FRICTION-LOCKED ANCHOR

Abstract

The utility model relates to the mining industry and can be used for lining the surface of mine workings. The technical problem addressed by the utility model is to improve reliability. The anchor includes a tubular rod 1 with a longitudinal slot 2 along its entire length and a stop on the rear portion 4, formed in the form of an open circular metal ring 5. The tail portion 6, projecting beyond the ring 5, is divided into sectors 7 by slots 8. The open portion of the ring is located between adjacent slots 8, and the height of the slots in the tail portion is equal to 1.2 times the wire diameter. 3 ill.

Description

[0001] Technical field

[0002] The utility model relates to the mining industry and can be used to support the surface of workings.

[0003] Prior Art

[0004] A known anchor comprises a hollow rod with a lock, made of longitudinally slit walls, and a support plate at the protruding end. The rod is equipped with additional locks, which are placed along it at intervals, with each subsequent lock oriented toward the protruding end of the rod and made with a cut area smaller than the previous ones (see USSR Patent Application No. 968439, 10.02.1981, E21D 21 / 00).

[0005] A drawback of the known device is its lack of reliability. The bolt is secured in the borehole by compressing the hollow rod, which causes the locks to lose stability and deform longitudinally. However, when the bolt is loaded by a rock layer in the area located between the first lock, starting from the borehole bottom, and the base plate, the hollow rod stretches. As a result, the locks located within this area open, reducing the pressure on the borehole walls, and allowing the rock layer to move toward the base plate. This rock movement reduces the reliability of the bolt.

[0006] The closest analogue to the claimed object is a tubular friction anchor consisting of a tubular rod with a longitudinal slot and a support unit on the tail part, which is a ring for fixing a support plate put on the tubular rod, wherein the ring is made of steel wire of a round cross-section with a diameter of 6.3 mm to 10 mm and is connected to the tubular rod by welding, wherein the weld is made from the side of the downhole part of the tubular rod along the entire perimeter of the junction of the ring with the tubular rod, the ring is made open, while the distance between its open ends is from 5 mm to 7 mm, the length of the tail part of the tubular rod protruding from the ring is from 4 mm to 6 mm, the tail part of the tubular rod protruding from the ring has 4 additional slots, where the angular distance between adjacent slots is from 65° to 75°,the diameter of the tubular rod before installation is from 39 mm to 48 mm (PM RF No. 171624, 09.26.2026, E21D 21 / 00).,

[0007] In the prototype, the wire diameter ranges from 6.3 to 10 mm, and the length of the tail section protruding from the ring is 4-6 mm. During the anchor insertion stage, the force exerted by the punch mounted on the anchor installation tool forms additional support from the tail section of the rod, starting from the section adjacent to the ring and encircling it. Selecting the tail section length based on numerical values ​​unrelated to the wire diameter results in a situation where additional support is virtually nonexistent. With the dimensions stated in the utility model formula, the ring grip angle of the tail section ranges from 45° to 72°. The center of the contact surface between the ring and the additional support is offset toward the rod wall.

[0008] During the final stage of anchor installation, a distributed force from the punch, directed along the rod wall, acts on the anchor ring. On the opposite side, a reactive distributed force acts on the ring from the support plate, also directed along the rod wall. As a result of these forces being offset relative to each other, shear stresses arise in the weld, leading to its failure.

[0009] Distributed forces acting with offset (shoulder) create a bending moment and, as a result, bending stresses are created in the rod in the weld zone.

[0010] Equivalent stresses are created in the weld seam as a result of the action of shear and normal stresses, which exceed the permissible values.

[0011] The combination of the wire diameter and the length of the tail section protruding from the ring, as stated in the utility model, allows for the formation of additional support only on a small mating surface that is insufficient to absorb the force from the support plate and does not provide the necessary rigidity of the assembly.

[0012] Due to the noted features, this technical solution is not reliable.

[0013] The technical problem that the utility model is aimed at solving is to increase reliability by providing a favorable force impact on the stop formed from the tail section.

[0014] Disclosure of Utility Model

[0015] The technical problem is solved in that in an anchor with friction fastening, including a tubular rod with a longitudinal slot along the entire length, with a front part with a conical surface shape, with a stop on the rear part, made of steel wire in the form of an open circular ring, secured by welding on the rod from the side of the front part, with a tail part protruding beyond the stop, divided into sectors by slots, the open part of the ring is located between adjacent slots, and the height of the slots is equal to 1.2 diameters of the wire.

[0016] Brief description of drawing figures

[0017] The utility model is illustrated by an image, where:

[0018] in Fig. 1 - a view of an anchor with friction fastening, combined with a longitudinal section;

[0019] in Fig. 2 - view A from Fig. 1;

[0020] in Fig. 3 - a fragment of the tail section after installing the anchor in the borehole.

[0021] Embodiment of the utility model

[0022] An anchor with friction fastening includes a tubular rod 1, along the entire length of which a longitudinal slot 2 is made (Fig. 1). The front part 3 of the rod 1 is made with a conical surface shape. On the rear part 4, a stop is made from steel wire with a diameter d in the form of a ring 5. The ring 5 is fixed on the rod 1 by welding from the side of the front part 3. The tail part 6 of the rod 1 protrudes beyond the ring 5 by a height h and is divided into sectors 7 by slots 8 (Fig. 2). The open part 9 of the ring 5 is located between adjacent slots 8.

[0023] The slots 8 are made to a height h, greater than one wire diameter d. The rod 1 is inserted into the borehole by acting on the tail section 6 of a special punch. Due to the deformation of the tail section 6, the material encircles sector 7 of the ring 5 along a surface whose angular dimension α is greater than 114° (Fig. 3).

[0024] Experimentation has shown that the most favorable value for h is 1.2 d. In this case, when installing rod 1 into the borehole, effective additional support is formed for ring 5, with the material of sectors 7 enveloping its surface at an angle α of 137°. This ensures efficient use of the rod material.

[0025] The adopted height h, equal to 1.2 d, when ring 5 reaches the support washer ensures the formation of a contact surface between ring 5 and the material of sector 7, resulting in a nearly coaxial arrangement of the distributed forces acting on ring 5 from the punch side and from the support plate on the other. Consequently, force impact on the weld is eliminated.

[0026] The location of the open section 9, ring 5, between adjacent slots 8 prevents it from being within longitudinal slot 2. Using welding, a closed circular shape is formed from ring 5 and rod 1, which has increased rigidity. This results in a more rigid and durable connection between ring 5 and rear section 4.

[0027] Function of the friction anchor

[0028] Anchor installation with friction locking is performed with a rod diameter (1) greater than the borehole diameter. For example, rod (1) with a diameter of d = 48 mm is installed in a borehole with a diameter of 45–46 mm. The impact of the anchor driver's hammer on rod (1) is achieved through a special punch.

[0029] The front part 3 is inserted into the borehole freely due to its conical surface shape. Further insertion of rod 1 into the borehole requires significant force. Consequently, under the action of the punch, sectors 7 are deformed in the direction of ring 5. Until the rod is fully inserted into the borehole, sectors 7 grip the surface of ring 5 within the angle α. As rod 1 is being inserted into the borehole, the forces exerted by the punch increase. Ring 5 is pressed against the surface of the base plate.

[0030] The angle α of the ring 5 grip by the additional support formed from sectors 7 exceeds 114°, and at the preferred height h equal to 1.2 d, the angle α is 137°. The distributed force from the punch to the additional support formed from sectors 7 is distributed almost opposite to the straightened force acting between ring 5 and the support plate. This eliminates the creation of shear stresses in the weld, reducing the likelihood of weld failure. The reliability of the anchor structure during installation is increased.

[0031] When the anchor is operating, a distributed longitudinal force F acts on ring 5 from the side of the support plate. оп The force acts normally to the contact surface and is directed along the longitudinal axis of the rod.

[0032] A distributed force F acts on the ring from the additional stop side уп (Fig. 3). Distributed force F упdirected along the normal to the center line of contact of the additional support and ring 5. When forming an additional support from sectors 7 and the height of the grooves 8 h equal to 1.2 d, its deviation from the longitudinal axis of the rod is 8°, i.e., practically opposite to the distributed force F оп As a consequence, the actions of distributed forces F оп and F уп in the material of rod 1 in the junction zone of sector 7 and the rear part 4, tensile stresses arise.

[0033] Rod 1 always has an allowable normal stress that exceeds the allowable shear stress by 1.7...2 times.

[0034] As a result, in the loading scheme of rod 1, when choosing the ratio h = 1.2 d, the load on the weld seam is reduced, the probability of its destruction is reduced and the reliability of the functioning of the anchor with friction fastening is increased.

[0035] When the open section 9 of ring 5 is positioned between adjacent grooves 8, it is prevented from being located within longitudinal slot 2. In this case, all sectors 7 have equal strength characteristics and deform equally during installation. As a result, the additional stop has equal rigidity in all directions, including the direction of longitudinal slot 2.

[0036] Thus, the claimed technical solution eliminates the possibility of destruction of the weld seam connecting the ring 5 with the rod 1 both at the stage of inserting the rod 1 into the borehole and during the operation of the anchor, and due to this, the reliability of the anchor with frictional fastening is increased.

Claims

An anchor with friction fastening, including a tubular rod with a longitudinal slot along its entire length, with a front part with a conical surface shape, with a stop on the rear part, made of steel wire in the form of an open circular ring, secured by welding to the rod from the side of the front part, with a tail part protruding beyond the stop, divided into sectors by slots, characterized in that the open part of the ring is located between adjacent slots, and the height of the slots is equal to 1.2 times the diameter of the wire.

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