square nut assembling step, namely loosening the square nut fixing piece, installing the square nut matched with the double-end stud in the square hole of the outer sleeve in a threaded manner, and fastening the square nut fixing piece;

a stud disassembling step, namely installing a square nut on a thread at one end exposed out of the stud to be disassembled, rotating the ratchet wrench in the loosening direction by installing a ratchet wrench in a square hole of the mandrel, moving the mandrel downwards, synchronously withdrawing the stud by the square nut, and under the same rotation angle, enabling the distance of the downward movement of the mandrel to be greater than the distance of the synchronous withdrawal of the square nut from the stud, wherein the stud assembling and disassembling device and the stud are locked into a whole, and the disassembling torque applied by the ratchet wrench acts on the stud and the thread of the machine body to disassemble the stud from the machine body.

10. The method of handling the stud according to claim 8 or 9, wherein: also comprises

And a step of replacing the square nut, namely installing a bolt with corresponding specification in the square nut threaded hole, screwing up the square nut fixing piece, pulling the bolt to take out the square nut, installing the square nut with required specification in the outer sleeve square hole, screwing the square nut fixing piece, and finishing the replacement of the square nut.

Technical Field

The invention belongs to the field of installation of double-end studs, and particularly relates to a device and a method for assembling and disassembling a double-end stud.

Background

At present, when assembling and disassembling the stud, a double-nut parallel tightening method is generally adopted, and the specific operation is as follows: two nuts are arranged on threads at one end of the stud and are mutually closed and clamped, so that the double nuts and the stud do not rotate relatively; when the stud is assembled, the nut on the backrest is rotated to drive the stud to rotate and screw; when the stud is disassembled, the nut which is close to the lower part is rotated to drive the stud to rotate and screw out; when the double nuts are disassembled, the lower nuts are fixed, the upper nuts are loosened, and the double nuts are not closed and clamped any more and are respectively taken down. This method has the following disadvantages: during operation, the double nuts are not good in closing and clamping effect, and are easy to rotate synchronously, so that the purpose of screwing or disassembling the double-end stud cannot be achieved. In order to ensure that the double nuts and the double-end studs do not rotate relatively, the double wrenches are used for clamping one nut respectively, force is applied in the opposite direction to enable the double nuts to be fastened, and the operation is complicated; in addition, the double nuts are closed and clamped, stress is concentrated on the threads screwed by the double nuts and the double-end studs, and the threads are easily damaged; if a tightening torque needs to be applied to the stud, the double nuts cannot be guaranteed to transmit the required torque to the stud; when removing the double nut, it is possible to unscrew the already screwed stud.

Chinese patent CN204277895U discloses a stud quick assembling and disassembling tool, which realizes quick assembling and disassembling of a stud and is composed of a connecting sleeve, a cylindrical sleeve, a movable thread block, an adjusting screw, a sliding screw, a compression spring and a connecting screw. During assembly, the tool sleeve is rotated to enable one end of the stud to completely enter the cylindrical sleeve; rotating the two adjusting screws to enable the movable thread block to move towards the interior of the cylindrical sleeve and to be matched with the fixed threads in the cylindrical sleeve, and fully compressing and locking the thread part of the stud; and connecting the ratchet wrench with the square opening of the connecting sleeve, rotating the ratchet wrench to drive the connecting sleeve to rotate, and driving the stud to be screwed in or out. After the assembly and disassembly are finished, the adjusting screw is loosened, the movable thread retracts under the action of the compression spring, and the separation of the tool and the stud is realized.

However, the above stud quick-mounting and dismounting tool still concentrates on the screw thread where the double nut and the stud are screwed, there are problems that the screw thread is damaged, and if a tightening torque needs to be applied to the stud, it cannot be guaranteed that the double nut can transmit the required torque to the stud, and when the double nut is dismounted, the screwed stud may be unscrewed, and the like.

Disclosure of Invention

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the invention.

The invention provides a loading and unloading device of a double-end stud and a method for loading and unloading the double-end stud, which solve the problems that the threads are damaged due to the fact that stress is concentrated on the threads screwed with the double-end stud when the double-end stud is assembled and disassembled by the existing tool, the double-end stud can not be ensured to transmit required torque to the double-end stud and the screwed double-end stud can be unscrewed when the double-end stud is disassembled, and have the characteristics that the applied screwing torque can completely act on the double-end stud, the threads are not easy to damage, the double-end stud cannot be unscrewed when the tool is disassembled, and the double-end stud is assembled, disassembled, replaced by a square nut and the like are integrated.

In one aspect, the invention discloses a device for assembling and disassembling a double-end stud, which comprises

The upper end in the outer sleeve is provided with a central hole, and the lower end in the outer sleeve is provided with a square hole;

the mandrel is assembled at the upper end in the outer sleeve through the central hole, a square hole for switching a wrench is formed in the top of the mandrel, and a top for pressing the end face of the stud is arranged at the bottom of the mandrel;

the square nut is assembled at the inner lower end of the outer sleeve through the square hole;

a mandrel driving assembly which is connected with the outer sleeve and the mandrel and enables the mandrel to move downwards relative to the outer sleeve when the outer sleeve and the mandrel rotate relatively;

and the square nut fixing piece is arranged on the side wall of the lower end of the outer sleeve corresponding to the square nut.

In some of these embodiments, the mandrel drive assembly further comprises:

the pair of V-shaped guide grooves are symmetrically formed in the cylindrical surface of the outer sleeve;

the through hole is formed in the mandrel and is perpendicular to the central line of the mandrel;

and the positioning pin penetrates through the through hole, and two ends of the positioning pin are embedded in the V-shaped guide groove.

In some of these embodiments, the V-shaped guide slot angle is greater than the lead angle of the stud.

In some of these embodiments, the square nut fixture includes:

the fastening piece is arranged in a first positioning hole in the side wall of the lower end of the outer sleeve;

and the elastic fixing piece is arranged in a second positioning hole on the side wall of the lower end of the outer sleeve corresponding to the fastening piece.

In some of these embodiments, the resilient mounting assembly comprises

The steel ball is abutted against the side face of the square nut;

the spring is abutted with the steel ball;

and the blocking cover is arranged outside the spring and blocks the second positioning hole.

In some of these embodiments, the tightening piece is a knock pin.

In some embodiments, the square nut is a component family with the same external dimension and threaded holes with different specifications in the center.

In another aspect, the present invention discloses a method for assembling a stud by using the handling device for a stud recited in any of the above embodiments, including the steps of:

a matched square nut assembling step, namely loosening the square nut fixing piece, installing the square nut matched with the double-end stud in the square hole of the outer sleeve in a threaded manner, and fastening the square nut fixing piece;

assembling a double-ended stud, namely, after the double-ended stud is preassembled on a machine body, installing the square nut on the thread at the exposed end of the double-ended stud, and installing a torque wrench in the square hole of the mandrel; to screwing up the direction rotating torque spanner, the dabber downstream, the top is tight stud terminal surface, stud handling device with the stud lock becomes a whole, the torque effect that torque spanner applied is in stud with on the screw thread of organism, screw up stud reaches predetermined torque value.

The invention also discloses a method for disassembling the stud by adopting the assembling and disassembling device of the stud, which comprises the following steps:

a matched square nut assembling step, namely loosening the square nut fixing piece, installing the square nut matched with the double-end stud in the square hole of the outer sleeve in a threaded manner, and fastening the square nut fixing piece;

a stud disassembling step, namely installing a square nut on a thread at one end exposed out of the stud to be disassembled, rotating the ratchet wrench in the loosening direction by installing a ratchet wrench in a square hole of the mandrel, moving the mandrel downwards, synchronously withdrawing the stud by the square nut, and under the same rotation angle, enabling the distance of the downward movement of the mandrel to be greater than the distance of the synchronous withdrawal of the square nut from the stud, wherein the stud assembling and disassembling device and the stud are locked into a whole, and the disassembling torque applied by the ratchet wrench acts on the stud and the thread of the machine body to disassemble the stud from the machine body.

In some of these embodiments, also include

And a step of replacing the square nut, namely installing a bolt with corresponding specification in the square nut threaded hole, screwing up the square nut fixing piece, pulling the bolt to take out the square nut, installing the square nut with required specification in the outer sleeve square hole, screwing the square nut fixing piece, and finishing the replacement of the square nut.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a loading and unloading device for a double-end stud, which can ensure that an applied tightening torque completely acts on the double-end stud, has the characteristics that threads are not easy to damage, the double-end stud cannot come back when a tool is disassembled, and the loading and unloading device integrates the functions of assembling, disassembling the double-end stud, replacing a square nut and the like; the invention also provides a method for assembling and disassembling the stud, which has the characteristics of simple operation, no damage to threads and good assembling and disassembling effects.

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 not to limit the invention. In the drawings:

FIG. 1 is an exploded perspective view of a stud handling apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a stud handling apparatus according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of the stud handling apparatus of FIG. 2 taken along the line A-A;

description of the drawings: 1. an outer sleeve; 2. a mandrel; 21. ejecting the head; 3. a square nut; 41. a V-shaped guide groove; 42. a through hole; 43. positioning pins; 51. a puller pin; 521. a steel ball; 522. a spring; 523. and (7) blocking the cover.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments provided by the present invention, belong to the protection scope of the present invention.

It is obvious that the drawings in the following description are only examples or embodiments of the invention, from which it is possible for a person skilled in the art, without inventive effort, to apply the invention also in other similar contexts. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one of ordinary skill in the art that the described embodiments of the present invention can be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention are not to be construed as limiting in number, and may be construed to cover both the singular and the plural. The present invention relates to the terms "comprises," "comprising," "includes," "including," "has," "having" and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. References to "connected," "coupled," and the like in the present disclosure are not to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as used herein means two or more. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. The terms "first," "second," and the like, as referred to herein, are used merely to distinguish similar objects from one another and do not denote a particular ordering for the objects.

An embodiment of the present invention provides a stud bolt handling device, and fig. 1 to 3 are a perspective exploded view, a schematic structural diagram, and a schematic sectional view of the stud bolt handling device according to the embodiment of the present invention. Referring to fig. 1-3, the apparatus includes at least: the square nut type electric wrench comprises an outer sleeve 1, a mandrel 2, a square nut 3, a mandrel 2 driving assembly and a square nut 3 fixing piece, wherein a central hole is formed in the upper end of the inner part of the outer sleeve 1, and a square hole is formed in the lower end of the inner part of the outer sleeve; the mandrel 2 is assembled at the upper end in the outer sleeve 1 through a central hole, a square hole for a switching wrench is formed in the top of the mandrel 2, and a top 21 for compressing the end face of the stud is arranged at the bottom of the mandrel 2; the square nut 3 is assembled at the inner lower end of the outer sleeve 1 through a square hole; the mandrel 2 driving assembly is used for connecting the outer sleeve 1 and the mandrel 2 and enabling the mandrel 2 to move downwards relative to the outer sleeve 1 when the outer sleeve 1 and the mandrel 2 rotate relatively; the fixing piece of the square nut 3 is arranged on the side wall of the lower end of the outer sleeve 1 corresponding to the square nut 3. This stud's handling device is through setting up 2 drive assembly of dabber and setting up the top 21 that is used for compressing tightly the stud terminal surface in 2 bottoms of dabber, in stud assembly or dismantlement in-process, guarantee that handling device and stud lock into a whole, guarantee when applying the tightening torque, the tightening torque of applying can be used in on stud completely, the damage to stud screw thread has been avoided, it can transmit requirement moment to stud to two nuts when needing to apply the tightening torque to stud to double-end, and when dismantling two nuts, can not unscrew the stud of having screwed, collect the assembly, dismantle stud and change functions in an organic whole such as square nut 3.

Wherein, dabber 2 drive assembly further includes: the pair of V-shaped guide grooves 41 are symmetrically arranged on the cylindrical surface of the outer sleeve 1; the through hole 42 is arranged on the mandrel 2 and is vertical to the central line of the mandrel 2; the positioning pin 43 passes through the through hole 42 and both ends thereof are embedded in the V-shaped guide groove 41. Through the design of the V-shaped guide groove 41, the assembling and disassembling device is more convenient to assemble and disassemble the double-end stud, and tools with independent functions do not need to be designed respectively. Optionally, the angle of the V-shaped guide slot 41 is greater than the lead angle of the stud. By limiting the angle of the V-shaped guide groove 41 to be larger than the thread lead angle of the stud, when the stud is disassembled, the downward movement distance of the mandrel 2 is larger than the distance of the square nut 3 which is withdrawn from the stud, so that the head of the mandrel 2 is propped against the end face of the stud, the square nut 3 cannot continue to rotate on the stud, and the purpose of disassembling the stud is achieved.

Wherein, 3 mountings of square nut include: the fastening piece is arranged in a first positioning hole in the side wall of the lower end of the outer sleeve 1; the elastic fixing piece is arranged in the second positioning hole of the side wall of the lower end of the outer sleeve 1 corresponding to the fastening piece. Through setting up tight piece and elastic fixing spare to the fixed action can be realized to square nut 3 to the convenience, on the other hand, the square nut 3's of being convenient for change, take out and installation are convenient for in elastic fixing spare's setting. Optionally, the elastic fixing component further includes a steel ball 521, a spring 522 and a blocking cover 523, the steel ball 521 abuts against the side surface of the square nut 3, the spring 522 abuts against the steel ball 521, and the blocking cover 523 is disposed outside the spring 522 and blocks into the second positioning hole. Specifically, the tightening member is a tightening pin 51. The outer side surfaces of the puller pin 51 and the blocking cover 523 are provided with grooves which are convenient for the mounting and the removal of the puller pin 51 and the blocking cover 523.

Furthermore, the square nut 3 is a component family with the same external dimension and different specifications of threaded holes in the center. The square nuts 3 with different specifications can be replaced according to the requirements.

The embodiment of the invention also provides a method for assembling the stud by adopting the assembling and disassembling device of the stud enumerated by any one of the above embodiments, which comprises a matching square nut 3 assembling step and a stud assembling step, specifically, a fixing part of the square nut 3 is loosened, the square nut 3 matched with the stud thread is arranged in a square hole of the outer sleeve 1, and the fixing part of the square nut 3 is fastened; after the stud is preassembled on the machine body, a square nut 3 is arranged on the thread at the exposed end of the stud, and a torque wrench is arranged in a square hole of the mandrel 2; and rotating the torque wrench in the screwing direction, moving the mandrel 2 downwards, jacking the end surface of the stud by the jacking head 21, locking the stud assembling and disassembling device and the stud into a whole, and screwing the stud to reach a preset torque value by applying torque applied by the torque wrench to the threads of the stud and the machine body. The method further comprises a device disassembling step, wherein the outer sleeve 1 is rotated after the stud assembling and disassembling device is screwed down to the position, and the stud assembling and disassembling device is disassembled from the stud. Further, when the stud is assembled, a square nut 3 corresponding to the specification of the stud is selected to be installed in a square hole of the outer sleeve 1, the stud is exposed out of one end of the machine body and screwed into a threaded hole of the square nut 3 to tightly push the top 21 of the mandrel 2, the other end of the stud is screwed into a threaded hole of the machine body, a torque wrench is used for externally connecting the stud in the square hole of the mandrel 2, when the stud is screwed, the mandrel 2 moves downwards under the action of the positioning pin 43 and the V-shaped guide groove 41, the head of the stud abuts against the stud, all parts form a whole, relative rotation does not occur any more, applied torque acts on the stud, and screwing torque of the stud on the machine.

The embodiment of the invention also provides a method for disassembling the stud by adopting the assembling and disassembling device of the stud enumerated by any one of the above embodiments, which comprises a matching square nut 3 assembling step and a stud disassembling step, specifically, a fixing part of the square nut 3 is loosened, the square nut 3 matched with the stud thread is arranged in a square hole of the outer sleeve 1, and the fixing part of the square nut 3 is fastened; the method comprises the following steps that a square nut 3 is arranged on a thread at one exposed end of a stud to be disassembled, a ratchet wrench is arranged in a square hole of a mandrel 2 and rotates towards a loosening direction, the mandrel 2 moves downwards, the square nut 3 synchronously withdraws from the stud, the distance of downward movement of the mandrel 2 is larger than the distance of synchronous withdrawal of the square nut 3 from the stud under the same rotation angle, a stud assembling and disassembling device and the stud are locked into a whole, disassembling torque applied by the ratchet wrench acts on the threads of the stud and a machine body, and the stud is disassembled from the machine body. The method further comprises a device disassembling step, wherein the outer sleeve 1 is rotated after the stud assembling and disassembling device is screwed down to the position, and the stud assembling and disassembling device is disassembled from the stud. Furthermore, when the stud is disassembled, the mandrel 2 is reversely rotated, the mandrel 2 moves downwards, and the angle of the V-shaped guide groove 41 is larger than the thread lead angle, so that the downward movement distance of the mandrel 2 is larger than the withdrawing distance of the square nut 3 from the stud, the head of the mandrel 2 is propped against the end face of the stud, the square nut 3 cannot continue to rotate on the stud, and the purpose of disassembling the stud is achieved.

Optionally, the above method for assembling the stud and the method for disassembling the stud further include a step of replacing the square nut 3, specifically, a bolt of a corresponding specification is installed in the threaded hole of the square nut 3, a fixing part of the square nut 3 is screwed up, the square nut 3 is taken out by pulling the bolt, the square nut 3 of a required specification is installed in the square hole of the outer sleeve 1, and the fixing part of the square nut 3 is screwed up to complete the replacement of the square nut 3.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.