WO2009082063A1

WO2009082063A1 - Dust proof strike for door fixing

Info

Publication number: WO2009082063A1
Application number: PCT/KR2008/002136
Authority: WO
Inventors: Ye-Myung Lee
Original assignee: Ye-Myung Lee
Priority date: 2007-12-26
Filing date: 2008-04-16
Publication date: 2009-07-02

Abstract

A flexible dust-proof door strike includes a body having open upper and lower ends, a rotating socket support inserted inside the lower space of the body, a body plug coupled in the lower end of the body, a rotating socket inserted inside the upper space of the body, and coupled to rotate in the upper space of the body, a guide spring coupled between the rotating socket and the inner surface defining the upper space of the body, a sliding cylinder inserted into a sliding cylinder inserting bore of the rotating socket and adapted to move up and down, and a compression spring coupled to the lower portion of the sliding cylinder and providing an elastic force when the sliding cylinder moves up and down. The center axis of the door strike is automatically aligned with the center axis of a door bolt.

Description

DUST PROOF STRIKE FOR DOOR FIXING

Technical Field

[1] The present invention relates to a flexible dust-proof door strike, more particularly, in which the center axis of the dust-proof door strike is automatically aligned with the center axis of a door locking device when a bolt of the door locking device is inserted into a sliding cylinder inserting bore of the flexible dust-proof door strike, so that the bolt can be easily inserted, and the center axis of the flexible dust-proof door strike can be fixed and kept at the adjusted position once it is aligned with the door bolt.

[2]

Background Art

[3] In general, a dust-proof door strike can be used together with a door locking device in a fire door, a steel door, and a reinforced glass door. The dust-proof door strike is installed on the floor surface matching with the related door locking device, and a bolt of the door bolt can be inserted and fixed inside the door strike so as to close and lock the door.

[4] FIG. 1 of the attached drawings is an illustrative view of a conventional dust-proof door strike. Referring to FIG. 1, the dust-proof door strike 10 includes a U-shaped body 12, with a dish-shaped rim 11 attached to the top portion thereof, a sliding cylinder 14 inserted into the U-shaped body 12, and a compression spring 13 disposed on the lower portion of the sliding cylinder 14, so that a bolt 21 of a door locking device installed on the lower end of a door 20 can simply move up and down.

[5] The dust-proof door strike is designed to be fixedly installed below a floor surface to accept the bolt of the door locking device into the U-shaped body when the door is closed.

[6] However, the inner diameter of the conventional dust-proof door strike is made with about the same size with the outer diameter of the door bolt of the locking device. As such, if the center axis of the dust-proof door strike buried in and fixed to the floor surface is not accurately aligned with the center axis of the door bolt of the locking device, the door bolt cannot be readily inserted into the dust-proof door strike and the door will not be closed and locked.

[7] Therefore, when the dust-proof door strike is not properly installed in the floor surface and is not aligned with the center axis of the door bolt of the locking device, the door will not be completely closed and the door cannot be completely locked.

[8] In addition, when a worker installs the dust-poof door strike in the floor surface, the worker has to align the center axis of the dust-proof door strike with the center axis of the door bolt of the locking device only depending on his sight, and thus the installation job is itself difficult to be done accurately. [9]

Disclosure of Invention

Technical Problem

[10] The present invention has been designed to solve the above mentioned problems, and therefore the present invention is directed to a flexible dust-proof door strike, in which the center axis of the door strike flexibly moves so that a bolt of a door locking device can be easily inserted into the door strike even though the center axis of the door strike is not accurately installed to align with the center axis of the door bolt of the door locking device.

[11] The invention is also directed to a flexible dust-proof door strike, in which the center axis of the flexible dust-proof door strike can flexibly move so that a bolt of a door locking device can be easily inserted into the door strike although the flexible dust-proof door strike is properly aligned with the center axis of the bolt of the door locking device, and the center axis of the flexible dust-proof door strike can be fixed and kept at the adjusted position once it is aligned with the door bolt.

[12] Furthermore, the invention is also directed to a flexible dust-proof door strike, in which a sliding cylinder and a compression spring installed inside the flexible dust- proof door strike can be easily inserted and removed.

[13]

Technical Solution

[14] According to an aspect of the present invention, there is provided a flexible dust- proof door strike. The flexible dust-proof door strike includes a body open at upper and lower ends thereof and having an upper space and a lower space inside thereof; a rotating socket support inserted inside the lower space of the body; a body plug coupled in the lower end of the body; a rotating socket inserted inside the upper space of the body, having a rotating portion inserted and coupled between a top surface of the rotating socket support and a lower end of an inner surface defining the upper space of the body so as to rotate in the upper space, the rotating socket including a sliding cylinder inserting bore extending through a middle portion thereof; a guide spring coupled between the rotating socket and the inner surface defining the upper space of the body; a sliding cylinder inserted into the sliding cylinder inserting bore of the rotating socket and adapted to move up and down; and a compression spring coupled to the lower portion of the sliding cylinder and providing an elastic force when the sliding cylinder moves up and down.

[15] The flexible dust-proof door strike may further include a fixing rim fixed and coupled to the upper end of the body such that the rotating socket and the sliding cylinder are fixed and not separated.

[16] In addition, the rotating socket may include a top flange bent outwardly to form a smoothly curved surface; the middle portion extending perpendicular to the top flange and provided inside thereof with the sliding cylinder inserting bore; and the rotating portion bent outwardly perpendicular to the middle portion and formed in a smaller size than the diameter of the lower space of the body.

[17] The outer peripheral surface of the rotating portion may have an eccentric structure constituted by connecting each other two circular arcs having different curvature radiuses.

[18] Meanwhile, the sliding cylinder may include a top surface formed in a concave curved surface, a compression spring inserting recess formed inside a lower portion thereof, and a catching shoulder formed on a lower end thereof and adapted to be caught on the bottom surface of the rotating socket to prevent the sliding cylinder from escaping outwardly by an expanding force of the compression spring after inserted into the sliding cylinder inserting bore of the rotating socket.

[19] According to another aspect of the present invention, there is provided a flexible dust-proof door strike. The flexible dust-proof door strike includes a body portion including an upper body and a lower body, the upper body provided in a side surface thereof with a securing member inserting hole, and the lower body adapted to be coupled to the upper body; a rotating socket coupled to rotate in an inner space of the upper body; a sliding cylinder coupled in the rotating socket and having a compression spring inserting recess formed inside thereof; a compression spring coupled in the compression spring inserting recess of the sliding cylinder and providing an elastic force when the sliding cylinder moves up and down; and a securing member coupled in the securing member inserting hole of the upper body in order to secure a position of the rotating socket.

[20] The inner surface of the securing member inserting hole of the upper body may be formed with a thread and the outer surface of the securing member may be formed with a matching thread such that the securing member and the securing member inserting hole is configured to be coupled each other by threaded connection.

[21] In addition, the rotating socket may include a top flange bent outwardly to form a smoothly curved surface; a middle portion extending perpendicular to the top flange and provided inside thereof with a sliding cylinder inserting bore; and a rotating portion bent outwardly perpendicular to the middle portion, wherein the rotating portion has an outer peripheral surface formed in an eccentric structure constituted by connecting each other three circular arcs having different or same curvature radiuses.

[22] Furthermore, a thread may be formed in an inner surface of a lower end of the upper body and a matching thread may be formed on an outer surface of a lower end of the lower body such that the body portion is configured to allow the upper and lower bodies to be separated and coupled each other by threaded connection. [23]

Advantageous Effects

[24] The flexible dust-proof door strike according to the invention as mentioned above has the following effects.

[25] Firstly, the flexible dust-proof door strike can be readily inserted therein with the door bolt of the locking device upon inserting of the door bolt therein, even if not exactly coaxial- aligned with the center axis of the door bolt of the locking device.

[26] Secondly, the flexible dust-proof door strike has a structure to automatically align the center axis of the flexible dust-proof door strike with the center axis of the door bolt upon inserting the door bolt therein, even if a worker did not exactly align the center axis of the flexible dust-proof door strike with the center axis of the door lock of the locking device when burying the flexible dust-poof door strike on a floor surface, and thus, the worker can easily perform an installation job of the flexible dust-proof door strike.

[27] Thirdly, the center axis of the flexible dust-proof door strike can be fixed after being adjusted therein with the center axis of the door bolt of the locking device in an aligned state with the center axis of the flexible dust-proof door strike, and thus, the center axis of the door bolt of the flexible dust-proof door strike can be repeatedly inserted in a fixed position.

[28] Finally, the body of the flexible dust-proof door strike has a coupling structure which can be separated into an upper body and a lower body, and thus, the insertion and removal of the compression spring and the sliding cylinder are easily accomplished.

[29]

Brief Description of the Drawings

[30] FIG. 1 is an illustrative view showing a usage of a conventional dust-proof door strike;

[31] FIG. 2 is a dismantled perspective view showing a constitution of a flexible dust- proof door strike according to a first embodiment of the invention;

[32] FIG. 3 is a perspective view showing an assembled state of FIG. 2;

[33] FIG. 4 is a partial cross sectional view showing the flexible dust-proof door strike according to the first embodiment of the invention;

[34] FIG. 5 is a partial cross sectional view showing an assembled state of FIG.4;

[35] FIGS. 6 and 7 are views showing the operations of the flexible dust-proof door strike according to the first embodiment of the invention;

[36] FIG. 8 is a dismantled perspective view showing a constitution of a flexible dust- proof door strike according to a second embodiment of the invention;

[37] FIG. 9 is a perspective view showing an assembled state of FIG. 8; and

[38] FIGS. 10 to 12 are views showing the operations of the flexible dust-proof door strike according to the first embodiment of the invention.

[39] <Major Reference Numerals and Symbols of the Drawings>

[40] 100, 300: dust-proof door strike

[41] 110: body 110a: upper space

[42] 110b: lower space 112: catching shoulder

[43] 120: rotating socket support

[44] 130: body plug 140, 340: rotating socket

[45] 141, 341: top flange 142, 342: middle portion

[46] 143, 343: rotating portion 150: guide spring

[47] 160, 350: sliding cylinder 170, 360: compression spring

[48] 180: fixing rim 200: door bolt

[49] 310: upper body 311: securing member insertion hole

[50] 320: lower body 330: body portion

[51] 351: compression spring inserting recess

[52] 370: securing member

[53]

Best Mode for Carrying Out the Invention

[54] Hereinafter, a flexible dust-proof door strike will be described in detail of the invention with reference to the attached drawings, in which exemplary embodiments thereof are shown.

[55]

[56] First Embodiment

[57] In the attached drawings, FIG. 2 is a dismantled perspective view showing a constitution of a flexible dust-proof door strike according to a first embodiment of the invention, FIG. 3 is a perspective view showing an assembled state of FIG. 2, FIG. 4 is a partial cross sectional view showing the flexible dust-proof door strike according to the first embodiment of the invention, and FIG. 5 is a perspective view showing an assembled state of FIG.4.

[58] The flexible dust-proof door strike, according to the invention, can be used along with a door locking device in a fire door, a steel door, a reinforced glass door or the like, and is installed on the floor surface facing the door locking device in order to insert and lock a door bolt of the locking device therein. [59] Referring to the above-mentioned figures, the flexible dust-proof door strike 100, according to the first embodiment of the invention, includes a body 110, a rotating socket support 120, a body plug 130, a rotating socket 140, a guide spring 150, a sliding cylinder 160, and a compression spring 170.

[60] The body 110 is open at upper and lower ends thereof, and has an upper space 110a and a lower space 110b defined inside thereof. Also, the body 110 preferably includes a threaded portion 111 formed on an outer periphery of the upper end, which will be coupled with a fixing rim 180; and a catching shoulder 112 formed in the lower end, which will be engaged with the body plug 130 inserted therein.

[61] The fixing rim 180 is coupled on the upper end of the body 110, such that the rotating socket 140 and the sliding cylinder 160 caught in the rotating socket 140, as described below, are fixed together and not separated outwardly.

[62] The rotating socket support 120 is inserted into the lower space 110b of the body

110, which has a through-bore formed at the center portion thereof, and supports a lower end of the rotating socket 140. Also, the rotating socket support 120 defines an inner space for allowing the sliding cylinder 160 to move up and down, and the compression spring 170 is located in the inner space.

[63] The body plug 130 is installed in the lower end of the body 110 and is coupled with the catching shoulder 112, such that any components inserted in the inner space of the body 110 can be prevented from escaping outwardly.

[64] The rotating socket 140 is inserted in the upper space 110a of the body 110, such that a rotating portion 143 thereof is inserted between a top surface of the rotating socket support 120 and a lower end of an inner surface 110c, and can be rotated inside the upper space 110a.

[65] The rotating socket 140 includes a top flange 141 having a smoothly curved surface and bent outwards, a middle portion 142 extending perpendicular to the top flange 141 and provided inside thereof with a sliding cylinder inserting bore 140a, and the rotating portion 143 bent outwardly perpendicular to the middle portion 142 and formed in a smaller size than the diameter of the lower space 110b of the body 110.

[66] Preferably, the outer peripheral surface of the rotating portion 143 has a structure constituted by connecting, each other, two circular arcs 143a and 143b having different curvature radiuses.

[67] The rotating socket 140 is able to rotate 360 degrees in the inner space of the body

110, and therefore, when a door bolt 200 of the locking device (see FIG. 6) is inserted into the top flange 141, but is not inserted along the center axis of the rotating socket 140, the rotating portion 143 formed in an eccentric structure automatically rotates and aligns with the center axis of the door bolt 200 (see FIG. 6). Consequently, the door bolt 200 of the locking device (see FIG. 6) is smoothly inserted into the rotating socket 140 and pushes down the sliding cylinder 160.

[68] In other words, even though the door bolt 200 of the locking device (see FIG. 6) is inserted unaligned with the center axis of the body 110, the rotating socket 140 rotates and the center axis is automatically aligned when the door bolt contacts the top of the flange 141, and finally the door bolt 200 (see FIG. 6) pushes down the sliding cylinder 160.

[69] The guide spring 150 is coupled between the rotating socket 140 and the inner surface 110c forming the upper space 110a of the body 110, and allows the center axis of the rotating socket 140 to be automatically aligned with the center axis of the body 110 when the door bolt 200 (see FIG. 6) is extracted from the rotating socket 140. One end of the guide spring 150 is fixed to the middle portion 142 of the rotating socket 140 thereof, and the other end thereof is fixed to a lower end of the inner surface 110c of the body 110 thereof.

[70] The sliding cylinder 160 inserted in the sliding cylinder inserting bore 140a of the rotating socket 140 moves down when the door bolt 200 of the locking device (see FIG. 6) is inserted, and moves back to the original position by an elastic force of the compression spring when the door bolt 200 of the locking device (see Fig 6) is extracted. This prevents the dusts or foreign substances from entering the body 100 such that the door bolt 200 (see FIG. 6) can be smoothly inserted into the body 110.

[71] The top portion of the sliding cylinder 160 is formed in a concave curved surface, the inside of the lower portion is formed with a compression spring inserting recess 160a, the lower portion is formed with a catching shoulder 160b thereof and so as to be caught on the bottom surface of the rotating socket 140 to prevent the sliding cylinder 160 from escaping outwardly by an expanding force of the compression spring 170 after inserted in the sliding cylinder inserting bore 140a of the rotating socket 140.

[72] The compression spring 170 is inserted in the compression spring inserting recess

160a formed in the lower portion of the sliding cylinder 160, and returns back the sliding cylinder 160 to an original position when the sliding cylinder 160 is moved down. That is, the sliding cylinder 160 moves down by inserting the door bolt 200 (see FIG. 6), and moves back by the elastic force of the compression spring 170 when the door bolt 200 is extracted outwardly, thereby returning back to the original position.

[73] Next, the operation of the flexible dust-proof door strike, according to the first embodiment of the invention constituted as mentioned above, will be described. In the attached drawings, FIGS. 6 and 7 show the operating states of the flexible dust-proof door strike according to the first embodiment of the invention.

[74] The flexible dust-proof door strike 100, according to the invention, constitutes a door- lock system together with the door bolt 200, and is installed on the floor surface.

[75] When the door bolt 200 of the locking device is contacted with the top flange 141 of the rotating socket 140, the rotating socket 140 rotates inside the body 110 and the axis is automatically aligned with the center axis of the door bolt 200.

[76] Thus, when the door bolt 200 is aligned with the center axis of the rotating socket

140 by the rotation of the rotating socket 140, the door bolt 200 pushes down the sliding cylinder 160, and the compression spring 170 is compressed as the sliding cylinder 160 moves down. Then, the door bolt 200 is inserted into the sliding cylinder inserting bore 140a of the rotating socket 140 such that the door is finally locked.

[77] When the door bolt 200 is extracted from the sliding cylinder inserting shaft 140a of the rotating socket 140, the sliding cylinder 160 moves up to the original position thereof by the elastic force of the compression spring 170, and at the same time, the rotating socket 140 is centered the center axis of the body 110 by the guide spring 150.

[78]

[79] Second Embodiment

[80] In the attached drawings, FIG. 8 is a dismantled perspective view showing a constitution of a flexible dust-proof door strike according to a second embodiment of the invention, and FIG. 9 is a perspective view showing an assembled state of FIG. 8.

[81] Referring to the above-mentioned figures, the flexible dust-proof door strike 300 according to the invention includes a body portion 330, a rotating socket 340, a sliding cylinder 350, a compression spring 360 and a securing member 370.

[82] The body portion 330 consists of an upper body 310 and a lower body 310. The upper body 310 is designed with a securing member insertion hole 311 for the insertion of the securing member 370 as described below, and the lower body 320 is configured to be separated and coupled by threaded connection to the upper body 310.

[83] In addition, a thread is formed in the inner surface the securing member insertion hole 311, and a matching thread is formed in the outer surface of the securing member 370, described below, such that the securing member 370 and the securing member inserting hole 311 are coupled with each other by threaded connection, and thus the compression spring 360 inserted inside the body 330 and the sliding cylinder 350 are designed to be easily inserted and removed.

[84] Preferably, the rotating socket 340 is coupled and eccentrically moves inside the upper body 310, and a through-hole 322 is formed at a lower end of the lower body 310 to easily remove foreign substances such as dusts accumulated inside the body portion 330.

[85] The rotating socket 340 is coupled to rotate in an inner space of the upper body 310, and includes a top flange 341, a middle portion 342, and a rotating portion 343.

[86] Preferably, the top flange 341 is bent outwardly from the middle portion 342 to form a smoothly curved surface, and has a cylindrical shape.

[87] Next, the middle portion 342 is provided inside thereof with a sliding cylinder inserting bore 342a such that the sliding cylinder 350 as described below can be inserted and vertically move in the sliding cylinder inserting bore 342a.

[88] Also, the rotating portion 343 has an outer peripheral surface formed in an eccentric structure constituted by connecting each other three circular arcs 343a having different or same curvature radiuses, and rotates to align the sliding cylinder 350 with the center axis of a door bolt 200 of a locking device (see FIG. 10) when the door bolt 200 is inserted in a space A (see FIG. 10) formed by assembling the upper body 310 with the lower body 320.

[89] The rotating socket 340 as mentioned above is able to rotate 360 degrees in the inner space of the body 110, and therefore, when the door bolt 200 of the locking device (see FIG. 4) is inserted from the top flange 341, but not inserted along a center axis of the rotating socket 340, the rotation of the rotating portion 343 formed in the eccentric structure make it possible for a center axis of the door bolt 200 to be automatically aligned with the center axis of the rotating socket 340.

[90] Consequently, the door bolt 200 of the locking device (see FIG. 4) is smoothly inserted into the rotating socket 340 and pushes down the sliding cylinder 350. Thus, once the center axis of the door bolt 200 of the locking device (see FIG. 4) is aligned with the center axis of the rotating socket 340, the rotating socket 340 is fixed by tightening the securing member 370 such that the axes of the door bolt 200 of the locking device (see FIG. 4) and the rotating socket 340 can be continuously kept aligned.

[91] The sliding cylinder 350 is coupled with the sliding cylinder inserting bore 342a of the rotating socket 340 and moves up and down in accordance with the insertion and extraction of the door bolt 200 of the locking device (see FIG. 4), and has a compression spring inserting recess 351 inside thereof.

[92] The diameter of the sliding cylinder 350 is almost equal to the inner diameter of the sliding cylinder inserting bore 342a of the rotating socket 340 to minimize the foreign substances entered into the dust proof strike 300 from the outside.

[93] The above mentioned compression spring 360 is inserted into the compression spring inserting recess 351 of the sliding cylinder 350, and allows the sliding cylinder 350 to move down by descending the door bolt 200 of the locking device (see FIG. 4) and then to move back to the original position when the door bolt 200 of the locking device (see FIG. 4) is ascended. That is, the sliding cylinder 350 moves down by inserting the door bolt 200 (see FIG. 4), and moves back to the original position by the elastic force of the compression spring 360 when the door bolt 200 is extracted outwardly.

[94] The above mentioned securing member 370 is coupled inside the securing member insertion hole 311 extending through a side surface of the upper body 310, and secures a side surface of the rotating socket 340. That is, once the center axis of the rotating socket 340 is aligned with the door bolt 200 of the locking device (see FIG. 4) by pressing the door bolt 200 of the locking device (see FIG.4) and thus pushing down the sliding cylinder 350, the securing member 370 can secure the side surface of the rotating socket 340 to avoid a cumbersomeness of re-aligning the center axis of the rotating socket 340 when the door bolt 200 of the locking device (see FIG. 4) is inserted again.

[95] A burying recess (not shown) is formed in the matching floor surface of the door- lock system to receive the flexible dust-proof door strike 300. After the flexible dust- proof door strike 300 is inserted into this burying recess, the rotating socket 340 rotates to align the center axis of the door bolt with the center axis of the flexible dust-proof door strike. Then, once the alignment of the two center axes is accomplished by the rotation of the rotating socket 340, the rotating socket can be fixed to maintain the aligned two center axes.

[96] A screw bolt is preferably recommended as the securing member 370, and can be coupled with a matching thread formed in the securing member insertion hole 311 of the upper body 310.

[97] Next, the operation of the flexible dust-proof door strike will be explained in accordance with the second embodiment of the invention as mentioned above. In the attached drawings, FIGS. 10 and 12 are the illustrating views showing the operation of the flexible dust-proof door strike according to the second embodiment of the invention.

[98] According to the invention, the flexible dust-proof door strike 300, constituting the door- lock system together with the door bolt 200, is installed on a floor surface.

[99] Firstly, if the center axis of the rotating socket 340 is not aligned with the center axis of the door bolt 200 when the door bolt 200 of the locking device contacts with the top flange 341 of the rotating socket 340, the center axis of the rotating socket 340 is aligned or automatically aligned with the center axis of the door bolt 200, and then, the rotating socket 340 is secured at the side surface thereof by tightening the door bolt 370 to fix the position of the rotating socket 340.

[100] Therefore, once the two center axes of the door bolt 200 of the locking device and the rotating socket 340 are aligned each other by securing the side surface of the rotating socket 340, the rotating socket 340 will not move out of position and the alignment of the two center axes can be continuously maintained.

[101] After the two center axes of the door bolt 200 of the locking device and the rotating socket 340 are aligned each other as mentioned above, the door bolt 200 of the locking device moves down and pushes down the sliding cylinder 350, and thus the compression spring 360 is pressed down as the sliding cylinder 350 is descended. Then, the door bolt 200 is inserted into the sliding cylinder inserting bore 342a of the rotating socket 340 such that the door bolt 200 is engaged with the flexible dust-proof door strike 300, and finally the door is closed and locked.

Claims

[1] A dust proof strike for door fixing, comprising: a body open at upper and lower ends thereof and having an upper space and a lower space inside thereof; a rotating socket support inserted inside the lower space of the body; a body plug coupled in the lower end of the body; a rotating socket inserted inside the upper space of the body, having a rotating portion inserted and coupled between a top surface of the rotating socket support and a lower end of an inner surface defining the upper space of the body so as to rotate in the upper space, the rotating socket including a sliding cylinder inserting bore extending through a middle portion thereof; a guide spring coupled between the rotating socket and the inner surface defining the upper space of the body; a sliding cylinder inserted into the sliding cylinder inserting bore of the rotating socket and adapted to move up and down; and a compression spring coupled to the lower portion of the sliding cylinder and providing an elastic force when the sliding cylinder moves up and down

[2] The dust proof strike for door fixing according to claim 1, further comprising a fixing rim fixed and coupled to the upper end of the body such that the rotating socket and the sliding cylinder are fixed and not separated.

[3] The dust proof strike for door fixing according to claim 1, wherein the rotating socket includes: a top flange bent outwardly to form a smoothly curved surface; the middle portion extending perpendicular to the top flange and provided inside thereof with the sliding cylinder inserting bore; and the rotating portion bent outwardly perpendicular to the middle portion and formed in a smaller size than the diameter of the lower space of the body.

[4] The dust proof strike for door fixing according to claim 3, wherein the outer peripheral surface of the rotating portion has an eccentric structure constituted by connecting, each other, two circular arcs having different curvature radiuses.

[5] The dust proof strike for door fixing according to claim 1, wherein the sliding cylinder includes a top surface formed in a concave curved surface, a compression spring inserting recess formed inside a lower portion thereof, and a catching shoulder formed on a lower end thereof and adapted to be caught on a bottom surface of the rotating socket to prevent the sliding cylinder from escaping outwardly by an expanding force of the compression spring after inserted in the sliding cylinder inserting bore of the rotating socket.

[6] A dust proof strike for door fixing, comprising: a body portion including an upper body and a lower body, the upper body provided in a side surface thereof with a securing member inserting hole, and the lower body adapted to be coupled to the upper body; a rotating socket coupled to rotate in an inner space of the upper body; a sliding cylinder coupled in the rotating socket and having a compression spring inserting recess formed inside thereof; a compression spring coupled in the compression spring inserting recess of the sliding cylinder and providing an elastic force when the sliding cylinder moves up and down; and a securing member coupled in the securing member inserting hole of the upper body in order to secure a position of the rotating socket.

[7] The dust proof strike for door fixing according to claim 6, wherein an inner surface of the securing member inserting hole of the upper body is formed with a thread and an outer surface of the securing member is formed with a matching thread such that the securing member and the securing member inserting hole is configured to be coupled each other by threaded connection.

[8] The dust proof strike for door fixing according to claim 6, wherein the rotating socket includes a top flange bent outwardly to form a smoothly curved surface; a middle portion extending perpendicular to the top flange and provided inside thereof with a sliding cylinder inserting bore; and a rotating portion bent outwardly perpendicular to the middle portion, wherein the rotating portion has an outer peripheral surface formed in an eccentric structure constituted by connecting each other three circular arcs having different or same curvature radiuses.

[9] The dust proof strike for door fixing according to claim 6, wherein a thread is formed in an inner surface of a lower end of the upper body and a matching thread is formed on an outer surface of a lower end of the lower body such that the body portion is configured to allow the upper and lower bodies to be separated and coupled each other by threaded connection.