JP7601533B2 - Ball expansion anchor - Google Patents

Description

This invention relates to an expansion anchor suitable for attaching various components to stone-based components such as concrete and brick, and in particular to a ball expansion anchor that uses a group of balls as the expansion means.

Post-installation expansion anchors are used as a means of attaching various components to concrete structures such as buildings and tunnels. These expansion anchors have a cylindrical anchor body, and an expansion section with a group of slits is formed in the anchor body, allowing the expansion section to expand and deform (swell) in the direction that intersects with the axis.

Many of these use a hammer-in type core rod (expansion pin) as the expansion operating member that pushes the expansion part open, 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 periphery of the plug (expansion pin) to improve the sliding of the plug. Meanwhile, Patent Document 2 discloses the latter ball expansion type anchor.

Hammer-in type expansion anchors have the problem that a heavy hammer must be swung around, which places a heavy burden on the worker, and that machining errors in the pilot holes can easily cause variations in the fastening force. 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 necessary fastening strength can be ensured even if there are machining errors in the pilot holes.

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 damage to the cone at the installation site.

Japanese Unexamined Patent Publication No. 48-50151 International Publication No. WO2016/121993

Although ball expansion anchors have the advantages mentioned above, there have been cases where the fastening force was inconsistent. When the inventors of this application analyzed this issue, they found that the balls were crushed and deformed inside the expansion section, forming a ball-like mass, which caused them to get stuck midway before moving to the tip of the expansion section, resulting in insufficient expansion of the expansion section.

In this regard, it would be sufficient to be able to deform the group of balls and push them towards the tip. Therefore, as in Patent Document 1, we tried applying lubricant to the balls before using them, but no improvement was seen. It is not clear why applying lubricant to the balls does not improve the variation, but 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 applying lubricant to the balls does not contribute to promoting sliding between the balls and the expansion part.

The present invention was made against this background, and aims to provide a ball expansion anchor that can stably secure a high fastening force by eliminating variation between individual anchors, while also reducing the force required to push in the ball group.

The expansion anchor of the present invention is
"The anchor body has an expansion part that enters the pilot hole of the installation part, a group of balls enclosed in the expansion part of the anchor body, and an expansion bolt that presses the group of balls to expand the expansion part,
A friction reducing means is provided which is located on the inner surface of the expanding portion of the anchor body and promotes sliding of the group of balls at least when the group of balls expands.
The friction reducing means can also be called a lubricating means.

The expansion anchors of the present invention include both a split-tip type in which the expansion section 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 section does not reach the tip of the anchor body.

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, wax, paste, paraffin, and vegetable or animal wax."
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.

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

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

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 expanding portion. The "ball" exemplified in claim 6 includes not only a perfect sphere but also an oval sphere such as a rugby ball.

In claim 6, the shaped lubricant serving as the friction reducing means can adopt various shapes other than the ball shape shown as an example. For example, it can be a rectangular parallelepiped shape like a small sugar cube, a columnar shape, a granular shape, a cylindrical shape, a string shape, a disk shape, a flake shape, or a confetti shape with many protrusions. In any case , it is necessary that the size does not slip out of the slit forming the expansion part. Only shaped lubricants of the same shape may be used, or those of different shapes may be used in combination. As for the size, it is also possible to use ones of a constant size, or to mix ones of different sizes.

As for the structure, it is possible to solidify waxes and oils into a stable form to make the whole thing a single composition, or it is possible to have a multi-layer structure with a thin skin and a fluid sealed inside, so that when the expansion section expands, the skin breaks and the fluid flows out. If the latter structure is spherical, it will be in a state similar to salmon roe.

In the present invention, the balls are pushed by the bolt and crushed and deformed inside the expansion section, forming a mass. However, in the present invention, friction reduction means is provided on the inner surface of the expansion section, which makes it easier for the balls to be 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.

More specifically, the balls undergo plastic deformation and become lumpy, but they also undergo elastic deformation, so that the lumpy balls exert an elastic restoring force on the expansion section as they are pushed toward the tip of the expansion section, and this elastic restoring force is used to ensure a high fastening force.

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 bolt can be reduced. This reduces the burden on the worker. Furthermore, reducing the force required to screw in the expansion bolt makes it possible to use a small screwdriver tool to push it in, which will contribute to promoting the use of ball anchors.

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 slip-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 as the expansion part expands, but applying it to the inner surface of the expansion part in advance, as in claim 4, ensures high quality stability.

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.

As in claim 5, by configuring the friction reduction means to have the appearance of a bag, the work of loading into the anchor can be easily performed. In addition, since the ball group can be sealed in advance, there is also the advantage that the work of loading the balls can be simplified.

By adopting the configuration of claim 6, the fixed lubricant can be mixed with the ball group and enclosed in the anchor body, which makes it easy to work with. Also, since the fixed lubricant is crushed when the expansion part expands to exert its lubricating effect, it will not run off even if stored in a high temperature environment. Therefore, it has excellent storage properties.

FIG. 1 shows the first embodiment, in which (A) is a side view, (B) is a front view taken along line B-B of (A), (C) is a rear view taken along line C-C of (A), (D) is a longitudinal side view, (E) is a longitudinal side view with the ball group and bolt removed, and (F) is a longitudinal side view in use. FIG. 11 is a vertical sectional side view of the second embodiment. FIG. 13 is a vertical sectional side view of the third embodiment. FIG. 13 is an exploded vertical sectional side view of the fourth embodiment. FIG. 13 is an exploded vertical sectional side view of the fifth embodiment. 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. FIG. 23 is an exploded vertical sectional side view of the eighth embodiment. 13A is a partially broken side view of the ninth embodiment, (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.

(1) Structure of the First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. First, the 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).

The anchor body 1 is cylindrical with a hollow portion, and has an expansion section 3 with four slits 2 formed at the tip side. In other words, the expansion section 3 is formed at 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 at the tip surface 3a of the expansion section 3 (or the anchor body 1). Therefore, the anchor of this embodiment is of the split type.

In the embodiment, the expansion section 3 is divided into four sections by four slits 2 for ease of processing, but the number of slits 2 can be set as desired. From the viewpoint of evenly expanding the expansion section 3, it is presumed that it is preferable to form three slits 2 at equal intervals.

A group of balls 4 are loaded inside the anchor body 1 as a means for expanding the expansion section 3 (for convenience, the cross-sectional view shows balls 4 and balls 4, and balls 4 and slits 2 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 section 3.

Although multiple types of balls 4 with 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.

The tip of the anchor body 1 is formed with an inner bulge (stopper) 8 that prevents the ball 4 from slipping out. The inner bulge 8 is also divided by a slit 2. The inner peripheral surface of the expansion section 3 is formed straight except for the inner bulge 8. The inner diameter of the expansion section 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 section 3 larger or smaller than the pilot hole diameter of the female thread 5.

In this embodiment, the expansion section 3 is approximately half the length of the anchor body 1, but the length, outer diameter, inner diameter, and length of the expansion section 3 can be set as desired according to the conditions required at the site. For example, most anchors used to attach various tools to the walls of buildings have a short overall length of around 40 mm, while most anchors for tunnels are long, measuring 100 mm or more.

As an example of a friction reduction means, a lubricating film (or lubricating layer) 9 made of a lubricant is formed on the inner surface (inner peripheral surface) of the expansion portion 3. In FIG. 1(E), the area of the lubricating film 9 is shown shaded.

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 periphery 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 core is used as an applicator for cosmetic mascara, and it is also preferable to use an applicator of a similar shape.

(2) Implementation Figure 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.

And because a lubricating film 9 is formed on the inner surface of the expansion section 3, the group of balls 4 is allowed to slide toward the tip even if it deforms into a lump, and the group of balls 4 is pressed and crushed, and moves toward the tip of the expansion section 3. This makes it possible to forcibly drive the group of balls 4 toward the tip of the expansion section 3, and to widely expand the expansion section 3 as a whole into a trumpet shape. As a result, it is possible to eliminate variation due to individual differences and stably ensure a high fastening force (pull-out resistance). In addition, it is possible to reduce the screwing torque of the expansion bolt 6, which also contributes to reducing the burden on the worker.

The inventors of this application conducted experiments and found that silicone oil (lubricating oil) and car wax were equally effective, but it is believed that the use of waxes is preferable in terms of preventing dripping after use and cost. It is also presumed that the higher the molecular weight of either oil or wax, the greater the lubricating effect. In addition, looking at the anchor body 1 and ball 4, it is presumed that the ball 4 becomes more slippery as the anchor body 1 becomes harder.

There are various specific ways in which anchors can be used. 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 hanging bolt into the anchor body 1 and hang the member on the hanging bolt.

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 for the molecular weight to be as large as possible.

(3) Second to fifth embodiments Figures 2 and 3 show other examples of the anchor structure. In the second embodiment shown in Figure 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.

In this embodiment, a flange 1a is formed at the base end of the male threaded portion 14 of the anchor body 1, which abuts against the edge of the pilot hole 11. This allows the insertion depth of the anchor body 1 to be constant even if the pilot hole 11 is deep.

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 tends to stay near the entrance of the expansion portion 3. Therefore, if a lubricating film 9 is provided to improve sliding, it is expected that the expansion portion 3 will be reliably swelled and deformed in a mountain shape throughout its entirety. Therefore, it is expected that the expansion promotion effect of 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, a male thread portion 14 as shown in FIG. 2 can be provided.

Figures 4 and 5 show examples in which a sheet material is used as a friction reducing means. In the fourth embodiment shown in Figure 4, a bag body 16 with one open end is formed from 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 a 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.

In the fifth embodiment shown in FIG. 5, both ends of the bag are sealed. Therefore, after filling the bag 16 with a group of balls 4, 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 of preventing mistakes in the insertion of the balls 4. It also provides excellent workability in assembling the anchor.

The inventors of the present application conducted an experiment in which they wrapped oil-impregnated rust-preventive paper and resin film around the inner surface of the expanding section 3 to see if they would have a sliding effect on the group of balls 4. However, in both cases, the paper and film were crushed into small pieces and became caught between the balls 4 and the expanding section 3, and no sliding promotion effect was observed.

Therefore, in order to give the bag body 16 the effect of promoting the sliding of the ball 4, it is necessary to devise a material and thickness. For example, it is possible to form the bag body 16 into a double structure of an inner layer and an outer layer, and apply a liquid or wax-like lubricant between the two layers. It is also considered to be beneficial to make the bag body 16 out of a tough material such as an extremely thin stainless steel plate, and 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 body 16.

(4) Sixth to Ninth Embodiments Fig. 6 shows embodiments that embody 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 lubricants 17 are used as friction reduction means, with a large number of fixed lubricants 17 being mixed in with the group of balls 4.

The fixed lubricant 17 can have a variety of structures, such as solidified waxes or oils, or a salmon roe-like film of fluid oils or greases. The size can be set as long as it does not slip out of the slit 2, but since it is important that it is crushed by the pressure when the expansion section 3 expands, it is preferable for it to be large enough to fit into the gaps between the balls before use.

Therefore, it is preferable that the balls are smaller than the group of balls. If the balls 4 are made up of different sizes, it may be sufficient to make them about the same size 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. as materials and make them into spheres using a granulator.

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

In the seventh embodiment shown in FIG. 6(B), in addition to the embodiment in 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 torn when the expansion section 3 is expanded, the fixed lubricant 17 is crushed and expanded, so that the lubricant can be applied to the inner surface of the expansion section 3.

Mixing the shaped lubricant 17 with the group of balls 4 can also be applied to the male thread type anchor shown in Figure 2. The embodiment in Figure 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 Figure 6, and the work (member to be fixed) 12 and nut 18 are also shown with dashed lines. The anchor shown in Figure 8 is almost the same as that shown in Figure 7, and in Figure 8, the external appearance is clearly shown (the balls and friction reduction means are omitted in Figure 8).

Now, there are two types of post-installation anchors: female thread type, where the entire body of the anchor fits into the pilot hole, and male thread type, where the male thread is exposed on the outside of the installation surface. Patent Document 2 also discloses female thread type and male thread type.

And with male thread anchors, the anchor can be attached to the installation part beforehand, and then the mounting hole of the part to be fixed to the male thread can be fitted into the male thread, so that the part to be fixed can be temporarily fixed to the installation surface, so to speak. Therefore, it is particularly suitable for attaching parts to a wall surface.

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 hammer-in anchors, to achieve a consistent depth, the nut must first be screwed into the specified position before the anchor is set in the installation area, and then the nut must be removed, the component inserted, and then the nut reattached, which is a tedious process.

In contrast, if 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 constant, eliminating the need to reset the nut 13, and thus significantly improving the ease of attaching the components.

The same effect can be achieved by providing a flange 15 as in Figure 2, but if the flange 15 is too small in diameter, it will penetrate into the pilot hole 11, making it useless, and if it is too large in diameter, 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, making it more practical.

In addition, by forming the male thread portion 14 with a large diameter, as shown by the dashed line in Figure 8, a bolt with a head 6a such as a hexagon socket bolt can be used as the expansion bolt 6, which has the advantage of being able to increase the pressing force against the group of balls 4 and to reduce costs.

Furthermore, as shown by the two-dot chain line in Figure 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, and the step surface formed by the male thread section 14 of the sleeve 19 can also be used as a stopper for the sleeve 19, thereby stabilizing the quality of the anchor equipped with the sleeve 19.

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. Furthermore, the shape of a post-installed anchor with the male thread portion 14 formed with a large diameter is novel, and therefore can be subject to 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.

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

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 polygon 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.

It is also possible to provide the anchor with a pilot hole drilling function by integrating a drill section into the tip of the anchor body.

As a means of reducing friction, it is possible to form a carbon layer on the inner surface of the expansion section by gluing or spraying. It is also possible to form a thin cylinder mainly made of carbon powder and load this inside the expansion section, 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.

The present invention can be embodied in an expansion anchor. Therefore, it can be used industrially.

REFERENCE SIGNS LIST 1 Anchor body 2 Slit constituting expansion section 3 Expansion section 4 Ball 5 Female thread 6 Expansion bolt 8 Inner bulge section (stopper section)
9 Lubricating film as an example of friction reducing means 10 Construction part (concrete)
11 pilot hole 12 member (work)
13 Fastening bolt 14 Male thread portion 16 Bag body as an example of friction reducing means 17 Shaped lubricant as an example of friction reducing means 18 Nut

Claims (6)

The anchor body has an expansion portion that enters a pilot hole in an installation portion, a group of balls enclosed in the expansion portion of the anchor body, and an expansion bolt that presses the group of balls to expand the expansion portion,
a friction reducing means is provided that is located on an inner surface of the expansion portion of the anchor body and promotes sliding of the group of balls at least when the group of balls expands;
Ball expansion anchor. 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. The friction reducing agent is a wax.
3. The ball expansion anchor according to claim 2. The friction reducing means is pre-applied to the inner surface of the expansion portion.
4. A ball expansion anchor according to claim 1. 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. 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.

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