CN209945862U - A special jig for stretching - Google Patents

Abstract

The utility model provides a special stretching clamp for concrete tensile bonding strength test, which comprises an upper clamp and a lower clamp; the upper clamp comprises two side plates, a pressing plate, a cover plate and bolts for fixing the side plates and the cover plate, the top of each side plate is provided with a bent part for bearing the cover plate, and the bent parts of the side plates and the end parts of the cover plate are provided with corresponding through holes for inserting the bolts; the lower clamp comprises a groove for accommodating a test piece, a supporting plate positioned in the groove and a spring positioned at the bottom of the supporting plate and the groove. The utility model discloses a tensile special fixture crosses this anchor clamps and can the side bonding centre gripping test piece, eliminates the influence of eccentric power, destroys earlier at the test piece middle part when avoiding experimental, has guaranteed that the face of bonding destroys to experimental success rate has been guaranteed. And the spring of lower anchor clamps can offset the test piece dead weight when the centre gripping test piece, guarantees to offset the dead weight and the experimental result is accurate in the test piece atress test.

Description

A special jig for stretching

technical field

The invention belongs to the field of water conservancy and hydropower engineering construction, and particularly relates to a special clamp used for holding concrete test pieces in a concrete tensile bond strength test.

Background technique

The test value of bond strength in the design process of lining support of hydraulic engineering is of great significance to determine the design strength grade of concrete. During the construction process, the strength mix ratio of concrete can be optimized through bond strength test data, so bond strength test is a clear design parameter. and important aspects of the construction plan.

At present, there is no direct indoor test method for concrete bond strength in China, and the split test is mostly used to indirectly calculate the concrete bond strength. However, the split test cannot completely simulate the stress state of concrete bond strength, so the test results are not consistent with the actual bond strength. certain deviation. When doing the bond strength test between surrounding rock and shotcrete, the ideal state is that the dowel bar is perpendicular to the bonding surface, and the jack output is coaxial with the dowel bar. Therefore, according to the force model of bond strength failure, it is necessary to design a tensile fixture, which can keep the failure force perpendicular to the bonding surface during the test process, and eliminate the influence of force eccentricity and the weight of the test piece on the test data.

SUMMARY OF THE INVENTION

In order to ensure that the force received by the test piece during the experiment is a normal force and eliminate the influence of eccentric force, the utility model provides an improved special clamp for stretching, through which the test piece can be bonded and clamped on the side to avoid the test. During the process, the middle part of the test piece is damaged before the bonding surface, which ensures that the test is damaged first on the bonding surface and ensures the success rate of the test.

Specifically, the utility model provides a special tensile clamp for concrete tensile bond strength test, which includes an upper clamp and a lower clamp; the upper clamp includes two side plates, a pressure plate, a cover plate and a fixed The bolts of the side plate and the cover plate, the top of the side plate has a bending part for receiving the cover plate, the bending part of the side plate and the end part of the cover plate have corresponding through holes for inserting the bolts; The groove, the plate in the groove and the spring at the bottom of the plate and groove. The lower clamp with spring installed can offset the weight of the specimen when clamping the specimen.

The special tensile clamp of the utility model can be used for the bond strength test between concrete and various rigid materials.

In some preferred embodiments, the cross section of the cover plate is an inverted "convex" convex structure, and the size of the lower surface of the inverted "convex" cover plate is the same as that of the surface of the pressing plate.

In some preferred embodiments, the pressure plate is located below the cover plate and between the two side plates. Specifically, the pressing plate is located between the cover plate and the test piece, and is used for pressing the test piece so that the test piece is vertically positioned in the upper fixture.

In some preferred embodiments, the upper clamp further includes a connector and a screw rod fixed at the center of the outer surface of the cover plate; the screw rod and the recess of the connector are detachably connected.

Through the cooperation of the side plate of the upper fixture, the pressure plate and the cover plate, the specimen is laterally clamped, which can ensure that when the specimen is stressed, the interior of the specimen will not be damaged prior to the bonding surface, resulting in failure to test the adhesion. knot strength issue.

In some preferred embodiments, the symmetrical two sides of the groove are respectively provided with concave holes for accommodating the up and down movement of the pallet.

In some preferred embodiments, the center of the two sides of the support plate has symmetrical protrusions; the two protrusions are respectively located in the concave holes on both sides of the groove, and the protrusions can move up and down in the concave holes.

In some preferred embodiments, the lower clamp further includes a pull rod, and one end of the pull rod is fixed at the center of the outer wall of the bottom of the groove.

In some preferred embodiments, the other end of the tie rod is provided with a hole. This hole is used to connect the tensile testing machine so that the lower fixture is connected to the tensile testing machine.

In some preferred embodiments, the screw rod is connected with the recess of the connector in a screw type.

In some preferred embodiments, the screw rod and the recess of the connector are snap-connected.

beneficial effect

The special tensile clamp of the utility model can be used to bond and hold the test piece on the side through the clamp, eliminate the influence of eccentric force, avoid the first damage in the middle of the test piece during the test, ensure the damage of the bonding surface, and thus ensure the success rate of the test. . In addition, the spring of the lower fixture can offset the self-weight of the test piece when clamping the test piece, so as to ensure that the self-weight of the test piece is offset and the experimental result is accurate in the force test of the test piece.

Description of drawings

Fig. 1 is a schematic diagram of the utility model for clamping a specimen with a special clamp for stretching.

FIG. 2 is a schematic view of the upper clamp of the present invention for clamping the test piece.

FIG. 3 is a schematic view of the side plate of the upper clamp of the present invention.

FIG. 4 is a schematic diagram of the cover plate of the upper clamp of the present invention.

FIG. 5 is a schematic diagram of the lower clamp of the present invention.

FIG. 6 is a schematic view of the pallet of the lower clamp of the present invention.

FIG. 7 is a view of the groove of the lower clamp of the present invention from the side A (side).

FIG. 8 is a schematic diagram of the cooperation between the special clamp of the present invention and the tensile testing machine.

reference number

Upper clamp 100, side plate 110, bending part 111, pressing plate 120, bending part through hole 112, cover plate 130, cover plate through hole 131, bolt 140, connector 150, recess 151, screw 160, lower clamp 200 , groove 210, concave hole 211, support plate 220, support plate bump 221, spring 230, tie rod 240, hole 241 on the tie rod, concrete specimen 300, base specimen 400, tensile testing machine 500, oil cylinder 501, ten thousand knuckle 502, pin 503

Detailed ways

The structures involved in the present invention or the used technical terms are further described below. In the following detailed description, the reference text accompanying the figures is a part hereof and is described by way of illustration of specific embodiments in which the invention may be practiced. We do not exclude that the invention can also be implemented in other specific solutions and the structure of the invention can be changed without departing from the scope of use of the invention.

As shown in Figures 1-5, the special tensile fixture for concrete tensile bond strength test of the present invention is composed of two parts: an upper fixture 100 and a lower fixture 200, through the cooperation of the upper fixture 100 and the lower fixture 200, the clamping A specimen, wherein the specimen includes a base specimen 400 and a concrete specimen 300 bonded together, and the base specimen 400 is a surrounding rock structure. The tensile special tool holding the test piece is connected to the tensile testing machine 500, and a tensile force is applied to test the bond strength between the test pieces (the base test piece and the concrete test piece). Through the special clamping fixture of the present invention, especially the lateral clamping of the upper fixture 100, the correct position of the specimen in the fixture is ensured, thereby ensuring that the tensile force received is a positive force, thereby ensuring the accuracy of the experiment and the validity of the results. sex.

The upper fixture 100 includes two side plates 110, a pressing plate 120 and a cover plate 130. As shown in FIGS. 2-4, the side plates 120 are used to fit on two symmetrical side walls of the concrete specimen 300. The top of the plate has a bent portion 111 . When the side wall is located on the side wall of the concrete specimen 300 , the two bent portions 111 are both away from the concrete specimen 300 . The pressing plate 120 is placed between the concrete specimen 300 and the cover plate 130 . The cover plate 130 is located on the pressing plate 120 , and the end of the cover plate 130 is located on the side plate bending portion 111 , and the cover plate 130 is fixedly connected to the side plate bending portion 111 by bolts 140 . Specifically, there are through holes 112 and 131 for inserting bolts on the bent portion 111 of the side plate and the end of the cover plate 130 . After the bolts 140 are inserted into the through holes 112 and 131 , the nuts lock the bolts 140 . In order to ensure that the test piece 300 is closely matched with the upper fixture 100, the upper cover plate 130 has an inverted convex structure with steps. The inverted convex lower surface of the cover plate has the same size as the surface of the pressing plate 120. The pressing plate 120 is in contact, thereby ensuring that the test piece 300 can be positioned in the upper jig 100 .

When in use, evenly coat the two side plates 110 of the upper fixture and both sides of the test piece 300 with epoxy resin, place the side plate 110 close to the side wall of the test piece 300, put the pressure plate 120 above the test piece 300, and then place the two The bent portion 111 of the side plate 110 is installed on the cover plate 130 with bolts 140 but do not tighten the nuts, so that the two side plates 110 have a small space for movement; after completion, the two side plates 110 are pasted on both sides of the bond strength test piece , after adjusting the side plate 110 so that the side of the side plate is parallel to the side of the bond strength test piece, tighten the nut to fix the test piece 300 and the upper fixture 100 .

In some embodiments, the upper fixture 100 further includes a connector 150 and a screw rod 160 fixed at the center of the outer surface of the cover plate 130 ; the screw rod 160 is detachably connected to the recess 151 of the connector. Specifically, the connector 150 has a recess 151 for receiving the screw rod 160 . The screw 160 and the recess 141 of the connector are connected in a screw type or a snap-type connection.

In the present invention, as shown in FIG. 5 , the lower clamp 200 includes a groove 210 for accommodating the test piece, a support plate 220 located in the groove, and a spring 230 connected between the support plate 220 and the bottom of the groove. In a specific embodiment, the groove 210 is formed by a bottom and two symmetrical sides; the other two sides are vacant for pushing the test piece. In addition, the tops of the two side edges of the groove 210 are respectively provided with bending parts in the direction of the groove, so that the objects in the groove will not be separated from the groove after being stressed.

As shown in FIG. 7 , two symmetrical sides of the groove 210 respectively have concave holes 211 for accommodating the support plate 220 to move up and down. Symmetrical bumps 221 are provided at the center of both sides of the support plate 220 , as shown in FIG. 6 . When the support plate 220 is located in the groove, the two protrusions 221 are respectively located in the concave holes 211 on both sides of the groove. Since the concave holes 211 are elongated, the convex blocks 221 can move up and down in the concave holes 211 .

The spring 230 located between the support plate 220 and the bottom of the groove 210 can counteract the self-weight of the test piece when clamping the test piece. When the test piece is installed, the spring 230 of the lower fixture is pressed down, and the support plate 220 will also descend accordingly. The lower fixture 200 further includes a pull rod 240 , one end of the pull rod 240 is fixed on the bottom outer wall of the groove 210 , and the other end of the pull rod 240 has a hole 241 through which the pull rod 240 is connected to the tensile testing machine 500 .

During the test, install the specimen with the special tensile fixture (the concrete specimen and surrounding rock specimen bonded together) on the tensile testing machine 500, and insert the fixing pin 503, as shown in Figure 8, Specifically, the screw rod 160 of the upper clamp 100 of the special clamp is inserted into the universal joint 502 on the tensile testing machine for fixed connection, the universal joint is connected to the oil cylinder 501, and the pull rod 240 of the lower clamp is passed through the hole 241 by the pin 503 The insert locks onto the base of the tensile testing machine 500 . Before the tensile testing machine 500 applies force, that is, before the test piece is stressed, the spring 230 should be pressed down to allow the test piece to sag freely, and then the spring 300 should be loosened to allow the spring 300 to bear against the test piece to offset the self-weight of the test piece. Then start the tensile testing machine 500 to apply a tensile force to the special fixture through the oil cylinder 501 at a speed of 5mm/min, so that the upper fixture 100 is pulled up, and the lower fixture 200 is fixed on the base, so that the coagulation strength test piece is stressed, until the concrete The bond between the test piece 300 and the base test piece 400 was broken.

Claims (10)

1. a tensile special clamp, used for concrete tensile bond strength test, is characterized in that, comprises upper clamp and lower clamp; Described upper clamp comprises two side plates, pressing plate, cover plate and fixed side plate and cover The bolts of the plate, the top of the side plate has a bending part for receiving the cover plate, and the bending part of the side plate and the end of the cover plate have corresponding through holes for inserting bolts; the lower clamp includes a groove for accommodating the test piece, located in The plate in the groove and the spring at the bottom of the plate and groove. 2 . The special-purpose jig for stretching according to claim 1 , wherein the cross-section of the cover plate is an inverted "convex" structure, and the lower surface of the inverted "convex" cover has the same size as the surface of the pressing plate. 3 . 3 . The special-purpose jig for stretching according to claim 1 , wherein the pressing plate is located under the cover plate and between the two side plates. 4 . 4. The special-purpose jig for stretching according to claim 1, wherein the upper jig further comprises a connector and a screw rod fixed at the center of the outer surface of the cover plate; the recesses of the screw rod and the connector are detachable connect. 5 . The special clamp for stretching according to claim 1 , wherein the symmetrical two sides of the groove are respectively provided with concave holes for accommodating the up and down movement of the pallet. 6 . 6 . The special clamp for stretching according to claim 5 , wherein the center of both sides of the support plate has a symmetrical convex block; the two convex blocks are respectively located in the concave holes on both sides of the groove, And the bump can move up and down in the concave hole. 7 . The special clamp for stretching according to claim 1 , wherein the lower clamp further comprises a pull rod, and one end of the pull rod is fixed at the center of the outer wall of the bottom of the groove. 8 . 8 . The special clamp for stretching according to claim 7 , wherein the other end of the tie rod is provided with a hole. 9 . 9 . The special-purpose jig for drawing according to claim 3 , wherein the screw rod and the recess of the connector are connected in a spiral type. 10 . 10 . The special clamp for stretching according to claim 3 , wherein the screw rod and the recess of the connector are connected by a snap connection. 11 .

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