KR102354023B1 - sanding method for floor - Google Patents

Abstract

The present invention relates to a method of sanding wooden flooring. More particularly, the present invention relates to a sanding method for repairing wooden flooring in buildings such as houses, shopping malls, schools, and sports facilities. According to the present invention, if the surface of the flooring installed in houses, shopping malls, schools, sports facilities, or the like is scratched, contaminated, or deformed over time, the surface of the flooring is cut off and coated several times, thereby improving the durability of the flooring, and prolonging the lifespan of the flooring. In addition, when the life of the flooring is extended by sanding the flooring according to the present invention, it is better and more efficient in terms of price and performance than replacing the flooring with a new one.

Description

Sanding method for floor

The present invention relates to a sanding method for flooring, and more particularly, to a sanding method for repairing wooden flooring constructed in buildings such as houses, shopping malls, schools, and sports facilities.

In general, the flooring is constructed by assembling wooden flooring in a tongue-and-groove, click structure, etc. in succession, and is installed on a concrete base surface or a floor frame through an adhesive.

Parquet floors are being installed on the floors of various buildings such as houses, shopping malls, schools, and sports facilities. Due to the nature of the wood, the surface of these parquet floors is dented or scratched over time, and discoloration and contamination occur. In addition, there are cases in which the flooring material is not maintained horizontally due to warping over time.

In order to solve this problem, it is necessary to reconstruct the entire installed flooring. It is possible to restore to a new surface condition only after removing the wood flooring material, concrete adhesive, and even some concrete of the floor and then constructing a new one.

Even though most of the damage occurred on the surface of the floor, it takes a lot of money and time because the entire floor must be removed and reconstructed.

Korean Patent Laid-Open Publication No. 10-2006-0119240 discloses a UV curing coating method for a constructed floor.

The UV curing coating method includes a pretreatment process of scratching or polishing the surface with loofah or sandpaper and removing residual foreign substances, a coating process of applying UV paint to the pretreated surface, and curing to harden the UV paint with a mobile curing machine made by the process

The UV curing coating method has a problem in that durability is weak because it repairs the floor by simply applying a UV paint with only one layer.

Korean Patent Laid-Open Patent No. 10-2006-0119240: UV curing coating method of the installed floor

The present invention was created to improve the above problems, and in more detail, scratches, contamination, deformation, etc. may occur on the surface of the flooring installed in buildings such as houses, shopping malls, schools, and sports facilities over time. In this case, the purpose of the present invention is to provide a flooring sanding method that can increase the durability of the flooring and extend its lifespan by coating it several times after cutting the surface of the flooring.

In order to achieve the above object, the present invention provides a floor sanding method comprising: a floor sanding step of cutting the floor to a predetermined depth and polishing the surface of the floor; a first cleaning step of removing the dust generated in the floor sanding step and remaining on the surface of the parquet floor; an undercoating step of forming an undercoating layer by applying a primer to the surface of the parquet after the first cleaning step; a slip sanding step of forming a smooth surface of the undercoating layer by polishing the surface of the undercoating layer after hardening of the undercoating layer; a secondary cleaning step of removing the dust generated in the slip sanding step and remaining on the surface of the undercoating layer; a middle coating step of forming a middle coating layer by applying a middle agent to the surface of the base coating layer after the second cleaning step; and a topcoating step of forming a topcoating layer by applying a topcoating agent to the surface of the intermediatecoating layer after curing the intermediatecoating layer.

The method further includes a line marking step of forming a line on the surface of the undercoating layer after the secondary cleaning step.

In the floor sanding step, the surface of the floor is polished while moving a sander in a zigzag direction, and the sander includes a housing, a handle frame coupled to one side of the housing, a motor installed on the upper part of the housing, and the housing; a dust collecting cover coupled to a lower portion of the dust collecting cover, a rotating shaft installed inside the dust collecting cover and having an upper portion extending inside the housing, a driving shaft coupled to the motor and extending to the inner side of the housing, the driving shaft and the A power transmission unit for connecting the rotating shaft, a polishing pad detachably coupled to the lower part of the rotating shaft to polish the floor, and a blower installed on the upper part of the housing to suck and collect dust from the inside of the dust collection cover. and a vibration suppressing means for reducing the transmission of vibrations between the motor and the housing, the vibration suppressing means comprising: a first buffering unit installed on the upper portion of the housing to attenuate vibrations in the lateral direction; A second shock absorber coupled to the upper portion of the first shock absorber and installed below the support bracket formed in the motor to attenuate vibration in the longitudinal direction, and the first and second shock absorbers inserted into the mounting hole formed in the support bracket a fixing bolt penetrating through the upper surface of the housing; a nut screwed to the fixing bolt; and a third buffering part installed between the nut and the upper surface of the housing, wherein the first buffering part includes the second buffering part An inner box with an empty interior, an open top, and a conical conical groove formed on the bottom, a steel ball positioned in the conical groove, and a first formed to surround the outer surface and the bottom of the inner box so that the part can be inserted inside An elastic body, an enclosure formed to surround the outer surface of the first elastic body, and a second perforated hole formed in a transverse direction to the first elastic body, one side of which is in contact with the outside of the inner box, and the other side of the enclosure A second elastic body having a first spring in contact with the inside, wherein the second shock absorber includes a bottom plate in contact with the upper portion of the steel ball, and a second elastic body coupled to the upper portion of the bottom plate and having a protrusion inserted into the mounting hole on the upper portion Wow, A second spring is inserted into the second perforated hole formed in the longitudinal direction of the second elastic body, the upper part is in contact with the head of the fixing bolt, and the lower part is provided with a second spring in contact with the bottom plate.

As described above, in the present invention, if the surface of the flooring installed in a building such as a house, a shopping mall, a school, or a sports facility is scratched, contaminated, or deformed over time, the surface of the flooring is cut off several times. By coating, the durability of the floor can be increased and the lifespan can be extended.

In addition, in the case of extending the lifespan of the parquet by sanding the parquet according to the present invention, it is more excellent and efficient in terms of price/performance than replacing the parquet with a new one.

1 is a block diagram showing step by step a sanding method according to an example of the present invention;
2 is a cross-sectional view showing an example of a sanding machine applied to the present invention,
3 is a cross-sectional view showing another example of a sanding machine applied to the present invention,
4 is an exploded perspective view in which the main part of FIG. 3 is extracted.

Hereinafter, a sanding method of the floor according to a preferred embodiment of the present invention will be described.

Referring to FIG. 1, in the floor sanding method of the present invention, the floor sanding step of grinding the surface of the floor by cutting the floor to a certain depth, and the dust generated in the floor sanding step and remaining on the surface of the floor After the first cleaning step to remove, the undercoating step of applying a primer to the surface of the flooring to form an undercoating layer after the first cleaning step, and after curing the undercoating layer, the surface of the undercoating layer is polished by grinding the surface of the undercoating layer A slip sanding step of smooth formation, a secondary cleaning step of removing the dust generated in the slip sanding step and remaining on the surface of the undercoat layer, and after the second cleaning step, a middle coating agent is applied to the surface of the undercoat layer to form an intermediate coating layer and a top coat step of forming a top coat layer by applying a top coat agent to the surface of the intermediate coat layer after curing of the intermediate coat layer. Hereinafter, each step will be described in detail.

1. Floor sanding step

The floor sanding step is a process of sanding the surface of the floor by cutting the floor that has been constructed and used for a certain period to a certain depth.

Buildings such as houses, shopping malls, schools, and sports facilities have flooring made of wood flooring. As time goes by, the installed parquet floor may become dented or scratched. In addition, discoloration and contamination occur on the floor due to penetration of moisture or various contaminants. In addition, the wooden flooring material is warped and the surface of the floor is not maintained horizontally.

Through the floor sanding step, it is possible to remove damaged areas, scratches, and contaminated areas on the surface of the floor. In addition, in the floor sanding step, the floor can be leveled by cutting and polishing the floor.

In the floor sanding step, the floor can be cut by a sanding method that rubs the surface of the floor with an abrasive pad such as sandpaper. When the thickness of the wooden flooring material is 22mm, the flooring can be cut by 2 to 10mm through the floor sanding step. It goes without saying that the cutting depth can be adjusted within the range of 2 to 10 mm depending on the surface condition of the floor.

The floor sanding step may be performed using a sander. An example of a sanding machine is shown in FIG. 2 .

Referring to FIG. 2 , the sanding machine includes a housing 10 , a handle frame 11 coupled to one side of the housing 10 , a motor 15 installed on the upper portion of the housing 10 , and the housing 10 . A dust collecting cover 20 coupled to the lower portion, a rotating shaft 23 installed inside the dust collecting cover 20 and having an upper portion extending inside the housing 10 , and a motor 15 coupled with a lower portion of the housing 10 ), a drive shaft 16 extending inside, a power transmission unit connecting the drive shaft 16 and the rotary shaft 23, and a polishing pad detachably coupled to the lower portion of the rotary shaft 23 to polish the floor ( 25) and a dust collecting unit 40 for sucking and collecting dust from the inside of the dust collecting cover 20 by the blower 41 installed on the upper part of the housing 10.

The housing 10 has a cylindrical structure with an empty interior. A power transmission unit is installed inside the housing 10 .

A handle frame 11 is provided so that an operator can move or change the direction of the sander. The handle frame 11 is coupled to the rear surface of the housing 10 to extend a predetermined length. The handle frame 11 is provided with a handle so that the operator can hold it by hand.

The motor 15 is installed on the upper part of the housing 10 . A support bracket 17 is coupled to the motor 15 to fix the motor 15 to the housing 10 . The support bracket 17 is fixed to the upper surface of the housing 10 by a fixing bolt 90 and a nut 95 . The drive shaft 16 of the motor 15 extends into the housing 10 .

The dust collecting cover 20 is coupled to the lower portion of the housing 10 . The dust collecting cover 20 is provided with a circular space inside. A flexible skirt portion 21 is provided under the dust collecting cover 20 . The skirt part 21 serves to block the dust generated during grinding in contact with the floor from being discharged to the outside of the dust collecting cover 20 .

The rotating shaft 23 is installed inside the dust collecting cover 20 . An upper portion of the rotating shaft 23 extends inside the housing 10 .

The rotating shaft 23 receives power from the driving shaft 16 by a power transmission unit. The power transmission unit includes, for example, a driving pulley 31 coupled to the driving shaft 16 , a driven pulley 33 coupled to the rotating shaft 23 , and a belt 35 connecting the driving pulley 31 and the driven pulley 33 . ) is made of When power is supplied to the motor 15 and the motor 15 is driven, the rotating shaft 23_ can rotate in a predetermined direction.

The polishing pad 25 is coupled to the lower portion of the rotation shaft 23 . The polishing pad 25 is located inside the dust collecting cover 20 . The polishing pad 25 is coupled to the rotation shaft 23 to be detachably attached. The polishing pad 25 is formed in a disk shape. Abrasive particles are attached to the surface to be scraped off by rubbing the floor with the polishing pad 25 . A disk-shaped sandpaper may be used as the polishing pad 25 . The roughness of the polishing pad 25 may be between No. 24 (#24) and No. 180 (#180).

The dust collecting unit 40 sucks and collects dust generated when the polishing pad 25 rubs the floor.

The illustrated dust collecting unit 40 includes a blower 41 installed on the upper part of the housing 10 , a suction pipe 43 connected to the inside of the dust collecting cover 20 connected to the suction side of the blower 41 , and a blower 41 . ) consists of a discharge pipe 45 connected to the discharge side, and a collecting bag 47 coupled to the discharge pipe 45 to collect dust.

The blower 41 is also provided with a support bracket 42 to be fixed to the housing 10 like the motor 15 , and the support bracket 42 is fixed to the upper surface of the housing 10 by a fixing bolt and a nut.

The suction pipe 43 is connected to the suction side of the blower 41 and is connected to the inside of the dust collecting cover 20 . When the blower 41 operates, the dust generated inside the dust collection cover 20 is sucked through the suction pipe 43 and discharged to the discharge pipe 45 .

The collecting bag 47 is coupled to the end of the discharge pipe 45 . The collecting bag 47 is formed of a breathable material. Accordingly, the air introduced into the collecting bag 47 together with the dust through the discharge pipe 45 is discharged to the outside of the collecting bag 47 , and the dust does not pass through the collecting bag 47 and is inside the collecting bag 47 . is captured in

The above-described sanding machine can effectively perform sanding of the floor while the operator pushes it. In addition, since the sander is equipped with a dust collecting unit, it is possible to work while collecting dust generated during grinding, thereby improving the working environment.

In the floor sanding step, the surface of the floor is sanded while moving the sander in the zigzag direction. One-time sanding reduces the thickness of the floor by 0.5~1mm. Sanding can be repeated two or more times. For example, sanding may be repeated 3 to 4 times.

When sanding is repeated several times, start with a coarse abrasive pad and end with a fine abrasive pad. For example, when sanding is repeated three times, in the case of rough sanding, a polishing pad having a roughness of No. 24 (#24) is used, and at the time of sanding using a conglomerate sanding, a polishing pad having a roughness of No. can be polished with a polishing pad having a roughness of No. 180 (#180).

In addition, corners that are difficult to grind with a sander because the sander does not reach can be polished using a hand grinder.

Meanwhile, it goes without saying that, in addition to the sanding machine shown in FIG. 2 , a conventional floor sanding machine may be used.

2. 1st cleaning stage

Next, a primary cleaning step is performed to remove the dust generated in the floor sanding step and remaining on the surface of the parquet floor.

If the coating is performed while dust remains on the surface of the floor, the coating layer is lifted and the quality of the coating layer is deteriorated. Therefore, in the first cleaning stage, it is necessary to remove the dust remaining on the surface of the floor.

Since the present invention performs the floor sanding step using a sander having a dust collecting function, most of the dust is removed in the floor sanding step. Therefore, the amount of dust remaining on the surface of the parquet is not large.

Dust is removed using a conventional vacuum cleaner. Remove the dust remaining on the surface of the floor by suctioning it with a vacuum cleaner.

3. Undercoating step

Next, an undercoating layer is formed by applying a primer to the surface of the parquet floor. The undercoating layer may have a thickness of 10 to 100 μm. The primer fills the fine gaps on the polished floor surface and strengthens the bonding strength of the intermediate coating layer.

A conventional sanding sealer may be used as a primer. As a sanding sealer, commercially available Hi-Lok Plus Sanding Sealer (Noroo Paint, Korea) can be used.

It is preferable to apply the primer using a brush or roller. However, if necessary, it can be applied by spraying using a spray gun.

A primer coating layer can be formed by uniformly applying a primer to the entire surface of the polished flooring and then leaving it to stand for a certain period of time to harden.

4. Slip Sanding Step

Next, a slip sanding step of polishing the surface of the undercoat layer after curing of the undercoat layer is performed.

The slip sanding step is to cut the surface of the undercoating layer to level the undercoating layer and to smooth the surface.

The slip sanding step may be performed using a sander shown in FIG. 2 . In the slip sanding step, the undercoating layer is rubbed and polished using a soft polishing pad having a roughness of 220 to 320.

5. Secondary cleaning stage

Next, the dust generated in the slip sanding step and remaining on the surface of the undercoating layer is removed.

The second cleaning step may be performed in the same way as the first cleaning step. Therefore, the second cleaning step also removes dust using a vacuum cleaner. Remove the dust remaining on the surface of the floor by suctioning it with a vacuum cleaner.

6. Intermediate coating step

Next, an intermediate coating layer is formed by applying an intermediate agent to the surface of the primer coating layer. The intermediate coating layer may be formed to a thickness of 10 to 100 μm.

A nitrocellulose (superscreen)-based varnish can be used as a neutralizer. As such an intermediate agent, commercially available Hi-Lak Plus Transparent (Noroo Paint, Korea) can be used.

It is preferable to apply the intermediate agent using a brush or roller. If necessary, it can be applied by spraying with a spray gun.

The intermediate coating layer can be formed by uniformly applying the intermediate agent to the entire surface of the polished undercoating layer and then leaving it to cure for a certain period of time.

7. Top coat step

Next, a topcoat is formed by applying a topcoat to the surface of the intermediate coating layer. The top coat layer is located on the top layer and serves as a finishing layer. The top coating layer may be formed to a thickness of 10 to 100 μm.

A urethane-based varnish may be used as a top coater. As such a topcoat, a commercialized green varnish new DV-2800 (Noroo Paint, Korea) can be used.

It is preferable to apply the top coat using a brush or roller. If necessary, it can be applied by spraying with a spray gun.

A top coat layer can be formed by uniformly applying the top coat to the entire surface of the intermediate coat layer and then leaving it to cure for a certain period of time. When the top coat layer is formed, the floor sanding method is completed.

As described above, according to the present invention, the durability of the floor can be increased and the lifespan of the floor can be extended by coating the floor by sequentially performing the lower coat, the middle coat, and the upper coat after the surface of the floor is cut.

In addition, in the case of extending the lifespan of the parquet by sanding the parquet according to the present invention, it is more excellent and efficient in terms of price/performance than replacing the parquet with a new one.

On the other hand, the present invention may further perform the line marking step. The line marking step is performed between the secondary cleaning step and the intermediate coating step.

A line can be formed on the surface of the undercoating layer after the secondary cleaning step through the line marking step. In the case of the gym floor, lines for various sports are required.

The line marking step includes a taping step of attaching a tape for line marking to the floor, a painting step of applying a paint of a specific color along the line marked by the tape, and a tape removal step of removing the tape after the paint is cured. is done

Meanwhile, the sanding machine shown in FIGS. 3 and 4 may be used as the sanding machine used in the present invention.

Referring to FIGS. 3 and 4 , the sander further includes vibration suppressing means for blocking vibration transmission between the motor 15 and the housing 10 . Since the sanding machine shown in the figure has the same configuration as in FIG. 2 except for the vibration suppressing means, a description of the remaining components except for the vibration suppressing means will be omitted.

The vibration suppressing means includes a first shock absorber 50 that is installed on the upper portion of the housing 10 to attenuate vibration in the lateral direction, and a support bracket that is coupled to the upper portion of the first shock absorber 50 and is formed on the motor 15 ( 24), the second shock absorber 60 is installed in the lower part to attenuate vibration in the longitudinal direction, and the first and second shock absorbers 50 and 60 are inserted into the mounting hole 18 formed in the support bracket 24. ) and a fixing bolt 90 passing through the upper surface of the housing 10 , a nut 95 screwed to the fixing bolt 90 , and a third installed between the nut 95 and the upper surface of the housing 10 . A buffer unit 70 is provided.

The first shock absorber 50 is installed on the upper surface of the housing 10 and serves to attenuate vibration in the lateral direction. A first bolt insertion hole 57 penetrating vertically is formed in the first buffer unit 50 . The first bolt insertion hole 57 is formed to have a larger diameter than the fixing bolt 90 .

The first shock absorber 50 has an empty interior so that the second shock absorber 60 can be inserted into the inner box 51, the top is open, and the bottom has a conical conical groove 52 formed therein, and a conical groove ( The steel ball 53 positioned at 52, the first elastic body 54 formed to surround the outer surface and the bottom of the inner box 51 from the outside, and the outer box formed to surround the outer surface of the first elastic body 54 (55) and a first spring (56) mounted in a perforated hole formed in the transverse direction in the first elastic body (54), one side being in contact with the outside of the inner box (51) and the other side being in contact with the inside of the enclosure (55) to provide

The inner box 51 is formed of a metal material. The inner box 51 has a cylindrical structure with an open top. A plurality of conical grooves 52 are formed at the bottom of the inner box 51 . The conical groove 52 is disposed around the first bolt insertion hole 57 penetrating the first cushioning part 50 up and down. The conical groove 52 is formed in a shape that gradually deepens toward the center.

The steel ball 53 is positioned in the conical groove 25 and is in contact with the upper surface of the second cushioning unit 60 . The steel ball 53 is formed of a metal material having excellent strength. For example, it may be formed of high carbon chromium steel. The steel ball 53 is formed in a spherical shape. The diameter of the steel ball 53 is formed larger than the depth in the central portion of the conical groove (52).

Since the first shock-absorbing part 50 and the second shock-absorbing part 60 are in contact with the steel ball 53 , the lower part of the second shock-absorbing part 60 is spaced apart from the bottom of the inner box 51 . When the second cushioning part 60 moves horizontally and the steel ball 53 deviates from the center of the conical groove 52 , the steel ball 53 tries to roll toward the center of the conical groove 52 . ) can easily return to the original position.

The first elastic body 54 is formed to surround the outer surface and the bottom of the inner box 51 from the outside. The first elastic body 51 is formed of a material having excellent elasticity, such as rubber. A plurality of first perforated holes 57 are formed in the first elastic body 54 . Four first perforated holes 57 may be installed at intervals of 90 degrees. The first perforated hole 57 is formed to pass through the first elastic body 54 in the horizontal direction.

The enclosure 55 is formed to surround the outer surface of the first elastic body 54 . The enclosure 55 has a cylindrical structure with an open top and a bottom. The enclosure 55 may be formed of a metal material.

The first spring 56 is mounted in the first perforated hole 57 so that one side is in contact with the outside of the inner box 51 and the other side is in contact with the inside of the enclosure 55 . This first spring 56 reduces vibration in the transverse direction.

The second shock absorber 60 is coupled to the upper portion of the first shock absorber 50 to attenuate vibration in the longitudinal direction. A second bolt insertion hole 66 penetrating vertically is formed in the second buffer unit 60 . The second bolt insertion hole 66 has a smaller diameter than the first bolt insertion hole 57 . The inner peripheral surface of the second bolt insertion hole 66 is in close contact with the outer peripheral surface of the fixing bolt (90).

The second shock absorber 60 includes a bottom plate 61 in contact with the upper portion of the steel ball 53 and a protrusion 63 coupled to the top of the bottom plate 61 and inserted into the mounting hole 18 at the top. It is mounted on the second elastic body 62 and the second perforated hole 64 formed in the longitudinal direction in the second elastic body 62, one side is in contact with the bolt 90 and the other side is in contact with the bottom plate 61 A second spring (65) is provided.

The bottom plate 61 is made in the shape of a disk. The bottom plate 61 may be formed of a metal material.

The second elastic body 62 is formed of a material having excellent elasticity, such as rubber. The protrusion 63 is formed on the second elastic body 62 . A plurality of second perforated holes 64 are formed in the second elastic body 62 . In the illustrated example, four second perforated holes 64 are formed. The second perforated hole 64 is formed to penetrate from the upper portion of the protrusion 63 to the lower portion of the second elastic body 62 .

The second spring 65 is inserted into the second perforated hole 64 . The upper portion of the second spring (65) inserted into the second perforated hole (64) is in contact with the head of the fixing bolt (90), and the lower portion is in contact with the bottom plate (61). This second spring 65 reduces vibration in the longitudinal direction.

The fixing bolt 90 is inserted into the mounting hole 18 formed in the support bracket 24 and penetrates the first and second shock absorbers 50 and 60 and the upper surface of the housing 13 .

The third cushioning unit 70 is formed of a rubber material having excellent elasticity. A third bolt insertion hole 73 penetrating vertically is formed in the third buffer part 70 . The third bolt insertion hole 73 has a smaller diameter than the first bolt insertion hole 57 . The inner peripheral surface of the third bolt insertion hole 73 is in close contact with the outer peripheral surface of the fixing bolt (90).

The third cushioning part 70 has a protrusion 72 formed thereon. The protrusion 72 is inserted into the fixing hole 12 formed on the upper surface of the housing 13 .

The third shock absorber 70 serves to support the lower portion of the fixing bolt 90 . A nut 95 is fastened to the fixing bolt 90 passing through the third bolt insertion hole 73 of the third buffer unit 70 .

On the other hand, the vibration suppressing means blocks the transmission of vibrations between the blower 41 and the housing 10, of course. In this case, a vibration suppressing means having the same structure as the above-described vibration suppressing means is also provided between the support bracket 42 of the blower 41 and the housing 10 .

As mentioned above, although the present invention has been described with reference to one embodiment, it will be understood that this is only exemplary, and that those skilled in the art may make various modifications and equivalent embodiments therefrom. Accordingly, the true protection scope of the present invention should be defined only by the appended claims.

10: housing 15: motor
20: dust collection cover 25: polishing pad
40: dust collection unit 41: blower
47: collection bag

Claims (3)

a floor sanding step of cutting the floor to a predetermined depth and polishing the surface of the floor;
a first cleaning step of removing the dust generated in the floor sanding step and remaining on the surface of the parquet floor;
a primer coating step of forming a primer coating layer by applying a primer to the surface of the floor after the first cleaning step;
a slip sanding step of polishing the surface of the undercoating layer after curing the undercoating layer to form a smooth surface of the undercoating layer;
a secondary cleaning step of removing the dust generated in the slip sanding step and remaining on the surface of the undercoating layer;
a middle coating step of forming a middle coating layer by applying a middle agent to the surface of the base coating layer after the second cleaning step;
a topcoating step of forming a topcoating layer by applying a topcoating agent to the surface of the intermediatecoating layer after curing the intermediatecoating layer;
In the floor sanding step, the surface of the floor is polished while moving the sander in a zigzag direction,
The sander includes a housing, a handle frame coupled to one side of the housing, a motor installed on the upper portion of the housing, a dust collecting cover coupled to a lower portion of the housing, and a dust collecting cover installed inside the dust collecting cover so that the upper portion is the housing a rotary shaft extending inward of the motor, a drive shaft having a lower portion extending inside the housing, a power transmission unit connecting the drive shaft and the rotary shaft, and detachably coupled to the lower portion of the rotary shaft to be detachably attached to the lower portion of the rotary shaft. A polishing pad for polishing the floor, a dust collecting unit for sucking and collecting dust from the inside of the dust collecting cover, and vibration suppression means for reducing vibration transmission between the motor and the housing,
The dust collection unit includes a blower installed on the upper part of the housing, a suction pipe connected to the suction side of the blower and connected to the inside of the dust collection cover, a discharge pipe connected to the discharge side of the blower, and the dust is coupled to the discharge pipe and a collecting bag formed of a breathable material capable of collecting and discharging air to the outside;
The vibration suppression means includes a first shock absorber that is installed on the upper portion of the housing to attenuate vibration in the lateral direction, is coupled to the upper portion of the first shock absorber, and is installed under the support bracket formed in the motor to prevent longitudinal vibration. a second cushioning unit for damping; a fixing bolt inserted into a mounting hole formed in the support bracket and penetrating the first and second cushioning units and an upper surface of the housing; a nut screwed to the fixing bolt; and the nut; and a third cushioning part installed between the upper surface of the housing,
The first cushioning unit has an inner box with an empty interior so that the second cushioning unit can be inserted inside, an inner box having a conical conical groove on the bottom, a steel ball positioned in the conical groove, and an outer surface of the inner box; A first elastic body formed to surround the bottom from the outside, an enclosure formed to surround the outer surface of the first elastic body, and a first perforated hole formed in the transverse direction to the first elastic body, one side of the inner box A first spring is provided in contact with the outside and the other side is in contact with the inside of the enclosure,
The second cushioning unit includes a bottom plate in contact with the upper portion of the steel ball, a second elastic body coupled to the top of the bottom plate and having a protrusion inserted into the mounting hole on the second elastic body in the longitudinal direction of the second elastic body. and a second spring inserted into the formed second perforated hole so that the upper part is in contact with the head of the fixing bolt and the lower part is in contact with the floor plate. The method of claim 1, further comprising a line marking step of forming a line on the surface of the undercoating layer after the second cleaning step. delete

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