Adapter for self-drilling, chemically anchorable fastening element

Abstract

An adapter (21) for a self-drilling, chemically anchorable fastening element (11) is described, having a shank (12) with a first end (13) on which a drill bit head (16) is provided, and with a second, free end (14), the second end (14) of the shank (12) being provided with a threadlike outer profile (15). The adapter (21) which may be placed on the second, free end (14) of the shank (12) has an external engagement device on one end for a rotary tool receptacle of a drill which is to be used, a base section provided on the other end at a distance from the engagement means, and a hollow cylindrical connecting sleeve section which connects the base section and the engagement device. The connecting sleeve section has a threadlike inner profile which corresponds to the threadlike outer profile (15) on the shank (12). The adapter (21) is formed by a first element part (22) and a second element part (32) which are detachably connected to one another via a clutch device (41).

Description

[0001] This claims the benefit of German Patent Application DE 10 2009 001 464.0, filed Mar. 11, 2010, and hereby incorporated by reference herein.

[0002] The present invention relates to an adapter for a self-drilling, chemically anchorable fastening element.

BACKGROUND

[0003] Self-boring fastening elements, such as rock anchors and in particular chemical shear connectors, and suitable drills having rotary tool receptacles, as well as the use thereof in mining and tunneling have been known to those skilled in the art for quite some time. These fastening elements are primarily used to stabilize walls in cavities, such as in tunnels, mine shafts, or the like. In the production of cavities, the mechanical properties and in particular the load-bearing capacity of the rock layers are decreased. With the aid of the fastening elements, i.e., chemical shear connectors, these rock layers are anchored and therefore secured to undamaged rock layers located farther away.

[0004] The shank of the fastening elements is used on the one hand as a drilling rod, and on the other hand, in the case of a chemical shear connector, as the receptacle for the compound to be pressed out. A drill bit head is mounted on the first end of the shank situated in the setting direction. The second end of the shank is inserted into a rotary tool receptacle of a drill which is used to drill the fastening element into the substrate.

[0005] An adapter for a self-drilling, chemically anchorable fastening element is known from DE 103 36 040 B4. The fastening element has a shank which has a first end with a drill bit head and a second, free end, the second end of the shank being provided in places with a threadlike outer profile. The adapter is situated on the second, free end of the shank, and on one end has external engagement means for a rotary tool receptacle of a drill which is to be used, a base section provided on the other end at a distance from the engagement means, and a hollow cylindrical connecting sleeve section which connects the base section and the engagement means. The connecting sleeve section has a threadlike, i.e. threaded, inner profile in places which corresponds to the threadlike outer profile on the shank. The connecting sleeve section is provided with perforations for producing predetermined breaking points on the adapter.

[0006] The adapter is screwed onto the second, free end of the shank of the fastening element, and then the rotary tool receptacle of the drill is mounted on the engagement means designed as a quick-engagement device, for example. After the intended drilling depth is achieved, a curable, for example quick-curing, compound is applied. When the curable compound reaches a given degree of hardness the drill is started up again, and after a specified torque is exceeded, the predetermined breaking points break, and the portion of the adapter having the external engagement means, rotationally driven by the drill, is moved along the shank in the direction of the substrate or in the direction of the drill bit head in order to brace the fastening element anchored in the substrate.

[0007] Using the known adapter greatly simplifies the setting process for the self-drilling, chemically anchorable fastening element, the disengagement torque being clearly definable within a certain tolerance range.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide an adapter for a self-drilling, chemically anchorable fastening element, having a narrower tolerance range for the disengagement torque.

[0009] The present invention provides an adapter for a self-drilling, chemically anchorable fastening element, having a shank with a first end on which a drill bit head is provided, and with a second, free end, the second end of the shank being provided, at least in places, with a threadlike outer profile, the adapter which may be placed on the second, free end of the shank having external engagement means or device on one end for a rotary tool receptacle of a drill which is to be used, a base section provided on the other end at a distance from the engagement means, and a hollow cylindrical connecting sleeve section which connects the base section and the engagement means, at least the connecting sleeve section having a threadlike inner profile, at least in places, which corresponds to the threadlike outer profile on the shank.

[0010] According to the present invention, the adapter is formed by a first element part and a second element part which are detachably connected to one another via a clutch device.

[0011] The disengagement torque may be precisely defined as a result of the design of the clutch device located between the two element parts which are separate from one another. When this defined disengagement torque is exceeded, the clutch device is disengaged and the second element part having the engagement means is available in a freely rotatable manner for pretensioning the fastening element, which is already anchored in the substrate. The disengagement torque of the clutch device is set in such a way that during the drilling process the two element parts remain in a coupled state for transmitting drilling torque.

[0012] The adapter has a small number of parts, which are connected to one another. The two element parts are easily manufacturable and may have a robust design, which represents an important economic advantage in particular for a mass-produced product, as is the case for the adapter according to the present invention.

[0013] At the start of the drilling process, the adapter does not have to be screwed in until it appears at the free end of the shank. During operation of the drill, the adapter rotates until it contacts the screw stop on the second, free end of the shank. The shank is then drilled into the substrate, via the adapter, with the aid of the drill until the intended drilling depth is reached. The base section of the adapter provides a screw stop for the adapter.

[0014] For a fastening element in the form of a chemical shear connector, the shank has a hollow cylindrical design, the interior space formed by the shank being used to conduct the curable compound or to accommodate a curable compound in the shank. The base section on the first element part of the adapter may be used as a retaining device for the compound, situated in the shank, to be pressed out. The compound to be pressed out is packaged in a film bag, for example, and is situated in a receptacle, for example in an interior tube, in the shank. This is particularly advantageous for overhead applications, since due to the base section the compound to be pressed out is not able to slide out of the hollow cylindrical shank. A preferably central opening is advantageously provided in the base section which allows a pressing mechanism to be inserted in order to apply the compound to be pressed out, situated in the shank, without having to remove the adapter from the free end of the shank for this work step.

[0015] The shank, for example an anchor tube, may be provided as piece goods which are cut to the required or desired length on site. Because the drill bit head is mounted only on the shank, this preassembly step may also be carried out on site. To improve the extraction parameters of fastening elements such as rock anchors, the shank is often provided with exterior profiling along its entire length. The inner thread of the adapter is preferably matched to the outer thread, which is provided as profiling. If the shank does not have an outer thread on its exterior, a suitable thread may be provided, for example cut, on site on the free end of the shank for connecting the adapter. Generous tolerances may be present between the inner thread on the adapter and the outer thread on the shank without greatly limiting the functioning of the connection of these two parts. As a result, for a shank cut to size on site, deburring of the cut surfaces may usually be dispensed with.

[0016] The quick-engagement device advantageously has a wrench connection. A bihexagonal or polygonal design, for example, is used as the wrench connection, thus minimizing the angle of twist for finding the geometries for connecting the rotary tool receptacle of the drill to the fastening element. In addition, a tool may be placed on the wrench connection, if necessary, for screwing and unscrewing the adapter on the shank.

[0017] The clutch device preferably includes an axially extending stop surface situated on the first element part and an axially extending counterstop surface situated on the second element part for transmitting the drilling torque. In the case of a clutch device having elements which shear or break off, a disengagement torque of the clutch device may be easily defined via the size of the contact surfaces of the stop surface and counterstop surface which may be brought into contact with one another.

[0018] For a drilling process having a reverse rotation of the drive of the drill, first the fastening element is drilled into the substrate, the stop surface and the counterstop surface being in mutual contact for transmission of the drilling torque. After the anchoring depth is reached and the curable compound is at least partially cured, the drill is started up again, the rotational direction of the drive being reversed with respect to the drilling rotational direction. The second element part is then freely rotatable, and in order to pretension the fastening element which is already anchored in the substrate, may then be moved by the drill in the direction of the substrate or in the direction of the drill bit head, for example, until contacting an anchor plate provided on the substrate.

[0019] On one of the element parts the clutch device preferably includes at least one cam which projects beyond a free edge, and at least one recess provided on the free edge of the other element part, the at least one cam engaging in the at least one recess for transmission of torque. For transmission of drilling torque, the side face of the cam extending in the rotational direction comes into contact with the corresponding side face of the recess. When the fastening element already anchored in the substrate is braced, the cam, for example, slides out of the recess on the other element part, and the element part having the engagement means may be moved along the shank in a freely rotatable manner.

[0020] Alternatively, the at least one cam breaks off when the disengagement torque of the clutch device is exceeded, so that the element part having the engagement means may be moved along the shank in a freely rotatable manner. The height of the at least one cam of the corresponding element part which projects beyond the free edge of the corresponding free edge is selected in such a way that the center of gravity of the sheared or broken-off cam element is situated within the recess. This ensures that the at least one sheared or broken-off cam element remains within the recess after the clutch device is disengaged.

[0021] At least one of the side walls of the at least one recess preferably extends at an angle relative to the center of rotation of the corresponding element part. The side wall extending at an angle relative to the rotation, i.e., obliquely or transversely with respect to a radius, may be used, depending on the orientation of the inclination, on the one hand as a securing surface for retaining a sheared or broken-off cam element, or on the other hand as a guide surface to facilitate sliding of the at least one cam from the at least one recess when the disengagement torque of the clutch device is exceeded.

[0022] If the fastening element is set in a reverse rotation process, the side wall of the recess lying or extending in the drilling direction advantageously has an inclination which extends axially and essentially in the direction of the center of rotation, so that at this location the entire contact surface is available for transmitting the drilling torque. The side wall of the recess located opposite and trailing the side wall situated in the drilling direction advantageously extends at an angle relative to the center of rotation of the corresponding element part, the angle relative to the center of rotation being selected according to the requirements, for example for retaining a section of the at least one cam, or to facilitate sliding of the at least one cam from the at least one recess.

[0023] Retaining means are preferably provided in the region of the clutch device which advantageously hold the two element parts together in the installed state of the adapter. This allows the adapter to be situated as a unit on the free end of the shank, so that the two element parts do not have to be separately assembled on the free end of the shank. The retaining element also ensures that, for example, a sheared or broken-off cam element remains in the recess. The retaining means are advantageously flexible, and also advantageously produce a radially inward pretension on the corresponding edges of the element parts, thus ensuring simple installation. The retaining means are made of plastic or metal, and are also advantageously designed as a closed ring. Alternatively, the retaining element is made of multiple interconnected tab elements which join the two element parts together in places in their contact region.

[0024] A radially circumferential depression is preferably provided in each case on the free edges of the element parts, and the retaining means are situated in this depression, thus ensuring simple installation of the adapter.

[0025] The first element part is preferably secured on the second end of the shank in a rotationally fixed manner, thus preventing the first element part having the base section from accidentally coming loose during the setting process for the fastening element. In particular for a setting process for the fastening element using reverse rotation of the drill drive, the first element part which is secured on the second end of the shank in a rotationally fixed manner ensures simple anchoring and pretensioning of the fastening element. During the drilling process, the second element part having the engagement means is moved in the direction of the free, second end of the shank, the first element part which is secured on the second end of the shank in a rotationally fixed manner preventing the adapter from twisting off from the shank of the fastening element. In the subsequent reversed rotation, the second element part is moved away from the first element part which is secured in a rotationally fixed manner. The type of securing of the first element part is advantageously selected in such a way that the first element part is able to sufficiently absorb the forces which arise in the drilling process.

[0026] The first element part is preferably secured on the second end of the shank in a positive-fit manner, which ensures that the first element part is adequately secured on the second end of the shank. Axially extending bore holes are advantageously provided in the first element part and the shank of the fastening element, which together form a receptacle for a connecting pin. The bore holes advantageously extend starting from the base section of the first element part, and are externally accessible for installation of the connecting pin. Alternatively, the section of the bore hole extends, at least in the first element part, starting from the end facing the second element part, in the direction of the base section of the first element part, it being possible to similarly insert the connecting pin from this end for securing the first element part on the second end of the shank in a rotationally fixed manner. In a further alternative, a bore hole oriented radially inward is provided in the first element part, and a connecting pin which engages in the end region of the second end of the shank is inserted into the bore hole.

[0027] Further options for securing the first element part on the second end of the shank in a rotationally fixed manner include providing an adhesive or a clamping connection, for example by deforming the corresponding contact surfaces between the first element part and the end region on the second end of the shank. A further option includes, but is not limited to, shrink-fitting the first element part on the second end of the shank.

[0028] The adapter is advantageously manufactured in a casting process. Subsequent machining of the cast adapter may be dispensed with on account of the allowable tolerances. Besides this economical manufacturing method, the adapter may also be manufactured in a casting/milling process, for example.

[0029] The present invention is explained in greater detail below with reference to exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows a self-drilling, chemically anchorable rock anchor in a side view;

[0031] FIG. 2 shows a first exemplary embodiment of an adapter in an enlarged side view;

[0032] FIG. 3 shows the first element part of the adapter according to FIG. 2 in a partial section;

[0033] FIG. 4 shows the adapter according to FIG. 2 in a longitudinal section;

[0034] FIG. 5 shows a second exemplary embodiment of an adapter in a side view;

[0035] FIG. 6 shows the adapter in a first longitudinal section according to line VI-VI in FIG. 5;

[0036] FIG. 7 shows the adapter in a second longitudinal section offset by 90.degree. relative to the first longitudinal section, according to line VII-VII in FIG. 5; and

[0037] FIG. 8 shows the adapter in a cross section according to line VIII-VIII in FIG. 5.

[0038] Identical parts are basically provided with the same reference numerals in the figures.

DETAILED DESCRIPTION

[0039] Chemically anchorable fastening element 11 illustrated in FIG. 1, in the form of a rock anchor, has a hollow cylindrical shank 12 or anchor tube which is provided with a drill bit head 16 on a first end 13, and which has a second, free end 14 situated opposite first end 13. Shank 12 is provided with a threadlike outer profile 15 in places at an end region on second end 14. Threadlike outer profile 15 advantageously extends over the entire longitudinal extension of shank 12. A curable compound 17 packaged in a film bag is provided in the receptacle formed by hollow cylindrical shank 12.

[0040] An adapter 21, illustrated in detail in FIGS. 2 through 4, is provided on second, free end 14 of shank 12. Adapter 21 is formed by a first element part 22 and a second element part 32 which are detachably connected to one another via a clutch device 41.

[0041] First element part 22 has a base section 23 with a central opening 24, and has a first hollow cylindrical connecting sleeve section 25 which projects from base section 23 on one side of base section 23. A sealing element 27 is situated in opening 24 in base section 23. The interior of first hollow cylindrical connecting sleeve section 25 is provided in places with a threadlike inner profile 26 which may screwed onto threadlike outer profile 15 at the end region on second end 14 of shank 12.

[0042] Two bore holes 28 situated opposite each other extend, starting from base section 23, and in places each bore hole merges into a groove 18 on second, free end 14 of shank 12. Two connecting pins 29 may be inserted into these bore holes 28, thus allowing first element part 22 to be secured on second end 14 of shank 12 in a rotationally fixed and positive-fit manner.

[0043] Second element part 32 has a hollow cylindrical design, and on one end 33 has a radially outwardly projecting collar 34 which adjoins exterior engagement means or device 35, having a polygonal design, for a rotary tool receptacle of a drill which is to be used. The section adjoining engagement means 35 forms second hollow cylindrical connecting sleeve section 36. The interior of second element part 32 is provided in places with a threadlike inner profile 37 which may be screwed onto threadlike outer profile 15 of shank 12.

[0044] Second hollow cylindrical connecting sleeve section 36 also has an exterior threadlike outer profile 15 in places for mounting fastening means, such as a lock nut. Since adapter 21 for the most part remains on shank 12 even after fastening element 11 is set, adapter 21 may be used, for example, for fixing a pad to the wall of the cavity to be secured. Such pads are, for example, reinforcing mats or mesh pads made of metal or plastic which provide protection from unsecured falling rock. These pads are advantageously situated in an overlapping manner in the region of the set fastening element 11. As the result of providing fastening means on adapter 21, in a first step a first pad may be secured as such to adapter 21. A second pad is then placed over adapter 21 and is secured using the same or other fastening means.

[0045] For transmitting the drilling torque, clutch device 41, which detachably connects first element part 22 and second element part 32 to one another, includes two axially extending stop surfaces 42 situated opposite each other on first element part 22, and two axially extending counterstop surfaces 46 similarly situated with respect to one another on second element part 32. The free end of first hollow cylindrical connecting sleeve section 25 of first element part 22 extends in a spiral manner between stop surfaces 42, the pitch being designed to be greater than the pitch of threadlike outer profile 15 of shank 12. The free end of second hollow cylindrical connecting sleeve section 36 of second element part 32 likewise extends in a spiral manner between counterstop surfaces 46, the pitch being designed to be greater than the pitch of threadlike outer profile 15 of shank 12.

[0046] After adapter 21 is placed on free end 14 of shank 12, a drill is used to set fastening element 11 in rotation in drilling direction 49 via adapter 21. After the intended drilling depth is reached, the drill is shut off and curable compound 17 is pressed out, for example with the aid of a pressing device inserted through opening 24 in base section 23 of first element part 22. When curable compound 17 reaches a specified degree of hardness, the drill is started up again, this time a rotation being exerted on adapter 21 in bracing direction 50, in the opposite direction of drilling direction 49. Second element part 32 is moved in a freely rotatable manner in the direction of drill bit head 16, along threadlike outer profile 15 of shank 12, until fastening element 11 is braced. Due to the spiral design of the free ends of first connecting sleeve section 25 as well as second connecting sleeve section 36, counterstop surfaces 46 are able to slide past stop surfaces 42 of first element part 22, which is on free end 14 of shank 12 in a rotationally fixed manner, when element part 32 is axially displaced.

[0047] Adapter 51 illustrated in FIGS. 5 through 8 differs from previously described adapter 21 essentially in the design of clutch device 71 which detachably connects first element part 52 to second element part 62. First element part 52 is advantageously secured on the free end of the shank of the fastening element in a rotationally fixed manner. Clutch device 71 includes two cams 76 situated opposite each other which project beyond free edge 63 of second connecting sleeve section 66 of second element part 62. Clutch device 71 also includes recesses 72, provided on free edge 53 of first connecting sleeve section 55 of first element part 52, corresponding to the orientation of cams 76; for transmitting torque, cams 76 engage in the recesses.

[0048] Also provided on free edge 63 of second connecting sleeve section 66 of second element part 62 are two spacing cams 64 situated opposite each other, which in the installed state of adapter 51 lie against free edge 53 of first connecting sleeve section 55 of first element part 52. Spacing cams 64 prevent free edges 53 and 63 from making surface contact with one another, thus preventing adhesion between these free edges and therefore preventing the free edges from influencing the disengagement torque of clutch device 71.

[0049] Leading side wall 73 of recesses 72, which is situated in rotary drilling direction 78, essentially extends in the direction of center of rotation 56 of first element part 52. Trailing side wall 74 of recesses 72, which is situated in bracing rotary direction 79, extends at an angle relative to center of rotation 56 of first element part 52, the inclination of these side walls 74 being oriented to retain a broken-off cam section in recess 72.

[0050] In the region of clutch device 71, first element part 52 as well as second element part 62 are provided with a radially circumferential depression 81 in which flexible retaining means 82 designed as a circumferentially closed ring are provided.

Claims

1. An adapter for a self-drilling, chemically anchorable fastening element comprising: a shank with a first end, a drill bit head being provided on the first end, and with a second, free end, the second end of the shank being provided, at least in part, with a threaded outer profile, an adapter placable on the second, free end of the shank and having an external engagement device on one adapter end for a rotary tool receptacle of a drill to be used, a base section being provided on the other adapter end at a distance from the engagement device, and a hollow cylindrical connecting sleeve section connecting the base section and the engagement device, at least the connecting sleeve section having a threadlike inner profile, at least in part, corresponding to the threaded outer profile on the shank, the adapter being formed by a first element part and a second element part detachably connected to one another via a clutch device.

2. The adapter as recited in claim 1 wherein the clutch device includes an axially extending stop surface situated on the first element part and an axially extending counterstop surface situated on the second element part for transmitting the drilling torque.

3. The adapter as recited in claim 1 wherein the clutch device on one of the first and second element parts includes at least one cam projecting beyond a free edge, and at least one recess provided on the free edge of the other of the first and second element parts, the at least one cam engaging in the at least one recess for transmission of torque.

4. The adapter as recited in claim 3 wherein at least one of the side walls of the at least one recess extends at an angle relative to a center of rotation of the corresponding first or second element part.

5. The adapter as recited in claim 1 wherein a retainer is provided in the region of the clutch device.

6. The adapter as recited in claim 5 wherein a radially circumferential depression is provided in each case on free edges of the first and second element parts, the retainer being situated in the depression.

7. The adapter as recited in claim 1 wherein the first element part is secured on the second end of the shank in a rotationally fixed manner.

8. The adapter as recited in claim 7 wherein the first element part is secured on the second end of the shank in a positive-fit manner.