CN210236873U

CN210236873U - Lifting appliance for belt forming die

Info

Publication number: CN210236873U
Application number: CN201920904797.6U
Authority: CN
Inventors: Yiyi Ruan; 阮益谊; Yanfeng Jiang; 蒋燕峰; Jian Hang; 杭舰; Yang Shen; 沈阳; Jianguang Kong; 孔建光; Xiangjun Zhong; 钟祥均
Original assignee: Zhejiang Acron Power Transmission System Co ltd
Current assignee: Zhejiang Acron Power Transmission System Co ltd
Priority date: 2019-06-17
Filing date: 2019-06-17
Publication date: 2020-04-03
Anticipated expiration: 2029-06-17

Abstract

The utility model discloses a lifting appliance for a belt forming die, which comprises a forming die and a lifting appliance, wherein a cavity is arranged in the forming die, the cavity comprises an upper cavity, an inclined part and a lower cavity, the lifting appliance comprises a lock catch, the lower end of the lock catch is connected with two fixed plates, a mounting plate is embedded between the two fixed plates, two ends of the mounting plate are clamped with a rotating block, the rotating block comprises a plug board and a connecting part, one end of the plug board is hinged on the mounting plate, the other end of the mounting plate is provided with a contraction hole or an expansion hole at intervals, the connecting part is fixedly connected with a fixed rod, the lower end of the fixed rod is provided with a positioning rod, a spring sleeved on the positioning rod is arranged between the first fixed block and the connecting part, one end of the spring is provided with a compression block, the lower part of the mounting plate is connected, through the arrangement, the forming die can be conveniently carried, and the carrying process is safe and convenient to operate.

Description

Lifting appliance for belt forming die

Technical Field

The utility model relates to a technical field of lifting claw, in particular to a hoist for belt forming die.

Background

The forming mould for the agricultural machine belt is generally adopted in the production and processing process of the existing agricultural machine belt, the forming mould is generally made of iron with heavier weight, and the carrying of the forming mould is mainly carried out by two ways at present, namely, 1, carrying by using a carrying trolley manually, on one hand, the forming mould is carried to the carrying trolley by staff, which wastes time and labor, and on the other hand, the forming mould is easy to cause industrial injury due to falling of the forming mould in the carrying engineering; 2. carry through the bridge type crane, through installation magnet on this bridge type crane to make this forming die adsorbed by magnet, and then forming die carries under the bridge type crane pulls, but if the power failure situation appears in handling the condition will certainly lead to the fact serious consequence.

In summary, the carrying manner described above affects the carrying efficiency of the forming mold, and further affects the production efficiency of the agricultural machinery belt, so a device for carrying the forming mold needs to be designed urgently.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a hoist for belt forming die, simple structure can conveniently carry forming die, and the handling is comparatively safe and convenient operation, and then can improve the production efficiency in agricultural machinery area.

The above technical purpose of the present invention can be achieved by the following technical solutions: a lifting appliance for a belt forming die comprises a forming die and a lifting appliance used for clamping the forming die, wherein a cavity penetrating through the upper end face and the lower end face of the forming die is formed in the forming die, the cavity comprises an upper cavity, an inclined part with a narrow upper part and a lower cavity from top to bottom, the lifting appliance comprises a lock catch used for connecting a lifting machine, a flat part is arranged at the lower end of the lock catch, two ends of the flat part are respectively connected with two fixing plates arranged at intervals, a mounting plate is embedded between the two fixing plates, one end of the mounting plate is hinged to the fixing plates at two sides through a first fixing pin to form a first hinge end, and one end of the mounting plate, relative to the first hinge end, is connected to the fixing plates at two;

the two ends of the mounting plate are clamped with rotating blocks, each rotating block comprises a plug board attached to two ends of the mounting plate and a connecting part for connecting the two plug boards, the connecting part is positioned on one side close to the first hinged end, one end, far away from the connecting part, of each plug board is hinged to the mounting plate through a third fixing pin to form a second hinged end, one end, far away from the second hinged end, of each mounting plate is provided with a contraction hole or an expansion hole at intervals, the contraction holes are positioned at the upper ends of the expansion holes, the connecting parts are fixedly connected with fixing rods, the fixing rods are provided with first fixing blocks and second fixing blocks which are arranged at intervals, the lower ends of the first fixing blocks and the second fixing blocks are provided with positioning rods capable of sliding along the length direction of the fixing rods, the connecting parts are provided with transition holes capable of enabling the positioning rods to extend into the contraction holes, one end of the spring, which is close to the connecting part, is provided with a compression block, and a handle on the positioning rod is tensioned to separate the positioning rod from the contraction hole or the expansion hole, so that the connecting part can rotate by taking the second hinged end as a fulcrum, and the positioning rod can be switched to be ejected into the contraction hole or the expansion hole;

the lower part of the mounting plate is connected with a connecting disc, the center of the connecting disc is provided with a center hole, a center shaft which can slide up and down along the center hole is arranged in the center hole, the upper end of the central shaft extends to the plug board, the middle part of the plug board is provided with a strip-shaped groove which penetrates through the two plug boards, a fourth fixing pin for hinging the central shaft with the flashboards at the two sides is arranged in the strip-shaped groove, the lower end of the connecting disc is provided with a jointing part, at least three groups of lifting claws which are uniformly distributed in the circumferential direction by taking the central shaft as the axis are hinged in the connecting part, the lower end of the central shaft is provided with a cone part, the inner end of the lifting claw is provided with a guide part matched with the pyramid part, the outer end of the lifting claw is convexly provided with a clamping part with a narrow outside and a wide inside, when the positioning rod extends into the shrinkage hole at the upper end of the mounting plate, the central shaft retracts upwards along the central hole to enable the lifting claw to be folded under the action of gravity, and then the lifting claw can extend into a cavity of a forming die; when the positioning rod extends into the expansion hole at the lower end of the mounting plate, the central shaft downwards extrudes the hanging claws along the central hole so that the hanging claws radially outwards expand, and then the clamping part tightly abuts against the inclined part of the forming die.

Further, still include the mistake proofing device, the mistake proofing device is including welding in the only locking strip of fixed plate outer end and welding in the only locking piece on the picture peg, only locking mouth has been seted up to the lower extreme of only locking strip, be equipped with the only locking portion with only locking mouth cooperation locking on the only locking piece.

Furthermore, the two fixing plates are provided with elongated slots at one ends opposite to the first hinged ends, the elongated slots respectively penetrate through the two fixing plates, and second fixing pins for hinging the mounting plate to the fixing plates are arranged in the elongated slots.

Furthermore, the mounting plate and one end of the connecting disc, which is close to the elongated slot, are provided with connecting screws, and the two connecting screws are connected through a damping spring.

Furthermore, a rectangular groove penetrating through the end face of the second fixing block is formed in the second fixing block, a guide block in clearance fit with the rectangular groove is arranged on the positioning rod, the two ends of the guide block are respectively connected with the positioning rod and the handle, and a placement groove in clearance fit with the positioning rod is formed in the first fixing block.

Furthermore, the connection part is provided with a limiting block for limiting the extension angle of the hanging claw, and the limiting block is circumferentially arranged at the lower end of the connection part by taking the central shaft as an axis.

Further, a circular truncated cone-shaped groove convenient for extending the lifting claw into the cavity is formed in the upper end of the forming die, and the lower end of the circular truncated cone-shaped groove extends to the upper cavity.

Furthermore, chamfers which are convenient for extending the lifting claws into the cavity are arranged at the lower ends of the lifting claws.

To sum up, the utility model discloses following beneficial effect has:

the utility model provides a hoist for belt forming die, the top of three groups above lifting claw of this hoist is established at the center pin under, the clamping part of lifting claw all outwards expands and the cooperation chucking of the oblique part on the forming die to make and carry forming die, concrete operation as follows: in the shrinkage cavity was arranged in to the handle on the taut locating lever, the chamfer of lifting claw lower extreme got into forming die's cavity along round platform type recess, breaks away from the switching to stretching into the expansion downthehole with the locating lever from the shrinkage cavity, and the center pin is crowded lifting claw downwards so that the lifting claw is with radial outside extension, and then makes the card head tightly support in forming die's slope portion, carries forming die to required position through bridge type crane at last.

Drawings

Fig. 1 is a front view of a spreader of the present invention;

FIG. 2 is an enlarged view of the utility model at A;

fig. 3 is a schematic structural diagram of the spreader of the present invention;

fig. 4 is a schematic view of an assembly structure of the fixing plate and the mounting plate of the present invention;

fig. 5 is a schematic view of an assembly structure of the mounting plate and the rotating block of the present invention;

FIG. 6 is an enlarged view of the utility model at B;

fig. 7 is a schematic structural view of the fixing rod of the present invention;

fig. 8 is a schematic structural view of the rotating block of the present invention;

fig. 9 is a schematic structural view of the hanging claw of the present invention when it is folded;

fig. 10 is a schematic structural view of the expanded lifting claw of the present invention;

fig. 11 is a schematic structural view of the forming die of the present invention;

fig. 12 is a sectional view of the molding die of the present invention.

In the figure: 1. forming a mold; 11. a cavity; 111. an upper cavity; 112. a bevel portion; 113. a lower cavity; 12. a truncated cone-shaped groove; 2. a spreader; 21. locking; 211. a flat portion; 22. a fixing plate; 221. a locking bar; 222. a locking notch; 223. a long groove; 23. mounting a plate; 231. a first fixing pin; 232. a first hinged end; 233. a second fixing pin; 234. a connecting screw; 235. a damping spring; 236. a shrink hole; 237. an expanding hole; 24. rotating the block; 241. inserting plates; 2411. a third fixing pin; 2412. a second hinged end; 2413. a strip-shaped groove; 2414. a locking block; 2415. a locking portion; 242. a connecting portion; 2421. a transition hole; 25. fixing the rod; 251. a first fixed block; 252. a second fixed block; 253. a rectangular groove; 254. a guide block; 255. a placing groove; 26. positioning a rod; 261. a spring; 262. compressing the block; 263. a handle; 3. a connecting disc; 31. a central bore; 32. a central shaft; 321. a fourth fixing pin; 322. a pyramid part; 33. a joining section; 331. a limiting block; 34. a lifting claw; 341. chamfering; 342. a guide portion; 343. and a clamping part.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1-12, a hoist for belt forming die, includes forming die 1 and is used for the chucking forming die 1's hoist 2, set up the cavity 11 that runs through forming die 1 up and down the terminal surface in the forming die 1, cavity 11 top-down includes upper cavity 111, narrow down wide slant 112 and cavity 113 down, hoist 2 is including being used for connecting the hasp 21 of crane, the lower extreme of hasp 21 is equipped with flat portion 211, the both ends of flat portion 211 are connected with two fixed plates 22 that the interval set up respectively, inlays between two fixed plates 22 and is equipped with mounting panel 23, the one end of mounting panel 23 articulates in the fixed plate 22 of both sides in order to form first articulated end 232 through first fixed pin 231, and mounting panel 23 passes through the second fixed pin for the one end of first articulated end 232 and connects in the fixed plate 22 of both sides.

The two ends of the mounting plate 23 are provided with rotating blocks 24 in a clamped manner, each rotating block 24 comprises an inserting plate 241 attached to the two ends of the mounting plate 23 and a connecting part 242 connecting the two inserting plates 241, the connecting part 242 is positioned on one side close to the first hinged end 232, one end of the inserting plate 241 far away from the connecting part 242 is hinged to the mounting plate 23 through a third fixing pin 2411 to form a second hinged end 2412, one end of the mounting plate 23 far away from the second hinged end 2412 is provided with a contraction hole 236 or an expansion hole 237 at an interval, the contraction hole 236 is positioned at the upper end of the expansion hole 237, the connecting part 242 is fixedly connected with a fixing rod 25, the fixing rod 25 is provided with a first fixing block 251 and a second fixing block 252 at an interval, the lower ends of the first fixing block 251 and the second fixing block 252 are provided with a positioning rod 26 capable of sliding along the length direction of the fixing rod 25, the connecting part 242 is provided with an excessive hole, a spring 261 sleeved on the positioning rod 26 is arranged between the first fixing block 251 and the connecting portion 242, a compression block 262 is arranged at one end of the spring 261 close to the connecting portion 242, and a handle 263 on the positioning rod 26 is pulled to separate the positioning rod 26 from the contraction hole 236 or the expansion hole 237, so that the connecting portion 242 can rotate with the second hinged end 2412 as a fulcrum, and the positioning rod 26 can be switched to be pushed into the contraction hole 236 or the expansion hole 237.

The sub-unit connection of mounting panel 23 has connection pad 3, centre bore 31 has been seted up at the center of connection pad 3, install the center pin 32 that can follow centre bore 31 and slide from top to bottom in the centre bore 31, the upper end of center pin 32 extends to picture peg 241, the middle part of picture peg 241 is seted up and is run through two picture pegs 241 strip groove 2413, be equipped with the fourth fixed pin 321 that articulates center pin 32 in both sides picture peg 241 in strip groove 2413, the lower extreme of connection pad 3 is equipped with linking portion 33, it has at least three groups to use center pin 32 as the lifting claw 34 of axle center circumference equipartition to articulate in linking portion 33, the lower extreme of center pin 32 is equipped with pyramis 322, the inner of lifting claw 34 is equipped with the guide portion 342 with 322 matched with, the protruding chucking portion 343 that is equipped with outer narrow inside width in the outer end of lifting claw 34, when locating bar 26 stretched into the shrinkage cavity 236 of mounting panel 23 upper end, center pin 32 upwards retracts so that, the hanging claws 34 can extend into the cavity 11 of the forming die 1; when the positioning rod 26 extends into the expanding hole 237 at the lower end of the mounting plate 23, the central shaft 32 pushes the hanging claws downward along the central hole 31 to expand the hanging claws 34 radially outward, so that the clamping part 343 is pressed against the inclined part 112 of the forming die 1.

The utility model provides a hoist for belt forming die, still includes the mistake proofing device, the mistake proofing device is including welding in the only locking strip 221 of fixed plate 22 outer end and welding in the only locking piece 2414 on picture peg 241, only locking mouth 222 has been seted up to the lower extreme of only locking strip 221, only be equipped with on the only locking piece 2414 with only locking mouth 222 cooperation locking portion 2415.

On one hand, one end of the positioning rod 26 close to the expanding hole 237 is worn under long-term operation, and when the wear reaches a certain degree, the positioning rod 26 cannot tightly abut against the inner end of the expanding hole 237, so that the forming die 1 is separated from the lifting claw 34 in the carrying process and falls, and further serious consequences are caused; on the other hand, when the positioning rod 26 does not extend into the extension hole 237 to lift the molding die 1, there is also a risk that the molding die 1 falls down during transportation. By arranging the error-proofing device, when the positioning rod 26 is worn to a certain degree or the positioning rod 26 does not extend into the expanding hole 237, the forming die 1 is lifted, and the locking parts 2415 on the locking blocks 2414 are all clamped in the locking openings 222 on the locking strips 221, so that the purpose of error proofing is achieved.

When the locking portion 2415 is engaged with the locking opening 222, the positions of the fixing plate 22 and the mounting plate 23 can be adjusted through the elongated slot 223 on the fixing plate 22, so that the locking portion 2415 is disengaged from the locking opening, and if one end of the positioning rod 26 close to the expanding hole 237 is seriously worn, the positioning rod 26 needs to be replaced.

The two fixing plates 22 have elongated slots 223 at one end thereof opposite to the first hinge end 232, the elongated slots 223 respectively penetrate through the two fixing plates 22, and second fixing pins for hinging the mounting plate 23 to the fixing plates 22 are disposed in the elongated slots 223.

The mounting plate 23 and one end of the connecting disc 3 close to the elongated slot 223 are both provided with a connecting screw 234, the two connecting screws 234 are connected through a damping spring 235, the connecting screw 234 is provided with a positioning ring for positioning the damping spring 235, when the hanging claw 34 does not extend into the cavity 11 and collides with the forming die 1, the mounting plate 23 and the fixing plate 22 can achieve the purpose of buffering through the manner of movably connecting the mounting plate 23 and the fixing plate 22 through the elongated slot 223 and the damping spring 235 sleeved on the connecting screw 234, so that the collision degree of the mounting plate 23 and the fixing plate 22 is reduced, and the service life of the hanging claw 34 is prolonged.

The second fixing block 252 is provided with a rectangular groove 253 penetrating through the end face of the second fixing block 252, the positioning rod 26 is provided with a guide block 254 in clearance fit with the rectangular groove 253, two ends of the guide block 254 are respectively connected with the positioning rod 26 and the handle 263, the first fixing block 251 is provided with a placement groove 255 in clearance fit with the positioning rod 26, and through the arrangement, the positioning rod 26 can be abutted against the inner end of the contraction hole 236 or the expansion hole 237 under the elastic force action of the spring 261.

The engagement portion 33 is provided with a limit block 331 for limiting the extension angle of the lifting claw 34, the limit block 331 is circumferentially arranged at the lower end of the engagement portion 33 by taking the central shaft 32 as an axis, and the lifting claw 34 is prevented from swinging back and forth when extending out of the cavity 11 by the limit block 331 so as to avoid injuring an operator due to overlarge swinging amplitude of the lifting claw 34.

The upper end of the forming die 1 is provided with a truncated cone-shaped groove 12 which is convenient for extending the hanging claw 34 into the cavity 11, and the lower end of the truncated cone-shaped groove 12 extends to the upper cavity 111; the lower ends of the lifting claws 34 are provided with chamfers 341 which are convenient for the lifting claws 34 to extend into the cavity 11, and the arrangement is favorable for extending more than three groups of lifting claws 34 into the cavity 11 of the forming die 1 together.

The utility model discloses a basic operating principle does:

a hanger for belt forming mold, more than three groups of hanging claws 34 of the hanger 2 are arranged at the top of a central shaft 32, the clamping parts 343 of the hanging claws 34 are all expanded outwards to be matched and clamped with the inclined parts 112 on the forming mold 1, so as to convey the forming mold 1, the operation is as follows: the handle 263 on the positioning rod 26 is pulled tightly to place the positioning rod 26 in the shrinkage hole 236, the chamfer 341 at the lower end of the hanging claw 34 enters the cavity 11 of the forming die 1 along the circular truncated cone-shaped groove 12, the positioning rod 26 is separated from the shrinkage hole 236 and switched to extend into the expansion hole 237, the central shaft 32 pushes the hanging claw downwards to enable the hanging claw 34 to expand outwards in a radial manner, the clamping part 343 is tightly abutted to the inclined part 112 of the forming die 1, and finally the forming die 1 is carried to a required position through a bridge crane.

The above is only the preferred embodiment of the present invention, so all the equivalent changes or modifications made by the structure, features and principles in accordance with the claims of the present invention are included in the claims of the present invention.

Claims

1. The utility model provides a hoist for belt forming die, includes forming die (1) and is used for the chucking hoist (2) of forming die (1), its characterized in that: the lifting appliance comprises a forming die (1), and is characterized in that a cavity (11) penetrating through the upper end face and the lower end face of the forming die (1) is formed in the forming die (1), the cavity (11) comprises an upper cavity (111), an inclined part (112) with a narrow upper part and a wide lower part and a lower cavity (113) from top to bottom, the lifting appliance (2) comprises a lock catch (21) used for connecting a lifting machine, a flat part (211) is arranged at the lower end of the lock catch (21), two ends of the flat part (211) are respectively connected with two fixing plates (22) arranged at intervals, a mounting plate (23) is embedded between the two fixing plates (22), one end of the mounting plate (23) is hinged to the fixing plates (22) on two sides through a first fixing pin (231) to form a first hinged end (232), and one end of the mounting plate (23) relative to the first;

the both ends card of mounting panel (23) is equipped with rotatory piece (24), rotatory piece (24) are including laminating in picture peg (241) at mounting panel (23) both ends and connecting portion (242) of connecting two picture pegs (241), connecting portion (242) are located the one side of being close to first hinged end (232), the one end that connecting portion (242) were kept away from in picture peg (241) articulates in mounting panel (23) through third fixed pin (2411) in order to form second hinged end (2412), the one end interval that second hinged end (2412) were kept away from in mounting panel (23) is equipped with shrink hole (236) or expansion hole (237) just shrink hole (236) are located the upper end of expansion hole (237), fixedly connected with dead lever (25) are gone up in connecting portion (242), be equipped with first fixed block (251) and second fixed block (252) that the interval set up on dead lever (25), first fixed block (251) are equipped with the lower extreme of second fixed block (252) and can follow dead lever (25) length direction and slide The movable positioning rod (26), a transition hole (2421) which can enable the positioning rod (26) to extend into the contraction hole (236) or the expansion hole (237) is formed in the connecting portion (242), a spring (261) which is sleeved on the positioning rod (26) is arranged between the first fixing block (251) and the connecting portion (242), a compression block (262) is arranged at one end, close to the connecting portion (242), of the spring (261), a handle (263) is arranged at each of the fixing rod (25) and one end, far away from the connecting portion (242), of the positioning rod (26), the handle (263) on the positioning rod (26) is tensioned to enable the positioning rod (26) to be separated from the contraction hole (236) or the expansion hole (237), so that the connecting portion (242) can rotate by taking the second hinged end (2412) as a fulcrum, and the positioning rod (26) can be switched to be pushed into the contraction hole (236;

the sub-unit connection of mounting panel (23) has connection pad (3), centre bore (31) have been seted up at the center of connection pad (3), install center pin (32) that can slide from top to bottom along centre bore (31) in centre bore (31), the upper end of center pin (32) extends to picture peg (241), strip groove (2413) that run through two picture pegs (241) are seted up at the middle part of picture peg (241), be equipped with in strip groove (2413) and articulate center pin (32) in fourth fixed pin (321) of both sides picture peg (241), the lower extreme of connection pad (3) is equipped with linking portion (33), articulated in linking portion (33) have at least three groups use center pin (32) as hanging claw (34) of axle center circumference equipartition, the lower extreme of center pin (32) is equipped with pyramis (322), the inner of hanging claw (34) is equipped with pyramis (342) matched with pyramis direction portion (322), the outer end of the lifting claw (34) is convexly provided with a clamping part (343) which is narrow outside and wide inside, when the positioning rod (26) extends into a contraction hole (236) at the upper end of the mounting plate (23), the central shaft (32) retracts upwards along the central hole (31) to enable the lifting claw (34) to be folded under the action of gravity, and then the lifting claw (34) can extend into the cavity (11) of the forming die (1); when the positioning rod (26) extends into the expanding hole (237) at the lower end of the mounting plate (23), the central shaft (32) extrudes the hanging claws downwards along the central hole (31) so that the hanging claws (34) expand outwards in a radial shape, and the clamping part (343) is tightly abutted to the inclined part (112) of the forming die (1).

2. A spreader for a belt molding die as claimed in claim 1, wherein: still include the mistake proofing device, the mistake proofing device is including welding in only locking strip (221) of fixed plate (22) outer end and welding in only locking piece (2414) on picture peg (241), only fore shaft (222) have been seted up to the lower extreme of only locking strip (221), only be equipped with on locking piece (2414) with only fore shaft (222) cooperation locking part (2415) of locking.

3. A spreader for a belt molding die as claimed in claim 1, wherein: the two fixing plates (22) are provided with long grooves (223) relative to one end of the first hinged end (232), the long grooves (223) penetrate through the two fixing plates (22) respectively, and second fixing pins (233) which enable the mounting plates (23) to be hinged to the fixing plates (22) are arranged in the long grooves (223).

4. A spreader for a belt molding die as claimed in claim 3, wherein: and the mounting plate (23) and one end of the connecting disc (3) close to the long groove (223) are both provided with connecting screws (234), and the two connecting screws (234) are connected through a damping spring (235).

5. A spreader for a belt molding die as claimed in claim 1, wherein: the positioning device is characterized in that a rectangular groove (253) penetrating through the end face of the second fixing block (252) is formed in the second fixing block (252), a guide block (254) in clearance fit with the rectangular groove (253) is arranged on the positioning rod (26), two ends of the guide block (254) are respectively connected with the positioning rod (26) and the handle (263), and a placing groove (255) in clearance fit with the positioning rod (26) is formed in the first fixing block (251).

6. A spreader for a belt molding die as claimed in claim 1, wherein: the connection part (33) is provided with a limit block (331) for limiting the expansion angle of the hanging claw (34), and the limit block (331) is circumferentially arranged at the lower end of the connection part (33) by taking the central shaft (32) as an axis.

7. A spreader for a belt molding die as claimed in claim 1, wherein: the upper end of the forming die (1) is provided with a circular truncated cone-shaped groove (12) which is convenient for extending the lifting claw (34) into the cavity (11), and the lower end of the circular truncated cone-shaped groove (12) extends to the upper cavity (111).

8. A spreader for a belt molding die as claimed in claim 1, wherein: the lower ends of the lifting claws (34) are provided with chamfers (341) which are convenient for extending the lifting claws (34) into the cavity (11).