CN207057294U - Band claw hollow cylinder and withdrawing pattern seat - Google Patents

Abstract

The utility model provides a kind of band claw hollow cylinder and withdrawing pattern seat, is related to metal drawing equipment technical field, cylinder body, hollow piston, deck, claw and the claw reset assembly of both ends open are included with claw hollow cylinder；Deck is provided with the first through hole passed through for bar, deck includes connecting portion and function part, connecting portion is affixed with hollow piston, the side wall of function part is provided with multiple second through holes, claw is set in the second through hole, claw reset assembly and claw are affixed, can make claw towards in the through hole of end face retraction second of first through hole；Claw can contact away from the end face of first through hole with the inwall of cylinder body, claw is stretched out the second through hole by relative movement of the hollow piston in cylinder body towards the end face of first through hole and clamp the bar stretched into first through hole.Alleviate be used to clamp and convey on withdrawing pattern seat in the prior art bar device stability it is low, easily occur because of insufficient clamping force bar can not undergauge, in turn result in the technical problem of low production efficiency.

Description

Band claw hollow cylinder and withdrawing pattern seat

Technical field

Metal drawing equipment technical field is the utility model is related to, in particular to a kind of band claw hollow cylinder and is pulled out Die holder.

Background technology

Drawbench is for draw ferrous and nonferrous metals bar material under normal temperature and the tubing after hot rolling, extruding is carried out The machine of secondary operation, it is that production is small-bore, accurate, thin-walled, the main process apparatus of high-mechanical property tubing, prior art During the specific draw steel pipe of drawbench, bar is penetrated in the endoporus of withdrawing pattern seat first, restart pretension cylinder, make screw die pressure bar Material, then promoting bar, until withdrawing pattern seat is stretched out in bar one end, now drawn-car clamps bar and stretched out by undergauge mould One end, master cylinder start start draw.

It is that screw die pressure bar material is directly controlled by cylinder in the prior art, to the clamping force of bar depending on cylinder drives Screw die to the pressure of bar, and bar is carried out when preliminary undergauge is handled be also by the frictional force between screw die and bar come The thrust advanced is provided, now the requirement to cylinder is higher, it is desirable to provide enough thrusts, screw die and bar otherwise occurs Relative situation about sliding, and then influence production efficiency；In addition, cylinder directly controls the structural stability of screw die activity low, hold very much Broken down easily as long-time uses, equally influence production efficiency, it is impossible to meet the needs of user.

Utility model content

The purpose of this utility model is to provide a kind of band claw hollow cylinder and withdrawing pattern seat, to alleviate withdrawing pattern in the prior art On seat be used for clamp and convey bar device stability it is low, easily occur because of insufficient clamping force bar can not undergauge, and then Cause the technical problem of low production efficiency.

The utility model provides a kind of band claw hollow cylinder, including the sky that the cylinder body of both ends open and cylinder body are slidably connected It is indecisive and changeable plug, deck, claw and claw reset assembly；

The deck is provided with the first through hole passed through for bar, and the deck includes connecting portion and function part, the connection Portion and the hollow piston are affixed, and the side wall of the function part is provided with multiple second through holes, and the claw is set in described second In through hole, the claw reset assembly and the claw are affixed, and the claw can be made to be contracted towards the end face of the first through hole Enter in second through hole；

The claw can contact away from the end face of the first through hole with the inwall of the cylinder body, make multiple claws Described second can be stretched out towards the end face of the first through hole by relative movement of the hollow piston in the cylinder body Through hole simultaneously clamps the bar stretched into the first through hole.

Further；Also include fixing nut, the connecting portion include the first hollow cylinder that end face is connected with each other and Second hollow cylinder, first hollow cylinder can pass through the hollow piston, second hollow cylinder it is straight Footpath is more than the internal diameter of the hollow piston, and less than the external diameter of the hollow piston, first hollow cylinder stretches out the sky The lateral wall of one end of plug of being indecisive and changeable is provided with external screw thread, and the fixing nut can be by being threadedly coupled with the external screw thread.

Further；The function part is open circles stage body, the end face of the smaller external diameter of open circles stage body and described the End face of two hollow cylinders away from first hollow cylinder is connected with each other, and second through hole is distributed in described in a ring In the side wall of open circles stage body, the claw can be reciprocal along the radial direction of the open circles stage body in second through hole Slide.

Further；The function part includes open circles stage body and ring-type fixing plate, the smaller external diameter of open circles stage body The end face of end face and second hollow cylinder away from first hollow cylinder be connected with each other, the ring-type fixing plate Second through hole is collectively constituted by the end face for being detachably secured to the larger external diameter of open circles stage body.

Further；The one side of the claw towards the larger outer-diameter end face of open circles stage body is provided with screwed hole, described Screwed hole internal thread is fixed with bolt, and the nut of the bolt is against the inner face of the ring-type fixing plate.

Further；The claw reset assembly includes back-moving spring and L-shaped bar, and the lateral wall of the open circles stage body is set There are multiple accommodating chambers, the accommodating chamber is set around the claw, and the back-moving spring is arranged in the accommodating chamber；

One end of the L-shaped bar and the claw side wall are affixed, the other end towards the accommodating chamber and with the reset bullet Spring is affixed.

Further；The claw at least three, each claw are correspondingly provided with six back-moving springs and six The individual L-shaped bar.

Further；The claw towards the end face of the first through hole be with the bar coordinate arcwall face.

The utility model also provides a kind of withdrawing pattern seat, including band claw hollow cylinder as described above.

Further；The band claw hollow cylinder is hollow hydraulic jack, and the stroke of the hollow hydraulic jack is 5- 7cm。

Relative to prior art, having the beneficial effect that with claw hollow cylinder and withdrawing pattern seat provided by the utility model：

Band claw hollow cylinder provided by the utility model, deck are fixedly connected by connecting portion with hollow piston, its function Portion is provided with multiple the second through holes for being used to be arranged claw, and now, function part is located fully or partially in the accommodating chamber of cylinder body, is ensured Claw can contact away from the end face of first through hole with the inwall of cylinder body, and then when needing claw to clamp bar, hollow piston Moved relative to cylinder body to a direction, also opposing cylinder moves function part therewith, and the inwall of cylinder body can extrude claw entrance First through hole, and then clamp the bar stretched into first through hole；And when needing to unclamp bar, hollow piston opposite direction is moved Dynamic, claw has the trend departed from inboard wall of cylinder block away from the end face of first through hole, now claw reset assembly by claw towards the The end face of one through hole by the through hole of first through hole retraction second, also make claw away from first through hole end face and inboard wall of cylinder block always Contact, not only facilitates next bar to stretch into first through hole, also ensure that the high efficiency and uniformity for clamping bar next time.

In above process, it is the extrude clamping force that is formed to bar of the inboard wall of cylinder block to claw, it is logical that claw stretches into first Hole and after clamping bar, now, cylinder body and claw can not carry out relative motion again, as drive device persistently drives bar to carry out Undergauge processing, inboard wall of cylinder block can be gradually increased the extruding to claw, and then claw is had bigger clamping force to bar, further Ensure that the stable of bar is conveyed, further, since deck, claw and claw reset assembly are all located at the interior of cylinder body substantially Portion, the interference in the external world, therefore working stability are little affected by, service life length, ensure that the production efficiency to bar withdrawing pattern.

The technical advantage of withdrawing pattern seat provided by the utility model is identical with the above-mentioned technical advantage with claw hollow cylinder, herein Repeat no more.

Brief description of the drawings

, below will be right in order to illustrate more clearly of the utility model embodiment or technical scheme of the prior art The required accompanying drawing used is briefly described in embodiment or description of the prior art, it should be apparent that, describe below In accompanying drawing be some embodiments of the present utility model, for those of ordinary skill in the art, do not paying creativeness On the premise of work, other accompanying drawings can also be obtained according to these accompanying drawings.

Fig. 1 is a kind of structural representation with claw hollow cylinder that the utility model embodiment provides；

Fig. 2 is another structural representation with claw hollow cylinder that the utility model embodiment provides；

Fig. 3 is the structural representation for the deck with claw hollow cylinder that the utility model embodiment provides；

Fig. 4 is the deck with claw hollow cylinder, claw and the claw reset assembly that the utility model embodiment provides Dimensional structure diagram；

Fig. 5 is the enlarged drawing of A in Fig. 4；

Fig. 6 is the claw dimensional structure diagram with claw hollow cylinder that the utility model embodiment provides.

Icon：1- cylinder bodies；2- hollow pistons；3- decks；4- fixing nuts；5- claws；6- ring-type fixing plates； 7- bolts；8- claw reset assemblies；31- first through hole；The through holes of 32- second；The hollow cylinders of 33- first；34- second Hollow cylinder；35- open circles stage bodies；51- arcwall faces；81-L shape bars；82- back-moving springs.

Embodiment

The technical solution of the utility model is clearly and completely described below in conjunction with accompanying drawing, it is clear that described Embodiment is the utility model part of the embodiment, rather than whole embodiments.Based on the embodiment in the utility model, sheet The every other embodiment that field those of ordinary skill is obtained under the premise of creative work is not made, belongs to this practicality Novel protected scope.

, it is necessary to explanation in description of the present utility model, term " " center ", " on ", " under ", it is "left", "right", " perpendicular Directly ", the orientation of the instruction such as " level ", " interior ", " outer " or position relationship are based on orientation shown in the drawings or position relationship, are only Described for the ease of description the utility model and simplifying, rather than instruction or imply signified device or element must have it is specific Orientation, with specific azimuth configuration and operation, therefore it is not intended that to limitation of the present utility model.In addition, term " the One ", " second ", " the 3rd " are only used for describing purpose, and it is not intended that instruction or hint relative importance.

, it is necessary to which explanation, unless otherwise clearly defined and limited, term " are pacified in description of the present utility model Dress ", " connected ", " connection " should be interpreted broadly, for example, it may be it is affixed or be detachably connected, or integratedly connect Connect；Can be mechanical connection or electrical connection；Can be joined directly together, can also be indirectly connected by intermediary, can To be the connection of two element internals.For the ordinary skill in the art, above-mentioned term can be understood with concrete condition Concrete meaning in the utility model.

Fig. 1 is a kind of structural representation with claw hollow cylinder that the utility model embodiment provides；Fig. 2 is that this practicality is new Another structural representation with claw hollow cylinder that type embodiment provides；Fig. 3 is the band card that the utility model embodiment provides The structural representation of the deck of pawl hollow cylinder；Fig. 4 is the deck with claw hollow cylinder, the claw that the utility model embodiment provides And the dimensional structure diagram of claw reset assembly；Fig. 5 is the enlarged drawing of A in Fig. 4；Fig. 6 carries for the utility model embodiment The claw dimensional structure diagram with claw hollow cylinder supplied.

Embodiment one

As shown in Figure 1, Figure 2 and shown in Fig. 4, the utility model embodiment provides a kind of band claw hollow cylinder, including both ends are opened The cylinder body 1 of mouth, hollow piston 2, deck 3, claw 5 and the claw reset assembly 8 being slidably connected with cylinder body 1；Deck 3, which is provided with, to be supplied The first through hole 31 that bar passes through, deck 3 include connecting portion and function part, and connecting portion and hollow piston 2 are affixed, the side of function part Wall is provided with multiple second through holes 32, and claw 5 is set in the second through hole 32, and claw reset assembly 8 and claw 5 are affixed, can make Claw 5 is towards in the second through hole of end face retraction 32 of first through hole 31；Claw 5 can be with cylinder body away from the end face of first through hole 31 1 inwall contact, enables relative shifting of multiple claws 5 towards the end face of first through hole 31 by hollow piston 2 in cylinder body 1 It is dynamic to stretch out the second through hole 32 and clamp the bar stretched into first through hole 31.

The band claw hollow cylinder that the utility model embodiment provides, deck 3 is fixed by connecting portion and hollow piston 2 to be connected Connect, its function part is provided with multiple the second through holes 32 for being used to be arranged claw 5, and now, function part is located fully or partially at cylinder body 1 In accommodating chamber, ensure that claw 5 can contact away from the end face of first through hole 31 with the inwall of cylinder body 1, and then working as needs claw 5 to press from both sides During tight bar, hollow piston 2 moves relative to cylinder body 1 to a direction, and also opposing cylinder 1 moves function part therewith, cylinder body 1 Inwall can extrude claw 5 and enter first through hole 31, and then clamp the bar stretched into first through hole 31；And working as needs to unclamp rod During material, the opposite direction of hollow piston 2 is moved, claw 5 has the trend departed from the inwall of cylinder body 1 away from the end face of first through hole 31, Now claw reset assembly 8 by claw 5 towards the end face of first through hole 31 by the second through hole of retraction 32 of first through hole 31, also making Claw 5 is permanently connected to away from the end face of first through hole 31 with the inwall of cylinder body 1, not only facilitates next bar to stretch into first through hole 31, It also ensure that the high efficiency and uniformity for clamping bar next time.

In above process, it is that the inwall of cylinder body 1 extrudes the clamping force formed to bar to claw 5, claw 5 stretches into first Through hole 31 and after clamping bar, now, cylinder body 1 and claw 5 can not carry out relative motion again, as drive device continues driving rod Material carries out undergauge processing, and the inwall of cylinder body 1 can be gradually increased the extruding to claw 5, and then claw 5 is had bigger clamping to bar Power, it further ensure that and the stable of bar conveyed, further, since deck 3, claw 5 and claw reset assembly 8 are substantially all Positioned at the inside of cylinder body 1, the interference in the external world, therefore working stability are little affected by, service life length, ensure that to bar withdrawing pattern Production efficiency.

Specifically, it is described below for the concrete structure with claw hollow cylinder in the present embodiment：

As shown in Figure 1 to Figure 3, the present embodiment also includes fixing nut 4, and connecting portion includes the first sky that end face is connected with each other The hollow cylinder 34 of heart cylinder 33 and second, the first hollow cylinder 33 can pass through hollow piston 2, the second hollow cylinder 34 diameter is more than the internal diameter of hollow piston 2, and less than the external diameter of hollow piston 2, the first hollow cylinder 33 stretches out hollow piston 2 The lateral wall of one end be provided with external screw thread, fixing nut 4 can be by being threadedly coupled with external screw thread.

The both ends open of hollow piston 2 for the hollow cylinder that the present embodiment provides, is fixedly connected in hollow piston 2 with connecting portion Afterwards, the first through hole 31 in connecting portion and the cavity of hollow piston 2 need concentric setting, i.e. connecting portion and the phase of hollow piston 2 To fixation, and then ensure, when bar original diameter and first through hole 31 are smaller, bar will not occur because of the relatively hollow work of connecting portion Plug 2 rocks and can not insert first through hole 31.Therefore, in the present embodiment, the external diameter of the first hollow cylinder 33 is equal to or omited Less than the internal diameter of hollow piston 2, after ensureing the first hollow cylinder 33 insertion hollow piston 2 and being fixed by fixing nut 4, two Person is relatively fixed substantially.

Further, since hollow piston 2 is located inside cylinder body 1, and fixing nut 4 is to be close to fixation with hollow piston 2, is Hollow piston 2 is not influenceed relative to the movable of cylinder body 1, and the maximum outside diameter of fixing nut 4 is set again smaller than hollow piston 2 External diameter.

Further, as shown in figure 4, it is open circles stage body 35 that the present embodiment, which also sets up function part, open circles stage body 35 is smaller The end face of external diameter is connected with each other with end face of second hollow cylinder 34 away from the first hollow cylinder 33, and the second through hole 32 is in ring Shape is distributed in the side wall of open circles stage body 35, and claw 5 can be in the second through hole 32 along the radial direction of open circles stage body 35 Reciprocatingly slide.

Specifically, hollow cavity and the above-mentioned hollow cylinder 34 of first hollow cylinder 33 and second in open circles stage body 35 The first through hole 31 that hollow cavity diameter is identical and all concentric setting, collectively constitutes deck 3, it is preferred that cylinder body 1 is arranged hollow The section chambers of round estrade 35 are also truncated conical shape, and it is to match somebody with somebody with the inwall of cylinder body 1 to be also provided with claw 5 away from the end face of first through hole 31 The arc of conjunction, so that the end face of claw 5 is bonded with cylinder body 1, cylinder body 1 is set to be relatively moved relative to open circles stage body 35 and by claw 5 When being pushed into first through hole 31, evenly, both contact position friction texturizings are few, are further ensured that both uses for the stress of claw 5 Life-span.

Further, it is hollow as shown in Fig. 2 function part can also be set to include open circles stage body 35 and ring-type fixing plate 6 The end face of 35 smaller external diameter of round estrade is connected with each other with end face of second hollow cylinder 34 away from the first hollow cylinder 33, ring Shape fixed plate 6 collectively constitutes second through hole 32 by being detachably secured to the end face of 35 larger external diameter of open circles stage body.

Now, claw 5 is from the top of the second through hole 32 except can take out, can also by by ring-type fixing plate 6 from sky After being removed on heart round estrade 35, taken out from along the axis direction of first through hole 31, now, when needing to change claw 5, without will be whole Individual deck 3 takes out from cylinder body 1 removes claw 5 again, only need to dismantle ring-type fixing plate 6, convenient and swift.

Specifically, as shown in Fig. 2 the present embodiment sets ring-type fixing plate 6 and the company of being bolted of open circles stage body 35 Connect.

Claw 5 in the present embodiment is the elongate in shape that both ends of the surface are small one and large one, it is difficult to clamps, and due to itself and second The fitting contact of through hole 32, along with the reason such as get rusty, claw 5 is difficult to be taken out from the second through hole 32.In order to avoid claw 5 is difficult to take Situation about going out, on the basis of the above, the one side that the present embodiment also sets up claw 5 towards 35 larger outer-diameter end face of open circles stage body are set There is screwed hole, screwed hole internal thread is fixed with bolt 7, and the nut of bolt 7 is against the inner face of ring-type fixing plate 6.

During normal work, bolt 7 moves back and forth together with claw 5；And when needing to dismantle claw 5, kept off by annular After plate dismounting, staff can be fixed by socket the nut of bolt 7, Ran Houzai by clamps such as pipe wrench or by latch closure Go into overdrive, you can easily take out claw 5 at the second through hole 32.

Further, as shown in Figure 4 and Figure 5, the present embodiment sets claw reset assembly 8 to include back-moving spring 82 and L-shaped Bar 81, the lateral wall of open circles stage body 35 are provided with multiple accommodating chambers, and accommodating chamber is set around claw 5, and back-moving spring 82 is arranged on In the accommodating chamber；One end of L-shaped bar 81 and the side wall of claw 5 are affixed, the other end towards accommodating chamber and with the back-moving spring 82 It is affixed.

Back-moving spring 82 compresses stress when claw 5 is clamped to bar, and when unclamping bar, back-moving spring 82 Thrust resets claw 5, and the stroke of whole process is small, and passes through multiple collective effects of back-moving spring 82, the work of back-moving spring 82 It is also low to make intensity, and then makes the working stability of claw reset assembly 8, service life is longer, meets the needs of user.

In addition, the present embodiment sets claw 5 at least three, each claw 5 is correspondingly provided with six back-moving springs 82 and six Individual L-shaped bar 81, wherein, the back-moving spring 82 and L-shaped bar 81 of supporting setting are separately positioned on the both sides of claw 5, and relative claw 5 Correspond, ensure that frictional force when claw 5 resets between uniform force, with the inwall of the second through hole 32 is smaller.

As shown in fig. 6, also set up claw 5 towards the end face of first through hole 31 be with bar coordinate arcwall face 51.

On the basis of at least three claws 5 are set, claw 5 and tubular bar contact area are bigger, Jin Erjing Frictional force is also bigger, further ensures the clamping dynamics to bar, while it also avoid claw 5 and the shadows such as deformation are caused to bar Ring.

It is noted that the present embodiment is the analysis carried out by taking cylindrical bar as an example, for such as polygonal cylinder shape Bar, can be correspondingly arranged the claw 5 of varying number, and set claw 5 towards the end face of first through hole 31 be other shapes Shape, no longer repeat one by one herein.

Embodiment two

The utility model embodiment provides a kind of withdrawing pattern seat, including band claw hollow cylinder as described above.

Specifically, with claw hollow cylinder, one end of the connecting portion of deck 3 is towards the charging aperture of withdrawing pattern seat, function part band One end of claw 5 and ensures first through hole 31 and charging aperture and the concentric setting of necking towards the necking of stem reducing mould.This When, hollow piston 2 is to unclamp bar towards the movement of stem reducing mould direction, is to clamp bar towards the movement of charging aperture direction.

Further, it is hollow hydraulic jack that the present embodiment, which sets band claw hollow cylinder, and the stroke of hollow hydraulic jack For 5-7cm.

Hydraulic cylinder is compared to cylinder, and its stroke is stable, and power is bigger, and when the mass of deck 3 is larger, its reaction is cleverer It is quick quick, more it is not easy to go wrong in withdrawing pattern seat Automated condtrol.

In addition, by controlling hollow piston 2, in the case where stroke is 5-7cm, claw 5 can be completed to clamp and unclamp The operation of bar, so, not only reduce the volume of whole hollow cylinder, save cost of manufacture, also reduce the operation of the step Time, improve to bar undergauge or the efficiency stretched.

Finally it should be noted that：Various embodiments above is only to illustrate the technical solution of the utility model, rather than it is limited System；Although the utility model is described in detail with reference to foregoing embodiments, one of ordinary skill in the art should Understand：It can still modify to the technical scheme described in foregoing embodiments, either to which part or whole Technical characteristic carries out equivalent substitution；And these modifications or replacement, the essence of appropriate technical solution is departed from this practicality newly The scope of each embodiment technical scheme of type.

Claims (10)

1. a kind of band claw hollow cylinder, it is characterised in that the cylinder body (1) including both ends open, the sky being slidably connected with cylinder body (1) It is indecisive and changeable plug (2), deck (3), claw (5) and claw reset assembly (8)；

The deck (3) is provided with the first through hole (31) passed through for bar, and the deck (3) includes connecting portion and function part, institute State connecting portion and the hollow piston (2) is affixed, the side wall of the function part is provided with multiple second through holes (32), the claw (5) it is set in second through hole (32)；

The claw reset assembly (8) and the claw (5) are affixed, can make the claw (5) towards the first through hole (31) in the second through hole (32) described in end face retraction；

The claw (5) can contact away from the end face of the first through hole (31) with the inwall of the cylinder body (1), make multiple institutes State the phase that claw (5) can be by the hollow piston (2) in the cylinder body (1) towards the end face of the first through hole (31) To mobile stretching second through hole (32) and clamp the bar stretched into the first through hole (31).

2. band claw hollow cylinder according to claim 1, it is characterised in that also including fixing nut (4), the connecting portion The first hollow cylinder (33) and the second hollow cylinder (34) being connected with each other including end face, first hollow cylinder (33) hollow piston (2) can be passed through, the diameter of second hollow cylinder (34) is more than the hollow piston (2) Internal diameter, less than the external diameter of the hollow piston (2), first hollow cylinder (33) stretches out the one of the hollow piston (2) The lateral wall at end is provided with external screw thread, and the fixing nut (4) can be by being threadedly coupled with the external screw thread.

3. band claw hollow cylinder according to claim 2, it is characterised in that the function part is open circles stage body (35), The end face of the smaller external diameter of the open circles stage body (35) is with second hollow cylinder (34) away from first hollow cylinder The end face of body (33) is connected with each other, and second through hole (32) is distributed in the side wall of the open circles stage body (35) in a ring, The claw (5) can reciprocatingly slide in second through hole (32) along the radial direction of the open circles stage body (35).

4. band claw hollow cylinder according to claim 2, it is characterised in that the function part includes open circles stage body (35) With ring-type fixing plate (6), the end face of the smaller external diameter of the open circles stage body (35) and second hollow cylinder (34) are remote The end face of first hollow cylinder (33) is connected with each other, and the ring-type fixing plate (6) is by being detachably secured to the sky The end face of heart round estrade (35) larger external diameter collectively constitutes second through hole (32).

5. band claw hollow cylinder according to claim 4, it is characterised in that the claw (5) is towards the hollow round table The one side of body (35) larger outer-diameter end face is provided with screwed hole, and the screwed hole internal thread is fixed with bolt (7), the bolt (7) Nut be against the inner faces of the ring-type fixing plate (6).

6. the band claw hollow cylinder according to claim 3 or 4, it is characterised in that the claw reset assembly (8) includes multiple Position spring (82) and L-shaped bar (81), the lateral wall of the open circles stage body (35) are provided with multiple accommodating chambers, and the accommodating chamber surrounds The claw (5) is set, and the back-moving spring (82) is arranged in the accommodating chamber；

One end of the L-shaped bar (81) and the claw (5) side wall are affixed, the other end towards the accommodating chamber and with the reset Spring (82) is affixed.

7. band claw hollow cylinder according to claim 6, it is characterised in that the claw (5) at least three, Mei Gesuo State claw (5) and be correspondingly provided with six back-moving springs (82) and six L-shaped bars (81).

8. band claw hollow cylinder according to claim 7, it is characterised in that the claw (5) is towards the first through hole (31) end face is the arcwall face (51) coordinated with the bar.

9. a kind of withdrawing pattern seat, it is characterised in that including the band claw hollow cylinder as any one of claim 1-8.

10. withdrawing pattern seat according to claim 9, it is characterised in that the band claw hollow cylinder is hollow hydraulic jack, and The stroke of the hollow hydraulic jack is 5-7cm.