CN219817746U - A pillar type mould moving arm for automatic mould changing - Google Patents

Abstract

The utility model relates to a pillar type mould moving arm for automatic mould changing, which comprises a supporting seat, a supporting plate, a roller assembly, a jack, a limit base, a front limit stop and a first locking piece, wherein a guide groove is formed in the supporting plate, the inner wall of the guide groove is wrapped with a buffer cushion, the limit base is slidably connected in the guide groove, two ends of the limit base extend out of the guide groove, the front limit stop is hinged to two sides, which are positioned outside the guide groove and are close to a machine tool end, of the limit base, the front limit stop can rotate up and down relative to the limit base, and the first locking piece is simultaneously connected with the limit base and the front limit stop. According to the technical scheme, the limiting base is used for providing direction guidance for the die during die replacement, so that the die can be kept to linearly move, the die can be ensured to be accurately and automatically moved into the working area of the machine tool, manual assistance of an operator is not needed in the whole process, the labor intensity can be further reduced, and the labor burden of the operator is effectively reduced.

Description

A pillar type mould moving arm for automatic mould changing

Technical Field

The utility model relates to the technical field of mould moving arms, in particular to a pillar type mould moving arm for automatic mould changing.

Background

The die shifting arm is a die replacing mechanical arm system which is specially used for replacing manual die replacing modes such as a manual forklift and a crane, and the die shifting arm is used for die replacing, so that rapid conveying and transferring of the die can be realized, complicated manual operation is avoided, labor intensity of operators is reduced, the die replacing time is shortened, and the production efficiency is improved.

The subordinate classification of the mould moving arm comprises a prop type mould moving arm, a detachable mould moving arm and a rotary mould moving arm, and the subordinate classification of the mould moving arm comprises a supporting plate, a driving wheel assembly and a supporting seat, wherein the supporting plate is connected with the side edge of a machine tool through the supporting seat, a driving wheel set is arranged on the supporting plate, the driving wheel set can rotate around a connecting position with the supporting plate, a mould to be transported is supported by the driving wheel set after being placed on the supporting plate, an operator pushes the mould, the driving wheel set can rotate at the moment, sliding friction can be converted into rolling friction under the action of the driving wheel set, the mould can be easily moved onto the machine tool, one end of the traditional prop type mould moving arm is connected with the supporting seat, the other end of the traditional prop type mould moving arm is connected with a supporting column, the two ends of the supporting column are kept horizontal, but the traditional prop type mould moving arm has the problem that the mould is still forced when the mould can only move horizontally along the supporting plate due to the horizontal state.

To this, chinese patent with publication No. CN212285581U, patent name "a mould moving arm" discloses a novel pillar mould moving arm, it includes the mould arm body, mould moving arm body upper surface is provided with a plurality of rotatory roller bearings of connecting, mould moving arm body includes the fixed arm and can around the rotatory lifting arm of vertical plane, the fixed arm is connected to the lifting arm, be provided with the waist hole on the lifting arm, the slip is provided with the bracing piece in the waist hole, the bracing piece bottom is provided with the jack, when the installation, will move the mould arm and install at the lathe lateral wall, when the retooling, through jack lifting arm, make mould moving arm body both ends appear the difference in height, under the action of gravity, can make the automatic direction slip of lathe of mould.

However, the strut type mould moving arm with the structure has the problems that the moving direction of the mould automatically moving along the mould moving arm body cannot be controlled, when the mould moving arm slides downwards, the mould moving arm cannot be kept to move linearly, the moving path of the mould moving arm easily deviates from the mould moving arm body, so that the mould cannot be directly moved to the working area of a machine tool, even the mould is dropped to be damaged, and in order to keep the mould moving linearly, operators are required to participate in manual assistance, the mould is huge, and the mould is not easy to be controlled by hands, so that the labor intensity is increased.

Disclosure of Invention

Aiming at the situation, in order to overcome the problems that the existing prop type mould moving arm capable of enabling the mould to automatically move onto the machine tool cannot keep linear movement, so that the mould cannot directly move onto the working area of the machine tool and even is damaged due to falling, and the labor intensity is increased due to the fact that an operator is needed to assist in the linear movement of the mould, the utility model aims to provide the prop type mould moving arm capable of enabling the mould to keep linear movement and accurately and automatically move onto the working area of the machine tool without manual assistance of the operator.

In order to achieve the above object, the technical solution of the present utility model is:

the utility model provides a pillar type mould shifting arm for automatic retooling, it includes the supporting seat, a supporting plate, roller assembly and jack, the supporting seat is located on the lathe, the both ends of supporting plate are articulated with the output of supporting seat and jack respectively, roller assembly locates in the backup pad, it still includes spacing base, preceding limit stop and first locking piece, the guide way has been seted up in the backup pad, the guide way inner wall parcel has the blotter, spacing base sliding connection is in the guide way, its both ends extend to outside the guide way, preceding limit stop articulates in spacing base and is located the guide way and is close to the both sides of lathe end, preceding limit stop can rotate about spacing base, and can bulge to the top of backup pad when rotating, first locking piece is connected with spacing base and preceding limit stop simultaneously, it is used for controlling preceding limit stop and switches under fixed and movable state.

Preferably, the front limit stop is located on the upper end surface of the limit base, a sinking groove opposite to the front limit stop is formed in the limit base, the front limit stop is embedded in the opposite sinking groove and hinged to the side wall of the sinking groove, the front limit stop can be embedded into the sinking groove through rotation, and the first locking piece penetrates through the limit base to be connected with the front limit stop in the sinking groove.

Preferably, the first locking member is threadedly coupled to the limit base, and is rotatably extended into the countersink and is opposite to the front limit stop.

Preferably, the cushion pad is made of rubber.

Preferably, the device further comprises a rear limit stop, wherein the rear limit stop is arranged on the limit base and is opposite to the front limit stop, and the rear limit stop is provided with a base connected with the limit base and a block arranged on the base.

Preferably, the device further comprises a second locking piece, wherein the block body of the rear limit stop is hinged with the base, can rotate up and down relative to the base and the limit base and can extend to the upper side of the supporting plate when rotating, and the second locking piece is connected with the base and the block body at the same time and is used for controlling the block body to switch between a fixed state and a movable state.

Preferably, one end of the second locking piece passes through the base of the rear limit stop to be abutted with the block body of the rear limit stop, and is in threaded connection with the base, and the second locking piece can be separated from the abutting position with the block body when rotating.

Preferably, the device further comprises a third locking piece, the limit base is provided with a chute opposite to the rear limit stop, the base of the rear limit stop is slidably connected in the chute, and the third locking piece is connected with the limit base and the base at the same time and is used for controlling the base to be switched between a fixed state and a movable state.

Preferably, the third locking piece is in threaded connection with the limit base, one end of the third locking piece penetrates into the sliding groove, a connecting pipe is arranged on the base of the rear limit stop, an annular front connecting block is arranged in the opening end of the connecting pipe, one end of the third locking piece, which is located in the sliding groove, penetrates into the connecting block, and a rear connecting block which abuts against the front connecting block is arranged.

Compared with the prior art, the utility model has the advantages that:

according to the utility model, when the supporting plate is lifted under the action of the jack, the die and the limit base slide under the action of gravity, the die placed on the supporting plate can be blocked by the front limit stop, the speed of the limit base sliding along the guide groove is smaller than the speed of the die sliding on the roller assembly under the action of the cushion, so that the die can always keep abutting with the front limit stop when sliding downwards, the die is prevented from being separated from the relative position of the limit base under the action of the front limit stop, the die pressure acts on the front limit stop, so that the limit base connected with the limit stop and the die can keep synchronous sliding, and the die and the front limit stop always keep abutting to realize synchronous linear movement with the limit base due to no relative movement, the limit base provides direction guide for the die, the problem of deviating from a linear path in the sliding process of the die is avoided, the whole process is ensured to be accurately slid into the working area of a machine tool, the labor intensity is prevented from being participated in manual assistance by operators, and the labor intensity of the operators can be further reduced, and the labor burden of the operators is effectively reduced.

Drawings

FIG. 1 is a schematic view of the overall structure of an embodiment 1 of a strut type shift arm of the present utility model;

FIG. 2 is an enlarged schematic view of the portion A of FIG. 1 according to the present utility model;

FIG. 3 is a schematic view of the overall structure of example 2 of the column-type shifting arm of the present utility model;

FIG. 4 is an enlarged schematic view of the structure of portion B of FIG. 3 according to the present utility model;

FIG. 5 is a schematic view showing the overall structure of an embodiment 3 of the column-type shifting arm of the present utility model;

FIG. 6 is an enlarged schematic view of the structure of portion C of FIG. 5 in accordance with the present utility model;

FIG. 7 is a schematic view showing the overall structure of a column-type shifting arm of embodiment 4 of the present utility model;

FIG. 8 is an enlarged schematic view of the structure of portion D of FIG. 7 in accordance with the present utility model;

fig. 9 is a schematic diagram showing the overall structure of the third locking member of embodiment 4 of the column type shifting arm of the present utility model.

As shown in the figure:

1. a support base; 2. a support plate; 201. a guide groove; 3. a roller assembly; 4. a jack; 5. a limit base; 501. sinking grooves; 502. a chute; 6. a front limit stop; 7. a first locking member; 8. a cushion pad; 9. a rear limit stop; 901. a base; 902. a block; 903. a connecting pipe; 904. a front connecting block; 10. a second locking member; 11. a third locking member; 1101. and a rear connecting block.

Detailed Description

The utility model will be described in further detail with reference to the drawings and the specific examples.

In the description of the present utility model, it should be noted that, directions or positional relationships indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on directions or positional relationships shown in the drawings, or directions or positional relationships in which the inventive product is conventionally put in use, are merely for convenience of description, and are not intended to indicate or imply that the directions are necessarily specific directions and specific direction configurations and operations, and thus should not be construed as limiting the present utility model.

Example 1:

as shown in fig. 1 and 2, the present utility model relates to a column type mold shifting arm for automatic mold changing, which comprises a supporting seat 1, a supporting plate 2, roller assemblies 3 and a jack 4 which are shared with a conventional column type mold shifting arm, wherein the supporting seat 1 is arranged on the side edge of a machine tool, the supporting plate 2 is composed of two sets of opposite plate bodies, the two plate bodies are fixed by a plurality of bolts, the two plate bodies are weighed away from a distance under the action of the bolts, a gap is formed between the two plate bodies, the roller assemblies 3 are arranged in the gap, the column type mold shifting arm is provided with a plurality of groups, each roller assembly 3 is composed of a roller and a rotating shaft, the roller is sleeved on the rotating shaft and can rotate around the rotating shaft, two ends of the rotating shaft are connected with the plate bodies on two sides, the upper end of the roller is configured to exceed the upper end face of the supporting plate 2, a part of the roller is exposed outside the gap between the two plate bodies, the jack 4 is arranged on one side far away from the machine tool and is opposite to the supporting seat 1, the two ends of the supporting plate 2 are respectively hinged with the output ends of the supporting seat 1 and the jack 4, when the jack 4 plunger moves, the supporting plate 2 can be lifted or lowered with one end connected with the supporting plate, the other end of the supporting plate 2 rotates around the connecting position with the supporting seat 1 during lifting and lowering, at the moment, an included angle is formed between the supporting plate 2 and the horizontal plane, the two ends of the supporting plate have a height difference, a die placed on the supporting plate 2 can automatically slide down to a machine tool under the action of gravity and the roller assembly 3, in order to keep a linear moving path when the die slides along the supporting plate 2, a limit base 5, a front limit stop 6 and a first locking piece 7 are additionally arranged, wherein the supporting plate 2 is provided with a guide groove 201 which penetrates through two sides of the supporting plate 2, more specifically, the guide groove 201 is positioned on two plate bodies forming the supporting plate 2, the guide grooves 201 on the two plate bodies relatively form a complete guide groove 201, the inner wall of the guide slot 201 is wrapped with a buffer pad 8, the limit base 5 passes through the guide slot 201 and is slidably connected in the guide slot 201, the buffer pad 8 is used for increasing the sliding friction force of the limit base 5 in the guide slot 201, two ends of the limit base 5 extend out of the guide slot 201, the front limit stop 6 is hinged to two sides of the limit base 5, which are positioned out of the guide slot 201 and are close to the machine tool end, the front limit stop 6 can rotate up and down relative to the limit base 5, it is understood that the rotation range of the front limit stop 6 is a space between a position parallel to the upper end surface and the lower end surface of the limit base 5 and a position disposed in the position, and along with the rotation, the rotation can be projected above the support plate 2, the part of the front limit stop 6, which is far away from the machine tool side, is used for placing a die to be transferred, slides the limit base 5 along the guide slot 201 after the die is placed on the support plate 2, and the front limit stop 6 is rotated to protrude above the supporting plate 2 until the front limit stop 6 is abutted against the mold, when the supporting plate 2 is lifted under the action of the jack 4, the mold and the limit base 5 slide under the action of gravity, the mold placed on the supporting plate 2 can be blocked by the front limit stop 6, under the action of the buffer cushion 8, the speed of the limit base 5 sliding down along the guide groove 201 is smaller than the speed of the mold sliding on the roller assembly 3, so that the mold can always keep abutting with the front limit stop 6 when sliding down, under the action of the front limit stop 6, the mold is prevented from being separated from the relative position with the limit base 5, the mold pressure acts on the front limit stop 6, so that the limit base 5 connected with the limit stop and the mold can keep synchronously sliding, and the mold and the front limit stop 6 always keep abutting to realize synchronous linear movement with the limit base 5 due to no relative movement, the direction guide is provided for the die through the limit base 5, the problem that a linear path is deviated in the sliding process of the die is avoided, the die can be ensured to slide to the working area of the machine tool accurately, meanwhile, the whole process is free of manual assistance of operators, the labor intensity can be further reduced, the labor burden of the operators is reduced more effectively, the first locking piece 7 is simultaneously connected with the limit base 5 and the front limit stop 6 and is used for controlling the front limit stop 6 to switch in a fixed state and a movable state, when the limit base 5 reaches the maximum moving stroke, the front limit stop 6 can rotate freely through controlling the first locking piece 7, at the moment, the front limit stop 6 can rotate to the lower direction of the supporting plate 2 automatically under the action of the die pressure, and after the blocking of the front limit stop 6 is released, the die can slide to the working area of the machine tool accurately.

As shown in fig. 1 and 2, the positive limit stop 6 is located on the upper end surface of the limit base 5, a sink 501 opposite to the positive limit stop 6 is provided on the limit base 5, the positive limit stop 6 is embedded in the opposite sink 501 and hinged to the side wall of the sink 501, the positive limit stop 6 is rotatably embedded in the sink 501, the first locking member 7 penetrates through the limit base 5 to the sink 501 and is connected with the positive limit stop 6, when the positive limit stop rotates into the sink 501, the positive limit stop can be completely separated from the die placed on the support plate 2, i.e. separated from the contact position, so as to avoid obstructing the moving path of the die, when the limit base 5 reaches the maximum moving stroke, the die can smoothly slide onto the machine tool, and meanwhile, the damage of the die pressure to the positive limit stop 6 is greatly reduced.

As shown in fig. 1 and 2, the first locking member 7 is screwed to the limit base 5, and is rotatably extended into the sink 501 and is opposite to the front limit stopper 6, the first locking member 7 is rotatably adjustable to a length of a portion extending into the sink 501, when the length of the portion of the first locking member 7 located in the sink 501 is zero, no blocking object is present on the rotation path of the front limit stopper 6, at this time, normal rotation of the front limit stopper 6 can be realized, and when the first locking member 7 penetrates into the sink 501, rotation of the front limit stopper 6 can be blocked, so that the rotation angle is maintained, and locking is realized.

Further, the cushion pad 8 wrapped on the inner wall of the guide groove 201 of the support plate 2 is made of rubber.

Example 2:

as shown in fig. 3 and 4, this embodiment is an optimized design based on the above embodiment 1, and the pillar type mold shifting arm of the present utility model further includes a rear limit stop 9, wherein the rear limit stop 9 is disposed on the limit base 5 and is opposite to the front limit stop 6, the rear limit stop 9 has a base 901 connected to the limit base 5 and a block 902 disposed on the base 901, and the rear limit stop 9 is used to cooperate with the front limit stop 6 to form front and rear clamping for the mold placed on the support plate 2, so that the mold can be more stably kept moving synchronously with the limit base 5, and the mold is prevented from being separated from the relative position with the limit base 5 from the rear side.

Example 3:

as shown in fig. 5 and 6, this embodiment is an optimized design based on the above embodiment 2, the post-type mold shifting arm of the present utility model further includes a second locking member 10, wherein the block 902 of the rear limit stop 9 is hinged to the base 901, and can rotate up and down relative to the base 901 and the limit base 5, and can extend above the support plate 2 when rotating, and the second locking member 10 is connected to the base 901 and the block 902 for controlling the block 902 to switch between a fixed and a movable state, and based on the above arrangement, when the mold is to be placed on the support plate 2, the block 902 of the rear limit stop 9 can be rotated by controlling the second locking member 10 and rotated to a position below an upper end surface of the support plate 2, at this time, the mold is placed on the support plate 2, the contact with the rear limit stop 9 can be avoided, the rear limit stop 9 is prevented from breaking under a huge pressure, and after the mold is placed, the second locking member 10 is rotated again, the block 902 of the rear limit stop 9 is made to fit with the placed mold, and then the front limit stop 6 is clamped together.

As shown in fig. 5 and 6, one end of the second locking member 10 passes through the base 901 of the rear limit stop 9 to be in contact with the block 902 thereof, and is in threaded connection with the base 901, the second locking member 10 can be disengaged from the contact position with the block 902 when rotated, the second locking member 10 locks the block 902 of the rear limit stop 9 by applying pressure to the block 902, when the second locking member 10 is screwed, the pressure applied to the block 902 is maximized, at this time, the block 902 cannot rotate around the connection position with the base 901, and when the second locking member 10 is disengaged from the contact position with the block 902, the block 902 can freely rotate.

Example 4:

as shown in fig. 7 and 8, an optimized design is made on the basis of the above embodiment 3, the pillar type mold shifting arm of the present utility model further includes a third locking member 11, a chute 502 opposite to the rear limit stop 9 is provided on the limit base 5, the base 901 of the rear limit stop 9 is slidably connected to the chute 502, the third locking member 11 is simultaneously connected to the limit base 5 and the base 901, which is used for controlling the base 901 to switch between a fixed state and a movable state, the slidable rear limit stop 9 can avoid the blocking of the rotation path of the block 902 when the mold is placed on the support plate 2, and only the rear limit stop 9 is required to be moved to a position not opposite to the mold through the base thereof, so that the block 902 can smoothly rotate above the support plate 2, and then the front limit stop 6 clamps the mold together, and the above arrangement enables the spacing between the front limit stop 6 and the rear limit stop 9 to be adjustable, so that the molds of different sizes placed on the support plate 2 can be clamped.

As shown in fig. 7 to 9, the third locking piece 11 is screwed with the limit base 5, and one end of the third locking piece is penetrated into the chute 502, and it should be mentioned that in the present utility model, the third locking piece 11 is parallel to the length direction of the chute 502, that is, the third locking piece is introduced from one end of the chute 502, the base 901 of the rear limit stop 9 is provided with the connecting pipe 903, the opening end of the connecting pipe 903 is internally provided with the annular front connecting block 904, one end of the third locking piece 11 located in the chute 502 penetrates into the connecting block, and is provided with the rear connecting block 1101 which abuts against the front connecting block 904, the third locking piece 11 abuts against the front connecting block 904 in the connecting pipe 903 from the inside and outside through the rear connecting block 1101, so that dislocation from the connecting pipe 903 can be avoided, and when the third locking piece 11 rotates, the connecting block 901 and the base 902 can be prevented from synchronously rotating, and when the third locking piece 11 rotates, the length of the third locking piece located in the chute 502 changes, and the rear limit stop 9 can be driven to move.

In combination with embodiments 1 to 4 and referring to fig. 1 to 9, when the pillar type movable arm with direction guide of the present utility model is used to transfer a mold, under the condition that the mold is placed on the supporting plate 2, the first locking member 7 is rotated first to disengage from the rotation path of the front limit stop 6, then the front limit stop 6 is rotated to the upper position of the supporting plate 2, then the first locking member 7 is rotated to lock the front limit stop 6 at the rotation angle, then the limit base 5 is moved along the guiding groove 201 until the front limit stop 6 contacts with the mold, then the third locking member 11 is rotated to drive the base 901 of the connected rear limit stop 9 to slide in the sliding groove 502 until the rear limit stop 9 is disengaged from the relative position of the upper mold, then the second locking member 10 is rotated to disengage from the abutting position of the block 902 of the rear limit stop 9, the block 902 is ensured to be able to freely rotate, the block 902 is rotated to the upper position of the supporting plate 2, then the second locking member 10 is rotated again to keep the rotation angle, then the top 4 is controlled to slide down to the position of the supporting plate 2, the two sides of the top limit stop 5 can slide down to the side of the mold, and the pressure of the top of the machine tool can be controlled to disengage from the upper limit stop 5 when the top end of the mold is reached to the upper limit stop 5, and the pressure difference can be controlled to slide down to the side of the upper limit stop 5 accurately, and the position of the top end of the supporting plate can slide down to the mold can slide down to the die down to the position down.

The foregoing embodiments and description have been provided merely to illustrate the principles and best modes of carrying out the utility model, and various changes and modifications can be made therein without departing from the spirit and scope of the utility model as defined in the appended claims.

Claims (9)

1. The utility model provides a pillar type mould shifting arm for automatic retooling, it includes supporting seat (1), backup pad (2), roller assembly (3) and jack (4), on the lathe was located to supporting seat (1), the both ends of backup pad (2) are articulated with the output of supporting seat (1) and jack (4) respectively, on backup pad (2) are located to roller assembly (3), its characterized in that, it still includes limit base (5), positive limit stop (6) and first locking piece (7), guide slot (201) have been seted up on backup pad (2), guide slot (201) inner wall parcel has blotter (8), limit base (5) sliding connection is in guide slot (201), and its both ends extend outside guide slot (201), positive limit stop (6) are articulated in limit base (5) and are located the both sides of guide slot (201) and are close to the lathe end, positive limit stop (6) can rotate down relative limit base (5) to can be when rotating protrusion to backup pad (2) top, first locking piece (7) and positive limit stop (6) and fixed limit stop (6) are used for under the fixed state (6) and the same time.

2. The prop type mould moving arm for automatic mould changing according to claim 1, wherein the front limit stop (6) is located on the upper end face of the limit base (5), a sinking groove (501) opposite to the front limit stop (6) is formed in the limit base (5), the front limit stop (6) is embedded in the opposite sinking groove (501) and hinged to the side wall of the sinking groove (501), the front limit stop (6) can be rotationally embedded in the sinking groove (501), and the first locking piece (7) penetrates through the limit base (5) to the sinking groove (501) to be connected with the front limit stop (6).

3. A post-transfer arm for automatic mold change according to claim 2, characterized in that the first locking member (7) is screwed with a limit base (5) which extends into the countersink (501) by rotation and is opposite to the front limit stop (6) in front and rear.

4. A post-transfer arm for automatic mold change according to claim 1, characterized in that the material of the cushion pad (8) is rubber.

5. A post-transfer arm for automatic mold changing according to claim 1, characterized in that it further comprises a rear limit stop (9), said rear limit stop (9) being provided on the limit base (5) opposite to said front limit stop (6), said rear limit stop (9) having a base (901) connected to the limit base (5) and a block (902) provided on the base (901).

6. A prop-type mould-moving arm for automatic mould-changing according to claim 5, characterized in that it further comprises a second locking member (10), the block (902) of the rear limit stop (9) being hinged to the base (901), being rotatable up and down in relation to the base (901) and limit base (5), and being extendable above the support plate (2) upon rotation, the second locking member (10) being connected to both the base (901) and the block (902) for controlling the switching of the block (902) in fixed and movable conditions.

7. A post-transfer arm for automatic mold change according to claim 6, characterized in that one end of the second locking member (10) is abutted against its block (902) through the base (901) of the rear limit stop (9) and is screwed to the base (901), and the second locking member (10) is rotatable out of abutment with the block (902).

8. The prop type moving arm for automatic mold changing according to claim 6, further comprising a third locking member (11), wherein the limit base (5) is provided with a chute (502) opposite to the rear limit stopper (9), the base (901) of the rear limit stopper (9) is slidably connected to the chute (502), and the third locking member (11) is connected to both the limit base (5) and the base (901) and is used for controlling the base (901) to switch between a fixed state and a movable state.

9. The prop type moving arm for automatic mold changing according to claim 8, wherein the third locking piece (11) is in threaded connection with the limit base (5), one end of the third locking piece penetrates into the sliding groove (502), a connecting pipe (903) is arranged on the base (901) of the rear limit stop (9), an annular front connecting block (904) is arranged in the opening end of the connecting pipe (903), and one end of the third locking piece (11) located in the sliding groove (502) penetrates into the connecting block and is provided with a rear connecting block (1101) propped against the front connecting block (904).