CN107796263B

CN107796263B - Cross bends package assembly

Info

Publication number: CN107796263B
Application number: CN201610800697.XA
Authority: CN
Inventors: 刘吉昌
Original assignee: Poe Lang Enterprise Co Ltd
Current assignee: Poe Lang Enterprise Co Ltd
Priority date: 2016-09-01
Filing date: 2016-09-01
Publication date: 2019-07-23
Anticipated expiration: 2036-09-01
Also published as: CN107796263A

Abstract

A kind of cross bow package assembly, including a bent body, a fixing piece and a bow arm, wherein: the bent body has a first end and a second end, and a tank is equipped between first end and second end, the fixing piece is mounted on bent body tank, and group bent body and a fixing piece are worn with a bolt, bent body tank is detached to limit fixing piece, the bolt has a head and the whole body portion, the body portion side be equipped with a sliding slot, one first positioning it is recessed and one second positioning it is recessed, first positioning it is recessed with the second positioning is recessed is located at sliding slot both ends, and further with certain hyte fastening screw in bent body；A bowstring is installed between the bow arm both ends, by that will bend after arm is fixed on fixing piece, secures the holder to bend low through bolt, enables fixing piece that can quickly assemble, dismantles in bent body tank, and achievees the purpose that quickly to assemble, disassembly.

Description

Cross bends package assembly

Technical field

The present invention relates to the related fieldss of cross bow, particularly relate to the package assembly of a kind of cross bow bent body and bow arm.

Background technique

Bow and arrow, as the term suggests being exactly by bending a kind of weapon arranged in pairs or groups and formed with arrow, the two is indispensable, in use then It is to be stretched and bow and arrow of arranging in pairs or groups is hit bow and arrow using the elastic force that bowstring is sprung back through the bowstring being installed between bow arm both ends Hair.And bow and arrow is that ancient times are a kind of one of weapons being widely used in war and hunting, however, with the epoch Evolution and change, bow and arrow are developed via war, the use killed into the event of agonistic sports, and archery not only needs Want the concentration of extreme, more require wrist, arm exercise one's skill with both feet stability, actually one can be to body, psychology The fine tradition movement being all trained.

However, being largely directly to be locked on bent body, cross being caused to bend since the bow arm that cross bends now is in assembling Volume itself is excessive, causes transporting, needing to occupy sizable space in portable, moreover, if user will tie up bow arm When repairing, adjust, replacing, need just to can be carried out after first dismantling fixed bow arm all with the screw combined of bending low subsequent maintenance, adjustment, The related operation such as replacement, for a user comparable inconvenience.

Therefore, there is related dealer to study, develop for above-mentioned missing, as TaiWan, China patent announcement M519229 " Cross bow bow arm combination fixing structure ", the Patent Case in specification recorded in [0010] section, " this Patent Case in assembling or When replacement bow arm, cooperation moves back the holding tank that loose fixing piece is detached from bent body refering to Fig. 5 and Fig. 6, and moves back loose spiro part and be detached from bent body Combined hole, sliding slide open the holding tank of bent body, by the limit of spacer pin and limit groove, slide are prevented to be detached from sliding rail, It is intended to the bow arm for assembling or being replaced to be placed in holding tank by opening, and between two gaskets, bowstring is located at bent body top, rotation Turn the fixing piece to protrude into and push compressed tablets in holding tank, bend arm using the compressed tablets and two gasket clamping positions, makes to bend arm and bow Body intersects to form crosswise, then slides the holding tank of slide closing bent body, with the combined hole of the external screw thread of spiro part and bent body The locking of internal screw thread spiro can will bend arm and bent body is assembled or completes the replacement of bow arm ".

Though above-mentioned Patent Case can solve inconvenience of the existing bent body with bow arm in assembly and disassembly, still there is its inconvenience Sharp place, the Patent Case need to first move back loose fixing piece and be detached from the holding tank of bent body and move back loose spiral shell during disassembly or assembling It ties after part is detached from the combined hole of bent body, sliding seat could be slided and open the holding tank of bent body, then be intended to the bow for assembling or separating Arm is taken out by holding tank or by opening merging holding tank, although in this way, eliminate it is previous it is existing need to through many and diverse assembling, Operation is dismantled, but unavoidably need to be through dismantling fixing piece with after spiro part, user just can be carried out assembling, replacement bow arm, For the place for still having it inconvenient on assembling, dismantling, therefore, how user is provided and more rapidly, easily assembles, dismantle bow arm And the combination of bent body needs related dealer further to think deeply, and how this to improve, improves and can more meet user's demand.

In view of said circumstances, the present inventor puts into many time study relevant knowledges, and is compared every superiority and inferiority, into The research and exploitation of row Related product, and after many experiments and test, and release a kind of " cross bow package assembly " finally Improve above-mentioned missing, to meet use needed for masses.

Summary of the invention

Technical problem underlying to be solved by this invention is, overcomes drawbacks described above of the existing technology, and provides one Kind of cross bends package assembly, will secure the holder to bend low through bolt, and enable fixing piece fast after bow arm is fixed on fixing piece The assembling of speed is dismantled in bent body tank, and achievees the purpose that quickly assembling, disassembly；It can quickly be assembled by fixing piece, dismantle bow The characteristic of body tank, and the bow arm for enabling assembling be fixed on fixing piece can quickly be assembled together with fixing piece, be dismantled, so that Cross bends volume itself and becomes smaller, and reaches and be convenient for carrying, do not take up space and facilitate the purpose of maintenance, adjustment, replacement bow arm.

The technical solution adopted by the present invention to solve the technical problems is:

A kind of cross bends package assembly comprising a bent body, a fixing piece and a bow arm, in which: the bent body has one the One end and a second end, and a tank is equipped between first end and second end, and the tank is equipped with close to the wall surface of first end One engaging slot；The fixing piece is laterally equipped with a receiving hole of fixed bow arm, and the corresponding outwardly extending convex block of engaging slot；Separately Convex block is screw-locked at a locking part and packing bow arm is supported in receiving hole hole wall with one end, and the bow arm is enabled to be fixed on the appearance of fixing piece It receives hole and spiral shell moves back locking part to loosen and compress packing to bow arm, and substitute, adjust the bow arm in the setting of receiving hole；It should Fixing piece is mounted on bent body tank, and wears group bent body and a fixing piece convex block with a bolt, is detached from bent body tank to limit fixing piece, And the bolt have a head and the whole body portion, the body portion side be equipped with a sliding slot, one first positioning it is recessed and one second positioning it is recessed, and First positioning it is recessed with the second positioning is recessed is located at sliding slot both ends, and further with certain hyte fastening screw in bent body；It should Bow installs a bowstring between arm both ends.

Wherein the bent body tank has an arcwall face and an inclined surface close to the wall surface of second end, and the engaging slot is close to first The wall surface at end has a snap-latch surface and an inclined-plane, and the fixing piece has an arc surface and an oblique surface, and the convex block has one Retaining surface and a scarf, the arc surface and oblique surface are correspondingly arranged in arcwall face and the inclined surface of fixing piece, and the retaining surface And scarf is also correspondingly arranged in the snap-latch surface and inclined-plane of fixing piece simultaneously.

Wherein the bent body is equipped with the perforation through engaging slot two sides cell wall, and wherein a cell wall top surface is equipped with the engaging slot A positioning hole, and the location hole is connected with perforation, and the convex block corresponds to engaging slot punch position equipped with a through-hole, and axially A perforation equipped with connection receiving hole, which is mounted on bent body tank, and wears group bent body perforation and a projection through hole with bolt, It is detached from bent body tank to limit fixing piece, and location hole is mounted on Fixed latches with the positioning group.

Wherein the positioning group include a fixed screw, an elastic component and a positioning bead, and the positioning group sequentially with positioning bead, Elastic component, fixed screw are set to location hole, and are screw-locked at location hole by the fixed screw to limit elastic component with positioning bead and take off From location hole, and the elastic component distinguishes butted positioning bead and fixed screw, and the positioning bead is enabled to be supported by elastic force and be positioned at first It is recessed to position recessed or the second positioning.

It is further provided with a first clamping piece and a second intermediate plate, the first clamping piece and second intermediate plate, which are respectively arranged to be located at, to be held Receive the two sides for bending arm in hole, and the locking part spiral shell group enables the second intermediate plate compel in perforation and in supporting second intermediate plate in receiving hole Tight bow arm and first clamping piece make the bow arm be fixed on the receiving hole of fixing piece in receiving hole hole wall.

Wherein the receiving hole of the fixing piece and perforation are inclined to set by scarf towards arc surface.

Wherein the arcwall face connects downwards inclined surface to tank slot bottom by tank notch, and the snap-latch surface is by engaging slot notch Connection inclined-plane to engaging slot slot bottom, the arc surface is somebody's turn to do by connection oblique surface downward at the top of fixing piece to fixing piece bottom downwards Retaining surface is by connecting downwards scarf to convex block bottom at the top of convex block.

The invention has the advantages that securing the holder to bend low through bolt after bow arm is fixed on fixing piece, enable Fixing piece can be assembled quickly, be dismantled in bent body tank, and achieved the purpose that quickly to assemble, be dismantled；It can be quick by fixing piece Assembling, the characteristic for dismantling bent body tank, and the bow arm for enabling assembling be fixed on fixing piece can quickly be assembled together with fixing piece, be torn open It unloads, becomes smaller so that cross bends volume itself, and reach and be convenient for carrying, do not take up space and facilitate maintenance, adjustment, replacement bow The purpose of arm.

Detailed description of the invention

Present invention will be further explained below with reference to the attached drawings and examples.

Fig. 1 is partially exploded diagram of the present invention.

Fig. 2 is that fixing piece of the present invention is intended to be assembled in the schematic diagram of bent body tank.

Fig. 3 is Three-dimensional combination diagram of the present invention.

Fig. 4 is fixing piece stereoscopic schematic diagram of the present invention.

Fig. 5 is another visual angle schematic diagram of fixing piece of the present invention.

Fig. 6 is the line VI -- VI section diagrammatic cross-section of Fig. 3.

Fig. 7 is the VII-VII line segment diagrammatic cross-section of Fig. 3.

Fig. 8 is the diagrammatic cross-section that the sliding of Fig. 5 bolt is positioned at second location hole.

Fig. 9 is the schematic diagram that fixing piece of the present invention installs that another size bends arm.

Figure label explanation:

It bends low 1 first end 11

12 tank 13 of second end

131 inclined surface 132 of arcwall face

133 snap-latch surface 1331 of engaging slot

The perforation of inclined-plane 1,332 14

15 fixing piece 2 of location hole

21 arc surface 22 of receiving hole

23 convex block 24 of oblique surface

241 scarf 242 of retaining surface

243 perforation 244 of through-hole

Bend 3 locking part 4 of arm

5 head 51 of bolt

52 sliding slot 521 of body portion

Recessed 522 second positioning recessed 523 of first positioning

6 fixed screw 61 of positioning group

62 positioning bead 63 of elastic component

7 first clamping piece 8 of bowstring

Second intermediate plate 9

Specific embodiment

It please refers to shown in Fig. 1 to Fig. 9, a kind of cross bow package assembly is shown in figure comprising 1, one fixing piece 2 of bent body An and bow arm 3, in which: the bent body 1 has a first end 11 and a second end 12, and sets between first end 11 and second end 12 There is a tank 13, and the tank 13 is equipped with an engaging slot 133 close to the wall surface of first end 11；2 side of fixing piece is to equipped with fixation Bend a receiving hole 21 of arm 3, and the corresponding outwardly extending convex block 24 of engaging slot 133；Convex block is separately screw-locked at a locking part 4 24 and with one end support packing bow arm 3 in 21 hole wall of receiving hole, enable the bow arm 3 be fixed on the receiving hole 21 and spiral shell of fixing piece 2 Locking part 4 is moved back to loosen and compress packing to bow arm 3, and substitutes, adjust the bow arm 3 in the setting of receiving hole 21；The fixing piece 2 It is mounted on 1 tank 13 of bent body, and group bent body 1 and 2 convex block 24 of fixing piece are worn with a bolt 5, is detached from bent body 1 to limit fixing piece 2 Tank 13, and the bolt 5 has a head 51 and the whole body portion 52, it is recessed which is equipped with a sliding slot 521, one first positioning 522 and one second positioning recessed 523, and first positioning recessed 522 positions with second and recessed 523 is located at 521 both ends of sliding slot, goes forward side by side One step is with certain 6 fastening screw 5 of hyte in bent body 1；A bowstring 7 is installed between 3 both ends of bow arm.

By above-mentioned, the present invention first penetrates in terms of assembling by fixing piece 2,1 tank 13 of bent body and the setting of bolt 5 Locking part 4 will bend after arm 3 is fixed on the receiving hole 21 of fixing piece 2, then by the tank 13 of the installation of fixing piece 2 to bent body 1, finally Bolt 5 is worn into group bent body 1 and 2 convex block 24 of fixing piece, and in terms of disassembly, 5 bottom end of bolt only need to be pushed against, enables the releasing pair of bolt 5 After the limitation of fixing piece 2, fixing piece 2 can be separated to 1 tank 13 of bent body, therefore, no matter the present invention is in the process of assembling, disassembly In be all not required to that the work of assembling, disassembly can be completed through complicated installation steps, for user, whether go out to take Band when being intended to carry out storage storage, can pass through above-mentioned demounting procedure i.e. and can reach and quickly dismantle, be convenient for carrying, saving space-efficient function Effect, and when user is intended in use, also can pass through above-mentioned assembling steps quickly carries out assembling use, furthermore, when user be intended into When substituting or being adjusted bow arm 3 of different bow 3 sizes of arm of row, also only needs to move back on 4 spiral shell of locking part and loosens supporting to bow arm 3 Compel next, can carry out quickly assembling and substitute, adjust, therefore the present invention can say it is a kind of quite to have practicability and progressive Invention.

It please refers to shown in Fig. 1 to Fig. 6, which is equipped with the perforation 14 through 133 two sides cell wall of engaging slot, and the card Closing slot 133, wherein a cell wall top surface is equipped with a positioning hole 15, and the location hole 15 is connected with perforation 14, and the convex block 24 is corresponding Engaging slot 133 perforates 14 positions equipped with a through-hole 243, and is axially arranged with a perforation 244 of connection receiving hole 21, the fixing piece 2 are mounted on 1 tank 13 of bent body, and wear 1 perforation 14 of group bent body and 24 through-hole 243 of convex block with bolt 5, to limit the disengaging of fixing piece 2 It bends low 1 tank 13, and location hole 15 is mounted on Fixed latches 5 with the positioning group 6, and the bolt 5 has a head 51 and one Body portion 52,52 side of body portion are equipped with a sliding slot 521, one first positioning recessed 522 and one second positioning recessed 523, and this is first fixed Position recessed 522 and the second positioning recessed 523 are located at 521 both ends of sliding slot, which includes a fixed screw 61, an elastic component 62 and a positioning bead 63, and the positioning group 6 is sequentially set to location hole 15 with positioning bead 63, elastic component 62, fixed screw 61, and Location hole 15 is screw-locked at by the fixed screw 61 to limit elastic component 62 and positioning bead 63 and be detached from location hole 15, and the elastic component 62 Butted positioning bead 63 and fixed screw 61 respectively enable the positioning bead 63 be supported by elastic force and be positioned at the first positioning recessed 522 or the Two positioning recessed 523 will first wear group in the perforation of bent body 1 and convex block when user is intended to separating fixing piece 2 into bent body tank 13 originally The bolt 5 of 24 through-holes 243 enables script positioning card be butted on the first positioning recessed 522 by headward 51 pushing and pressing in the bottom end in the body portion 52 Positioning bead 63 position of the second positioning recessed 523 is slid by sliding slot 521, position bolt 5 by the second positioning recessed 523 Fastening for pearl 63 is fallen without directly pusheding away from bent body 1, conversely, when user is intended to install fixing piece 2 to 1 tank 13 of bent body When, first fixing piece 2 is placed in 1 tank 13 of bent body and then enables 5 body portion 52 of bolt wear on pushing and pressing 5 head 51 of bolt 1 perforation 14 of bent body and 24 through-hole 243 of convex block, the positioning bead 63 for enabling script positioning card be butted on the second positioning recessed 523 are slided by sliding slot 521 The position for moving to the first positioning recessed 522 fastens bolt 5 without direct by positioning bead 63 by the first positioning recessed 522 It pushed away from bent body 1 to fall, therefore, the present invention slides and positioning card by the positioning bead 63 of positioning group 6 in the sliding slot 521 of bolt 5 Be butted on bolt 5 first positioning recessed 522 or second positioning it is recessed, no matter and enable user in assembling, disassembly during, the bolt 5 all without departing from bent body 1, and avoids the problem that bolt and fall to fall loss and generate (as shown in Figures 7 and 8).

It please refers to shown in Fig. 1 to Fig. 6, wherein 1 tank 13 of bent body has an arcwall face 131 close to the wall surface of second end 12 And an inclined surface 132, which has a snap-latch surface 1331 and an inclined-plane 1332 close to the wall surface of first end 11, and is somebody's turn to do Fixing piece 2 has an arc surface 22 and an oblique surface 23, and the convex block 24 has a retaining surface 241 and a scarf 242, the circle Cambered surface 22 and oblique surface 23 are correspondingly arranged in arcwall face 131 and the inclined surface 132 of fixing piece 2, and the retaining surface 241 and scarf 242 are also correspondingly arranged in the snap-latch surface 1331 and inclined-plane 1332 of fixing piece 2 simultaneously.

Connect by above-mentioned, the present invention by fixing piece 2 arc surface 22 it is corresponding with oblique surface 23 bent body 1 tank 13 arcwall face 131 with the setting of inclined surface 132, enable user in bend 7 (by 11 direction of first end towards 12 direction of second end), The active force of bend 7 then can be transferred to respectively arcwall face 131 and inclined surface 132 by arc surface 22 and oblique surface 23 backward, The transmitting of its active force is dispersed to bent body 1 by arcwall face 131 and inclined surface 132 again, and then reaches and increases intensity and stability Effect, and when user's pulloff fires, bowstring 7 is then by the elastic force pushing and pressing bow and arrow of itself rebound (by second end 12 directions are towards 11 direction of first end), by the retaining surface 241 of 2 convex block 24 of fixing piece 1 card of bent body corresponding with scarf 242 The setting of the snap-latch surface 1331 and inclined-plane 1332 of slot 133 is closed, and the active force that the elastic force of bowstring 7 itself is sprung back can be by fastening Face 241 and scarf 242 are transferred to snap-latch surface 1331 and inclined-plane 1332 respectively, then are made by snap-latch surface 1331 and inclined-plane 1332 Firmly transmitting is dispersed to bent body 1, and then reaches the effect of increasing intensity and stability, therefore, through arc surface 22, oblique surface 23, arcwall face 131, inclined surface 132, retaining surface 241, scarf 242, snap-latch surface 1331 and inclined-plane 1332 are correspondingly arranged, and are enabled User, can be by the work of above-mentioned state whether in the state of bend 7 or the state of pulloff percussion bow and arrow Firmly average dispersion is gone out, and can not only be reached except the effect of increasing intensity and stability, additionally it is possible to extend cross bow itself Service life.

It please refers to shown in Fig. 1 and Fig. 6, is further provided with a first clamping piece 8 and a second intermediate plate 9, the first clamping piece 8 and Two intermediate plates 9 are respectively arranged at the two sides for bending arm 3 in receiving hole 21, and the 4 spiral shell group of locking part is in perforation 244 and in receiving hole Second intermediate plate 9 is supported in 21, enables 9 packing of second intermediate plate bow arm 3 and first clamping piece 8 in 21 hole wall of receiving hole, and makes the bow arm 3 It is fixed on the receiving hole 21 of fixing piece 2, by the setting of first clamping piece 8 and second intermediate plate 9, is directly supported to avoid locking part 4 Arm 3 is bent in packing, and leads to the problem of and crush bow arm 3.

It please refers to shown in Fig. 6, the receiving hole 21 and perforation 244 of the fixing piece 2 are in incline towards arc surface 22 by scarf 242 Tiltedly setting.

It please refers to shown in Fig. 1, Fig. 4 and Fig. 5, which connects downwards inclined surface 132 to tank by 13 notch of tank 13 slot bottoms, and the snap-latch surface 1331 connects downwards inclined-plane 1332 to 133 slot bottom of engaging slot, the arc surface by 133 notch of engaging slot 22 by the downward connection oblique surface 23 in 2 top of fixing piece to 2 bottom of fixing piece, and the retaining surface 241 is connected downwards by 24 top of convex block Scarf 242 is connect to 24 bottom of convex block.

The above described is only a preferred embodiment of the present invention, be not intended to limit the present invention in any form, it is all It is any simple modification, equivalent change and modification to the above embodiments according to the technical essence of the invention, still falls within In the range of technical solution of the present invention.

In conclusion the present invention designs, in structure using on practicability and cost-effectiveness, complying fully with industry development institute It needs, and revealed structure is also to have unprecedented innovative structure, there is novelty, creativeness, practicability, meet related The regulation of invention patent requirement, therefore lift application in accordance with the law.

Claims

1. a kind of cross bends package assembly, which is characterized in that including a bent body, a fixing piece and a bow arm, in which:

The bent body has a first end and a second end, and a tank is equipped between first end and second end, and the tank leans on The wall surface of nearly first end is equipped with an engaging slot；

The fixing piece is laterally equipped with a receiving hole of fixed bow arm, and the corresponding outwardly extending convex block of engaging slot；Separately with one Locking part is screw-locked at convex block and supports packing bow arm in receiving hole hole wall with one end, and the bow arm is enabled to be fixed on the receiving of fixing piece Hole and spiral shell move back locking part to loosen and compress packing to bow arm, and substitute, adjust the bow arm in the setting of receiving hole；This is solid Determine part and be mounted on bent body tank, and group bent body and a fixing piece convex block are worn with a bolt, is detached from bent body tank to limit fixing piece, and The bolt has a head and a whole body portion, which is equipped with that a sliding slot, one first positioning is recessed and one second positioning is recessed, and is somebody's turn to do First positioning it is recessed with the second positioning is recessed is located at sliding slot both ends, and further with certain hyte fastening screw in bent body；

It is one bowstring of installation between the bow arm both ends；The bent body tank has an arcwall face and an inclination close to the wall surface of second end Face, which has a snap-latch surface and an inclined-plane close to the wall surface of first end, and the fixing piece has an arc surface and one tiltedly Guide face, and the convex block has a retaining surface and a scarf, the arc surface and oblique surface are correspondingly arranged in the arcwall face of fixing piece And inclined surface, and the retaining surface and scarf are also correspondingly arranged in the snap-latch surface and inclined-plane of fixing piece simultaneously.

2. cross according to claim 1 bends package assembly, which is characterized in that the bent body, which is equipped with, runs through engaging slot two sides One perforation of cell wall, and wherein a cell wall top surface is equipped with a positioning hole to the engaging slot, and the location hole is connected with perforation, and be somebody's turn to do Convex block corresponds to engaging slot punch position equipped with a through-hole, and is axially arranged with a perforation of connection receiving hole, which sets Group bent body perforation and a projection through hole are worn in bent body tank, and with bolt, is detached from bent body tank to limit fixing piece, and with the positioning Group is mounted on location hole with Fixed latches.

3. cross according to any one of claim 1 to 2 bends package assembly, which is characterized in that the positioning group includes One fixed screw, an elastic component and a positioning bead, and the positioning group is sequentially set to positioning bead, elastic component, fixed screw and is determined Position hole, and location hole is screw-locked to limit elastic component and positioning bead and be detached from location hole by the fixed screw, and the elastic component is distinguished Butted positioning bead and fixed screw, enable the positioning bead by elastic force support and be positioned at the first positioning it is recessed or second positioning it is recessed.

4. cross according to claim 3 bends package assembly, which is characterized in that be further provided with a first clamping piece and one the Two intermediate plates, the first clamping piece and second intermediate plate are respectively arranged at the two sides for bending arm in receiving hole, and the locking part spiral shell group in Perforation and in supporting second intermediate plate in receiving hole enables second intermediate plate packing bow arm and first clamping piece in receiving hole hole wall, and makes The bow arm is fixed on the receiving hole of fixing piece.

5. cross according to claim 4 bends package assembly, which is characterized in that the receiving hole of the fixing piece and perforation by Scarf is inclined to set towards arc surface.

6. cross according to claim 1 bends package assembly, which is characterized in that the arcwall face is connected downwards by tank notch Inclined surface is connect to tank slot bottom, and the snap-latch surface connects downwards inclined-plane to engaging slot slot bottom by engaging slot notch, the arc surface by At the top of fixing piece downwards connection oblique surface to fixing piece bottom, and the retaining surface by the top of convex block downwards connection scarf to convex block Bottom.

7. cross according to claim 5 bends package assembly, which is characterized in that the arcwall face is connected downwards by tank notch Inclined surface is connect to tank slot bottom, and the snap-latch surface connects downwards inclined-plane to engaging slot slot bottom by engaging slot notch, the arc surface by At the top of fixing piece downwards connection oblique surface to fixing piece bottom, and the retaining surface by the top of convex block downwards connection scarf to convex block Bottom.