BACKGROUND OF THE INVENTION
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1. Field of the Invention
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The present invention relates to an extrusion device for forcing out a mass from a self-drilling chemical rock anchor for mine and tunnel constructions and including a housing a motor-driven sleeve rotatably supported in the housing without a possibility of an axial displacement therein and having a first end with an insert opening in which there is provided a receptacle for rotation-imparting means of the rock anchor, and a second end located opposite the first end and having a through-opening, with the device further including a nozzle for feeding medium to the rock anchor.
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2. Description of the Prior Art
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For stabilization of walls of hollow spaces formed in a rock mass, e.g., in tunnels, galleries and the like, rock anchors, which extend perpendicular to the walls, are used for securing following one another rock strata which form the walls. At that, the rock strata which are located in an immediate vicinity of the wall and mechanical properties of which, in particular their loading capacity, are reduced in many cases as a result of formation of the hollow space, are secured to further located, undamaged rock strata.
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For setting a chemically anchored rock anchor in a rock mass with from low to medium hardness, a borehole is formed with a drilling tool (drill) into which a to-be-set rock anchor is driven in and a hardenable mass is injected. Finally, an anchor rod, at least the free end region of which is provided with an outer thread, is placed into the borehole. After the hardenable mass reaches a certain firmness, the rock anchor is secured in the rock mass with a locking nut.
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Each of the above-mentioned operational steps requires a different tool that must be mounted and dismounted. This leads to an increased time period for setting of each rock anchor, and at the start of the safety works, there exists a certain danger for the operator because the operator should perform the necessary works in unsecured regions of the hollow space.
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German Publication DE 197 00 701 A1 discloses a power drilling tool for setting a rock anchor and which is capable of performing several steps. The power drilling tool includes a housing, a motor, and motor-driven sleeves rotatably supported in the housing without a possibility of an axial displacement therein. Each sleeve has a first end with an insert opening in which there is provided a receptacle for rotation-imparting means for a rotatably driving a drill or a rock anchor, and a second end located opposite the first end and having an opening. The drilling tool further includes a feeding nozzle through which flushing water is delivered during the drilling. The sleeves are exchangeably received in the drilling tool receptacle. After a borehole has been drilled, the sleeve with a drill rod-rotation-imparting means is replaced with an anchor rod-roatation imparting means, and the anchor rod is set into the borehole and is tighten.
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The drawback of the drilling tool of DE 197 00 701 A1 consists in that exchange of sleeves, in particular at conditions existing under underground, is expensive. In addition, the free end of the anchor rod, which extends from the borehole, forms a stop that limits the displacement of the drilling tool toward the wall of the borehole, so that for tightening of the rock anchor at least one separate tool must be used. Because a portion of the anchor rod that projects from the borehole depends on the setting process, the underground, and the design of the rock anchor, this projecting portion is not constant.
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In order to further reduce the number of process steps for setting a rock anchor, so-called self-drilling chemical rock anchors were developed. U.S. Pat. No. 4,055,051 discloses a self-drilling chemical rock anchor with a tubular element provided at one of its end with drilling head and at its opposite end with rotation-transmitting means for rotatably driving the anchor. The tubular rock anchor has its interior partially filled with a hardenable mass. In the drilling head or in the setting direction end region of the tubular element, there are provided exit openings for the hardenable mass. With a power drilling tool, the self-drilling chemical rock anchor is rotatably driven in the ground. After reaching a desired borehole depth, the hardenable mass is pressed-out with a piston. As soon as the extruded mass reaches a satisfactory firmness, a locking nut is screwed over the free end for tightening the rock anchor until the rock anchor is locked in the ground.
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The drawback of the rock anchor of U.S. Pat. No. 4,055,051 consists in that with this anchor, the free end of the anchor rod that projects from the borehole, forms a stop that limits the displacement of the drilling tool in the direction of the wall of the borehole and a separate tool must be used for tightening the rock anchor.
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Accordingly, an object of the present invention is to provide an extrusion device for setting a self-drilling chemical rock anchor with which setting and, in particular, tightening of a rock anchor which is to-be-anchored in a borehole, is simplified.
SUMMARY OF THE INVENTION
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This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing an extrusion device for forcing out a mass from a self-drilling chemical rock anchor for mine and tunnel constructions and which includes a housing a motor-driven, sleeve rotatably supported in the housing without a possibility of an axial displacement therein, and a feeding nozzle through which medium is fed to the rock anchor. The sleeve has a first end with an insert opening in which there is provided a receptacle for rotation-imparting means of the rock anchor, and a second end located opposite the first end and having a through-opening. Between the first and second ends, there is provided a receiving space for a free end of the rock anchor and extending from the receptacle for the rock anchor rotation-imparting means in a direction toward the second end of the sleeve. The receiving space has an inner cross-section smaller than a cross-section of the receptacle for the rotation-imparting means. The feeding nozzle extends through the through-opening of the second end of the sleeve and into the receiving space. In order to provide a free space for the free end of the rock anchor, the feeding nozzle is spaced from the inner profile of the sleeve. Through the feeding nozzle, and extrusion medium is fed for forcing the mass, which is stored in the interior of the rock anchor, out of the rock anchor.
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The extrusion device according to the present invention substantially simplifies the setting process of a self-drilling chemical rock anchor. The rock anchor is drilled in, the mass is extruded, and the rock anchor is tightened with one and the same device. Thereby no retrofitting is necessary. By the arrangement of the feeding nozzle and shaping of the receiving space, a satisfactory process path is provided in the extrusion device for tightening the rock anchor in the borehole. The locking nut is displaced along the free end of the rock anchor, which projects from the borehole and is provided with an outer thread, during the entire tightening process, and is rotatably driven.
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During the drilling process, through the feeding nozzle or in its vicinity, flushing medium in form of flushing water is fed to the rock anchor. For extruding of the hardenable mass stored in the rock anchor, finally, e.g., water under high pressure as an extrusion medium is fed to the rock anchor. The inventive extrusion device is characterized by simplified design with few movable parts, which insures a high process reliability even at the condition existing underground. Wit the inventive extrusion device, in addition to chemically anchorable anchors, mechanically anchorable anchors are easily set and tightened.
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The inner profile of the receptacle is advantageously so formed that both the rotation-imparting means for rotatably driving the anchor and the locking nut can be received. In this way, with one and the same sleeve, all of the process steps for setting the rock anchor are carried out.
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The rotation-imparting means has a sleeve-shaped section that is provided with a predetermined break point and that at least regionwise surrounds the free end of the rock anchor. In addition, the sleeve-shaped section of the rotation-imparting means has an open bottom section through which the feeding nozzle is extendable. As soon as mortar mass, which has been forced out of the rock anchor, has reached a satisfactory firmness, the motor is actuated again, whereby the sleeve-shaped section of rotation-imparting means breaks in the area of the break point, and the portion of the rotation-imparting means that has the imparting profile, is displaced for tightening the rock anchor, as a locking nut, along the outer thread of the rock anchor in a direction toward the wall of the borehole. Alternatively, the rotation-imparting means for rotatably driving the rock anchor is formed as a locking screw that is temporarily secured in the free region, e.g., by soldering or welding points. When the rock anchor has been tightened, the temporarily securing means are lifted off, e.g., by mechanical forces and the rock anchor is tightened by the locking nut.
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Preferably, the receiving space has a cross-section that is greater than a cross-section of the feeding nozzle from two to four times. Thereby, with reference to the sleeve axis, in the radial direction, sufficient receiving space is provided for the free end of the rock anchor. In this embodiment, the free end of the rock anchor cannot contact the feeding nozzle or damage the same during tightening of the rock anchor and displacement of the device in the direction of the wall.
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Advantageously, the receiving space has an axial extent along a sleeve axis that is greater than a mean dimension of the sleeve inner cross-section from two to five times. This provides a sufficient travel path for the extrusion device for tightening of the rock anchor.
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Advantageously, there is provided a shank for securing the extrusion device in a chuck of a rock drill and operatively connected with the sleeve. This insures that the inventive extrusion device can be mounted on any conventional drill. Advantageously, in order to provide a one-piece component, the shank is formed directly on the sleeve.
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According to a further advantageous embodiment of the present invention, the sleeve is provided on its outer sides with a drive profile that provides for driving the sleeve directly by the motor directly or indirectly, via a drive unit. The drive profile is formed, e.g., by toothing that cooperates with the motor for transmission of a torque.
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Preferably, there is provided a multi-channel feeding unit for feeding of the flushing water and/or the extruding medium to the rock anchor. During the drilling process, flushing water is fed to the rock anchor. When the desired depth has been reached, the feeding of the flushing water is interrupted, and the feeding unit delivers the extruding medium to the rock anchor, resulting in forcing of the hardenable mass that fills the rock anchor out. In order to be able to perform this step, the feeding of the corresponding medium should be changed only once, without readjusting of the extrusion device.
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The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
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The drawings show:
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FIG. 1 a cross-sectional view of a first embodiment of an extrusion device according to the present invention;
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FIG. 2 a cross-sectional view of the extrusion device shown in FIG. 1 during the drilling process of a connection anchor;
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FIG. 3 a cross-sectional view of the extrusion device shown in FIG. 1 after completion of the setting process of the connection anchor; and
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FIG. 4 a cross-sectional view of a rock drill with an integrated extrusion device according to a second embodiment of the present invention.
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In the drawings, the same parts are shown with the same reference numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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An extrusion device 11 for extruding a mass 2 out of a self-drilling, chemical rock anchor 1 for mine and tunnel constructions, which is shown in FIGS. 1 through 3, includes a housing 12, a motor-driven sleeve 21 rotatably supported in the housing 12 without a possibility of axial displacement, and a feeding nozzle 31 through which media are fed to the rock anchor 1. The sleeve 21 has a first end 22 with an insert opening 23 that is provided with a receptacle 24 for rotation-imparting means 3 of the rock anchor 1, a second end 23 opposite the first end 22 and provided with a through-opening 26, and a sleeve axis 27.
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Between the first end 22 and the second end 25 of the sleeve 21, there is provided a receiving space 28 for receiving a free end 4 of the rock anchor 1. The receiving space 28 extends from the receptacle 24 for the rotation-imparting means 3 in a direction of the second end 25 of the sleeve 21. The receiving space 28 has a smaller cross-section than the cross-section of the receptacle 24 for the rotation-imparting means 3. The feeding nozzle 31 projects through the through-opening 26 of the sleeve 21 and into the receiving space 28. The feeding nozzle 31 is spaced from the inner surface 29 of the sleeve 21 to provide a free space for the free end 4 of the rock anchor 1 through the feeding nozzle 31, an extrusion medium, e.g., water under a high pressure is fed to the rock anchor 1 for extruding the mass 2 from the anchor 1.
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The receiving space 28 has a cross-section that is by 2.5 times greater than the cross-section of the feeding nozzle 31. The receiving space 28 has an axial extent L along the sleeve axis 27 and which is by three times greater than the average dimension of the inner profile of the sleeve 21.
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The sleeve 21 has a shank 36 formed thereon for mounting the extrusion device 11 in a chuck of a power drill (not shown in FIGS. 1-3).
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Below, with reference to FIGS. 2-3, a setting process of the rock anchor, with the extrusion device 11 will be described.
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The rotation-imparting means 3 of the rock anchor 1 includes a sleeve-shaped section 6 that is provided with a predetermined break point 7 and regionwise circumferentially engage the free end 4 of the rock anchor 1. The sleeve shape section 6 has an open bottom section 8 through which the feeding nozzle 31 projects into the rock anchor 1.
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During the drilling process (see FIG. 2), the free end 4 of the rock anchor 1 that projects through the insert opening 23 into the receiving space 28, is spaced from the end of the receiving space 28 adjacent to the second end 25 of the sleeve 21, by a distance A. During the drilling process, flushing water that forms the flushing medium is fed through the flushing water conduit 32 and channels 33 to the rock anchor 1.
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As soon as the necessary hole depth is reached, feeding of the flushing water is interrupted. Water is then fed to the rock anchor 1 over a separate conduit 34 through a feeding channel 35 under a high pressure as an extruding medium, whereby the hardenable mass 2, which is located in the rock anchor 1, is forced out. As soon as the mass 2 exits the borehole mouth 10, the user recognizes that the clearance between the rock anchor 1 and the hole wall has been filled, and stops delivery of the extruding medium.
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When the forced-out mass 2 reaches a satisfactory firmness, the motor is again actuated, whereby the sleeve section 6 of the rotation-imparting means 3 is broken in the region of the predetermined breaking point 7. The section of the rotation-imparting means 3 that remains in the receptacle 24 of the sleeve 21, is displaced along an outer thread 9 of the rock anchor 1 in the direction of the borehole wall 5 analogous to a locking nut for tightening the rock anchor. As shown in FIG. 3, the free end 4 of the rock anchor 1 can penetrate into the receiving space 28 until the bottom section 8 of the sleeve shaped section 6 abuts the end of the receiving space 28 adjacent to the second end 25 of the sleeve 21. The distance A between the free end 4 of the rock anchor 1 and the end of the receiving space 4 is so selected that it provides a necessary travel path of the extrusion device 11 for tightening the rock anchor 1.
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In the embodiment shown in FIG. 4, the extrusion device 51 with a receiving space 58 is integrated in a rock drill 41. The extrusion device 51 also has a sleeve 56 similar to the sleeve 21 of the extrusion device 1 1 shown in FIGS. 1-3. The sleeve 56 differs from the sleeve 21 in that the sleeve 56 is provided on its outer side 57 with a drive profile 59 in form of toothing that cooperates with the toothing of a gear wheel 43 driven by a motor 42, whereby the sleeve 56 is set in rotation. On the housing 44 of the drill 41, there is provided a multi-channel feeding unit 61 that provides for feeding of flushing water, on one hand, and on the other hand, of extruding medium for forcing out hardenable mass 47 located in the rock anchor 46. The setting process and the function of separate components of this embodiment of the invention are substantially the same as those of the extrusion device 11 described with reference to FIGS. 1-3.
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Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.
