Concrete Plaster Cutting Device Having a Multi-Core Drill Bit and Method for Non-Destructive Inspection of Plastered Concrete Structures

Abstract

The present invention relates to an apparatus for locally cutting and removing a plaster finish material from a plaster-finished concrete structure, and a method for non-destructively diagnosing the safety of a plaster-finished concrete structure using a Schmidt hammer, preferably by utilizing the apparatus. The cutting removal device for concrete plaster finish material according to the present invention is a device for locally cutting and removing plaster finish material from a plaster finish concrete structure, and is characterized by comprising: a drive unit that generates rotational force; a rotating shaft connected to the drive unit; a core bit having a rear end connected to the rotating shaft and a cutting edge formed at the front end, which receives rotational force from the drive unit and rotates to cut the plaster finish material in a circular shape; and a vacuum suction device mounted inside the core bit that vacuum-adsorbs and detaches from the plaster finish material being cut in a circular shape inside the core bit. Alternatively, the core bit is characterized by including a plurality of gears and belts to be provided as a multi-structure.

Description

Technology Field

[0001] The present invention relates to an apparatus for locally cutting and removing a plaster finish material from a plaster-finished concrete structure and a method for preferably using the apparatus. More specifically, the invention relates to an apparatus capable of locally and precisely cutting and removing a concrete plaster finish material, such as securing a local impact point for a Schmidt hammer during a safety diagnosis of a plaster-finished concrete structure, and a method for non-destructively diagnosing a plaster-finished concrete structure using a Schmidt hammer by preferably using the apparatus. Background Technology

[0003] One method for diagnosing the safety of concrete structures is non-destructive testing using a Schmidt hammer. A Schmidt hammer is a device that strikes the surface of concrete with a constant amount of energy, measures the degree of rebound, and estimates the compressive strength of the concrete. This non-destructive testing method using a Schmidt hammer is widely used for safety diagnosis of structures because it offers the advantage of simple and rapid strength estimation.

[0004] However, the surfaces of concrete structures are generally finished with plastering materials such as mortar. If a Schmidt hammer is struck directly onto a plaster-finished concrete structure for testing, the plastering material affects the rebound hardness measurement, making it difficult to obtain accurate test results. Therefore, a process is required to remove the plastering material from the concrete structure and expose the concrete surface prior to the test.

[0005] Conventionally, grinder-type devices have generally been applied to remove plaster finishes from concrete structures and expose the concrete surface. A representative example of a related patent is Patent No. 10-1924501, shown in Fig. 1. However, grinder-type devices have the disadvantage that it is difficult to precisely remove only the local impact points of a Schmidt hammer, and often removes an unnecessary large area. In addition, there are disadvantages such as dust and noise generation due to excessive grinding, increased subsequent work, and concerns about damage to the concrete surface. Prior art literature

[0007] (Patent Document 0001) KR 10-1924501 B1 The problem to be solved

[0008] The present invention was developed to improve a grinder-type device and has a technical objective of providing a new cutting and removal device capable of locally and precisely cutting and removing concrete plaster finishing materials, and a method for preferably applying such a cutting and removal device to the safety diagnosis of plaster-finished concrete structures. means of solving the problem

[0010] To solve the above-mentioned technical problem, the present invention provides a device for locally cutting and removing a plaster finish material from a plaster finish concrete structure, comprising: a drive unit that generates rotational force; a rotating shaft connected to the drive unit; a core bit having a rear end connected to the rotating shaft and a cutting edge formed at the front end, which receives rotational force from the drive unit and rotates to cut the plaster finish material in a circular shape; and a vacuum suction device mounted inside the core bit that vacuum-adsorbs and desorbs the plaster finish material being cut in a circular shape inside the core bit.

[0011] In addition, the present invention provides a device for locally cutting and removing a plaster finish material from a plaster finish concrete structure, comprising: a drive unit that generates rotational force; a rotating shaft connected to the drive unit; a first gear connected to the rotating shaft that receives the rotational force of the drive unit and rotates; a plurality of second gears installed to mesh with the first gear and rotate according to the rotation of the first gear; a first core bit provided on each of the plurality of second gears, having a rear end connected to the second gear and a cutting edge formed at the front end, which rotates according to the rotation of the second gear to cut the plaster finish material in a circular shape; and a vacuum suction device mounted inside the first core bit that vacuum-adsorbs and detaches the plaster finish material being cut in a circular shape inside the first core bit.

[0012] Furthermore, the present invention also provides a method for safety diagnosing a plaster-finished concrete structure using a cutting and removal device for concrete plaster finish material, comprising: a first step of marking the impact position of a Schmidt hammer on the surface of the plaster finish material in the plaster-finished concrete structure subject to safety diagnosis; a second step of preparing a cutting and removal device for concrete plaster finish material, positioning a vacuum suction nozzle at the location marked in the first step, and operating an actuator to rotate a core bit while cutting the plaster finish material in a circular shape with a cutting head; a third step of vacuum-adhering the vacuum suction nozzle of the cutting and removal device for concrete plaster finish material to the plaster finish material cut in a circular shape; and a fourth step of separating the cutting and removal device for concrete plaster finish material from the plaster-finished concrete structure while the vacuum suction nozzle is vacuum-adhered to the plaster finish material cut in a circular shape, thereby removing the plaster finish material cut in a circular shape from the plaster-finished concrete structure. A non-destructive safety diagnosis method for a plaster-finished concrete structure is provided, characterized by including: a fifth step of measuring rebound hardness by striking the concrete surface exposed after the plaster finish material has been removed from the plaster-finished concrete structure with a Schmidt hammer. Effects of the invention

[0014] According to the present invention, the following effects can be expected.

[0015] First, compared to conventional grinder methods, it can accurately and uniformly cut and remove only localized areas of concrete plaster finishes. Furthermore, because it generates less dust and noise, it is easy to apply indoors and in sensitive environments, and can reduce the burden on the worker.

[0016] Second, since localized areas of the concrete plaster finish are removed using a cutting method, the transmission of vibrations to the concrete structure during the removal process can be reduced, which is advantageous for maintaining the durability and safety of the structure.

[0017] Third, in the safety diagnosis of plaster-finished concrete structures, the concrete plaster finish can be selectively and easily removed only at the impact points of the Schmidt hammer, thereby preventing unnecessary damage to a large area. Brief explanation of the drawing

[0019] FIG. 1 shows a conventional grinder-type removal device disclosed in Patent No. 10-1924501. FIGS. 2 and 3 are structural diagrams of a single core bit structure, showing the structure of a cutting removal device for concrete plastering materials according to the present invention. Figure 4 is a flowchart of the operation sequence of the cutting removal device of Figure 2. FIG. 5 is a cross-sectional view of a cutting removal device for concrete plaster finish material according to the present invention, which is an embodiment of a 'multi-core bit structure' (cross-sectional view taken in the direction of A3-A3' in FIG. 6). FIG. 6 is a cross-sectional view of the cutting removal device of FIG. 5 viewed in the direction A1-A1'. Figure 7 is a cross-sectional view of the cutting removal device of Figure 5 viewed in the direction A2-A2'. Figure 8 is a diagram showing the operation process of the cutting removal device of Figure 5. Specific details for implementing the invention

[0020] The present invention will be described in detail below according to the attached drawings and preferred embodiments.

[0022] FIGS. 2 and 3 are structural diagrams of a cutting removal device (100) for a concrete plaster finish material according to the present invention, which are embodiments of a 'single-core drill bit structure', and FIG. 4 is a flowchart of the operation sequence of the cutting removal device (single-core drill bit structure) of FIG. 2. FIG. 5 is a cross-sectional view of a cutting removal device (100-1) for a concrete plaster finish material according to the present invention, which is an embodiment of a 'multi-core drill bit structure' (cross-sectional view taken in the A3-A3' direction of FIG. 6). FIG. 6 is a cross-sectional view of the cutting removal device (100-1) of FIG. 5 taken in the A1-A1' direction. FIG. 7 is a cross-sectional view of the cutting removal device (100-1) of FIG. 5 taken in the A2-A2' direction. FIG. 8 is a diagram showing the operation process of the cutting removal device (100-1) of FIG. 5. Hereinafter, an embodiment of a single-core drill bit structure will be described first, followed by an embodiment of a multi-core drill bit structure.

[0024] The cutting removal device (100) for concrete plaster finishing material according to the present invention is a device (single core bit structure) for locally cutting and removing plaster finishing material (220) from a plaster finishing concrete structure (200), and is configured to include a drive unit (110), a drive rotating shaft (120), a core barrel (130), a core bit (cutting blade, cutting head) (140), and a vacuum suction port (150), and according to this configuration, it is possible to cut and remove the plaster finishing material (220). Furthermore, the present invention may further include a vacuum means (160) and a scattering prevention unit (170).

[0025] The drive unit (110) is configured to generate rotational force using a motor or the like, and the main body of a power tool, such as an existing electric drill, can be utilized as is. A drive rotation shaft (120) is connected to the drive unit (110), and the rear end of the core barrel (130) is connected to the drive rotation shaft (120). As the rotational force of the drive unit (130) is transmitted to the core barrel (130) through the drive rotation shaft (120), the core barrel (130) and the cutting head (core bit or cutting edge) (140) rotate. If the drive unit (110) is provided as the main body of the power tool, components other than the drive unit (110) can be provided as replacement parts that are attached to and detached from the main body of the existing power tool.

[0026] A cutting head (core bit, core drill bit, or cutting edge) (140) is provided at the tip of the core barrel (130), thereby enabling the cutting head (140) to cut the plaster finishing material (220) in a circular shape as the core barrel (130) rotates. A scattering prevention part (170) may be further provided to cover the cutting head on the rotation axis or outside the core barrel (130), and the scattering prevention part (170) can prevent dust generated during the cutting process from scattering. The scattering prevention part can be configured in various forms, and in FIG. 2, an embodiment in which a plate-shaped (or disc-shaped, ring-shaped) scattering prevention part (170) is provided on the outside of the core barrel, and the scattering prevention part (170) can be attached to or detached from the core barrel in a detachable structure.

[0027] FIG. 3 illustrates another embodiment in which an umbrella-shaped (or dome-shaped, hemispherical) scattering prevention part (170-1) is coupled around a rotation axis. The scattering prevention part (170-1) shown in FIG. 3 can be coupled to the rotation axis by simply penetrating it through a central through hole. In addition, the surface of the rotation axis and the scattering prevention part (170-1) are spaced apart from each other by a predetermined distance so that the scattering prevention part (170-1) does not rotate together with the rotation axis even when the rotation axis rotates. However, the spacing may be within a few millimeters to prevent excessive release of scattered dust. Furthermore, the scattering prevention part (170-1) may be made of a transparent or translucent material so that the cutting process can be visually observed, and furthermore, it may be made of a structure or material capable of elastic deformation to respond flexibly to the cutting process. For example, in FIG. 3, the scattering prevention part (170-1) is in a shape where the radius increases as it approaches the plaster finish surface, but the scattering prevention part (170-1) may be inverted and coupled to the rotation axis in a shape where the radius increases as it moves away from the plaster finish surface. The reason for inverting the scattering prevention part (170-1) in this way is that the scattering prevention part (170-1) may interfere when setting the cutting position, so the position can be accurately set in the inverted state, and then the scattering prevention part (170-1) can be elastically deformed back to its original state before the cutting operation can be performed. To prevent wear caused by friction with the rotation axis, a ring-shaped member made of a wear-resistant material (e.g., metal material) may be placed at the inner diameter position of the scattering prevention part (170-1) that can come into contact with the rotation axis. That is, the scattering prevention part (170-1) may be provided with a ring-shaped member placed on the inner side (center) and a diffusion-shaped member made of an elastic material attached to the ring-shaped member.

[0028] The vacuum suction device (150) is mounted inside the core barrel (130) and configured to vacuum suction and detach from the plaster finishing material (220) that is cut in a circular shape inside the core barrel (130). This vacuum suction device (150) is appropriately designed to form a vacuum by means of a pressurization method or a suction method by a separately provided vacuum means (160) to suction onto the plaster finishing material (220). Meanwhile, when the vacuum suction device (150) is mounted inside the core barrel (130), the suction pad (151) can be mounted so that it is exposed outside the cutting head (140) at the tip of the core barrel. Since this vacuum suction device (150) can vacuum suction onto the plaster finishing material (220) before proceeding with the cutting process, it becomes possible to easily proceed with the cutting process while the cutting removal device (100) is fixed to the plaster finishing material (220) at the cutting location.

[0029] FIGS. 2 and 3 illustrate a vacuum suction device (150) having a structure comprising a suction pad (151) at the front end, a reciprocating moving part (152) at the rear end that reciprocates the suction pad (151), and a fixing part (153).

[0030] In the cutting process, the vacuum suction port (150) moves to the rear end of the core barrel as the suction pad (151) adheres to the plaster finish material (220), contrary to the cutting head (140) at the front end of the core barrel digging into the plaster finish material. During this movement, the reciprocating moving part (152) moves backward. The fixed part (153) may be a cylindrical member having an inner diameter larger than that of the reciprocating moving part (152). The reciprocating moving part (152) is coupled in such a way that it can be received inside the fixed part (153) when it retracts backward. Various embodiments of the material or configuration of the reciprocating moving part (152) of the vacuum suction port are possible. That is, the reciprocating moving part (152) can be provided in the form of a bellows (accordion), a piston, etc., and in FIGS. 2 and 3, a piston-shaped reciprocating moving part (152) configuration that can be accommodated inside the fixed part (153) is shown.

[0031] The vacuum means (160) is a separately provided configuration for forming a vacuum (or negative pressure) in the vacuum suction port (150), and any shape or structure is possible as long as it can form a vacuum in the vacuum suction port (150). As the vacuum means (160), a vacuum lever structure or a suction structure by a vacuum pump, which are commonly used for forming a vacuum (or negative pressure) in the past, can be appropriately applied, and FIGS. 2 to 4 illustrate a case where a suction structure by a vacuum pump is applied. As seen in FIGS. 2 to 4, a suction port (161) is provided on the upper surface or side of the core barrel (130) so as to be in communication with the vacuum suction port (150), and by connecting a vacuum pump to the suction port (161) and suctioning, a vacuum can be formed inside the vacuum suction port (150). If the vacuum means (160) is provided with a suction structure by a vacuum pump (or vacuum cleaner), dust and other debris on the cutting area may be cleaned by utilizing the vacuum pump (or vacuum cleaner) after the cutting operation is completed.

[0032] Figure 4 is a flowchart of the operation sequence of a cutting removal device for concrete plaster finish materials according to the present invention, and with reference thereto, a non-destructive safety diagnosis method for a plaster-finished concrete structure is examined step by step.

[0033] First, the impact location of a Schmidt hammer is marked on the surface of the plaster finish material (220) of the plaster finish concrete structure (200) subject to safety inspection (Step 1). Here, the plaster finish material (220) is typically a mortar finish, and the impact location marking is performed according to a conventional method.

[0034] Next, a cutting and removal device (100) for concrete plaster finish material as shown in FIG. 2 is prepared, and a vacuum suction port (150) is positioned at the location indicated in the first step. Then, the driving unit (110) is operated to rotate the core barrel (130) and the plaster finish material (220) is cut in a circular shape with the cutting head (140) (second step, FIG. 4(a)). If the suction pad (151) is provided to be exposed outside the cutting head (140) at the tip of the core barrel, the vacuum suction port (150) may be temporarily fixed by lightly vacuum-suctioning it at the indicated location prior to operating the driving unit (110), and then the driving unit (110) may be operated to perform the cutting process.

[0035] Next, a vacuum is formed in the vacuum suction port (150) in the cutting and removal device (100) for concrete plaster finishing material, and the suction part (151) is vacuum-adsorbed to the plaster finishing material (220) that has been cut into a circular shape (3rd step, FIG. 4(b)). While the vacuum suction in the 2nd step is an optional step for temporary close fixation, the vacuum suction in the 3rd step becomes an essential step for removing the plaster finishing material (220). If a vacuum means (160) is additionally included, a vacuum can be easily formed using the vacuum means. In particular, if the vacuum means is a suction structure by a vacuum pump (vacuum cleaner, etc.), a vacuum can be easily formed in FIG. 4(b) by connecting the suction port (161) and the vacuum pump (not shown) through the suction pipe (162) to discharge the air inside the vacuum suction port (150).

[0036] Next, with the vacuum suction device (150) vacuum-adhered to the circularly cut plaster finish material (220), the cutting removal device (100) for the concrete plaster finish material is separated from the plaster finish concrete structure (200) to remove the circularly cut plaster finish material (220) from the plaster finish concrete structure (200) (Step 4, FIG. 4(c). Since vibration is applied to the circularly cut plaster finish material (220) during the cutting process of Step 2, and additionally suction force is applied during the vacuum suction process of the vacuum suction device (150), the bonding force of the circularly cut plaster finish material (220) to the concrete surface will be weakened. Accordingly, if the cutting removal device (100) for the concrete plaster finish material is shaken or twisted while the vacuum suction part (151) vacuum-adhered to the circularly cut plaster finish material (220), it can be easily separated from the plaster finish concrete structure (200). Afterwards The vacuum of the vacuum suction port (150) can be released to detach the vacuum suction port (150) from the circularly cut plaster finish material (220).

[0037] Finally, the rebound hardness is measured by striking the surface of the exposed concrete (210) with a Schmidt hammer after the plaster finish material (220) has been removed from the plaster-finished concrete structure (200) (Step 5). If the surface of the exposed concrete (210) after the plaster finish material (220) has been removed is rough, the surface of the concrete (210) can be ground and cleaned before striking with the Schmidt hammer. In particular, if a vacuum means with a suction structure using a vacuum pump (vacuum cleaner, etc.) is applied, it is also possible to clean the surface of the exposed concrete (210) while using the vacuum means.

[0039] Hereinafter, an embodiment of the multi-core bit structure is described using FIGS. 5 to 8. FIG. 5 is a cross-sectional view of a cutting removal device (100-1) for concrete plastering materials according to the present invention, which is an embodiment of the 'multi-core bit structure' (a cross-sectional view taken in the direction A3-A3' of FIG. 6). FIG. 6 is a cross-sectional view of the cutting removal device (100-1) of FIG. 5 taken in the direction A1-A1'. FIG. 7 is a cross-sectional view of the cutting removal device (100-1) of FIG. 5 taken in the direction A2-A2'. FIG. 8 is a drawing showing the operation process of the cutting removal device (100-1) of FIG. 5.

[0040] The cutting removal device with a multi-core bit structure is similar to the structure of a single core bit overall, but differs in that a drive gear (131), a first gear (132-1), a second gear (132-2), and a belt (133-1, 133-2) are additionally provided so that the core barrels (130-1, 130-2, 130-3, 130-4) and core bits (140-1, 140-2, 140-3) are provided in multiple numbers and operate in conjunction with each other.

[0041] Specifically, the cutting removal device (100-1) of the multi-core bit structure comprises: a drive unit (110) (not shown) that generates rotational force; a drive rotation shaft (120) connected to the drive unit (110); a drive gear (131) connected to the drive rotation shaft (120) and rotating by receiving the rotational force of the drive unit (110); a first gear (132-1) installed to mesh with the drive gear (131) and rotating around a first rotation shaft (134-1) according to the rotation of the drive gear (131); and a second gear (132-2) installed to mesh with the drive gear (131) and rotating around a second rotation shaft (134-2) according to the rotation of the drive gear (131). A first core barrel (130-1) provided on the first gear, with a rear end connected to the first gear and a first core bit (cutting head or cutting blade) (140-1) formed on the front end, which rotates according to the rotation of the first gear (132-1) to cut the plaster finishing material in a circular shape; a second core barrel (130-2) provided on the second gear, with a rear end connected to the second gear and a second core bit (cutting head or cutting blade) (140-2) formed on the front end, which rotates according to the rotation of the second gear (132-2) to cut the plaster finishing material in a circular shape; A third core barrel (130-3) provided around the first core barrel (130-1), with a third core bit (cutting head or cutting blade) (140-3) formed at its tip, which rotates around a third rotation axis (134-3) to cut the plaster finishing material in a circular shape; a fourth core barrel (130-4) provided around the second core barrel (130-2), with a fourth core bit (cutting head or cutting blade) (140-4) formed at its tip, which rotates around a fourth rotation axis (134-4) to cut the plaster finishing material in a circular shape;A first belt (133-1) connecting the first core barrel (130-1) and the third core barrel (130-3) so that the rotational force of the first core barrel (130-1) is transmitted to the third core barrel (130-3) to cause the third core barrel (130-3) to rotate around the third rotation axis (134-3) as the first core barrel (130-1) rotates, and a second belt (133-2) connecting the second core barrel (130-2) and the fourth core barrel (130-4) so ​​that the rotational force of the second core barrel (130-2) is transmitted to the fourth core barrel (130-4) to cause the fourth core barrel (130-4) to rotate around the fourth rotation axis (134-4) as the second core barrel (130-2) rotates; A first vacuum suction device (not shown, corresponding to 150 in FIG. 2) mounted inside the first core barrel (130-1) and vacuum-adsorbing and desorbing a plaster finishing material cut in a circular shape inside the first core barrel (130-1); a second vacuum suction device (not shown) mounted inside the second core barrel (130-2) and vacuum-adsorbing and desorbing a plaster finishing material cut in a circular shape inside the second core barrel (130-2); and a third vacuum suction device (not shown) mounted inside the third core barrel (130-3) and vacuum-adsorbing and desorbing a plaster finishing material cut in a circular shape inside the third core barrel (130-3). It includes: a fourth vacuum suction device (not shown) mounted inside the fourth core barrel (130-4) to vacuum suction and detach from a plaster finishing material cut in a circular shape inside the fourth core barrel (130-4); a frame (190) that rotatably supports a drive rotation shaft (120), a first rotation shaft (134-1), a second rotation shaft (134-2), a third rotation shaft (134-3), and a fourth rotation shaft (134-4); and a scattering prevention part (170-2) that accommodates the first to fourth core barrels (130-1, 130-2, 130-3, 130-4) inside to prevent scattering of dust generated while the first to fourth core barrels (130-1, 130-2, 130-3, 130-4) rotate and cut.

[0043] A drive shaft (120) connected to a drive unit (not shown) can be rotatably coupled to a scatter prevention unit (170-2) and a frame (190). If necessary, a predetermined gap may be formed or a bearing may be installed between the drive shaft (120), the scatter prevention unit (170-2), and the frame (190) to reduce rotational friction.

[0044] A drive gear (131), which is connected to a drive rotation shaft (120) and receives rotational force from a drive (not shown), transmits rotational force to a first gear (132-1) and a second gear (132-2). When torque is important in cutting processes, it is preferable to have a gear ratio greater than 1 so that the number of teeth of the first gear (132-1) and the second gear (132-2) is greater than the number of teeth of the drive gear (131). Additionally, when rotational speed is important, it is preferable to have a gear ratio less than 1 so that the number of teeth of the first gear (132-1) and the second gear (132-2) is less than the number of teeth of the drive gear (131). In this embodiment, there are two gears that mesh with the drive gear (131), namely the first gear (132-1) and the second gear (132-2), but three or more gears may be provided and arranged in various configurations (triangular, square, etc.).

[0045] The first gear (132-1) is installed to mesh with the drive gear (131) and rotates around the first rotation axis (134-1) according to the rotation of the drive gear (131). The second gear (132-2) is installed to mesh with the drive gear (131) and rotates around the second rotation axis (134-2) according to the rotation of the drive gear (131). The first rotation axis (134-1) and the second rotation axis (134-2) are rotatably coupled to the frame (190).

[0046] The first core barrel (130-1) is coupled to rotate integrally with the first gear (132-1), and a first core bit (cutting head or cutting blade) (140-1) is formed at the bottom so that the plaster finishing material can be cut in a circular shape. Since the second core barrel (130-2) has a similar configuration, a redundant description is omitted.

[0047] The third core barrel (130-3) is positioned adjacent to the first core barrel (130-1), and a third core bit (cutting head or cutting edge) (140-3) is formed at its tip. It receives rotational force from the first gear (134-1) and rotates around the third rotation axis (134-3) to cut the plaster finishing material in a circular shape. Since the fourth core barrel (130-4) has a similar configuration, a redundant description is omitted.

[0048] The first belt (133-1) connects the first core barrel (130-1) and the third core barrel (130-3) to each other so that the third core barrel (130-3) rotates around the third rotation axis (134-3) as the first core barrel (130-1) rotates. The inner surface of the first belt (133-1) may be formed as a flat surface or may have protrusions formed thereon. For example, if there are no protrusions on the inner surface of the first belt (133-1), rotational force can be transmitted through frictional force between the inner surface of the first belt (133-1) and the outer surface of the third core barrel (130-3). If protrusions are formed on the inner surface of the first belt (133-1), rotational force can be transmitted by forming protrusions corresponding to the outer surfaces of the first core barrel (130-1) and the third core barrel (130-3). The first belt (133-1) may be composed of a material capable of elastic deformation, such as rubber, or may be composed of metal links connected in a continuous sequence, such as a chain. The second belt (133-2) is omitted as the description is redundant.

[0049] The first to fourth vacuum suction tubes are substantially identical components to the vacuum suction tube (150) in the embodiment corresponding to the single core bit structure. That is, since the first to fourth vacuum suction tubes are substantially identical components to the vacuum suction tube (150) of FIG. 2, a redundant description is omitted.

[0050] The frame (190) is a component that supports a plurality of rotation axes so that they can rotate stably. That is, the frame (190) includes a main body provided as a plate-shaped member, and a plurality of perforated holes are formed in the main body, and a driving rotation axis (120), a first rotation axis (134-1), a second rotation axis (134-2), a third rotation axis (134-3), and a fourth rotation axis (134-4) can be rotatably supported in each perforated hole. Bosses may be formed around each perforated hole so that each rotation axis can maintain a predetermined verticality. That is, a driving rotation axis boss, a first rotation axis boss, a second rotation axis boss, a third rotation axis boss, and a fourth rotation axis boss may be formed in the main body. Bearings may be installed on the inner surface of each perforated hole and boss for smoother and more fluid rotation.

[0051] The dust prevention unit (170-2) is a component that houses the first to fourth core barrels (130-1, 130-2, 130-3, 130-4) internally to prevent dust from scattering as the first to fourth core barrels (130-1, 130-2, 130-3, 130-4) rotate and cut. The dust prevention unit (170-2) may be coupled to a drive rotating shaft (120) so that it can be raised and lowered. In order to accurately adjust the cutting position of the plaster finish material, the dust prevention unit (170-2) can be raised to check whether the first to fourth core barrels (130-1, 130-2, 130-3, 130-4) are positioned in an appropriate location. The dust prevention unit (170-2) may be made of a material capable of elastic deformation or may be made of a material such as a rigid body. The scattering prevention part (170-2) may be made of a transparent or translucent material depending on the case.

[0052] A cutting removal device with a multi-core bit structure as shown in Fig. 5 can also be used in the same way as a single-core bit structure as shown in Fig. 4 to perform a non-destructive safety diagnosis method for plaster-finished concrete structures.

[0053] Although the present invention has been described in detail above with reference to specific embodiments, the embodiments are merely illustrative of the invention; therefore, substitutions, additions, and modifications made within the scope of the technical spirit of the invention shall also be deemed to fall within the scope of protection of the present invention as defined by the claims appended below. Explanation of the symbols

[0055] 100, 100-1: Cutting removal device for concrete plaster finishes 110: Actuator 120: Drive shaft 130-1: 1st Core Barrel 130-2: 2nd Core Barrel 130-3: 3rd Core Barrel 130-4: 4th Core Barrel 131: Drive gear 132-1: 1st gear 132-2: 2nd gear 133-1: 1st belt 133-2: 2nd Belt 140-1: 1st Core Bit 140-2: 2nd Core Bit 140-3: 3rd Core Bit 140-4: 4th Core Bit 150: Vacuum Suction Pot 170, 170-1, 170-2: Dust control unit

Claims

Claim 1 A device for locally cutting and removing plaster finishing material from a plaster-finished concrete structure, comprising: a frame; an actuator that generates rotational force; a drive rotating shaft connected to the actuator and rotatably coupled to the frame; a drive gear connected to the drive rotating shaft and rotating by receiving the rotational force of the actuator; a first gear and a second gear installed to mesh with the drive gear and coupled to the frame to rotate according to the rotation of the drive gear; a first core barrel provided on the first gear, having a rear end connected to the first gear and a core bit formed at the front end, which rotates according to the rotation of the first gear and cuts the plaster finishing material in a circular shape; a second core barrel provided on the second gear, having a rear end connected to the second gear and a core bit formed at the front end, which rotates according to the rotation of the second gear and cuts the plaster finishing material in a circular shape; and a third core bit at the front end and an internal vacuum suction port located around the first core barrel and rotatably coupled to the frame. A cutting and removal device for concrete plaster finish material, characterized by comprising: a third core barrel provided to be provided; a fourth core barrel located around the second core barrel and rotatably coupled to the frame, provided to have a fourth core bit at the tip and a vacuum suction port inside; a first belt connecting the first core barrel and the third core barrel to rotate the third core barrel according to the rotation of the first core barrel; a second belt connecting the second core barrel and the fourth core barrel to rotate the fourth core barrel according to the rotation of the second core barrel; a vacuum suction port mounted inside the first and second core barrels to vacuum suction and desorption of the plaster finish material being cut in a circular shape from the inside; and a dust prevention unit that accommodates the first to fourth core barrels inside to prevent dust scattering generated while the first to fourth core barrels rotate and cut. Claim 2 delete Claim 3 A method for safety diagnosing a plaster-finished concrete structure using a cutting and removal device for concrete plaster finish material according to claim 1, comprising: a first step of marking the impact location of a Schmidt hammer on the surface of the plaster finish material of the plaster-finished concrete structure subject to safety diagnosis; a second step of preparing a cutting and removal device for concrete plaster finish material, positioning a vacuum suction nozzle at the location marked in the first step, and operating a drive to rotate the core barrel while cutting the plaster finish material in a circular shape with a cutting blade; a third step of vacuum-suctioning the vacuum suction nozzle of the cutting and removal device for concrete plaster finish material onto the circularly cut plaster finish material; a fourth step of separating the cutting and removal device for concrete plaster finish material from the plaster-finished concrete structure while the vacuum suction nozzle is vacuum-suctioned onto the circularly cut plaster finish material, thereby removing the circularly cut plaster finish material from the plaster-finished concrete structure; and measuring the rebound hardness by striking the concrete surface exposed after the plaster finish material has been removed from the plaster-finished concrete structure with a Schmidt hammer. A non-destructive safety diagnosis method for plaster-finished concrete structures characterized by including Step 5.

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