Concrete wallboard type building convenient to assemble

Abstract

The concrete wallboard type building convenient to assemble comprises a roof body and an outer wall unit, a bracket is arranged on the inner side wall of the outer wall unit, the roof body is placed on the bracket, a grouting hole is formed in the roof body, a steel bar located in the grouting hole is arranged on the bracket, and the outer wall unit is arranged on the outer wall unit. A positioning cylinder is arranged in the grouting hole, and the positioning cylinder is detachably connected with the grouting hole; one end of the reinforcing steel bar is pre-buried in the corbel, a positioning rod is arranged at the other end of the reinforcing steel bar, and the outer diameter of the positioning rod is consistent with the inner diameter of the grouting hole. The roof body and the bracket can be accurately positioned by the aid of the positioning rod and the positioning cylinder, so that integral stability of a building is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to building construction technical field, concretely relates to a concrete wallboard formula building convenient to assemble. BACKGROUND

[0002] The concrete wallboard formula building is a modern building mode, and its main feature lies in that prefabricated boards are used for construction, the boards are prefabricated in a production workshop and then transported to a construction site for assembly, so that the construction period is greatly shortened.

[0003] When the existing concrete wallboard formula building is built, after the outer wall of the building is built, the roof is placed on the corbels of the outer wall by using hoisting equipment, the steel bars embedded in the corbels are inserted into the grouting holes of the wallboard, and then grouting is carried out at the grouting holes and the gap between the roof and the outer wall, so that the assembly between the roof and the outer wall is completed. However, since the grouting holes need to be filled with concrete, the inner diameter of the grouting holes on the roof needs to be larger than the diameter of the steel bars, so as to ensure that the concrete has high connecting strength with the steel bars. However, the above structure causes the roof to be unable to be accurately assembled on the corbels, so that the building is unbalanced and the stability of the building is affected. SUMMARY

[0004] The utility model solves the technical problems in the prior art, and aims to provide a concrete wallboard formula building convenient to assemble, which can realize accurate positioning between the roof body and the corbel by using the positioning rod and the positioning cylinder, so as to improve the stability of the building as a whole.

[0005] The utility model realizes the following technical scheme:

[0006] A concrete wallboard formula building convenient to assemble, comprising a roof body and an outer wall unit, wherein an inner side wall of the outer wall unit is provided with a corbel, the roof body is placed on the corbel, the roof body is provided with a grouting hole, the corbel is provided with a steel bar located in the grouting hole, the grouting hole is provided with a positioning cylinder, and the positioning cylinder and the grouting hole are detachably connected.

[0007] One end of the steel bar is embedded in the corbel, and the other end of the steel bar is provided with a positioning rod, and the outer diameter of the positioning rod is consistent with the inner diameter of the grouting hole.

[0008] Further, the positioning rod is sleeved on the steel bar, the steel bar is provided with a thread, and the steel bar is further provided with a nut, and the nut is used for fixing the positioning rod on the steel bar.

[0009] Further, a plurality of annular grooves are arranged on the circumferential side wall of the positioning rod.

[0010] Further, a fixing ring is arranged on the side wall of the positioning cylinder, and a movable rod is arranged on the fixing ring, one end of the movable rod is hinged to the fixing ring, and the other end of the movable rod is provided with an inner supporting block.

[0011] An active cylinder and an active ring are further arranged on the positioning cylinder, the active ring is sleeved on the positioning cylinder, and the active cylinder is connected with the positioning cylinder through threads, and the active cylinder is used for pushing the active ring to move axially along the positioning cylinder.

[0012] Further, the outer wall unit comprises two side plates, two rear plates and two front plates;

[0013] The corbels are arranged on the inner side walls of the side plates, the rear plates and the front plates.

[0014] The side plates, the rear plates and the front plates are all provided with thermal insulation layers.

[0015] Further, the outer side wall of the front plate is further provided with a parapet wall.

[0016] The outer side wall of the front plate and the inner side wall of the parapet wall are both pre-buried with first pre-buried cylinders, a steel I-beam is further arranged between the front plate and the parapet wall, the two ends of the steel I-beam are welded with connecting plates, and the connecting plates are provided with first bolts which are threadedly connected with the sleeve cylinders.

[0017] Further, the rear plates and the front plates are both pre-buried with second pre-buried cylinders, a first connecting piece is further arranged between the two front plates, the first connecting piece is provided with second bolts, and the second bolts are connected with the second pre-buried cylinders on the front plates.

[0018] A first connecting piece is also arranged between the two rear plates, the first connecting piece is provided with second bolts, and the second bolts are connected with the second pre-buried cylinders on the rear plates.

[0019] Further, the front plates, the rear plates and the side plates are all pre-buried with third pre-buried cylinders.

[0020] The front plates, the rear plates and the side plates are all further provided with L-shaped second connecting pieces between them, the second connecting pieces are provided with third bolts, and the third bolts are connected with the third pre-buried cylinders.

[0021] Further, a foamed polyethylene rod and a sealant are further arranged between the two rear plates.

[0022] A foamed polyethylene rod and a sealant are also arranged between the two front plates.

[0023] Further, one end of one of the front plates is provided with a notch, and one end of the other front plate is provided with a protrusion.

[0024] One end of one of the rear plates is also provided with a notch, and one end of the other rear plate is also provided with a protrusion.

[0025] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0026] 1、The utility model discloses a positioning cylinder and positioning rod are set up and can realize the accurate positioning between roof body and corbel, thereby improving the stability of the whole building, avoiding the imbalance of the building, and affecting the stability of the building, and the positioning rod is set up and can increase the contact area with the concrete in the grouting hole, thereby improving the connecting strength between the steel bar on the corbel and the concrete, and further improving the connecting strength between the roof body and the outer wall unit.

[0027] 2、The utility model discloses when hoisting the front plate, the I -steel set up between the parapet and the front plate can protect the parapet to a certain extent, avoids the parapet to be collided in hoisting and causes the damage to happen.

[0028] 3、The utility model discloses when splicing the front plate and the back plate, the convex and the notch set up on the front plate and the back plate can hinder the impurity to a certain extent, and the foamed polyethylene stick and the sealant can improve the sealing property of the whole building. DRAWINGS

[0029] The drawings described herein are used to provide further understanding of the embodiments of the utility model, and constitute a part of the present application, and do not constitute the limitation to the embodiments of the utility model.

[0030] Figure 1 It is the front view of the utility model structure;

[0031] Figure 2 It is the top view of the utility model structure;

[0032] Figure 3 It is the front view of the utility model side plate;

[0033] Figure 4 It is the side view of the utility model side plate;

[0034] Figure 5 It is the structure schematic view when the utility model front plate and roof body assemble;

[0035] Figure 6 It is the structure schematic view when the utility model front plate and roof body are in another state;

[0036] Figure 7 It is the structure schematic view when the utility model Figure 5 C part is enlarged;

[0037] Figure 8 It is the structure schematic view when the utility model Figure 6Structure schematic view of the middle D part after being enlarged;

[0038] Figure 9 Front view of the front plate of the utility model;

[0039] Figure 10 Structure schematic view of the rear plate when being spliced of the utility model;

[0040] Figure 11 Structure schematic view of the utility model Figure 10 Sectional view of the middle A-A;

[0041] Figure 12 Structure schematic view of the side plate and the rear plate when being spliced of the utility model;

[0042] Figure 13 Structure schematic view of the utility model Figure 12 Sectional view of the middle B-B;

[0043] Figure 14 Structure schematic view of the inside when the rear plate is spliced of the utility model.

[0044] Markings in the drawings and corresponding component names:

[0045] 1, side plate; 2, roof body; 3, rear plate; 4, front plate; 5, movable ring; 6, installation groove; 7, corbel; 8, I-steel; 9, parapet; 10, movable cylinder; 11, reinforcing bar; 12, nut; 13, inner supporting block; 14, movable rod; 15, fixed ring; 16, positioning cylinder; 17, positioning rod; 19, doorway; 20, first connecting piece; 21, second bolt; 22, polytetrafluoroethylene plate; 23, second connecting piece; 24, foamed polyethylene rod; 25, sealing glue; 26, notch; 27, protrusion; 28, thermal insulation layer; 29, third bolt. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model is further explained in detail below by combining with examples and drawings, and the schematic implementation mode and the explanation thereof of the utility model are only used for explaining the utility model, and do not serve as the limitation of the utility model.

[0047] EXAMPLE

[0048] As Figures 1 to 14The utility model discloses, including roof body 2 and outer wall unit, the inner side wall of outer wall unit is equipped with corbel 7, the roof body 2 is placed on corbel 7, be equipped with grouting hole on the roof body 2, be equipped with the reinforcing steel bar 11 in grouting hole on corbel 7, be equipped with the locating cylinder 16 in grouting hole, the locating cylinder 16 with grouting hole can dismantle formula connection, one end of reinforcing steel bar 11 is embedded in corbel 7, and the other end is equipped with locating rod 17, and the outer diameter of locating rod 17 is consistent with grouting hole inner diameter.

[0049] For prior art in the wallboard building is set up, usually first the pouring of foundation, then in turn builds the outer wall in four directions on the foundation, after the completion of the outer wall construction, using hoisting equipment will the roof to the corbel on the outer wall, and ensure that the embedded reinforcing steel bar 11 in corbel enters into the grouting hole on the roof, in this way, after the concrete in grouting hole pours, can the reinforcing steel bar 11 stable fixation in the roof, to ensure the stable connection between the roof and the outer wall, but, because the inner diameter of grouting hole is greater than the diameter of reinforcing steel bar 11, this leads to when installing the roof, can not guarantee the roof accurate placement in the corbel of outer wall, easy to cause building imbalance, influence the stability of building, for this, the technical scheme is set up in the grouting hole of existing roof body 2 locating cylinder 16, locating cylinder 16 and grouting hole adopt detachable connection, and the reinforcing steel bar 11 is provided with locating rod 17, and the inner diameter of locating cylinder 16 is consistent with the outer diameter of locating rod 17, therefore, when installing roof body 2, only need to ensure that the locating cylinder 16 on the roof body 2 is inserted into the locating rod on the corbel 7, can guarantee that the roof body 2 can be accurately installed on the outer wall unit, avoid building imbalance, influence the stability of building.

[0050] Meanwhile, after the installation of roof body 2, the locating cylinder 16 in grouting hole is taken out, then pours concrete in grouting hole again, so that the concrete can be connected with the locating rod 17 on the reinforcing steel bar 11, the locating rod 17 provided can increase the contact area with concrete, thereby improving the connecting strength between corbel and roof body 2.

[0051] The locating rod 17 is provided on the reinforcing steel bar 11, the reinforcing steel bar 11 is provided with a thread, and the reinforcing steel bar 11 is further provided with a nut 12, and the nut 12 is used to fix the locating rod 17 on the reinforcing steel bar 11.

[0052] In order to realize the stable connection between the locating rod 17 and the reinforcing steel bar 11 in the embodiment, the nut 12 is further provided on the reinforcing steel bar 11, and the locating rod 17 is stably fixed on the reinforcing steel bar 11 by the nut 12, so as to ensure that the locating rod 17 can be accurately positioned with the locating cylinder 16.

[0053] The circumferential side wall of the locating rod 17 is provided with a plurality of annular grooves.

[0054] In order to improve the connection strength between the positioning rod 17 and the concrete in the grouting hole in this embodiment, a plurality of annular grooves are further provided on the circumferential side wall of the positioning rod 17. The annular grooves are evenly distributed in sequence along the axial direction of the positioning rod 17. In this way, when concrete is injected into the grouting hole of the roof body 2, the reversing grooves on the positioning rod 17 can increase the contact area with the concrete, thereby improving the connection strength between the positioning rod 17 and the concrete.

[0055] A fixed ring 15 is also provided on the side wall of the positioning cylinder 16, and a movable rod 14 is provided on the fixed ring 15. One end of the movable rod 14 is hinged to the fixed ring 15, and the other end is provided with an inner support block 13; the positioning cylinder 16 is also provided with a movable cylinder 10 and a movable ring 5, and the movable ring 5 is sleeved on the positioning cylinder 16. The movable cylinder 10 is connected to the positioning cylinder 16 by a thread, and the movable cylinder 10 is used to push the movable ring 5 to move axially along the positioning cylinder 16.

[0056] In order to achieve a detachable connection between the positioning cylinder 16 and the grouting hole on the roof body 2 in this embodiment, a fixing ring 15 is further provided on the positioning cylinder 16, and a movable rod 14 is hinged on the fixing ring 15. At the same time, a movable cylinder 10 and a movable ring 5 are also provided on the positioning cylinder 16. In this way, when it is necessary to fix the positioning cylinder 16 in the grouting hole, the positioning cylinder 16 is first extended into the grouting hole of the roof body 2, and then the movable cylinder 10 is rotated so that the movable cylinder 10 can push the movable ring 5 to move on the positioning cylinder 16. When moving, the movable ring 5 uses its end face to push the movable rod 14 on the fixing ring 15 to deflect toward the inner wall of the grouting hole, and finally presses the inner support block 13 tightly into the grouting hole, thereby achieving a stable connection between the positioning cylinder 16 and the grouting hole.

[0057] After the installation of the roof body 2 is completed, the movable cylinder 10 is rotated in the opposite direction to move upward, removing the downward pressure on the fixing ring 15, so that the movable cylinder 10 can be quickly taken out of the grouting hole for grouting.

[0058] In another embodiment, an external thread is provided on the circumferential outer wall of the positioning cylinder 16, and an internal thread matching the external thread is also provided on the inner wall of the grouting hole. In this way, the positioning cylinder 16 and the grouting hole can be detachably connected by means of threads; at the same time, the internal thread provided in the grouting hole can increase the adhesion area of ​​the concrete, thereby further improving the connection strength between the roof body and the exterior wall unit.

[0059] The exterior wall unit includes two side panels 1, two rear panels 3 and two front panels 4; the corbels 7 are distributed on the inner side walls of the side panels 1, rear panels 3 and front panels 4; and the side panels 1, rear panels 3 and front panels 4 are all provided with insulation layers 28.

[0060] The outer wall unit in the embodiment comprises two side plates 1, two back plates 3 and two front plates 4, and the side plates 1, the back plates 3 and the front plates 4 form a rectangular wallboard type building frame. When the outer wall unit is built, the foundation is poured at the construction site. When the foundation is poured, a plurality of steel bars are embedded on the foundation and protrude upwards to the top of the foundation. The bottom of each of the side plates 1, the back plates 3 and the front plates 4 is provided with a fourth embedded sleeve. The side plates 1, the back plates 3 and the front plates 4 are further provided with grouting holes in communication with the fourth embedded sleeves. Thus, when the side plates 1, the back plates 3 and the front plates 4 are installed, the fourth embedded sleeves provided at the bottom of the side plates 1, the back plates 3 and the front plates 4 are connected with the steel bars on the foundation, and then the sleeves are filled with concrete through the grouting holes. After the concrete is solidified, the side plates 1, the back plates 3 and the front plates 4 are stably connected with the steel bars, thereby fixing the side plates 1, the back plates 3 and the front plates 4 on the foundation and realizing the assembly of the outer wall unit.

[0061] The outer side wall of the front plate 4 is further provided with a parapet 9. The outer side wall of the front plate 4 and the inner side wall of the parapet 9 are both pre-embedded with first embedded sleeves. A steel I-beam 8 is further arranged between the front plate 4 and the parapet 9. The two ends of the steel I-beam 8 are welded with connecting plates. The connecting plates are provided with first bolts in threaded connection with the sleeves.

[0062] The front plate 4 in the embodiment is further provided with a door 19 for personnel to enter and exit the wallboard type building. The parapet 9 is arranged above the door 19, so that the parapet 9 can be used as a rainproof platform of the door 19.

[0063] Since the front plate 4 needs to be hoisted and installed by hoisting equipment during installation, in order to avoid the parapet 9 with protrusions from colliding with other factors in the external environment during hoisting and causing damage to the parapet 9, the steel I-beam 8 is further arranged between the parapet 9 and the outer side wall of the front plate 4. The first bolts on the connecting plates at the two ends of the steel I-beam 8 can be detachably connected with the parapet 9 and the front plate 4. During hoisting and installation of the front plate 4, the steel I-beam 8 can provide internal support to the parapet 9, avoiding collision of the parapet 9 during hoisting and installation and causing damage to the parapet 9, thereby achieving a certain protection effect on the parapet 9.

[0064] After the installation between the front plate 4 and the foundation is completed, the first bolts on the steel I-beam are removed, and the first embedded sleeves on the parapet 9 and the front plate 4 are sealed with cement mortar.

[0065] The second embedded cylinder is embedded on the rear plate 3 and the front plate 4, the first connecting sheet 20 is arranged between the two front plates 4, the second bolt 21 is arranged on the first connecting sheet 20, the second bolt 21 is connected with the second embedded cylinder on the front plate 4, the first connecting sheet 20 is arranged between the two rear plates 3, the second bolt 21 is arranged on the first connecting sheet 20, and the second bolt 21 is connected with the second embedded cylinder on the rear plate 3.

[0066] In the embodiment, the second embedded cylinder is arranged on the rear plate 3 and the front plate 4, so that when the two front plates 4 are installed, the two second bolts 21 on the first connecting sheet 20 are respectively screwed with the second embedded cylinders on the two front plates 4, thereby realizing the splicing between the two front plates 4.

[0067] The third embedded cylinder is embedded on the front plate 4, the rear plate 3 and the side plate 1, the L-shaped second connecting sheet 23 is arranged between the front plate 4, the rear plate 3 and the side plate 1, the third bolt 29 is arranged on the second connecting sheet 23, and the third bolt 29 is connected with the third embedded cylinder.

[0068] In the embodiment, the third embedded cylinder is arranged on the connecting surface of the front plate 4, the rear plate 3 and the side plate 1, so that when the front plate 4 is installed with the side plate 1, the two third bolts 29 on the L-shaped second connecting sheet 23 are respectively connected with the third embedded cylinders on the front plate 4 and the side plate 1, thereby realizing the connection between the side plate 1 and the front plate 4.

[0069] In another embodiment, the mounting groove 6 is arranged on the side plate 1, the front plate 4 and the rear plate 3, the second embedded cylinder and the third embedded cylinder are located in the mounting groove 6, so that when the first connecting sheet 20 and the second connecting sheet 23 are installed, the first connecting sheet 20 and the second connecting sheet 23 are placed in the mounting groove 6, avoiding the first connecting sheet 20 and the second connecting sheet 23 from protruding outward, improving the appearance of the building, the polytetrafluoroethylene plate 22 is arranged between the first connecting sheet 20, the second connecting sheet 23 and the mounting groove 6, improving the sealing between the first connecting sheet 20, the second connecting sheet 23 and the outer wall unit, and after the installation of the first connecting sheet 20 and the second connecting sheet 23 is completed, the cement mortar is sealed in the mounting groove 6.

[0070] The foamed polyethylene rod 24 and the sealant 25 are arranged between the two rear plates 3, and the foamed polyethylene rod 24 and the sealant 25 are arranged between the two front plates 4.

[0071] In order to improve the sealing of the joint between the two rear plates 3 and the two front plates 4, the gap between the two rear plates 3 and the gap between the two front plates 4 are filled with foamed polyethylene rods 24 and sealant 25, thereby improving the sealing of the joint between the front plates 4 and the rear plates 3.

[0072] One end of one of the front plates 4 is provided with a notch 26, and one end of the other front plate 4 is provided with a protrusion 27; one end of one of the rear plates 3 is also provided with a notch 26, and one end of the other rear plate 3 is also provided with a protrusion 27.

[0073] In order to further improve the sealing of the joint between the two front plates 4 and the two rear plates 3, notches 26 and protrusions 27 are arranged at the joint between the two front plates 4; when the two front plates 4 are jointed, the protrusion 27 on one of the front plates 4 is located in the notch 26 of the other front plate 4; in this way, the protrusion 27 can block external impurities and improve the sealing of the front plates 4; similarly, the rear plates 3 are jointed in the above-mentioned manner.

[0074] In another embodiment, the top of the side plate 1, the front plate 4, and the rear plate 3 are pre-buried with a steel bar in the shape of an inverted U; in this way, the U-shaped steel bar can be used as a lifting ring, facilitating the lifting machine to lift and install the side plate 1, the front plate 4, and the rear plate 3; after the lifting and installation of the side plate 1, the front plate 4, and the rear plate 3 are completed, the U-shaped steel bar protruding outward is cut off; finally, the cutting part is sealed and glued.

[0075] The above specific embodiments further illustrate the purpose, technical solutions, and beneficial effects of the present application; it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application; any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A concrete wall panel type building that is easy to assemble, comprising a roof body (2) and an outer wall unit, wherein a corbel (7) is provided on the inner side wall of the outer wall unit, the roof body (2) is placed on the corbel (7), the roof body (2) is provided with a grouting hole, and the corbel (7) is provided with a steel bar (11) located in the grouting hole, characterized in that: A positioning cylinder (16) is provided in the grouting hole, and the positioning cylinder (16) is detachably connected to the grouting hole; One end of the steel bar (11) is pre-buried in the corbel (7), and the other end is provided with a positioning rod (17), and the outer diameter of the positioning rod (17) is consistent with the inner diameter of the grouting hole.

2. The easy-to-assemble concrete wall panel building according to claim 1, characterized in that: The positioning rod (17) is sleeved on the steel bar (11), the steel bar (11) is provided with a thread, and the steel bar (11) is also provided with a nut (12), and the nut (12) is used to fix the positioning rod (17) on the steel bar (11).

3. The easy-to-assemble concrete wall panel building according to claim 1, characterized in that: A plurality of annular grooves are provided on the circumferential side wall of the positioning rod (17).

4. The easy-to-assemble concrete wall panel building according to claim 1, characterized in that: A fixing ring (15) is further provided on the side wall of the positioning cylinder (16), and a movable rod (14) is provided on the fixing ring (15). One end of the movable rod (14) is hinged to the fixing ring (15), and the other end is provided with an inner support block (13); The positioning cylinder (16) is further provided with a movable cylinder (10) and a movable ring (5). The movable ring (5) is sleeved on the positioning cylinder (16). The movable cylinder (10) is connected to the positioning cylinder (16) via a thread. The movable cylinder (10) is used to push the movable ring (5) to move axially along the positioning cylinder (16).

5. The easy-to-assemble concrete wall panel building according to claim 1, characterized in that: The exterior wall unit comprises two side panels (1), two rear panels (3) and two front panels (4); The corbels (7) are distributed on the inner side walls of the side panels (1), the rear panel (3), and the front panel (4); The side panels (1), the rear panel (3), and the front panel (4) are all provided with a heat-insulating layer (28).

6. The easy-to-assemble concrete wall panel building according to claim 5, characterized in that: A parapet (9) is also provided on the outer side wall of the front plate (4); A first embedded tube is pre-buried on the outer side wall of the front plate (4) and the inner side wall of the parapet (9); an I-beam (8) is provided between the front plate (4) and the parapet (9); connecting plates are welded at both ends of the I-beam (8); and a first bolt is provided on the connecting plate and is threadedly connected to the sleeve.

7. The easy-to-assemble concrete wall panel building according to claim 5, characterized in that: A second embedded tube is pre-buried on both the rear plate (3) and the front plate (4); a first connecting piece (20) is provided between the two front plates (4); a second bolt (21) is provided on the first connecting piece (20); and the second bolt (21) is connected to the second embedded tube on the front plate (4); A first connecting piece (20) is also provided between the two rear plates (3), and a second bolt (21) is provided on the first connecting piece (20), and the second bolt (21) is connected to the second embedded tube on the rear plate (3).

8. The easy-to-assemble concrete wall panel building according to claim 5, characterized in that: The front plate (4), the rear plate (3) and the side plate (1) are all pre-buried with a third pre-buried cylinder; An L-shaped second connecting piece (23) is further provided between the front plate (4), the rear plate (3) and the side plate (1); a third bolt (29) is provided on the second connecting piece (23); and the third bolt (29) is connected to the third embedded tube.

9. The easy-to-assemble concrete wall panel building according to claim 5, characterized in that: A foamed polyethylene rod (24) and a sealant (25) are also provided between the two rear plates (3); A foamed polyethylene rod (24) and a sealant (25) are also provided between the two front plates (4).

10. The easy-to-assemble concrete wall panel building according to claim 5, characterized in that: One end of one of the front plates (4) is provided with a notch (26), and one end of the other front plate (4) is provided with a protrusion (27); One end of one of the rear plates (3) is also provided with a notch (26), and one end of the other rear plate (3) is also provided with a protrusion (27).

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