Ball expansion anchor

Abstract

To prevent unevenness of fastening force due to an individual difference and stabilize the quality with respect to an anchor with an extension part pushed and extended by a group of balls.SOLUTION: The anchor has an extension part 3 divided into a plurality of parts by a slit 2 and when the group of balls 4 are compressed by a bolt for extension 6, the extension part 3 is pushed and widened, expanded and deformed. A lubrication film 9 consisting of oil, wax or the like is formed at an inner surface of the extension part 3. The group of the balls 4 is crushed, deformed into a mass in a dumpling state, slide and move smoothly to a tip side. Thus, a phenomenon that the mass of the balls 4 is clogged at an entrance part of the extension part 3 is prevented and the extension part 3 is entirely strongly pushed and widened. As a result, an unevenness due to an individual difference is prevented and a high fastening strength can be stably maintained. As a torque needed for extension can be reduced, a burden of operators can be also reduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an expansion anchor suitable for attaching various members to stone-based members such as concrete and brick, and more particularly to a ball expansion anchor that uses a group of balls as the expansion means. [Background technology]

[0002] Post-installed expansion anchors are used as a means for attaching various components to concrete structures such as buildings and tunnels. These expansion anchors have a cylindrical anchor body, and by forming an expansion section with a group of slits in the anchor body, the expansion section expands and deforms in the direction intersecting the axis (swelling deformation).

[0003] As the expansion operation member for pushing the expansion part, a hammer-in type core rod (expansion pin) is often used, but a set of multiple balls and an expansion bolt that pushes them has also been proposed. Patent Document 1 is an example of a hammer-in type anchor, and this publication discloses that a lubricant such as rust-preventive oil is applied to the outer circumferential surface of the plug (expansion pin) to improve the sliding of the plug. On the other hand, Patent Document 2 discloses the latter ball expansion type anchor.

[0004] Hammer-in expansion anchors have problems such as the need to swing a heavy hammer, which places a heavy burden on the worker, and the tendency for the fastening force to vary due to machining errors in the pilot holes. However, with the method of expanding by pushing a group of balls with an expansion bolt as in Patent Document 2, there is no need to swing a hammer, which significantly reduces the burden on the worker, and the degree of expansion can be adjusted by how tightly the bolt is screwed in, which has the advantage that the required fastening strength can be ensured even if there are machining errors in the pilot holes.

[0005] In addition, by increasing the length of the expansion section, the tension force against the pilot hole can be distributed, which has the advantage of preventing cone destruction at the installation site. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Unexamined Patent Publication No. 48-50151 [Patent Document 2] International Publication No. WO2016 / 121993 Summary of the Invention [Problem to be solved by the invention]

[0007] Although ball expansion anchors have the above advantages, there have been cases where the fastening force was inconsistent. When the inventors analyzed this issue, they found that the balls were crushed and deformed inside the expansion section, forming a ball-like mass, which prevented the balls from moving to the tip of the expansion section and got stuck halfway, resulting in insufficient expansion of the expansion section.

[0008] In this regard, it would be sufficient to be able to push the group of balls toward the tip while deforming them. Therefore, as in Patent Document 1, we tried applying lubricant to the balls before using them, but no improvement was observed. Although it is not clear why the variation does not improve even when lubricant is applied to the balls, it is speculated that this is because, in a ball expansion anchor, the contact surface between the ball and the expansion part is small, so even if a lubricant is applied to the balls, it does not contribute to promoting sliding between the balls and the expansion part.

[0009] The present invention has been made against this background, and has as its object to provide a ball expansion anchor that can stably ensure high fastening force by eliminating variation between individual anchors, while also reducing the force required to press in the ball group. [Means for solving the problem]

[0010] The expansion anchor of the present invention is "An anchor body having an expansion part that enters a pilot hole of a construction part, and A group of enclosed balls and an expanding ball for pressing the group of balls to expand the expanding portion. It is equipped with At least the above ball When the anchor body is expanded by the group of A friction reducing means is provided to facilitate sliding of the group of balls. The friction reducing means can also be called a lubricating means. .

[0011] The expansion anchors of the present invention include both a split-end type in which the expansion portion extends to the front end of the anchor body, and a closed type in which the tip of the anchor body is closed and the expansion portion does not reach the tip of the anchor body.

[0012] The present invention can be developed in various ways. For example, in claim 2, "The friction reducing means is one or more selected from the group consisting of silicone oil, petroleum oil, natural or animal oil, grease, waxes, pastes, paraffins, and vegetable or animal waxes." These can be used alone or in combination. In the case of liquids such as oil, it is possible to gel them by adding an auxiliary agent to prevent dripping.

[0013] As a suitable development of claim 2, claim 3 uses wax (wax ester) as the friction reducing means. Here, wax is a paste having lubricating properties, and for example, wax (coating wax) used for polishing automobiles can be used as is. Wax for polishing floors and wax for skis are also worth considering.

[0014] In claim 4, in any one of claims 1 to 3, the friction reducing means is applied in advance to the inner surface of the widening portion. On the other hand, in claim 5, in any one of claims 1 to 3, the friction reducing means has the appearance of a bag, and the group of balls is stored inside it.

[0015] Furthermore, in the invention of claim 6, in any one of claims 1 to 3, The friction reducing means is a fixed-shaped lubricant that can be crushed and deformed into a ball-like or other shape, and a large number of these fixed-shaped lubricants are mixed in with the group of balls, and when expanding, the fixed-shaped lubricant is crushed by the pressing action of the group of balls and adheres to the inner surface of the expansion part. The "ball" exemplified in claim 6 includes not only a perfect sphere but also an oval sphere such as a rugby ball.

[0016] In claim 6, the shaped lubricating body, which is the friction reducing means, can have various shapes other than the ball shape shown as an example. For example, a rectangular parallelepiped shape like a small sugar cube, a cylindrical shape, a granular shape, a cylindrical shape, a string shape, etc. can be used. They may be in the shape of a round, disk, flake, or a confetti-like shape with many protrusions. Even , Expand It must be large enough that it does not slip through the slit that forms the opening. Only the lubricating body may be used, or different shapes may be used in combination. A fixed size may be used, or different sizes may be mixed.

[0017] As for the structure, it is possible to solidify waxes, oils, etc. into a stable form to make the whole a single composition, or to configure it as a multi-layer structure of a thin skin material and a fluid enclosed inside, so that when the expansion part expands, the skin material breaks and the fluid flows out. In the case of the latter structure and a spherical shape, it becomes like salmon roe. Effect of the Invention

[0018] In the present invention, the balls are pushed by the bolt and crushed and deformed inside the expansion section, but in the present invention, the friction reduction means is provided on the inner surface of the expansion section, so that the balls are easily pushed toward the tip of the expansion section, promoting the expansion action of the expansion section and ensuring a stable high fastening force. In other words, the variation due to individual differences can be eliminated and a stable high fastening force can be maintained.

[0019] Furthermore, the balls undergo plastic deformation into a lump, but they also undergo elastic deformation, so that the balls deformed into a lump are pushed toward the tip of the expansion portion, exerting an elastic restoring force on the expansion portion, and it can be said that this elastic restoring force is utilized to ensure a high fastening force.

[0020] In addition, because friction between the balls and the anchor body is reduced, the force required to screw in the expansion bolt when pushing the balls in with the expansion bolt can be reduced. This reduces the burden on the worker. Furthermore, if the force required to screw in the expansion bolt can be reduced, it becomes possible to use a small driver tool to push it in, which contributes to the promotion of the use of ball anchors.

[0021] As exemplified in claim 2, friction reducing means of various properties, compositions and appearances can be used, but the wax specified in claim 3 is suitable because of its excellent sliding promoting effect. Friction reducing means such as wax can be applied to the outer surface of each ball and transferred to the inner surface of the expansion part when the expansion part expands, but applying it to the inner surface of the expansion part in advance as in claim 4 provides high stability of quality.

[0022] Various friction reducing means can be used, but it is preferable to apply it so that it does not drip after use. A solid (non-liquid) such as the wax specified in claim 3 is preferable because it will not melt even when the temperature rises.

[0023] As in claim 5, the friction reducing means can be configured to have the appearance of a bag, which simplifies the loading work into the anchor. In addition, since the ball group can be enclosed in advance, there is also the advantage that the loading work of the balls can be simplified.

[0024] When the configuration of claim 6 is adopted, a fixed lubricant is mixed with the group of balls and sealed in the anchor body. In addition, the fixed lubricating body is crushed when the expansion section is expanded, and the lubricating effect is improved. Therefore, it is recommended for use in high temperature environments. in Even if you store it, it will run off. Therefore, it has excellent preservation properties. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a first embodiment, in which (A) is a side view, (B) is a front view seen from the direction BB of (A), (C) is a rear view seen from the direction CC of (A), (D) is a longitudinal sectional side view, (E) is a longitudinal sectional side view with the ball group and bolt removed, and (F) is a longitudinal sectional side view in use. [Diagram 2] FIG. 11 is a vertical sectional side view of the second embodiment. [Diagram 3] FIG. 11 is a vertical sectional side view of a third embodiment. [Figure 4] FIG. 13 is an exploded vertical sectional side view of a fourth embodiment. [Diagram 5] FIG. 13 is an exploded vertical sectional side view of the fifth embodiment. [Figure 6] 13A is a vertical sectional side view of a sixth embodiment, and FIG. 13B is an exploded vertical sectional side view of a seventh embodiment. [Figure 7] FIG. 23 is an exploded vertical sectional side view of the eighth embodiment. [Figure 8] FIG. 13 shows a ninth embodiment, in which (A) is a partially broken side view, (B) is a front view of (A) seen from the right, (C) is a rear view of (A) seen from the left, and (D) is a partial side view clearly showing the male thread portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] (1) Structure of the First Embodiment Next, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment shown in Fig. 1 will be described. An expansion anchor (hereinafter simply referred to as "anchor") is used, for example, in concrete structures, and includes an anchor body 1 made of steel (iron).

[0027] The anchor body 1 is cylindrical with a hollow portion, and has an expansion section 3 with four slits 2 formed on the tip side. In other words, the expansion section 3 is formed on the tip side by forming four slits 2 at equal intervals. Four slits 2 are formed at equal intervals in the circumferential direction, and each slit opens on the tip surface 3a of the expansion section 3 (or of the anchor body 1). Therefore, the anchor of this embodiment is of the split type.

[0028] In the embodiment, the expansion portion 3 is divided into four by four slits 2 for ease of processing, but the number of slits 2 can be set arbitrarily. From the viewpoint of the effect of evenly expanding the expansion portion 3, it is presumed that it is preferable to form three slits 2 at equal intervals.

[0029] A group of balls 4 are loaded inside the anchor body 1 as a means for expanding the expansion portion 3 (note that in the cross-sectional view, for convenience, the balls 4 and the balls 4 and the slits 2 are shown overlapping each other). A female thread 5 is formed on the inner circumference of the anchor body 1, and an expansion bolt 6 that presses the group of balls 4 is screwed into this female thread 5. The female thread 5 is formed by tapping from the base end of the anchor body 1, and extends to the entrance of the expansion portion 3.

[0030] Although balls 4 of different sizes are used, it is also possible to use only balls of the same diameter. It is preferable that the density of the group of balls 4 is as high as possible before use. The expansion bolt 6 does not have a head, and an engagement hole 7 is formed on the base end surface (rear end surface) into which a rod-shaped wrench (not shown) such as a hexagonal wrench engages.

[0031] The tip of the anchor body 1 is formed with an inward bulge (stopper) 8 that prevents the ball 4 from falling out. The inward bulge 8 is also divided by a slit 2. The inner peripheral surface of the expansion portion 3 is formed straight except for the inward bulge 8. The inner diameter of the expansion portion 3 is the same as the pilot hole diameter of the female thread 5, but it is also possible to form the inner diameter of the expansion portion 3 to be larger or smaller than the pilot hole diameter of the female thread 5.

[0032] In the embodiment, the expansion portion 3 is approximately half the length of the anchor body 1, but the length, outer diameter, inner diameter, and length of the expansion portion 3 can be set arbitrarily according to the conditions required at the site. For example, most anchors used to attach various instruments to the wall surface of a building are short, with a total length of around 40 mm, while most anchors for tunnels are long, with a length of 100 mm or more.

[0033] A lubricating film (or lubricating layer) 9 made of a lubricant is formed as an example of a friction reducing means on the inner surface (inner circumferential surface) of the expansion portion 3. In Fig. 1(E), the area of ​​the lubricating film 9 is indicated by hatching.

[0034] The lubricating film 9 is formed by applying a lubricant using, for example, a brush. When a liquid lubricant such as oil is used as the lubricating film 9, it can be applied using a spray or dispenser. It is also possible to immerse the anchor body 1 in a lubricant bath and then pull it out, and completely remove the lubricant from the outer circumferential surface using a brush or the like. In the case of solid substances (high viscosity agents) such as waxes and creams, they can be applied using a rod-shaped applicator like a cotton swab. A brush wound in a spiral shape around a shaft is used as an applicator for cosmetic mascara, and it is also preferable to use an applicator of a similar shape.

[0035] (2) Enforcement Fig. 1(F) shows the anchor in use. In this embodiment, the anchor body 1 is entirely inserted into the pilot hole 11 of the construction part 10, and when the expansion bolt 6 is screwed in with a wrench (not shown) to press the group of balls 4 toward the tip, the group of balls 4 is crushed and deformed, changing into one mass as a whole and expanding in the direction intersecting the axis, so that the expansion part 3 is pushed out like a trumpet and pushed against the pilot hole 11 (generally, the expansion part 3 bites into the pilot hole 11). As a result, the anchor body 1 is firmly fixed to the pilot hole 11.

[0036] Since the lubricating film 9 is formed on the inner surface of the expansion portion 3, the group of balls 4 is allowed to slide toward the tip even if it is deformed into a lump, and the group of balls 4 is pressed and crushed, and moves toward the tip of the expansion portion 3. Therefore, the group of balls 4 can be forcibly driven toward the tip of the expansion portion 3, and the expansion portion 3 can be largely expanded as a whole into a trumpet shape. As a result, it is possible to eliminate the variation due to individual differences and to stably secure a high fastening force (pull-out resistance). In addition, it is possible to reduce the screwing torque of the expansion bolt 6, which contributes to reducing the burden on the worker.

[0037] According to the inventors' experiments, silicone oil (lubricating oil) and car wax were equally effective, but it is understood that the use of waxes is preferable in terms of preventing dripping after use and cost. It is also assumed that the larger the molecular weight of either oil or wax, the higher the lubricating effect. In addition, when looking at the anchor body 1 and ball 4, it is assumed that the ball 4 becomes more slippery as the anchor body 1 becomes harder.

[0038] There are various specific modes of use for anchors. For example, as shown in the figure, after the anchor body 1 is fixed in a pilot hole 11, a member (workpiece) 12 can be fastened to the surface of the construction part 10 by a fastening bolt 13 that is screwed from the outside into the female thread 5 of the anchor body 1. It is also possible to expose the base end of the anchor body 1 from the surface of the construction part 10 and fit the member 12 into the exposed part. It is also possible to screw a suspension bolt into the anchor body 1 and suspend the member from the suspension bolt.

[0039] In addition to the lubricants mentioned above, pitch, coal tar, petrolatum, asphalt, graphite powder, etc. can also be used. Organic creams such as shoe cream (leather care oil) are also worth considering. For creams, it is preferable that the molecular weight is as large as possible.

[0040] (3) Second to fifth embodiments 2 and 3 show other examples of the anchor structure. In the second embodiment shown in Fig. 2, the anchor body 1 has a male thread portion 14 exposed to the outside of the construction part 10. The mounting hole of the member is adapted to be fitted into the male thread portion 14, and the member 12 is pressed and fixed to the construction part 10 with a nut (not shown). In a male thread type anchor such as this embodiment, it is also possible to use a hexagon socket bolt or a hexagon head bolt as the expansion bolt 6.

[0041] In this embodiment, a flange 1a that abuts against the edge of the pilot hole 11 is formed at the base end of the male thread portion 14 of the anchor body 1. Therefore, even if the pilot hole 11 is deep, the insertion depth of the anchor body 1 can be made constant.

[0042] In the third embodiment shown in FIG. 3, the slit 2 does not open at the tip of the anchor body 1, and the anchor is a closed type with a closed tip. Therefore, the expansion portion 3 swells and deforms in a mountain shape. In the closed type, the group of balls 4 is less likely to move than in the split type, and the group of balls 4 is more likely to stay near the entrance of the expansion portion 3. Therefore, if the lubricating film 9 is provided to improve the slip, it is expected that the expansion portion 3 can be reliably swelled and deformed in a mountain shape over its entirety. Therefore, it is expected that the expansion promotion effect by providing the lubricating film 9 can be enjoyed more significantly than in the split type. Although it is not necessary to mention it, even in the closed type, the male thread portion 14 as shown in FIG. 2 can be provided.

[0043] 4 and 5 show examples in which a sheet material is used as the friction reducing means. In the fourth embodiment shown in Fig. 4, a bag body 16 with one open end is formed by a sheet material having lubricity. In this example, the bag body 16 may be inserted into the inside of the anchor body 1 first and then filled with the group of balls 4, or the group of balls 4 may be placed in the bag body 16 beforehand and then inserted into the anchor body 1.

[0044] In the fifth embodiment shown in Fig. 5, both ends of the bag are sealed. Therefore, after a group of balls 4 is filled into the bag 16, the opening is closed and the bag 16 containing the balls 4 is inserted into the inside of the anchor body 1. This type has the advantage that it is possible to prevent mistakes in the insertion of the balls 4. In addition, the workability of assembling the anchor is also excellent.

[0045] The inventors of the present application conducted experiments by wrapping oil-impregnated rust-preventive paper and resin film around the inner surface of the expanding portion 3 to see if they would have a sliding effect on the group of balls 4. However, in both cases, the paper or film was crushed into small pieces and caught between the balls 4 and the expanding portion 3, and no sliding promotion effect was observed.

[0046] Therefore, in order to give the bag 16 the effect of promoting the sliding of the ball 4, it is necessary to devise a material and thickness. For example, it is conceivable to configure the bag 16 with a double structure of an inner layer and an outer layer, and to apply a liquid or wax-like lubricant between the two layers. It is also considered to be beneficial to make the bag 16 from a tough material such as a very thin stainless steel plate, and to apply a lubricant to either or both of the inner and outer surfaces. It is also considered to be beneficial to apply a lubricant to the outer surface of the bag 16.

[0047] (4) Sixth to Ninth Embodiments Fig. 6 shows an embodiment that embodies claim 6. Of these, the sixth embodiment shown in Fig. 6(A) has a structure of an anchor that is basically the same as that of the first embodiment, and differs from the first embodiment in that the lubricating film 9 of the first embodiment is not provided, and instead, ball-shaped fixed lubricating bodies 17 are used as friction reducing means, and a large number of fixed lubricating bodies 17 are mixed in with the group of balls 4.

[0048] The shaped lubricant 17 can have various structures, such as solidified wax or oils, or a salmon roe-like film of fluid oil or grease. The size can be set arbitrarily as long as it does not slip out of the slit 2, but since it is important that it is crushed by the pressing action when the expanding portion 3 expands, a size that fits into the gaps between the balls before use is preferable.

[0049] Therefore, it is preferable that the ball size is smaller than the group of balls. If the balls 4 are configured in different sizes, the ball size may be about the same as the smallest ball 4. If the shaped lubricant 17 is ball-shaped, it is also possible to use wax, solid oils and fats, asphalt, etc., and make them into spheres using a granulator.

[0050] In this embodiment, when the group of balls 4 is pressurized to expand the expanding portion 3, the fixed lubricating bodies 17 are crushed and adhere to the inner surface of the expanding portion 3, promoting the sliding of the group of balls 4 and widening the opening of the expanding portion 3. Therefore, although only a portion of the group of fixed lubricating bodies 17 contributes to lubrication, by mixing a large number of fixed lubricating bodies 17, an oil film can be formed on the entire inner surface of the expanding portion 3, thereby providing a lubricating function.

[0051] 6(B), in addition to the embodiment of FIG. 5, a fixed lubricant 17 is mixed inside the bag body 16. In this embodiment, even if the bag body 16 does not have lubricity, if the bag body 16 is broken when the expanding portion 3 is expanded, the fixed lubricant 17 is crushed and expanded, so that the lubricant can be applied to the inner surface of the expanding portion 3.

[0052] The inclusion of a shaped lubricant 17 in the group of balls 4 can also be applied to the male thread type anchor shown in Fig. 2. The embodiment in Fig. 7 is an example of application to a male thread type, but in this embodiment, the male thread portion 14 is formed with a larger diameter than the pilot hole 11. The arrangement of the shaped lubricant 17 is the same as in Fig. 6, and the work (member to be fixed) 12 and nut 18 are also shown by dashed lines. The anchor shown in Fig. 8 is almost the same as that shown in Fig. 7, and Fig. 8 clearly shows the appearance (the balls and friction reduction means are omitted in Fig. 8).

[0053] Post-installation anchors come in two types: female threaded, in which the entire body fits into the pilot hole, and male threaded, in which the male threaded portion is exposed to the outside of the installation surface. Patent Document 2 also discloses both the female threaded and male threaded types.

[0054] In addition, with a male thread type anchor, the anchor can be attached to the installation part beforehand, and then the installation hole of the member to be fixed to the male thread can be fitted into the male thread, so that the member to be fixed can be temporarily fixed to the installation surface, which is particularly suitable for attaching members to a wall surface.

[0055] However, conventional male thread anchors have the same diameter over their entire length, which means that the depth of insertion into the pilot hole is not consistent. With a hammer-in anchor, to ensure a consistent depth, the nut must be screwed into the desired position beforehand, the anchor must be set in the installation area, the nut must be removed, the component must be inserted, and then the nut must be reattached, which is a tedious process.

[0056] In contrast, when the male thread portion 14 is formed in a large diameter portion as in the embodiment of Figures 7 and 8, the insertion depth into the pilot hole 11 is automatically made constant, eliminating the need to reset the nut 13, and therefore significantly improving the ease of installation of the components.

[0057] The same effect can be obtained when a flange 15 is provided as in Figure 2, but with the flange 15, if the diameter is too small it will get into the pilot hole 11 and become meaningless, while if the diameter is too large it will be exposed on the outside of the construction surface and may come into contact with other components, resulting in a problem of poor reliability. In contrast, if the anchor body 1 is formed with a different diameter structure, with a small diameter insertion portion and a large diameter male thread portion 14 as in Figures 7 and 8, the insertion depth can be made constant regardless of variations in the pilot hole 10, which is highly practical.

[0058] Furthermore, by forming the male thread portion 14 with a large diameter, as shown by the dashed line in FIG. 8, a bolt with a head 6a, such as a hexagonal socket bolt, can be used as the expansion bolt 6, which has the advantages of being able to increase the pressing force against the group of balls 4 and keeping costs down.

[0059] Furthermore, as shown by the two-dot chain line in FIG. 8(A), a sleeve 19 that increases the frictional resistance between the expansion section 3 and the pilot hole 11 can be attached to the small diameter section of the anchor body 1. It is also possible to use the stepped surface formed by the male thread section 14 of the sleeve 19 as a stopper for the sleeve 19, thereby stabilizing the quality of the anchor equipped with the sleeve 19.

[0060] As can be understood from the above explanation, forming the male thread portion 14 with a large diameter can be an independent invention unrelated to the friction reduction means, and can also be applied to anchors that expand by hammering in a pin. In addition, the shape of a post-installed anchor with the male thread portion 14 formed with a large diameter is novel, and therefore, is also eligible for design registration. In this case, not only can the overall shape be subject to design registration, but it can also be registered as a partial design.

[0061] The part to be registered as a partial design can be considered to be only the stepped area shown by reference number 20 in Fig. 8(A), or it is also possible to specify the area 21 in which the slit 2 is formed in addition to the stepped area 20. The male screw type anchor can naturally be applied to the closed type shown in Fig. 3, and it goes without saying that the closed type is also eligible for design registration.

[0062] The present invention can be embodied in various ways other than the above-mentioned embodiments. For example, in each embodiment, the expansion portion is formed by a group of slits, but it is also possible to form the expansion portion by providing a long groove (a long groove that does not penetrate to the inner peripheral surface) on the outer surface. In addition, the outer shape of the anchor body is not limited to a circle (a perfect circle), and a polygonal shape such as a regular octagon or an elliptical shape can also be used. It is also possible to form a friction increasing means such as an annular groove or annular protrusion on the outer peripheral surface of the expansion portion.

[0063] It is also possible to provide the anchor with a pilot hole drilling function by integrally providing a drill portion at the tip of the anchor body.

[0064] As a means of reducing friction, it is possible to form a carbon layer on the inner surface of the expansion part by gluing or spraying, etc. It is also possible to form a thin cylinder mainly made of carbon powder and load this inside the expansion part, or to form oils or waxes into a thin cylinder using a resin material similar to a water-absorbing polymer (oil-absorbing polymer) and load this inside the anchor body. [Industrial Applicability]

[0065] The present invention can be embodied in an expansion anchor, and therefore has industrial applicability. [Explanation of symbols]

[0066] 1 Anchor body 2 Slits that form the expansion section 3 Expansion section 4. Ball 5 Female thread 6 Expansion bolt 8 Inner bulge (stopper) 9. Lubricating Film as an Example of a Friction Reduction Method 10 Construction section (concrete) 11 Pilot hole 12 Materials (work) 13 Fastening bolts 14 Male thread 16 Bags as an example of friction reduction means 17 Shaped lubricants as an example of friction reduction means 18 Nut

Claims

1. An anchor body having an expanded portion that enters a pilot hole in a construction part, and A group of enclosed balls and an expansion ball for pressing the group of balls to expand the expansion portion. It is equipped with At least when the balls are expanded, the balls are positioned on the inner surface of the expansion portion of the anchor body. and a friction reducing means is provided to promote sliding of the ball group. Ball expansion anchor.

2. The friction reducing means is one or more selected from the group consisting of silicone oil, petroleum oil, natural or animal oil, grease, wax, paste, paraffin, and vegetable or animal wax.

2. The ball expansion anchor according to claim 1.

3. The friction reducing agent is a wax.

3. The ball expansion anchor according to claim 2.

4. The friction reducing means is pre-applied to the inner surface of the expansion portion.

4. A ball expansion anchor according to claim 1.

5. the friction reducing means has the appearance of a bag, within which the group of balls is housed; 4. A ball expansion anchor according to claim 1.

6. The friction reducing means is a shaped lubricant that can be crushed and deformed into a ball shape or other shape, and a large number of these shaped lubricants are mixed in with the group of balls, and when expanding, the shaped lubricant is crushed by the pressing action of the group of balls and adheres to the inner surface of the expansion part.

4. A ball expansion anchor according to claim 1.

Images