Expansion screw with internal and external threads

Abstract

The utility model relates to the technical field of building materials, and discloses an expansion screw with internal and external threads, which comprises an external screw and an internal screw, the center of the external screw is provided with a through hole penetrating up and down, the internal screw is arranged in the through hole in the center of the external screw in a penetrating manner, and the internal screw is in threaded fit with the external screw. The bottom of the inner screw is exposed out of the outer screw; the meshing force between the screw and the fixing piece is provided by the outer screw and the inner screw, namely the meshing force between the external thread of the outer screw and the fixing piece and the meshing force between the opened steel teeth of the inner screw and the fixing piece; and when the external force is larger, the occlusal force between the steel teeth and the fixing piece is stronger, so that the steel teeth are not easy to withdraw and not easy to loosen.

Description

Technical Field

[0001] The utility model relates to the technical field of building materials, in particular to an internal and external thread expansion screw. Background Art

[0002] Screws are known as the rice of industry. They are widely applicable and can be used in various fields such as construction, machinery, and chemical industry. In addition, there are many types of screws, such as ordinary screws, self-tapping screws, etc. These screws are prone to repeated withdrawal and need to be re-fixed during use: 1) The material of the fixing is loose, and the bite force between the screw and the fixing is not strong, so it is easy to withdraw as a whole; 2) The screws are punched multiple times during the installation process, causing the inside of the fixing to loosen, and after the screws are installed, they are gradually withdrawn under the action of external force; 3) During the installation process, an electric drill is used to drill holes, and the diameter of the holes is too large, resulting in insufficient bite force between the expansion screw and the fixing, and the screw is pulled out as a whole when receiving external force.

[0003] When the screws are repeatedly withdrawn and re-fastened, the fixing parts are easily damaged at the screw hole position, causing the screw fixing function to fail. The screws need to be moved and fixed or other connection assemblies need to be used to re-fix, which brings instability to use.

[0004] Therefore, the utility model proposes an internal and external thread expansion screw. Utility Model Content

[0005] In order to solve the problems existing in the prior art, the utility model provides an internal and external thread expansion screw with reasonable structural design and efficient and convenient installation.

[0006] The technical solution of the utility model is as follows:

[0007] An internal and external thread expansion screw, comprising an external screw and an internal screw, wherein a through hole is provided in the center of the external screw and passes through the center of the external screw, the internal screw is inserted into the through hole in the center of the external screw, the internal screw is threadedly matched with the external screw, and the bottom of the internal screw is exposed from the external screw;

[0008] The external screw comprises an external screw head and an external screw shank, the outer wall of the external screw shank is provided with an external thread A, and the inner wall of the external screw shank is provided with an internal thread;

[0009] The inner screw comprises an inner screw head, an inner screw shank and an inner screw tail. The inner screw tail is detachably connected to the inner screw shank. The inner screw shank is provided with an external thread B. The inner screw tail is conical in shape. A group of steel teeth are arranged at intervals along the circumferential direction of the inner screw tail.

[0010] Furthermore, the outer screw head and the outer screw rod are an integral structure, the outer screw head is provided with an inner screw head mounting groove for placing the inner screw head, and the outer screw head is provided with a slotted groove for cooperating with a screwing tool.

[0011] Furthermore, the inner screw head and the inner screw rod are an integrated structure, and the inner screw head is provided with a slotted groove, which is arranged through the inner screw head along the diameter direction and can be connected with the slotted groove of the outer screw head, so that the inner screw and the outer screw can be screwed in at the same time. Furthermore, a hexagonal groove is provided in the middle of the slotted groove for matching with a hexagonal wrench.

[0012] Furthermore, the tail of the inner screw is provided with a connecting column, the connecting column is provided with a flat key, and the inner screw rod is provided with a keyway at a position corresponding to the flat key, so as to achieve a tight fit between the tail of the inner screw and the inner screw rod. In addition, the flat key here can also be a protruding structure integrated with the connecting column to play a role of tight fit and anti-rotation.

[0013] Furthermore, a flared opening is provided inside the end of the outer screw rod, which can cooperate with the steel teeth to limit the expansion of the steel teeth.

[0014] Furthermore, an annular groove is provided on the outer wall of the tail of the inner screw near the position of the steel teeth to facilitate the expansion of the steel teeth.

[0015] Furthermore, the outer screw head is provided with a protective outer ring, and in the initial state, the surface of the protective outer ring is higher than the surface of the inner screw head. After the inner screw is retracted and fixed, the protective outer ring is flush with the surface of the inner screw head.

[0016] Furthermore, the steel teeth are thin at the edges and thick in the middle, which facilitates cutting and screwing.

[0017] The beneficial effects of the utility model are as follows:

[0018] 1) The bite force between the screw and the fixing part is provided by both the external screw and the internal screw, that is, the bite force between the external thread of the external screw and the fixing part and the bite force formed between the open steel teeth of the internal screw and the fixing part; when the external force is greater, the bite force between the steel teeth and the fixing part is stronger, and it is not easy to withdraw and loosen.

[0019] 2) The outer edges of the upper edge, left and right edges of the steel teeth are thinner and slightly thicker in the middle, which is convenient for cutting the fixing parts when the screw is screwed in, making it easier and more convenient to screw in the screw.

[0020] 3) The annular groove at the tail of the inner screw cooperates with the flared bottom of the outer screw to facilitate the smooth opening of the steel teeth and form a bite force with the fixing part.

[0021] 4) A protective outer ring is set on the head of the outer screw. After the inner screw is retracted, the head of the inner screw is basically flush with the protective outer ring of the outer screw head, and the corners of the protective outer ring are transitioned with arcs to prevent accidental injuries. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the final state structure of the utility model;

[0023] Figure 2 This is a schematic diagram of the structure of the external screw of the utility model;

[0024] Figure 3 This is a schematic diagram of the internal screw structure of the utility model;

[0025] Figure 4 It is a schematic diagram of the overall top view structure of the utility model;

[0026] Figure 5 This is a schematic diagram of the tail structure of the inner screw of the utility model;

[0027] Figure 6 This is a schematic diagram of the initial state structure of the utility model;

[0028] In the figure: 1. external screw; 101. external screw head; 102. external screw shank; 103. internal screw head mounting groove; 104. internal thread; 105. external thread A; 106. through hole; 107. flared opening; 108. slotted groove; 109. protective outer ring; 2. internal screw; 201. internal screw head; 202. internal screw shank; 203. steel teeth; 204. internal screw tail; 205. annular groove; 206. external thread B; 208. slotted groove; 209. external thread connecting column. DETAILED DESCRIPTION

[0029] The utility model is further described below in conjunction with the accompanying drawings of the specification.

[0030] like Figure 1 As shown, an internal and external thread expansion screw includes an external screw 1 and an internal screw 2. The internal screw 2 is inserted into the center of the external screw 1, and the bottom of the internal screw 2 is exposed from the external screw 1, that is, the tail 204 of the internal screw is exposed from the bottom of the external screw 1.

[0031] like Figure 2 As shown, the external screw 1 includes an external screw head 101 and an external screw shaft 102 . A through hole 106 is formed in the center of the external screw 1 and extends from the external screw head 101 to the entire external screw shaft 102 .

[0032] An outer wall of the outer screw shank 102 is provided with an outer thread A105, which is used to cooperate with the fixing member to provide a bite force. An inner wall of the outer screw shank 102 is provided with an inner thread 104, which is used to cooperate with the inner screw 2 thread.

[0033] The outer screw head 101 and the outer screw shank 102 are integrally formed, and the outer screw head 101 is provided with an inner screw head mounting groove 103 for placing the inner screw head 201, and the outer screw head 101 is provided with a straight groove 108 (the through hole 106 divides the straight groove 108 into two U-shaped sections, such as Figure 4 for use with screwing tools.

[0034] The outer screw head 101 is provided with a protective outer ring 109, and in the initial state, the surface of the protective outer ring 109 is higher than the surface of the inner screw head 201. After the inner screw 2 is retracted and fixed, the protective outer ring 109 is flush with the surface of the inner screw head 201, maintaining safety in use.

[0035] like Figure 3 , 5 As shown, the inner screw 2 includes an inner screw head 201, an inner screw rod 202 and an inner screw tail 204. The inner screw tail 204 is detachably connected to the inner screw rod 202 (it can also be an integrated structure). An outer thread B206 is provided on the upper part of the inner screw rod 202. The outer thread B206 can cooperate with the inner thread 104, so as to provide a locking force for the inner screw 2 to be retracted.

[0036] The tail 204 of the inner screw is conical (the conical part can also be provided with an external screw to improve the drilling effect), and a group of steel teeth 203 are arranged at intervals along the circumferential direction of the tail 204 of the inner screw (the steel teeth 203 can be processed by a milling machine), and deformation grooves are formed between the steel teeth 203 to facilitate the opening of the steel teeth 203 and prevent interference. In addition, in this embodiment, the steel teeth 203 are thin at the edges and thick in the middle, which is convenient for cutting and screwing.

[0037] The inner screw tail 204 is provided with a connecting column, on which a flat key 207 is provided, and a keyway is provided on the inner screw rod 202 at a position corresponding to the flat key 207, so as to achieve a tight fit between the inner screw tail 204 and the inner screw rod 202. If processing conditions permit, the flat key 207 can be replaced by a protruding structure and integrally processed with the connecting column. (Other fixing methods can also be used to prevent the inner screw tail 204 from falling off).

[0038] The inner screw head 201 and the inner screw shank 202 are integrally formed, and the inner screw head 201 is provided with a slot 208, which is arranged through the inner screw head 201 along the diameter direction and can be connected with the slot 108. Figure 4 As shown, in the initial state, the slotted through groove 208 is butted against the slotted groove 108, and the outer screw 1 and the inner screw 2 are screwed in simultaneously by a screwing tool. When the inner screw 2 is retracted and expanded, the inner screw 2 can be screwed back alone.

[0039] An annular groove 205 is provided on the outer wall of the inner screw tail 204 near the steel teeth 203 to facilitate the expansion of the steel teeth 203; and a flared opening 107 is provided inside the end of the outer screw rod 102 to cooperate with the steel teeth 203 to limit the expansion of the steel teeth 203; the annular groove 205 cooperates with the flared opening 107 to improve the expandability of the steel teeth 203.

[0040] like Figure 1 , 6 As shown, how to use:

[0041] During initial installation, ensure that the slotted groove 108 and the slotted through groove 208 on the top of the outer screw 1 and the inner screw 2 are completely aligned;

[0042] The outer screw 1 and the inner screw 2 are integrally anchored into the fixing member by a screwdriver.

[0043] Use another screwdriver (or an external hexagonal wrench) to reversely retract the inner screw 2, while the outer screw 1 remains stationary. The steel teeth 203 encounter resistance from the fixing member and, under the action of the annular groove 205 and the flared opening 107, open to achieve bite fixation.

[0044] The inner screw 2 is retracted inwards to ensure that the protective outer ring 109 of the outer screw 1 is substantially flush with the top of the inner screw 2 .

[0045] Compared with traditional fixing screws, the utility model can greatly improve the reliability of screw fixing, is simple to install, easy to screw in, and reduces the need for secondary fixing.

Claims

1. An internal and external thread expansion screw, characterized in that: The invention comprises an outer screw (1) and an inner screw (2), wherein the center of the outer screw (1) is provided with a through hole (106) extending upward and downward, and the inner screw (2) is inserted into the through hole (106) in the center of the outer screw (1), the inner screw (2) and the outer screw (1) are threadably matched, and the bottom of the inner screw (2) is exposed from the outer screw (1); The external screw (1) comprises an external screw head (101) and an external screw shank (102); the outer wall of the external screw shank (102) is provided with an external thread A (105); and the inner wall of the external screw shank (102) is provided with an internal thread (104); The inner screw (2) comprises an inner screw head (201), an inner screw shank (202) and an inner screw tail (204); the inner screw tail (204) and the inner screw shank (202) are detachably connected; the inner screw shank (202) is provided with an external thread B (206); the inner screw tail (204) is conical; and a group of steel teeth (203) are arranged at intervals along the circumferential direction of the inner screw tail (204).

2. The internal and external thread expansion screw according to claim 1, characterized in that: The outer screw head (101) and the outer screw shank (102) are an integral structure, the outer screw head (101) is provided with an inner screw head mounting groove (103) for placing the inner screw head (201), and the outer screw head (101) is provided with a slotted groove (108) for matching with a screwing tool.

3. The internal and external thread expansion screw according to claim 2, characterized in that: The inner screw head (201) and the inner screw rod (202) are an integral structure, and the inner screw head (201) is provided with a slotted groove (208). The slotted groove (208) is arranged to pass through the inner screw head (201) in a diameter direction and can be connected to the slotted groove (108) of the outer screw head (101).

4. The internal and external thread expansion screw according to claim 1, characterized in that: The tail portion (204) of the inner screw is provided with a connecting column, and the connecting column is provided with a flat key (207). A keyway is provided on the inner screw shank (202) at a position corresponding to the connection with the flat key (207), thereby achieving a tight fit between the inner screw tail (204) and the inner screw shank (202).

5. The internal and external thread expansion screw according to claim 1, characterized in that: The end of the outer screw rod (102) is internally provided with a flared opening (107) which can cooperate with the steel teeth (203) to limit the expansion of the steel teeth (203).

6. The internal and external thread expansion screw according to claim 1, characterized in that: An annular groove (205) is provided on the outer wall of the inner screw tail (204) near the steel teeth (203) to facilitate the expansion of the steel teeth (203).

7. The internal and external thread expansion screw according to claim 1, characterized in that: The outer screw head (101) is provided with a protective outer ring (109), and in an initial state, the surface of the protective outer ring (109) is higher than the surface of the inner screw head (201); after the inner screw (2) is retracted and fixed, the protective outer ring (109) is flush with the surface of the inner screw head (201).

8. The internal and external thread expansion screw according to claim 1, characterized in that: The steel teeth (203) are thin at the edges and thick in the middle, which facilitates cutting and screwing.

9. The internal and external thread expansion screw according to claim 3, characterized in that: A hexagonal groove is provided at the middle of the slot (208) for cooperating with a hexagonal wrench.

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