AU666809B2

AU666809B2 - Knock-in anchor

Info

Publication number: AU666809B2
Application number: AU60011/94A
Authority: AU
Inventors: Heinrich Liebig
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-03-17
Filing date: 1994-02-02
Publication date: 1996-02-22
Anticipated expiration: 2014-02-02
Also published as: ES2094647T3; AU6001194A; WO1994021928A1; EP0641417B1; JPH07506895A; CA2136020A1; EP0641417A1

Description

Impact Installable Fastening The invention relates to an impact installable fastening with a fastening peg, whose elongate cylindrical shaft has a frusto-conically broadening expanding head at its front end in the direction of installation and slidably placed on which there is a fastening sleeve, which is multiply slotted over a proportion of its length from its front end in the direction of installation and in the slotted region defines a number of anchoring arms and w hose internal diameter substantially corresponds to the e-'-ernal diameter of the cylindrical shaft and provided in Jse outer surface at a small distance from the front end in the direction of installation there is a peripheral groove which makes the front end regions of the anchoring arms in the direction of installation able to swing out relative to the adjoining regions whilst deforming the material remaining in the base of the groove such that, when inserted into the associated bore, they are driven against the expanding head bearing against the base of the bore by the application of impacts to the end surface of the fastening sleeve directed away from the direction of installation and swung out so that their front end in the direction of installation penetrates into the material ot the wall of the bore to produce an undercut.

An impact fastening of this type is known (EP-B 0308619) in which the fastening peg has an expanding head of k 2 concave curved and broadening cross-section and which is provided at the region of the anchoring arms situated in front of the groove in the installation direction with a plurality of cutting teeth or cutting edges which are i! 1 1 2 spaced from one another in the direction of the central longitudinal axis of the fastening and which are supposed to dig into the material of the wall of the bore during spreading apart of these front regions by impacts on the end of the fastening sleeve directed out of the associated bore.

Due to the special shape of the expanding head and the regions of the anchoring arms provided with cutting teeth offset in the longitudinal direction, the manufacture of this fastening is laborious and correspondingly expensive.

By contrast, it is the object of the invention to providz an impact installable fastening which may be manufactu ed substantially more simply and thus more economical and may be installed without increased effort and xhibits the necessary load-bearing ability.

Starting from a fastening of the type ferred to above this object is solved in accordance wih the invention if the front end regions of the achoring arms in the direction of installation to ther have the external shape of two frustums who end surfaces of smaller diameter are adjacent and hose base surface defined at the front end in the di ction of installation on the one hand and at the gro e on the other hand each have, in the unexpanded s ate, a diameter which substantially corresponds to/the external diameter of the fastening sleeve. F tenings, the front end region of whose anchorin arms together have the external shape of two adjace frustums, are basically known (DE-G 1772225; DE- A 3 1784) but these fastenings differ in the functional p. iciple prvided for the c.panoion. That is to say, A L4" II i- By contrast, it would be desirable to provide an impact installable fastening which may be manufactured substantially more simply and thus more economically and may be installed without increased effort and exhibits the necessary load-bearing ability.

According to an aspect of the present invention, there is provided an impact-installable fastening of the type referred to above wherein the front end regions of the anchoring arms in the direction of installation together have the external shape of two frustums whose end surfaces of smaller diameter are adjacent and whose base surface defined at the front end in the direction of installation on the one hand and at the groove on the other hand each have, in the unexpanded state, a diameter which substantially corresponds to the external diameter of the fastening sleeve.

Fastenings, the front end region of whose anchoring |S arms together have the external shape of two adjacent frustums, are basically known (DE-G-1772225; DE A 3511784) but these known fastenings differ in the functional principle provided for the expansion. That is to say, •i C 3 0 C 4 2a 1 the fastening sleeve is not driven onto a frusto-conical expanding head but the fastening sleeve, which is pushed into the associated bore to the predetermined installation depth, is expanded exclusively radially by knocking in a wedge. Thus the removal of material in the bore which occurs in accordance with the invention due to the axial advance of the fastening sleeve does not occur.

Transferring the shape, which is provided in the known fastenings, of the anchoring arms in the front end region to impact fastenings installable by impacts onto t.ie fastening sleeve with the removal of material is absolutely not obvious due to the different installation function. On the other hand, impact fastenings are known (AT-A 378245) which are installable by impacts onto the fastening sleeve, which is expandable on a frusto-conical expanding body, and in which the anchoring arms are, however, not constructed in their front end region in the form of two adjacent frustums, whereby a different type of construction of the cutting edge and of the'front end region is then produced. A narrow annular groove which enables swinging motion of the front end regions of the anchoring arms during the installation process whilst deforming the material remaining in the base of the groove is also not provided in this known impact fastening.

The construction in a first exemplary embodiment of the invention is such that the frusto-conical surface 4 constructed adjacent to the front end surface in the 30 direction of installation has a smaller conical angle than the adjacent frusto-conical surface.

In a modified and currently preferred second exemplary embodiment, on the other hand, the construction is such i 4 that the frusto-conical surface constructed adjacent to the front end surface in the direction of installation has a larger conical angle than the adjacent frustoconical surface.

The conical angle of the front frusto-conical surface in the direction of installation is conveniently selected to be larger than 90° so that the angle defined between its front end surface in the direction of installation and the frusto-conical surface in a central longitudinal section forms a sharp edged peripheral edge which penetrates in the manner of a chisel into the wall of the bore during the installation process. The necessary impact force for installing the fastening is thereby significantly reduced because the sharp edged peripheral edge penetrates into the wall of the bored hole with a comparatively low impact force.

The angle defined between the front end surface in the i direction of installation and the frusto-conical surface can be in the range of btween 15° and 750, preferably in the range between 30° and 600°.

The construction is particularly convenient if the conical angle of the expanding head is so selected that the anchoring arms formed by slotting of the fastening sleeve in the region of the front frusto-conical surface in the direction of installation lie in an at least approximately radial position with respect to the central longitudinal axis of the bored hole in the region of their cone surface lines in the predetermined expanded state. Only small force components directed radially outwardly into the wall of the bore are then produced, whereby the fastening can thus also be used in those bored holes which are provided in the vicinity of a boundary side or the edge of the support. The reaction forces occurring dtlring anchoring of the workpiece to the support are instead directed substantially parallel to the central longitudinal axis of the fastening so that the fastening is in this respect comparable with the recently developed undercut plugs which may be installed without an expanding pressure on an undercut surface in a rough cut bore, whereby however the requirement of forming an undercut in a rough cut bore is eliminated and the fastening itself is of relatively simpler construction.

The breadth of the mouth of the groove measured in the installation direction can, in an advantageous further i embodiment of the invention, be so selected that it is substantially closed at the predetermined degree of expansion of the front anchoring arm regions. If an attempt is made for instance by applying an appropriate tension load to the fastening peg further to expand the front anchoring arm regions, the groove closes and the front anchoring arm regions are supported on the rear anchoring arm regions so that additional loads then attempt elastically to expand the anchoring arms bodily.

The peripheral groove can have either a rectangular or a substantially triangular cross-section with the triangle apex situated in the groove base. In the second case the limiting surfaces of the groove then engage one another over their surfaces in the predetermined expanded state of the front anchoring arm regions.

The conical angle of the front frusto-conical surface in the direction of expansion can advantageously be so selected that it corresponds approximately to the conical angle of the expanding head of the fastening peg.

In order to support the fastening as rigidly as possible in the associated bore during installation, it can be convenient to consuruct the free surface of the expanding head pointing in the direction of installation in the form of a cone whose conical angle is substantially the same as the angle of the cutting edges at the front end of the rock drill used to produce the bore.

The invention will be described in more detail in the following description of two exemplary embodiments in conjunction with the drawings, in which: Fig. 1 is a side view of a first embodiment of an impact fastening in accordance with the invention; Fig. 2 shows the fastening of Fig. 1 with the fastening sleeve sectioned along a central longitudinal plane inserted in a bore in a support, the fastening sleeve being shown in I the unexpanded initial state and the tool for I expanding the fastening sleeve being additionally indicated in chain-dotted lines; Fig. 3 is a view corresponding to Fig. 2 after expanding the front anchoring arm regions of oi 30 the fastening sleeve; Fig. 4 is a view corresponding to Figs. 2 and 3 in which a workpiece is mounted on the support provided with the bore by a nut screwed onto i i 7 the fastening peg with a washer; Fig. 5 is a side view of a second exemplary embodiment of an impact fastening in accordance with the invention; Fig. 6 shows the fastening of Fig. 5 with the fastening sleeve sectioned on a central longitudinal plane inserted in a bore in a support, the fastening sleeve being shown in the unexpanded initial state and the tool for expanding the fastening sleeve being additionally indicated in chain-dotted lines; Fig. 7 is a view corresponding to Fig. 6 after expanding the front anchoring arm regions of the fastening sleeve; and Fig. 8 is a view corresponding to Figs. 6 and 7 in which a workpiece is mounted on the support provided with the bore by a nut screwed onto the fastening peg with a washer.

The exemplary embodiment of an impact fastening in accordance with the invention, which is shown in Figures 1 to 4 of the drawings and is designated as a whole with 1 l 10, is composed substantially of two main portions, namely an elongate fastening peg 12 on the one hand and on the other hand a fastening sleeve 16 which is longitudinally slidably disposed on the cylindrical shaft 14 of the fastening peg.

At its front end in the installation direction, i.e. at the end of its shaft 14 which comes into engagement with L _1 IL 8 the inner end of the bored hole when installing it in a bored hole 18 in a support 20 (Figs. 2 to the fastening peg 12 has a staved, frusto-conical expanding head 22, which thus broadens out conically from the shaft .4 of the fastening peg 12. In order to produce support for the fastening peg 12 over a large area at the inner end of the bore when positioning the expanding plug, it can be convenient to construct this end 24, i.e. the base surface of the frusto-conical expanding head 22, in the manner illustrated in the drawings such that its shape is complementary to that or the inner end of the bored hole formed by the cutting edges of the rock drill which is used.

In its shaft region opposite to the expanding head 22 the shaft 14 of the fastening peg ift provided over at least a portion of its end region with a screwthread 26 so that the fastening of a workpiece 28 illustrated in Figure 4 to the support 20 is possible by means of a nut 32 which is screwed onto the screwth -ead 26 of the shaft 14 of the fastening which has previously been positioned in r the bored hole 18 and bears against the workpiece 28 via a washer Formed at the front end of the fastening sleeve 16 in the installation direction by in the illustrated case three longitudinal slots 34, which are machined from the inner end surface offset at uniform angular spacings over a proportion of the length of the sleeve, is a total of three anchoring arms 36, cut into whose outer surface at a small distance from the front end in the installation direction there is a peripheral groove 38 which renders the front end regions 40 in the installation direction of the anchoring arms 36 able to be swung out relative to r. r 9 the adjacent regions in the direction opposite to the installation direction whilst deforming the material remaining in the base of the groove. It is thus possible to drive the fastening sleeve 16, which is pushed until the front inner edges of the end regions 14 engage the peripheral surface of the expanding head 22, by means of impacts applied by a machine or manually to the impact sleeve 42 illustrated schematically in Figure 2 with chain-dotted lines further into the interior of the bored hole 18, whereby the end regions 40 spread out further corresponding to the conicity of the expanding head 22 and cut into the material of the wall of the bored hole 18 and in this region then form so to speak an undercut in the bored hole. The installed state of the fastening sleeve in the bored hole achieved by the application of impacts is shown in Figure 3. Since the end regions are expanded to an external diameter which is larger than the diameter of the bored hole, the fastening sleeve and thus the fastening as a whole can only be retracted from the bored hole 18 by destroying it. Forces actin: tn the retracting direction, for instance forces exerte 4 by the i nut 32 when tightening the workpiece 28 onto the shaft 14 of the fastening peg 12, attempt to retract the eypanding head 22 into the fastening sleeve, whereby the end regions 40 are swung further in the expanding direction 1 and the form-locking interlock of the end regions 40 in the wall of the bored hole is strengthened so to speak in i dependence on the load applied via the fasteniing peg.

The end regions 40 formed at the front end of the anchoring arms 36 by the peripheral groove 38 have the double frusto-conical shape which may best be seen in Figure 1 and in which twn adjoining frusto-conical surfaces 40a, 40b form a neck with their end surfaces of E smaller diameter, whereby the base surface of the frustoconical surface 40a, which is disposed at the front end in the installation direction, and the base surface formed at the groove 38 of the frusto-conical surface 40b, each have a diameter which substantially corresponds to the external diameter of the fastening sleeve 16 in the unexpanded state. The construction of the conical surfaces 40a, 40b is such that the front frusto-conical surface 40a in the installation direction has a smaller i 10 angle of taper than the adjoining conical surface The breadth of the peripheral groove 38, which is of rectangular cross-section in the illustrated exemplary H embodiment, is so selected that the breadth of its mouth measured in the installation direction is substantially or nearly closed in the predetermined installed position, as may be seen in Figures 3 and 4. If the end regions spread out further as a result of additional stresses acting via the fastening peg 14, the peripheral groove 38 then closes completely and the end regions 40 are then supported on the anchoring arms 34 by engagement with the opposing lateral limiting surface of the groove 38.

Further increased loads thus then attempt elastically to spread the anchoring arms bodily.

In an alternative to the described exemplary embodiment, the peripheral groove 38 can also be constructed with a Isubstantially triangular cross-section, the apex of the triangle forming the base of the groove and the angle of the apex of the triangle being so selected that the groove is just closed in the installed state, i.e. the lateral sides of the triangle come into engagement with one another.

11 The second exemplary embodiment of an impact fastening constructed in the manner in accordance with the invention, which is shown in Figures 5 to 8 and is designated as a whole with 110, substantially corresponds to the impact fastening 10 described above so that it will be sufficient to describe in detail below only those modifications which have been effected with respect to I the fastening 10, whilst for the features of the two fastenings 10 and 110 which are the same reference can be made to the preceding description, particularly as in the figures the same components of the two exemplary embodiments are associated with the same reference numerals preceded in the case of the fastening 110 merely by a 4In distinction to the fastening 10, the conical angle in i the fastening 110 of the front frusto-conical surface 140a in the installation direction is selected to be larger than the conical angle of the adjoining frustoconical surface 140b, whereby the front frusto-conical surface 140a in the installation direction is necessarily lower than the adjoining frusto-conical surface 140b.

This has the consequence that the angle at the merging of I the front end surface in the direction of installation and the surface lines of the adjoining frusto-conical surface 140a is smaller. The edge of the fastening sleeve, which penetrates into the wall of the bored hole 118 during the installation process, is thus sharpened in the manner of a chisel, whereby relatively lower impact forces are necessary for the installation of the fastening 110.

Of particular advantage is the lower height of the frusto-conical surface 140a in conjunction with an 12 expanding head 122 of the fastening peg 112 with a larger conical angle, also in comparison to the expanding head 22, since it is thereby possible that, in the installed state, the frusto-conical surface 140a extends substantially or nearly radially to the central axis of the bored hole in the manner illustrated in Figures 7 and 8. That is to say that the retaining force for the workpiece 128 produced by tightening the nut 132 is transmitted into the support by means of reaction forces directed substantially parallel to the central axis of the bored hole, i.e. radially outwardly directed components of loads, which could result in breaking up of the bored hole e.g. in the edge region of the support, are low.

i

Claims

1. Impact-installable fastening with a fastening peg, whose elongate cylindrical shaft has a frusto-conically broadening expanding head at its front end in a direction of installation and slidably placed on which there is a fastening sleeve, which sleeve is multiply slotted over a proportion of its length from its front end in the direction of installation and, in the slotted region, defines a number of anchoring arms and whose internal diameter substantially corresponds to the external diameter of the cylindrical shaft and provided in whose outer surface at a small distance from the front end in the direction of installation there is a peripheral groove which makes the front end regions of the anchoring arms in the direction of installation able to swing out relative to the adjoining regions whilst deforming the material remaining in the base of the groove such that, when inserted into the associated bore, they can be driven against the expanding head bearing against the base of the bore by the application of impacts to the end surface of the fastening sleeve directed away from the direction of installation and swung out so that their front end in the direction of installation penetrates into the material of the wall of the bore to produce an undercut, wherein the front end regions of the anchoring arms in the direction of installation together have the external shape of two frustums whose end surfaces of smaller diameter are adjacent and whose base surface defined at the front end in the direction of installation on the one hand and at the groove on the other hand each have, in the 1 unexpanded state, a diameter which substantially corresponds to the external diameter of the fastening sleeve.

2. Impact-installable fastening including: a fastening peg having an elongate cylindrical shaft and a frusto-conically ii: broadening expander head at a front end of the shaft in a direction of installation, j and a fastening sleeve slidably receivable on the fastening peg, which sleeve is multiply slotted over a proportion of its length from a front end thereof in the direction of installation to define a number of anchoring arms in the slotted region, an internal diameter of the sleeve substantially corresponding to an external diameter of the cylindrical shaft and the sleeve further including a peripheral groove provided in an outer surface thereof spaced from the fronit end whereby OG CAkWINWORD\DELILAH\NODELETE\6001.DOC ."N.&M.-MEMOM -14- the groove enables the front end regions of the anchoring arms to move outward relative to adjoining regions whilst deforming the material at the base of the groove such that, when inserted into an associated bore, the anchoring arms can be driven against the expander head which bears against the base of the bore by the applicatioh of an impact to the end surface of the fastening sleeve directed away from the direction of installation, the anchoring arms moving outward so that their front ends penetrate into the material of the wall of the bore to produce an undercut; wherein the front end regions of the anchoring arms in the direction of installation together have the external shape of two frustums whose end surfaces of smaller diameter are adjacent and the base surfaces of which, defined at the front end in the direction of installation on the one hand and at the groove on the Sother hand, each have in the unexpanded state a diameter which substantially corresponds to the external diameter of the fastening sleeve.

3. Fastening as claimed in Claim 1 or Claim 2 wherein the anchoring arm frusto-conical surface constructed adjacent the front end surface in the direction of installation has a smaller conical angle than the adjacent anchoring arm frusto-conical surface.

4. Fastening as claimed in Claim 1 or Claim 2 wherein the anchoring arm frusto-conical surface constructed adjacent the front end surface irn the 1 i. direction of installation has a larger conical angle than the adjacent anchoring arm frusto-conical surface.

I Fastening as claimed in Claim 4, wherein the conical angle of the front frusto-conical surface in the direction of installation is selected to be larger than 900 so that the angle defined between its front end surface in the direction of installation and the frusto-cnical surface in a central longitudinal section defines a sharp edged peripheral edge which penetrates into the wall of the bore in the .manner of a chisel during the installation process.

6. Fastening as claimed in Claim 5, wherein the angle defined S' 30 between the front end surface in the direction of installation and the frusto-conical surface lies in the range between 150 to 75°, preferably in the range between and SDGC:\WINWORD\DELILAH\NODELETE\60011.DOC i" 3 V],D

7. Fastening as claimed in any one of Claims 4 to 6, wherein the conical angle of the expanding head is so selected that the anchoring arms formed by slotting the fastening sleeve in the region of the front frusto-conical surface are situated, in the predetermined expanded state, in an at least approximately radial position with respect to a central longitudinal axis of the bored hole in a region of their conical surface lines.

8. iastening as claimed in any one of Claims 1 to 7, wherein the breadth of a mouth of the groove measured in the direction of installation is so selected that it is substantially closed when the front anchoring arm regions are expanded to the predetermined extent.

9. Fastening as claimed in any one of Claims 1 to 8, wherein the peripheral groove has a rectangular cross-section.

Fastening as claimed in any one of Claims 1 to 8, wherein the peripheral groove has a substantially triangular cross-section with the apex of the triangle lying at the base of the groove.

11. Fastening as claimed in one of Claims 3 to 10, wherein the conical angle of the front frusto-conical surface in the direction of installation approximately corresponds to the conical angle of the expanding head of the fastening peg. 20

12. Fastening as claimed in one of Claims 1 to 11, wherein the free 0 surface of the expanding head pointing in the direction of installation has the shape of a cone whose conical angle is substantially the same as the angle of the cutting edges at the front end of a rock drill used to produce the bore.

13 An impact-installable fastening substantially as herein described with 25 reference to any one of the embodiments illustrated in the accompanying drawings. C o o o DATED: 15 December, 1995 S" PHILLIPS ORMONDE FITZPATRICK 30 Attorneys for: HEINRICH LIEBIG DG C.\WINWORDXDELILAHXODELETE\60011.DOC i• KB4 Abstract Impact installable fastening (110) with a fastening peg (112) with a frusto-conically broadening expanding head (122) at the front end to be introduced into the associated fastening bore. Slidably placed onto the fastening peg (112) is a fastening sleeve (116) which is provided by virtue of slotting over a proportion, of its length with a plurality of anchoring arms (136). By applying impacts to the end of the fastening sleeve (116) at the outer end of the bore the anchoring arms (136) are driven onto the expanding head (122) and swung out and thus anchored in the fastening bore. The front end regions (140) of the anchoring arms (136) in the direction of installation, which are separated from the remainder of the fastening sleeve (116) by a peripheral groove (138), have together the external shape of two frustums (140a, 140b) whose end surfaces of smaller diameter are adjacent. i (Fig.