CN213541002U - Expansion screw - Google Patents

Abstract

The utility model discloses an expansion screw relates to hardware and tools technical field, including screw rod, expansion pipe, taper sleeve pipe and nut, the one end of screw rod is equipped with the toper portion, the other end and the nut threaded connection of screw rod, and on the screw rod was located to expansion pipe and taper sleeve pipe all cover, the expansion pipe was equipped with two at least expansion portions, expansion portion and taper sleeve pipe butt on the arbitrary expansion pipe. The utility model discloses a include the inflation portion that is not less than two, compare in the traditional inflation screw that only contains an inflation portion, the utility model discloses an inflation screw can be fixed more firmly.

Description

Expansion screw

Technical Field

The utility model relates to a hardware and tools technical field particularly, relates to expansion screw.

Background

The expansion screw is generally a metal expansion screw, and the expansion screw is fixed by utilizing wedge-shaped inclination to promote expansion to generate friction bond force so as to achieve the fixing effect. One end of the screw is provided with threads, and the other end of the screw is provided with conicity. The expansion pipe is wrapped outside, one end of the expansion pipe is provided with a plurality of notches, the notches are placed into a hole drilled on the wall surface or the ground together, then the screw cap is rotated, the screw rod is screwed out outwards, the taper is pulled into the expansion pipe, the expansion pipe is expanded, and then the outer wall of the expansion pipe is tightly abutted to the inner wall of the hole, so that the expansion pipe is generally used for fastening protective guards, awnings, air conditioners and the like on materials such as cement, bricks and the like.

The conventional expansion screw is not very reliable in fixation because only the expansion part (notch) is expanded and pressed against the inner wall of the hole, and a gap exists between the middle part and the inner wall of the hole, so that if the external load generates large vibration, the expansion screw may be loosened after a long time, and thus the expansion screw cannot be used for installing objects which are easy to generate large vibration, such as a ceiling fan.

SUMMERY OF THE UTILITY MODEL

In order to overcome the above problems or at least partially solve the above problems, embodiments of the present invention provide an expansion screw to improve the stability of its installation.

The embodiment of the utility model is realized like this:

the expansion screw comprises a screw rod, an expansion pipe, a conical sleeve and a nut, wherein a conical part is arranged at one end of the screw rod, the other end of the screw rod is in threaded connection with the nut, the expansion pipe and the conical sleeve are sleeved on the screw rod, the expansion pipe is provided with at least two expansion parts, and the expansion part on any one expansion pipe is abutted to the conical sleeve.

In some embodiments of the present invention, there are two expansion pipes, namely, a first expansion pipe and a second expansion pipe, the first expansion pipe is sleeved between the tapered portion and the tapered sleeve, and a first expansion portion is disposed at an end of the first expansion pipe close to the tapered portion and abuts against the tapered portion; the second expansion pipe is provided between the tapered sleeve and the nut, and a second expansion portion is provided at an end of the second expansion pipe close to the tapered sleeve and abuts against the tapered sleeve.

In some embodiments of the present invention, a third expansion portion is disposed at an end of the first expansion portion close to the tapered sleeve.

In some embodiments of the present invention, a tapered gasket is further sleeved on the screw rod, one end of the tapered gasket abuts against the nut, the other end of the tapered gasket abuts against the second expansion pipe, and the diameter of the tapered gasket is gradually reduced from one end close to the nut to one end away from the nut.

In some embodiments of the present invention, a fourth expansion portion is disposed at an end of the second expansion pipe close to the tapered gasket.

In some embodiments of the present invention, the outer sidewall of the expansion portion is provided with anti-slip lines.

In some embodiments of the present invention, the anti-slip pattern is a convex stripe disposed along the circumferential direction of the expansion portion.

In some embodiments of the present invention, the number of the slits formed in the expansion portion along the axial direction is 2 to 8.

In some embodiments of the present invention, a threaded area is disposed on the screw rod near the nut.

In some embodiments of the present invention, the threaded region is in the range of 1/6-1/3 of the screw length.

The embodiment of the utility model provides an at least, have following advantage or beneficial effect:

when the expansion screw is used, a drill bit with the same diameter as that of an expansion pipe of the expansion screw is selected, the drill bit is installed on an electric drill, then an installation hole is drilled on a wall or the ground, the depth of the hole is preferably the same as the length of a bolt, then the expansion screw is put into the hole, the nut is not required to be screwed, and the situation that the installation hole is drilled too deep and the bolt falls into the hole and is inconvenient to take out due to the fact that the diameter of the nut is larger than that of the installation hole can be avoided; after the expansion pipes on the expansion screws are all arranged in the mounting holes, the screw rod is screwed back by the screw cap, the conical part or the conical part on the conical sleeve is pulled into the expansion part to be expanded, the expansion part is propped open, the outer side wall of the expansion part is tightly abutted against the inner wall of the mounting hole, and the screwed screw rod part can be used for hanging or fixing other objects. Because the utility model discloses well inclusion is not less than two inflation portions, compares in the traditional inflation screw that only contains an inflation portion, the utility model discloses an inflation screw can be fixed more firmly.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic structural view of an embodiment of an expansion screw according to the present invention;

fig. 2 is a schematic structural view of another embodiment of the expansion screw of the present invention;

fig. 3 is an exploded view of an embodiment of the expansion screw of the present invention;

fig. 4 is a schematic structural view of another embodiment of the expansion screw of the present invention.

Icon: 1-a screw; 11-a conical portion; 12-a threaded zone; 2-expansion pipe; 21-a first expansion tube; 211-a first expansion; 212-a third expansion; 22-a second expansion tube; 221-a second expansion; 222-a fourth expansion; 23-incision; 3-a tapered sleeve; 4-a screw cap; 5-a tapered shim; 6-anti-skid lines.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the directions or positional relationships indicated by the terms "inside", "outside", etc. are based on the directions or positional relationships shown in the drawings, or the directions or positional relationships that the products of the present invention are usually placed when using, the description is only for convenience of description and simplification of the present invention, and it is not intended to indicate or imply that the device or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and therefore, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," "fourth," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, "a plurality" means at least 2.

In the description of the embodiments of the present invention, it should be further noted that unless explicitly stated or limited otherwise, the terms "disposed" and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; either mechanically or electrically. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Examples

Referring to fig. 1, the present embodiment provides an expansion screw, including a screw rod 1, an expansion tube 2, a tapered sleeve 3 and a nut 4, wherein a tapered portion 11 is disposed at one end of the screw rod 1, the other end of the screw rod 1 is in threaded connection with the nut 4, the expansion tube 2 and the tapered sleeve 3 are both sleeved on the screw rod 1, the expansion tube 2 is disposed with at least two expansion portions, and the expansion portion on any one of the expansion tubes 2 is abutted to the tapered sleeve 3.

In the above embodiment, the expansion screw is composed of the screw 1, the expansion tube 2, the nut 4, and the like. A taper part 11 is provided at one end of the screw 1, and the end of the taper part 11 having the smallest diameter is connected to one end of the screw 1, and the diameter thereof is larger as the distance from the middle of the screw 1 is larger. Wherein the number of the expansion pipes 2 is not less than two, and each expansion pipe 2 is provided with at least one expansion part. The internal diameter of inflation portion under the normality is unanimous with the internal diameter at inflation pipe 2 middle part, during the use, need expand it with the help of the cone, and consequently the inflation portion all need with it adjacent toper portion 11 or taper sleeve 3 strut it, and taper sleeve 3 is the utility model discloses in be used for propping the important part of inflation portion, its quantity is one or more, and any taper sleeve 3 all is located between two inflation pipes 2, therefore its quantity is compared inflation pipe 2 and is less one all the time. In addition, it may be tapered at only one end or both ends (as shown in FIG. 3). The nut 4, which is threaded to one end of the screw 1, is one of the important components for controlling the cone to be inserted into the expansion part, and is used for controlling the expansion and contraction of the screw 1. When the expansion screw is used, firstly, a drill bit with the same diameter as the expansion pipe 2 of the expansion screw is selected, the drill bit is installed on an electric drill, then an installation hole is drilled on the wall or the ground, the depth of the hole is preferably the same as the length of a bolt, then the expansion screw is put into the hole, the nut 4 is not required to be screwed off, and the situation that the installation hole is drilled too deep and the bolt is inconvenient to take out due to the fact that the diameter of the nut 4 is larger than the diameter of the installation hole can be prevented; after the expansion pipe 2 on the expansion screw is not arranged in the mounting hole, the screw rod 1 is screwed back by the nut 4, the conical part 11 or the conical part on the conical sleeve 3 is pulled into the expansion part to be expanded, the expansion part is expanded, the outer side wall of the expansion part is tightly abutted to the inner wall of the mounting hole, and the screwed screw rod 1 part can be used for hanging or fixing other objects. Because the utility model discloses well inclusion is not less than two inflation portions, compares in the traditional inflation screw that only contains an inflation portion, the utility model discloses an inflation screw can be fixed more firmly.

Referring to fig. 1, in the present embodiment, there are two expansion pipes 2, which are a first expansion pipe 21 and a second expansion pipe 22, respectively, the first expansion pipe 21 is sleeved between the tapered portion 11 and the tapered sleeve 3, and a first expansion portion 211 is disposed at one end of the first expansion pipe 21 close to the tapered portion 11 and abuts against the tapered portion 11; the second expansion pipe 22 is provided between the tapered sleeve 3 and the nut 4, and a second expansion part 221 is provided at one end of the second expansion pipe 22 close to the tapered sleeve 3 and abuts against the tapered sleeve 3.

In the above embodiment, the expansion pipes 2 include two expansion pipes, which are a first expansion pipe 21 and a second expansion pipe 22, and are both sleeved on the screw rod 1, and a tapered sleeve 3 is further disposed between the first expansion pipe 21 and the second expansion pipe 22, wherein the first expansion pipe 21 is provided with a first expansion portion 211 and abuts against the tapered portion 11, and the second expansion pipe 22 is provided with a second expansion portion 221 and abuts against the tapered sleeve 3 (as shown in fig. 1). The utility model discloses when using, at first need utilize the electric drill to beat out the mounting hole that diameter and expansion pipe 2 are close at wall or subaerial, squeeze into the mounting hole with this inflation screw in, make first expansion pipe 21 and second expansion pipe 22 all sink into in the mounting hole. Then, the screw rod 1 is screwed outwards by the screw cap 4, the conical part 11 is pulled into the first expansion part 211, the first expansion part 211 is expanded, then the first expansion pipe 21 moves outwards due to extrusion of the conical part 11, the conical sleeve 3 is further pushed, the conical part on one side of the conical sleeve 3 close to the second expansion part 221 is pushed into the second expansion part 221, the second expansion part 221 is expanded, and at the moment, the outer walls of the first expansion part 211 and the second expansion part 221 are tightly abutted to the inner wall of the mounting hole. Because the conventional expansion screw only comprises one expansion part and a gap exists between the middle part and the inner wall of the hole, the conventional expansion screw is easy to loosen after a long time, and the expansion screw in the embodiment is provided with two expansion parts, and the second expansion part 221 is positioned in the middle of the screw, so that the gap between the middle part and the inner wall of the mounting hole can be prevented from being too long, and the pressure generated by the load of the screw can be shared.

Referring to fig. 2, in the expansion screw of the present embodiment, a third expansion portion 212 is disposed at one end of the first expansion portion 211 close to the tapered sleeve 3.

In this embodiment, in addition to the first expansion part 211 and the second expansion part 221, a third expansion part 212 is further provided at one end of the first expansion pipe 21 close to the tapered sleeve 3, after the expansion screw is placed in the installation hole (as shown in fig. 2), the user screws the screw 1 outwards through the nut 4, in the early stage, the first expansion pipe 21, the second expansion pipe 22 and the tapered sleeve 3 are relatively stationary with the inner wall of the hole, gradually, as the length of the screw 1 left in the installation hole is gradually reduced, the tapered part 11 will firstly enlarge the first expansion part 211, and continue to rotate the nut 4 to move the screw 1 outwards, at this time, the length of the screw 1 left in the installation hole continues to be reduced, under the pushing of the tapered part 11, the first expansion pipe 21 will move forwards and then the third expansion part 212 will press the tapered sleeve 3, and the taper near one end of the third expansion part 212 will extend into the third expansion part 212, and (3) expanding the third expansion part 212, and continuing moving the screw 1 outwards to force the first expansion part 211 to push the conical sleeve 3 to move outwards, so that the conical sleeve 3 extrudes the second expansion part 221, and a cone at one end of the conical sleeve, which is close to the second expansion part 221, extends into the second expansion part 221 to expand the conical sleeve. In this way, the outer walls of the first expansion part 211, the second expansion part 221 and the third expansion part 212 are abutted against the inner wall of the mounting hole, and compared with the conventional expansion screw only comprising one expansion part, the expansion screw comprising three expansion parts in the embodiment can be fixed more firmly, and the service life of the screw can be prolonged.

Referring to fig. 2 and 3, the expansion screw of the present embodiment further includes a tapered washer 5, the tapered washer 5 is sleeved on the screw rod 1, one end of the tapered washer 5 abuts against the nut 4, the other end of the tapered washer 5 abuts against the second expansion pipe 22, and a diameter of the tapered washer 5 is gradually reduced from one end close to the nut 4 to one end far away from the nut 4.

In the above embodiment, a tapered washer 5 is further disposed between the second expansion tube 22 and the nut 4, the tapered washer 5 is also sleeved on the screw rod 1, and the end with the larger diameter abuts against the nut 4, and the end with the smaller diameter abuts against the second expansion tube 22 (as shown in fig. 4). The tapered gasket 5 can prevent the nut 4 from directly contacting the second expansion pipe 22, wherein the contact surface between the tapered gasket 5 and the nut 4 is a flat plane, which can reduce the resistance when screwing the nut 4, and the user can use the nut 4 to screw the screw rod 1 more easily. In addition, because the other end of the tapered gasket 5 has a small part extending into the second expansion pipe 22, so that the outer wall of the small part is abutted against the inner wall of the second expansion pipe 22, at this time, the tapered gasket 5 can provide an outward force to the inner wall of the second expansion pipe 22, when a user screws the screw rod 1 through the screw cap 4, the friction force between the second expansion pipe 22 and the inner wall of the hole can be increased, and the second expansion pipe 22 is prevented from sliding relatively.

Referring to fig. 3 and 4, in the expansion screw according to the present embodiment, a fourth expansion portion 222 is disposed at an end of the second expansion pipe 22 close to the tapered gasket 5.

In some embodiments, the expansion screw is provided with three expansions or four expansions. In the present embodiment, four expansion parts are taken as an example, that is, in addition to the first expansion part 211, the second expansion part 221 and the third expansion part 212, the expansion screw is provided with a fourth expansion part 222 on one end of the second expansion pipe 22 close to the tapered gasket 5. After the expansion screw is placed in the mounting hole, the user screws the screw 1 through the nut 4. In the earlier stage, the first expansion pipe 21, the second expansion pipe 22 and the tapered sleeve 3 are relatively static with the inner wall of the hole, gradually, the length of the screw rod 1 left in the mounting hole is gradually reduced, wherein the first expansion part 211, the third expansion part 212 and the second expansion part 221 are sequentially expanded, then the nut 4 is continuously rotated, further the tapered sleeve 3 pushes the first expansion pipe 21 to move outwards to enable the fourth expansion part 222 to extrude the tapered gasket 5, and the cone body of the tapered gasket 5 close to one end of the fourth expansion part 222 extends into the fourth expansion part 222 to expand the tapered gasket. Fig. 4 shows a schematic view of a configuration in which the first expansion portion 211, the third expansion portion, the second expansion portion 221, and the fourth expansion portion 222 of the expansion screw are expanded. The first expansion part 211 and the fourth expansion part 222 are respectively arranged at the head end and the tail end of the mounting hole, and the second expansion part 221 and the third expansion part 212 are arranged in the middle of the mounting hole. Four inflation portions evenly set up, greatly increased with the mounting hole in between the inner wall area of contact, more be favorable to sharing the pressure that inflation screw external load produced for the inflation screw can be fixed more firmly, and can prolong the life of inflation screw.

Referring to fig. 3, the present embodiment provides an expansion screw, and the outer sidewall of the expansion portion is provided with anti-slip threads 6.

In some embodiments, the outer side surface of the expansion part is provided with an anti-slip pattern 6. When the expansion screw outside the mounting hole is partially hung or fixed with other objects, the anti-slip lines 6 can increase the friction force between the outer surface of the expansion part and the inner wall of the hole, so that the expansion screw is fixed more firmly.

Referring to fig. 3, in the expansion screw provided in the present embodiment, the anti-slip pattern 6 is a convex stripe disposed along the circumferential direction of the expansion portion.

In this embodiment, the anti-slip stripes 6 are raised stripes arranged along the circumferential direction of the expansion part, the stripes are slightly protruded out of the surface of the expansion pipe body, the structure is simple, the tangent line at any position of any stripe is perpendicular to the axial direction of the mounting hole, the arrangement can increase the resistance of the collision pipe to move along the axial direction, and the expansion pipe 2 can be prevented from sliding relative to the inner wall of the hole when the expansion screw is hung or fixed with other objects.

Referring to fig. 3, the present embodiment provides an expansion screw, and the number of the slits 23 formed along the axial direction of the expansion portion is 2-8.

In some embodiments, the number of the slits 23 provided in the expansion part in the axial direction is 2 to 8. Wherein the quantity of incision 23 should not be too much nor too little, if incision 23 quantity is too little, then the inflation portion is difficult for being strutted, and is harder during the use, if incision 23 is too many, then easy deformation and resilience are not enough when the inflation portion is strutted, because the equal opposite direction of the size of its power of a pair of interact power, consequently the power that the cone replied also can diminish, then the extrusion force of inflation portion to hole inner wall is not enough, can lead to the expansion screw to become flexible easily. In the present embodiment, the number of the cuts 23 is preferably 4 in consideration of the material and the diameter of the expansion tube 2.

Referring to fig. 3, the embodiment provides an expansion screw, and a threaded region 12 is disposed on the screw rod 1 near the nut 4.

In this embodiment, the threaded area 12 is only disposed at one end of the screw rod 1 close to the nut 4, and other portions of the screw rod 1 are not provided with threads except the threaded area 12, so that the arrangement of the threaded area 12 can effectively control the moving range of the screw rod 1 in the axial direction, reduce unnecessary processing, and effectively control the cost and improve the profit.

Referring to fig. 1, the present embodiment provides an expansion screw, and the range of the thread region 12 is 1/6-1/3 of the length of the screw rod 1.

In this embodiment, the threaded region 12 extends from the end near the nut 4 to 1/6-1/3 of the screw 1 (as shown in FIG. 3). Since the thread on the screw 1 increases the friction between the screw 1 and the inner wall of the expansion tube 2, when the screw 1 is screwed back, the screw 1 moves outwards, and when the cone does not yet extend into the expansion, the rough thread may have already driven the expansion outwards, which is not desirable. In addition, threads too far from the nut 4 cannot be used. And through the feedback of a plurality of tests and trial experiencers, when the expansion pipe 2 is two, the 1/5-1/4 threaded area 12 has the best use effect and experience. The threaded area 12 in this range is more time-saving and labor-saving for the user during back-screwing, and the length of the screw 1 is most suitable for back-screwing.

To sum up, the embodiment of the utility model provides an expansion screw has following beneficial effect:

because the utility model discloses well inclusion is not less than two inflation portions, compares in the traditional inflation screw that only contains an inflation portion, the utility model discloses an inflation screw can be fixed more firmly. Preferably, four expansion portions are taken as an example, that is, the first expansion tube 21 is provided with the first expansion portion 211 and the third expansion portion 212, and the second expansion tube 22 is provided with the second expansion portion 221 and the fourth expansion portion 222. When the expansion screw is used, firstly, the expansion screw is placed into the mounting hole, and then a user screws the screw rod 1 through the screw cap 4; in the early stage, the first expansion pipe 21, the second expansion pipe 22 and the tapered sleeve 3 are relatively static with the inner wall of the hole, gradually, as the length of the screw rod 1 left in the mounting hole is gradually reduced, the tapered portion 11 firstly expands the first expansion portion 211, the screw rod 1 continues to move outwards by continuing to rotate the nut 4, at this time, the length of the screw rod 1 left in the mounting hole continues to be shortened, under the pushing of the tapered portion 11, the first expansion pipe 21 moves forwards and then the third expansion portion 212 extrudes the tapered sleeve 3, the tapered body of the tapered sleeve 3 close to one end of the third expansion portion 212 extends into the third expansion portion 212, the third expansion portion 212 is expanded, then the nut 4 continues to rotate, the first expansion pipe 21 pushes the tapered sleeve 3, the tapered sleeve 3 at the other side of the tapered sleeve 3 is extruded into the second expansion portion 221, the nut 4 continues to be screwed after the second expansion is expanded, the tapered sleeve 3 pushes the second expansion pipe 22 forwards, the fourth expansion part 222 presses the tapered spacer 5, and the portion of the vertebral body of the tapered spacer 5 near the fourth expansion part 222 extends into the fourth expansion part 222 to enlarge it.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims (10)

1. The expansion screw is characterized by comprising a screw rod, an expansion pipe, a conical sleeve and a nut, wherein a conical part is arranged at one end of the screw rod, the other end of the screw rod is in threaded connection with the nut, the expansion pipe is sleeved with the conical sleeve, at least two expansion parts are arranged on the expansion pipe, and any one of the expansion parts is abutted to the conical sleeve.

2. The expansion screw according to claim 1, wherein there are two expansion pipes, namely a first expansion pipe and a second expansion pipe, the first expansion pipe is sleeved between the tapered portion and the tapered sleeve, and a first expansion portion is arranged at one end of the first expansion pipe close to the tapered portion and abuts against the tapered portion; the second expansion pipe is arranged between the conical sleeve and the screw cap, and a second expansion part is arranged at one end, close to the conical sleeve, of the second expansion pipe and is abutted to the conical sleeve.

3. The expansion screw of claim 2, wherein the first expansion is provided with a third expansion near an end of the tapered sleeve.

4. The expansion screw as claimed in claim 2 or 3, wherein a tapered washer is further sleeved on the screw rod, one end of the tapered washer abuts against the nut, the other end of the tapered washer abuts against the second expansion pipe, and the diameter of the tapered washer gradually decreases from one end close to the nut to one end far away from the nut.

5. The expansion screw of claim 4, wherein a fourth expansion portion is provided on the second expansion tube at an end adjacent to the tapered washer.

6. The expansion screw according to claim 1, wherein the outer side wall of the expansion portion is provided with an anti-slip thread.

7. The expansion screw according to claim 6, wherein the anti-slip thread is a convex thread provided along a circumferential direction of the expansion portion.

8. The expansion screw according to claim 1, wherein the number of the slits provided in the expansion part in the axial direction is 2 to 8.

9. The expansion screw of claim 1 wherein said shank is provided with a threaded region adjacent said nut.

10. The expansion screw of claim 9 wherein the threaded zone ranges from 1/6-1/3 of the screw length.

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