A variable-diameter parapet plastering tool and plastering method

Abstract

The present application belongs to the technical field of building tools, and particularly relates to a variable-diameter plastering tool for parapet wall and a plastering method. The variable-diameter plastering tool for parapet wall comprises a handle, a metal plate and a fastener. The metal plate is a cylindrical tube surrounded by a rectangular plate. The two ends of the metal plate in the length direction are detachably connected with the fastener. The handle is installed on the outer side of the metal plate. The fastener is a butterfly bolt assembly. Compared with the prior art, the present application has the advantages and positive effects that the construction requirements of different roofs for different parapet wall bottom arc corners are solved. The radius change operation is simple and convenient. The plastering difficulty of the parapet wall is reduced. The working efficiency of workers is improved. The construction time of workers is reduced. The butterfly bolt and the butterfly nut are threadedly connected. The butterfly design of the head of the butterfly bolt increases the transverse stress surface, so that the hand twisting is more efficient. Frequent disassembly can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of building tools technology, specifically relating to a variable diameter plastering tool for parapet walls and a plastering method. Background Technology

[0002] Parapet walls, also known as eaves walls, are a type of wall that connects the roof to the exterior wall. They can prevent people from falling and also serve to waterproof the roof.

[0003] Nowadays, the construction quality requirements for roofs in building projects are relatively high, and the implementation of roof improvement projects is widespread. The construction of the arc-shaped corner at the bottom of the parapet wall is widely used. The arc-shaped corner at the bottom of the parapet wall refers to a rounded flashing structure made of cement mortar. However, the layout of roof plaza bricks is complex. In addition, the roof is usually tiled, and the width of the tiles is also required. They cannot be too narrow. The tiles near the parapet wall are generally not whole tiles, but the width of the tiles should not be less than one-third of the width of the tile. In order to adjust the width of the tiles, the size of the arc-shaped corner at the bottom of the parapet wall will be inconsistent.

[0004] When encountering situations where the size of the arc corner at the bottom of the parapet wall is inconsistent, different specifications of construction tools are required accordingly. Generally, traditional plastering tools are of fixed size. When the diameter of the arc corner at the bottom of the parapet wall changes, traditional plastering tools often cannot meet the construction requirements well, resulting in low construction efficiency and the inability to efficiently and conveniently complete the construction process of different arc corners at the bottom of the parapet wall. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a variable-diameter plastering tool and plastering method for parapet walls.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a parapet wall variable diameter plastering tool includes a handle, a metal plate, and fasteners. The metal plate is a cylindrical tube formed by rectangular plates. Both ends of the metal plate are detachably connected to the fasteners in the length direction. The handle is installed on the outer side of the metal plate.

[0007] Preferably, the metal plate has multiple locking holes distributed along the length of the metal plate.

[0008] Preferably, the fastener is a wing bolt assembly, which includes a wing bolt and a wing nut, and the wing bolt and wing nut are threaded together.

[0009] Preferably, the locking hole is a round hole or an elongated hole, and the locking hole includes an upper locking hole and a lower locking hole. The upper locking hole and the lower locking hole are symmetrically distributed vertically. There are multiple upper locking holes, and adjacent upper locking holes are equidistantly distributed along the length of the metal plate.

[0010] The metal plate further comprises a scale, and the locking holes correspond to the scale one by one.

[0011] As preferred, the inner layer support assembly further comprises a connecting part and a curved fitting plate, the curved fitting plate is installed on the connecting part, and one end of the curved fitting plate away from the connecting part is fitted with the inner side of the metal plate.

[0012] As preferred, the connecting part comprises a support connecting piece, a micro air cylinder and a spring, the micro air cylinder and the spring are respectively detachably connected with the support connecting piece, and the spring is in an elastic compression state.

[0013] As preferred, the connecting part comprises a chuck body, a chuck support shell and a plurality of chuck claws, the chuck body is installed in the cavity of the chuck support shell, the chuck body and the chuck support shell are rotationally connected, and the plurality of chuck claws are detachably connected with the corresponding curved fitting plates.

[0014] The chuck body comprises a spiral clamping strip, and one end of the chuck claw away from the curved fitting plate is provided with a groove, and the groove is fitted with the spiral clamping strip.

[0015] A variable-diameter rendering method for a parapet wall, and a variable-diameter rendering tool for a parapet wall, the rendering method comprising the following steps:

[0016] Step a: bending a rectangular metal plate into a cylindrical shape, and selecting a corresponding locking hole according to a scale corresponding to an arc-shaped corner of a bottom of a parapet wall to be processed;

[0017] Step b: fixing the bent metal plate by passing a butterfly bolt and a butterfly nut through the corresponding locking hole;

[0018] Step c: a construction worker processes the arc-shaped corner of the bottom of the parapet wall by holding a handle;

[0019] Step d: after the arc-shaped corner of the bottom of the parapet wall is processed, it is determined whether the diameter needs to be changed;

[0020] Step e: if the diameter does not need to be changed, the construction is continued, if the diameter needs to be changed, the butterfly bolt and the butterfly nut are disassembled, a corresponding locking hole is selected according to a scale, the butterfly bolt and the butterfly nut are reinstalled, and then steps c and d are repeated until the construction is completed.

[0021] As preferred, the step of determining whether the diameter needs to be changed in step d comprises:

[0022] Step d1: measuring a length of a brick side edge close to the parapet wall from the parapet wall, and marking the length as length one;

[0023] Step d2: comparing the length one with a value of an inner diameter of the bent metal plate;

[0024] The distance between the adjacent two locking holes is a hole spacing, if the absolute value of the difference between the length and the inner diameter of the metal plate is less than or equal to the hole spacing, no change is needed;

[0025] If the absolute value of the difference between the length and the inner diameter of the metal plate is greater than the hole spacing, change is needed, if the difference is positive, the inner diameter is increased, and if the difference is negative, the inner diameter is decreased.

[0026] As preferred, the step e when change is needed includes the following steps:

[0027] Step e1, the butterfly bolt assembly of the outermost edge of the metal plate at the upper end and the lower end is kept unchanged, and the remaining butterfly bolt assemblies are disassembled;

[0028] Step e2, the butterfly bolt and the butterfly nut of the outermost edge of the metal plate at the upper end are loosened, the positions of the new upper locking hole and the new lower locking hole are selected according to the scale and marked;

[0029] Step e3, the butterfly bolt and the butterfly nut of the outermost edge of the metal plate at the lower end are disassembled, then force is applied to the lower end of the metal plate, so that the distance between the original lower locking hole and the new lower locking hole of the lower end is threaded and connected by the butterfly bolt and the butterfly nut of the lower locking hole closest to the original lower locking hole;

[0030] Step e4, the butterfly bolt and the butterfly nut of the outermost edge of the metal plate at the upper end are disassembled, then force is applied to the upper end of the metal plate, so that the distance between the original upper locking hole and the new upper locking hole of the upper end is threaded and connected by the upper locking hole closest to the original upper locking hole;

[0031] Step e5, steps e3 and e4 are repeated until the new upper locking hole and the new lower locking hole of the outermost edge of the metal plate are threaded and connected by the butterfly bolt assembly;

[0032] Step e6, the butterfly bolt and the butterfly nut of the outermost edge of the metal plate are tightened, and the remaining butterfly bolt assemblies are assembled.

[0033] Compared with the prior art, the advantages and positive effects of the present application are:

[0034] (1) The metal plate is a rectangular plate surrounding a cylindrical barrel, and both ends of the metal plate in the length direction are detachably connected with the fasteners, which solves the construction needs of different roof for different female wall bottom arc corners, the radius change operation is simple and convenient, the difficulty of female wall plastering is reduced, the working efficiency of workers is improved, and the construction time of workers is reduced;

[0035] (2) The butterfly bolt and the butterfly nut are threaded and connected, the butterfly design of the head of the butterfly bolt increases the transverse stress surface, which makes the hand screwing more efficient and can realize frequent disassembly;

[0036] (3) The locking hole is a round hole, which is not easy to loosen. The inner diameter of the cylindrical tube corresponding to the hole position is discontinuous, so the positioning accuracy is high and the calibration time is less. The locking hole is a long strip hole, which can be precisely adjusted within a certain range by cooperating with the scale, and can better ensure that the inner diameter of the cylindrical tube meets the actual working requirements in actual operation.

[0037] (4) The miniature cylinder and the spring are detachably connected. When the diameter is changed, the miniature cylinder can extend and retract synchronously. The miniature cylinder makes the inner side of the metal plate always keep in contact with the curved bonding plate. Thus, after the diameter is changed, the curved bonding plate still supports the metal plate, preventing the inner diameter of the metal plate from changing during operation. The spring is in an elastic compression state, and the spring plays a pre-tightening role, preventing damage to the metal plate caused by the extension and retraction of the miniature cylinder.

[0038] (5) The chuck body includes a scroll bar and grooves are provided on the chuck claws. The grooves fit with the scroll bar. By rotating the chuck body around its own axis, multiple chuck claws can be synchronously extended and retracted in the radial direction of the chuck body. The radial extension and retraction of the chuck body ensures that the inner side of the metal plate always fits with the curved bonding plate.

[0039] (6) Step e5 Repeat steps e3 and e4 until the new upper and lower locking holes on the outermost edge of the marked metal plate are threaded together with wing bolt assemblies. During the diameter change, at least one wing bolt assembly is always connected to the locking hole. During the diameter change, the metal plate is still cylindrical. There is no need to bend the metal plate significantly, which enhances the service life of the parapet wall variable diameter plastering tool, avoids the threat to worker safety caused by direct pop-out, and improves the safety of worker operation. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below:

[0041] Figure 1 A schematic diagram of the variable-diameter plastering tool for the parapet wall;

[0042] Figure 2 A schematic diagram showing the interaction between a variable-diameter plastering tool for a parapet wall and the parapet wall.

[0043] Figure 3 A schematic diagram showing that the locking hole for the variable-diameter plastering tool on the parapet wall is a long, narrow hole;

[0044] Figure 4 A schematic diagram of a multi-layered cylindrical metal plate used as a variable-diameter plastering tool for a parapet wall;

[0045] Figure 5 A schematic diagram showing the connection part of a variable-diameter plastering tool for a parapet wall, including a miniature cylinder;

[0046] Figure 6 Schematic diagram of micro-cylinder and curved surface fitting plate matched with variable-diameter plastering tool for parapet wall;

[0047] Figure 7 Schematic diagram of connecting part including chuck claw and metal plate matched with variable-diameter plastering tool for parapet wall;

[0048] Figure 8 Schematic diagram of chuck body matched with chuck support shell of variable-diameter plastering tool for parapet wall Figure 1 ;

[0049] Figure 9 Schematic diagram of chuck body of variable-diameter plastering tool for parapet wall;

[0050] Figure 10 Schematic diagram of chuck claw of variable-diameter plastering tool for parapet wall;

[0051] Figure 11 Schematic diagram of chuck body matched with chuck support shell of variable-diameter plastering tool for parapet wall Figure 2 .

[0052] Reference signs:

[0053] 1 - metal plate, 11 - locking hole, 12 - upper locking hole, 13 - lower locking hole;

[0054] 2 - handle;

[0055] 3 - butterfly bolt assembly;

[0056] 4 - parapet wall main body;

[0057] 5 - inner layer support assembly, 51 - support connecting piece, 52 - curved surface fitting plate, 53 - micro-cylinder, 54 - spring, 55 - chuck body, 56 - chuck support shell, 57 - chuck claw, 58 - spiral clamping strip, 59 - groove. DETAILED DESCRIPTION

[0058] In order to enable the above-mentioned objects, features and advantages of the present application to be more clearly understood and appreciated, reference will be made, without limitation, to the following description and accompanying drawings.

[0059] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given herein, and that the present application is not limited to the specific embodiments described herein.

[0060] Example 1

[0061] The following will be described in conjunction with Figure 1 Figure 2 Figure 3 and Figures 7 to 11The application discloses a variable-diameter trowel for a parapet wall. Figure 1 A variable-diameter trowel for a parapet wall comprises a handle 2, a metal plate 1 and a fastener, the metal plate 1 is a cylindrical tube surrounded by a rectangular plate, the metal plate 1 is detachably connected with the fastener at both ends in the length direction, and the handle 2 is installed on the outer side of the metal plate 1.

[0062] As shown in Figure 1 and Figure 2 , a plurality of locking holes 11 are formed on the metal plate 1, the plurality of locking holes 11 are distributed along the length direction of the metal plate 1, and the fastener is installed on the corresponding locking hole 11.

[0063] As shown in Figure 1 , the fastener is a butterfly bolt assembly 3, the butterfly bolt assembly 3 comprises a butterfly bolt and a butterfly nut, and the butterfly bolt and the butterfly nut are threadedly connected.

[0064] As shown in Figure 1 , the locking hole 11 is a circular hole, as shown in Figure 3 , the locking hole 11 is an elongated hole, the locking hole 11 comprises an upper locking hole 12 and a lower locking hole 13, the upper locking hole 12 and the lower locking hole 13 are symmetrically distributed, the number of the upper locking hole 12 is multiple, and adjacent upper locking holes 12 are equidistantly distributed along the length direction of the metal plate 1.

[0065] The metal plate 1 further comprises a scale, and the locking hole 11 corresponds to the scale one by one.

[0066] As shown in Figure 7 and Figure 8 , it further comprises an inner layer support assembly 5, the inner layer support assembly 5 comprises a connecting part and a curved surface fitting plate 52, the curved surface fitting plate 52 is installed on the connecting part, and one end of the curved surface fitting plate 52 away from the connecting part is attached to the inner side of the metal plate 1.

[0067] As shown in Figure 8 and Figure 11 , the connecting part comprises a chuck body 55, a chuck support shell 56 and a chuck claw 57, the chuck body 55 is installed in the cavity of the chuck support shell 56, the chuck body 55 and the chuck support shell 56 are rotationally connected, the number of the chuck claw 57 is multiple, and the plurality of chuck claws 57 are detachably connected with the corresponding curved surface fitting plate 52.

[0068] As shown in Figure 9 , the chuck body 55 comprises a spiral clamping strip 58, as shown in Figure 10 , one end of the chuck claw 57 away from the curved surface fitting plate 52 is provided with a groove 59, and the groove 59 is attached to the spiral clamping strip 58.

[0069] As shown in Figure 8As shown, the chuck support shell 56 is provided with a plurality of rectangular through holes on the side surface, the rectangular through holes correspond to the chuck claws 57, the chuck claws 57 pass through the rectangular through holes, and the chuck body 55 is provided with a central hole.

[0070] The variable-diameter plastering tool for parapet wall further comprises a connecting shaft, the connecting shaft rotates synchronously with the chuck body 55, the connecting shaft is in sliding connection with the central hole of the chuck body 55 in the axial direction, the chuck support shell 56 is kept fixed while the connecting shaft is rotated, and the chuck body 55 is driven to rotate relative to the chuck support shell 56 by rotating the connecting shaft.

[0071] The chuck body 55 drives the chuck claws 57 to move, the chuck claws 57 are driven to move towards the axis of the chuck body 55 or away from the axis of the chuck body 55 by the rotation of the chuck body 55, so as to drive the curved surface fitting plate 52 connected with the chuck claws 57 to move inwards or outwards. The plurality of chuck claws 57 are uniformly distributed about the circumference of the chuck body 55, when one of the chuck claws 57 is driven to move by the chuck body 55, the remaining chuck claws 57 will also move synchronously, so as to accurately control the fitting of the curved surface fitting plate 52 and the inner wall of the metal plate 1, and ensure that the metal plate 1 always maintains a cylindrical shape without large deformation.

[0072] In order to ensure that the metal plate 1 can be smoothly bent into a cylindrical shape, the metal plate 1 is galvanized iron sheet, and the thickness of the galvanized iron sheet is 0.75 mm. In actual construction, the metal plate 1 is prone to elastic deformation, which leads to inaccurate precision. Therefore, the inner layer support assembly 5 plays an effective supporting role for the metal plate 1, and the inner layer support assembly 5 is radially telescopic, so as to ensure that the variable-diameter plastering tool for parapet wall is not prone to elastic deformation under the premise of variable diameter, thereby ensuring the construction precision.

[0073] As shown in Figure 2 The parapet wall body 4 is perpendicular to the horizontal plane, and the variable-diameter plastering tool for parapet wall acts on the angle between the parapet wall body 4 and the horizontal plane.

[0074] The butterfly bolt and the butterfly nut are designed for convenient hand screwing operation, the butterfly design of the head increases the horizontal stress surface, which makes the hand screwing more efficient, and frequent disassembly can be realized.

[0075] Embodiment 2

[0076] The difference between this embodiment and embodiment 1 is that, as shown in Figure 5 and Figure 6 The connecting part comprises a support connecting piece 51, a micro air cylinder 53 and a spring 54, the micro air cylinder 53 and the spring 54 are respectively detachably connected with the support connecting piece 51, and the spring 54 is in an elastic compression state.

[0077] Embodiment 3

[0078] The difference between this embodiment and embodiment 1 is that, as shown inFigure 4 As shown, the metal plate 1 is a multi-layered cylindrical tube.

[0079] The metal plate is a multi-layered cylindrical tube, which enhances the thickness of the working surface and the elasticity between layers, thereby enhancing the strength of the metal plate itself. In actual construction, the side of the metal plate in contact with the parapet wall is not prone to deformation, thereby ensuring the construction accuracy.

[0080] The parapet wall variable-diameter plastering tool includes the following steps:

[0081] Step a: bend the rectangular metal plate 1 into a cylindrical shape, and select the corresponding locking hole 11 according to the corresponding bottom arc corner of the parapet wall to be processed through the scale;

[0082] Step b: fix the bent metal plate 1 by passing the butterfly bolt and butterfly nut through the corresponding locking hole 11;

[0083] Step c: the construction personnel process the bottom arc corner of this section of the parapet wall by holding the handle 2;

[0084] Step d: after the bottom arc corner of this section of the parapet wall is processed, determine whether it needs to be changed in diameter;

[0085] Step e: if it does not need to be changed in diameter, continue construction, if it needs to be changed in diameter, disassemble the butterfly bolt and butterfly nut, select the corresponding locking hole 11 through the scale, re-install the butterfly bolt and butterfly nut, and then repeat steps c and d until the construction is completed.

[0086] The step of determining whether it needs to be changed in diameter in step d includes:

[0087] Step d1: measure the length of the brick side edge close to the parapet wall from the parapet wall, and mark it as length one;

[0088] Step d2: compare length one with the inner diameter value of the bent metal plate 1;

[0089] Step d3: the distance between the two adjacent locking holes is the hole spacing, if the absolute value of the difference between length one and the inner diameter of the metal plate 1 is less than or equal to the hole spacing, it does not need to be changed in diameter;

[0090] If the absolute value of the difference between length one and the inner diameter of the metal plate 1 is greater than the hole spacing, it needs to be changed in diameter, if the difference is positive, the inner diameter is increased, and if the difference is negative, the inner diameter is decreased.

[0091] When it needs to be changed in diameter in step e, it includes the following steps:

[0092] Step e1: the butterfly bolt assemblies 3 on the upper and lower ends of the outermost edge of the metal plate 1 remain unchanged, and the remaining butterfly bolt assemblies 3 are disassembled;

[0093] Step e2 unscrew the butterfly bolt and nut of the outermost edge of the upper end, select the new upper locking hole 12 and new lower locking hole 13 according to the scale and mark;

[0094] Step e3 remove the butterfly bolt and nut of the outermost edge of the lower end of the metal plate 1, then apply force to the lower end of the metal plate 1, so that the distance between the original lower locking hole 13 and the new lower locking hole 13 of the lower end of the metal plate 1 is the closest to the original lower locking hole 13, and the closest upper locking hole 12 is connected by the butterfly bolt and nut, but not tightened;

[0095] Step e4 remove the butterfly bolt and nut of the outermost edge of the upper end of the metal plate 1, then apply force to the upper end of the metal plate 1, so that the distance between the original upper locking hole 12 and the new upper locking hole 12 of the upper end of the metal plate 1 is the closest to the original upper locking hole 12, and the closest upper locking hole 12 is connected by the butterfly bolt and nut, but not tightened;

[0096] Step e5 repeat steps e3 and e4 until the new upper locking hole 12 and new lower locking hole 13 of the outermost edge of the metal plate 1 are connected by the butterfly bolt assembly 3.

[0097] Step e6 tighten the butterfly bolt and nut of the outermost edge of the metal plate 1, and assemble the remaining butterfly bolt assembly 3.

[0098] The above is only the preferred embodiment of the present application, not other forms of the present application is limited, any skilled in the art of technical personnel may use the above disclosed technical content to change or modify as equivalent to the equivalent embodiment applied to other fields, but any simple modification, equivalent change of the above embodiment according to the technical essence of the present application, still belongs to the protection scope of the present application technical scheme.

Claims

1. A parapet wall variable diameter plastering tool, comprising a handle (2), characterized in that: It also includes a metal plate (1) and fasteners. The metal plate (1) is a cylindrical tube formed by rectangular plates. Both ends of the metal plate (1) are detachably connected to the fasteners in the length direction. The handle (2) is installed on the outer side of the metal plate (1). It also includes an inner support assembly (5), which includes a connecting part and a curved bonding plate (52). The curved bonding plate (52) is installed on the connecting part, and the end of the curved bonding plate (52) away from the connecting part is bonded to the inner side of the metal plate (1). The connecting part includes a support connector (51), a miniature cylinder (53) and a spring (54). The miniature cylinder (53) and the spring (54) are detachably connected to the support connector (51) respectively, and the spring (54) is in an elastic compression state. or The connecting part includes a chuck body (55), a chuck support shell (56), and chuck claws (57). The chuck body (55) is installed in the cavity of the chuck support shell (56). The chuck body (55) and the chuck support shell (56) are rotatably connected. There are multiple chuck claws (57), and the multiple chuck claws (57) are detachably connected to the corresponding curved surface bonding plate (52). The chuck body (55) includes a spiral chuck strip (58), and the chuck claw (57) has a groove (59) at one end away from the curved bonding plate (52), and the groove (59) fits into the spiral chuck strip (58).

2. The parapet wall variable diameter plastering tool according to claim 1, characterized in that: The metal plate (1) has a number of locking holes (11), which are distributed along the length of the metal plate (1).

3. A parapet wall variable diameter plastering tool according to claim 2, characterized in that: The fastener is a wing bolt assembly (3), which includes a wing bolt and a wing nut, and the wing bolt and the wing nut are threaded together.

4. A parapet wall variable diameter plastering tool according to claim 3, characterized in that: The locking hole (11) is a round hole or an elongated hole. The locking hole (11) includes an upper locking hole (12) and a lower locking hole (13). The upper locking hole (12) and the lower locking hole (13) are symmetrically distributed vertically. There are multiple upper locking holes (12). Adjacent upper locking holes (12) are equidistantly distributed along the length of the metal plate (1). The metal plate (1) also includes a scale, and the locking hole (11) corresponds to the scale.

5. A method for plastering a parapet wall with variable diameter, characterized in that: The parapet wall variable diameter plastering tool of claim 4 includes the following steps: Step a: Bend the rectangular metal plate (1) into a cylindrical shape, and select the corresponding locking hole (11) according to the arc angle of the bottom of the parapet wall to be processed by scale. Step b involves securing the bent metal plate (1) by passing the wing bolts and wing nuts through the corresponding locking holes (11); Step c: The construction worker performs the arc corner processing at the bottom of this section of the parapet wall by holding the handle (2); Step d: After the bottom arc corner of this parapet wall is processed, determine whether a diameter change is required; If step e does not require diameter change, continue construction. If diameter change is required, disassemble the wing bolt and wing nut, select the corresponding locking hole (11) through the scale, reinstall the wing bolt and wing nut, and then repeat steps c and d until construction is completed.

6. A method for plastering a parapet wall with variable diameter according to claim 5, characterized in that: Step d, which determines whether a diameter change is needed, includes: Step d1: Measure the distance from the edge of the brick side closest to the parapet wall to the parapet wall, and mark it as length one; Step d2 compares the length of the bending metal plate (1) with the inner diameter of the bending metal plate (1); The distance between two adjacent locking holes in step d3 is the hole spacing. If the absolute value of the difference between length 1 and the inner diameter of the metal plate (1) is less than or equal to the hole spacing, then no diameter change is required. If the absolute value of the difference between the length and the inner diameter of the metal plate (1) is greater than the hole spacing, the diameter needs to be changed. If the difference is positive, the inner diameter is increased; if the difference is negative, the inner diameter is decreased.

7. A method for applying a variable-diameter plaster to a parapet wall according to claim 5, characterized in that: When a change in diameter is required in step e, the following steps are included: Step e1: The butterfly bolt assembly (3) at the top and bottom of the outermost edge of the metal plate (1) remains unchanged, and the remaining butterfly bolt assemblies (3) are removed. Step e2: Loosen the wing bolt and wing nut on the outermost edge of the upper end, select and mark the positions of the new upper locking hole (12) and the new lower locking hole (13) according to the scale; Step e3 removes the wing bolts and wing nuts on the outermost edge of the lower end of the metal plate (1), and then applies force to the lower end of the metal plate (1) to connect the original lower locking hole (13) and the new lower locking hole (13) with the wing bolts and wing nuts threaded together. Step e4 removes the wing bolts and wing nuts on the outermost edge of the upper end of the metal plate (1), and then applies force to the upper end of the metal plate (1) to connect the original upper locking hole (12) and the new upper locking hole (12) with the wing bolts and wing nuts threaded together. Step e5 Repeat steps e3 and e4 until the new upper locking hole (12) and new lower locking hole (13) on the outermost edge of the marked metal plate (1) are threaded together with the wing bolt assembly (3); Step e6 Tighten the wing bolts and wing nuts on the outermost edge of the marked metal plate (1), and assemble the remaining wing bolt assembly (3).

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