KR102588799B1 - Schmidt Hammer Guide Device - Google Patents

Abstract

The present invention relates to a Schmidt hammer guide device for structural safety diagnosis used to measure the rebound hardness of a concrete surface, one end of which is fixed to the shaft holder (40), and the other end of which is a base so that the body is perpendicular to the base plate (41). A spline axis 50 extending in a direction away from the plate 41; It moves along the spline axis 50, and has spline bushes 51 at both front and rear ends of the hammer holder 30; A hollow flange (61) fixed in close contact with the spline bush (51) located at the rear; A protective tube (60) whose end is inserted and fixed to the center of the hollow flange (61) and which accommodates the spline shaft (50); It is installed on the other end of the spline shaft 50 located inside the protection tube 60, and meets the spline bush 51 located at the rear to stop the movement of the hammer holder 30 to prevent the spline bush 51 from being separated. stop ring (53); It is installed at the other end of the protective tube 60 and includes a stopper 62 having a through hole 63 at the center.

Description

Schmidt Hammer Guide Device for structural safety diagnosis

The present invention relates to a Schmidt hammer guidance device for structural safety diagnosis used to measure the rebound hardness of a concrete surface. More specifically, the plunger of the Schmidt hammer enables precise right-angle hitting on the concrete surface to accurately measure the rebound hardness. It is about the Schmidt hammer guidance device for structural safety diagnosis that makes it possible.

In general, the rebound hardness method is a method of non-destructively estimating the compressive strength of concrete. When the hardened concrete surface is struck by a Schmidt hammer, the rebound hardness method is used to determine a certain correlation between the measured rebound hardness and the compressive strength of concrete. It is based on experimental data showing a relationship.

The measuring principle of the rebound hardness method using the Schmidt hammer is to attach the contact surface 4 formed at the tip of the plunger 2 to the surface of the concrete 2 as shown in (a) of Figure 1, and then ), the hammer (5), which is a certain distance away from the striking surface (7) of the plunger (2), is moved along the guide rod (6) with a constant momentum by a built-in impact spring (not shown). When an impact is applied to (7), the impact energy is transferred from the hammer (5) to the concrete (3) through the plunger (2). At this time, the repulsive force of the concrete (3) causes the hammer (5) to pass through the plunger (2). The repulsive force is transmitted.

At this time, as shown in (c) of FIG. 1, the distance that the hammer (5) moves away from the hitting surface (7) varies depending on the size of the repulsion force transmitted to the hammer (5). The distance distance is read through the scale to determine the concrete The rebound hardness in (3) is measured, and the compressive strength of the concrete is estimated from the measured rebound hardness of the concrete surface.

Rebound hardness is proportional to the elastic modulus of concrete, and the strength of concrete is related to the elastic modulus, so the compressive strength of concrete can be estimated using the relationship between rebound hardness and compressive strength.

This rebound hardness method using a Schmidt hammer causes deviations in measured values depending on the presence or absence of aggregate protrusion on the concrete surface, the depth from the concrete surface to the rebar, the roughness of the striking surface, and the presence or absence of pores inside the concrete. To reduce these measurement errors, For this purpose, approximately 20 impact points are marked in a grid shape on the surface of the concrete and then measured. Data with large errors are excluded and the average of the remaining values is calculated to calculate the rebound hardness of the concrete.

As shown in Figure 2, it is very important to keep the plunger (2) perpendicular to the surface of the concrete (3) in order to maintain the measurement accuracy of the rebound hardness method using the Schmidt hammer (1), but in the past, the operator There was a problem in that precise measurement was difficult because the work was done while holding the Schmidt hammer (1) with the hand and maintaining the approximately right angle of the plunger (2).

That is, as shown in the enlarged view of FIG. 2, when the plunger (2) does not maintain a right angle from the surface of the concrete (3) and is tilted to one side, there is a gap between the contact surface (4) of the plunger (2) and the surface of the concrete (3). This occurs, and for this reason, the impact energy transmitted to the plunger 2 is concentrated on the edge of the plunger 2, causing a problem in which the rebound hardness is measured inaccurately.

Domestic Registered Patent Publication No. 10-1358748 (announced on February 10, 2014) Domestic Registered Patent Publication No. 10-1848238 (announced on April 12, 2018) Domestic Registered Patent Publication No. 10-1381460 (announced on April 4, 2014)

The present invention was made to solve the above problems, and its purpose is to provide a Schmidt hammer guidance device for structural safety diagnosis that allows precise rebound hardness measurement by maintaining the plunger of the Schmidt hammer at a right angle to the surface of the concrete. .

The Schmidt hammer guidance device for structural safety diagnosis to achieve the purpose of the present invention includes a hammer holder for attaching and detaching the Schmidt hammer; A base plate in close contact with the surface of a concrete structure; In the Schmidt hammer guidance device for structural safety diagnosis including a shaft holder installed on the base plate,

a spline shaft at one end fixed to the shaft holder and at the other end extending in a direction away from the base plate so that the body is perpendicular to the base plate; A pair of spline bushes that move along the spline axis and are installed in a straight line at both front and rear ends of the hammer holder; A hollow flange that is closely attached to the spline bush located at the rear; A protective tube, one end of which is inserted and fixed to the center of the hollow flange, and which accommodates the spline shaft; A stop ring installed on the other end of the spline shaft located inside the protection tube and stops the movement of the hammer holder by meeting the spline bush located at the rear to prevent the spline bush from being separated; It is installed at the other end of the protective tube and has the feature of including a stopper having a hole in the center.

The present invention includes a rotating holder that has an open hole into which a spline shaft is inserted and changes its position by rotating around the spline shaft; A handle installed on the rotating holder; It has the feature of including a lever bolt that catches the spline shaft by releasing the engagement of the open hole or reducing the inner diameter of the open hole.

The hammer holder according to the present invention includes a movable clamp having a lower semicircular groove in close contact with the lower portion of the outer peripheral surface of the Schmidt hammer; An opening/closing clamp having an upper semicircular groove covering the upper portion of the outer peripheral surface of the Schmidt hammer; A dowel formed on one side of the moving clamp and the opening/closing clamp and meeting each other in the form of a tenon joint; A hinge pin that is installed to penetrate the dowel and becomes the center of rotation when opening and closing the opening and closing clamp; A cicada ring installed on the other side of the moving clamp; It is installed on the other side of the opening and closing clamp and has the feature of including a latch held by a cicada hook.

The present invention includes a pin head formed at one end of a hinge pin and having a press-fit hole formed at the center; A buffer spacer located between the recording paper cover and the pin head of the Schmidt hammer; It is formed at the center of the other end of the buffer spacer and has the feature of including a boss inserted into the press-fit hole.

As described above, the present invention is configured to guide the hammer holder 30 and the Schmidt hammer 20 in a straight direction using the spline shaft 50 and the spline bush 51 composed of a single axis, so the Schmidt hammer 20 ), it not only prevents rotation, but also makes it lighter, making it easier to handle and move.

Since the hammer holder (30) can be opened and closed by the cicada ring (34), latch (35), and hinge pin (33), the task of removing or installing the Schmidt hammer (20) from the hammer holder (30) is simple. It is effective in that it can be done quickly and conveniently.

Since the protection tube 60 is provided to accommodate the spline shaft 50 that protrudes backward when the Schmidt hammer 20 is advanced, it is effective in preventing injuries caused by the spline shaft 50.

The stop ring 53 installed on the other end of the spline shaft 50 has the effect of preventing the spline bush 51 from being separated from the spline shaft 50 when the Schmidt hammer 20 moves backward.

The gap between the recording paper cover 21 of the Schmidt hammer 20 and the hammer holder 30 is kept constant by the buffer spacer 37 and the pin head 36 installed on the pin head 36 of the hinge pin 33. There is an effect that can be done.

The effect of alleviating the impact applied to the Schmidt hammer (20) by the buffer spacer (37) can also be expected.

The effect of changing the position of the handle 70 to an appropriate position can be expected by the rotation holder 71 installed on the spline shaft 50.

1 is a diagram schematically illustrating the rebound hardness method using a general Schmidt hammer.
Figure 2 is a view showing that the plunger of a conventional Schmidt hammer does not form a right angle from the measurement surface and is struck in an inclined state.
Figure 3 is a perspective view showing that the plunger of the Schmidt hammer is perpendicular to the surface of the concrete structure by the spline axis according to the present invention.
Figure 4 is a perspective view showing the plunger of the Schmidt hammer hitting the surface of the concrete structure by the straight-line guidance of the spline shaft according to the present invention.
Figure 5 is a side cross-sectional view of Figure 3
Figure 6 is a side cross-sectional view of Figure 4
Figure 7 is a partially enlarged cross-sectional view of Figure 5
Figure 8 is a partially enlarged cross-sectional view of Figure 6
Figure 9 is a plan view of Figure 3
Figure 10 is a plan view of Figure 4
Figure 11 is a perspective view of Figure 3 viewed from the opposite side, below.
Figure 12 is an exploded perspective view according to the present invention
Figure 13 is an exploded perspective view showing the hammer holder, spline shaft, spline bush, hollow flange, protective tube, stop ring and stopper according to the present invention.
Figure 14 is an exploded perspective view showing the hammer holder according to the present invention
Figure 15 is an exploded perspective view showing the base plate, shaft holder, rotation holder, handle, spline shaft and lever bolt according to the present invention.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to Figures 3 to 15.

The present invention includes a hammer holder (30) for attaching and detaching the Schmidt hammer (20); A base plate (41) in close contact with the surface of the concrete structure (10); It includes a shaft holder 40 installed on the base plate 41.

The base plate 41 can be formed from a metal plate with a certain thickness. For example, as shown in FIG. 15, the base plate 41 can be formed into an H shape.

A holder flange 42 in close contact with the base plate 41 can be formed on the shaft holder 40 as shown in FIGS. 4 and 12. In this case, the shaft holder 40 can be fixed to the base plate 41 using the holder fixing bolt 43 that is coupled to the tapped hole formed in the base plate 41 through the hole formed in the holder flange 42.

A spline insertion hole 40h into which the spline shaft 50 is inserted can be formed in the center of the shaft holder 40, and a cut is made at a certain width from the outer peripheral surface of the shaft holder 40 toward the spline insertion hole 40h, The spline shaft 50 can be fixed to the shaft holder 40 by reducing the spline insertion hole 40h using the shaft fixing bolt 44 penetrating the cut portion in the width direction.

The present invention includes a spline shaft (50) whose one end is fixed to the shaft holder (40) and whose other end extends in a direction away from the base plate (41) so that the body is perpendicular to the base plate (41); It moves along the spline axis 50 and includes a pair of spline bushes 51 installed in a straight line at both front and rear ends of the hammer holder 30.

The spline bush 51 can be composed of a ball spline with a steel ball installed. In this case, a straight semicircular groove (50g) can be formed on the outer peripheral surface of the spline shaft 50 along the longitudinal direction of the spline shaft 50, as shown in the enlarged views of FIGS. 6 and 12. .

When the spline bush (51) moves along the spline shaft (50), the steel ball built into the spline bush (51) rolls along the semicircular groove (50g), allowing smooth movement.

At this time, the spline bush 51 cannot rotate around the spline shaft 50 due to the steel ball caught in the semicircular groove (50g). Since the spline bush (51) can only move linearly on the spline shaft (50) and cannot rotate, the Schmidt hammer (20) can be prevented from rotating even if the spline shaft (50) is configured as a single axis, and it is lightweight to handle. and movement becomes easier.

As shown in FIGS. 12 and 13, the spline bushes 51 are inserted into the bush insertion holes 31s formed in the movable clamp 31 in opposite directions and are coaxial with each other, and are formed on the spline bush 51. The bush flange (54) is in close contact with the front and rear surfaces of the moving clamp (31).

The bush flange 54 in close contact with the rear of the movable clamp 31 can be fixed by engaging the tapped hole 31t for bush fixing formed in the movable clamp 31 using the bush fixing bolt 55.

The hollow flange 61 overlaps the bush flange 54 in close contact with the front of the movable clamp 31, and a tapped hole for fixing the bush is formed in the movable clamp 31 through the hollow flange 61 and the bush flange 54. It can be fixed using the flange fixing bolt (56) coupled to (31t).

The present invention includes a hollow flange (61) fixed in close contact with a spline bush (51) located at the rear; A protective tube (60) whose end is inserted and fixed to the center of the hollow flange (61) and which accommodates the spline shaft (50); It is installed on the other end of the spline shaft 50 located inside the protection tube 60, and meets the spline bush 51 located at the rear to stop the movement of the hammer holder 30 to prevent the spline bush 51 from being separated. stop ring (53); It is installed at the other end of the protective tube 60 and includes a stopper 62 having a through hole 63 at the center.

The hollow flange 61 and the protective tube 60 are inserted into the hole formed in the center of the hollow flange 61, as shown in FIGS. 7, 8, 12, and 13, and then inserted into the hollow flange. The protective tube 60 can be fixed to the hollow flange 61 by coupling the tube fixing bolt 64 penetrating through (61) to the tube fixing tapped hole 60t formed on the outer peripheral surface of the protective tube 60.

As another example, the hollow flange 61 and the protection tube 60 may be welded or glued together.

Anaerobic adhesive can be applied to the inner peripheral surface of the stop ring 53 and the outer peripheral surface of the spline shaft 50, and then the stop ring 53 can be permanently fixed by inserting it into the rear end of the spline shaft 50.

The stopper 62 can be press-fitted into the protective tube 60, and the through hole 63 formed in the center of the stopper 62 allows air to enter and exit when the spline shaft 50 enters and exits the inside of the protective tube 60. This is to prevent the air inside the protective tube 60 from being compressed or negative pressure from occurring.

The present invention includes a rotating holder (71) that has an open hole (72) into which the spline shaft (50) is inserted and changes its position by rotating around the spline shaft (50); A handle (70) installed on the rotating holder (71); It includes a lever bolt (73) that catches the spline shaft (50) by releasing the engagement of the open hole (72) or reducing the inner diameter of the open hole (72).

By loosening the lever bolt 73, the rotary holder 71 can be rotated around the spline shaft 50 and the position of the handle 70 can be changed. For example, as shown in Figure 3, the handle 70 can be positioned vertically downward using the rotating holder 71 and the lever bolt 73, and as shown in Figure 11, the hammer holder 30 and the lever bolt Using (73), the handle (70) can be positioned horizontally toward the right.

As shown in Figure 15 of the attached drawing, the handle bolt 74 installed on the top of the handle 70 is coupled to the tapped hole 40t for fixing the handle formed on the bottom of the rotary holder 71, thereby attaching the handle 70 to the rotary holder. It can be installed at (71).

The open hole 72 formed in the rotating holder 71 can be formed by cutting a certain width from the upper surface of the rotating holder 71 toward the open hole 72, as shown in FIG. 12. In this case, if the lever bolt (73) is loosened, the open hole (72) becomes loose, allowing the rotation holder (71) to move or rotate along the spline shaft (50), and if the lever bolt (73) is tightened, the open hole (72) becomes loose. ) is reduced and strongly bites the outer peripheral surface of the spline shaft 50, and the rotation holder 71 is fixed to the spline shaft 50.

The hammer holder 30 according to the present invention includes a movable clamp 31 having a lower semicircular groove 31g in close contact with the lower portion of the outer peripheral surface of the Schmidt hammer 20; An opening/closing clamp (32) having an upper semicircular groove (32g) covering the upper portion of the outer peripheral surface of the Schmidt hammer (20); It is formed on one side of the moving clamp 31 and the opening/closing clamp 32, and includes dowels 31a and 32a that meet each other in the form of a mortise joint.

As shown in Figures 12 to 14 of the accompanying drawings, when installing the Schmidt hammer 20 in the hammer holder 30, unlock the cicada ring 34 and the latch 35 and open the opening and closing clamp 32. (32) opens while rotating around the hinge pin (33).

The moving clamp 31 and the opening/closing clamp 32 can be molded from, for example, plastic.

The hammer holder 30 according to the present invention includes a hinge pin 33 that is installed to penetrate the dowels 31a and 32a and serves as the center of rotation when opening and closing the opening and closing clamp 32; A cicada ring (34) installed on the other side of the moving clamp (31); It is installed on the other side of the opening and closing clamp 32 and includes a latch 35 caught by a cicada hook 34.

As shown in FIGS. 13 and 14, the hinge pin 33 is installed by inserting into the pin holes 31h and 32h formed in the dowels 31a and 32a formed in the moving clamp 31 and the opening and closing clamp 32. You can.

At this time, an annular groove (33g) is formed on the outer peripheral surface of the tip of the hinge pin (33), and when the snap ring (38) is coupled to the annular groove (33g), the hinge pin (33) is prevented from being separated from the pin holes (31h) (32h). It can be prevented.

When the U-shaped steel wire ring (34r) provided on the cicada ring (34) is fastened to the latch (35), the opening and closing clamp (32) and the moving clamp (31) are maintained in a closed state.

As shown in FIG. 14, the cicada ring 34 is connected to the cicada ring fixing bolt 34b by screwing it into the tab hole 34t for fixing the cicada ring formed on one side of the movable clamp 31. ) can be fixed to.

As shown in FIG. 14, the latch 35 is fixed to the opening and closing clamp 32 using a latch fixing bolt 35b that is screwed into the latch fixing tab hole 35t formed on one side of the opening and closing clamp 32. can do.

The present invention includes a pin head (36) formed at one end of the hinge pin (33) and having a press-fit hole (36h) at the center; A buffer spacer (37) located between the recording paper cover (21) and the pin head (36) of the Schmidt hammer (20); It is formed at the center of the other end of the buffer spacer 37 and includes a boss 37b inserted into the press-fit hole 36h.

The pin head 36 and the buffer spacer 37 are used to maintain a constant distance between the pin head 36 and the recording paper cover 21 installed on the Schmidt hammer 20, as shown in FIGS. 9 to 11. , When installing the Schmidt hammer 20 in the hammer holder 30, the positioning of the Schmidt hammer 20 can be precisely determined by the pin head 36 and the buffer spacer 37, as shown in Figure 6. Likewise, the holding button 23 provided on the Schmidt hammer 20 can be prevented from moving to the stopper 62.

In particular, the buffer spacer 37 serves to absorb the impact applied to the Schmidt hammer 20 and prevents damage to the recording paper cover 21.

In the drawing, symbol 22 represents a plunger installed at the tip of the Schmidt hammer 20, and symbol 24 represents a scale window installed on the upper part of the recording paper cover 21 of the Schmidt hammer 20.

Hereinafter, the operation according to the present invention will be described in detail based on the attached drawings.

Hold the handle 70 and bring the base plate 41 into close contact with the surface of the concrete structure 10, then contact the front end of the plunger 22 of the Schmidt hammer 20 with the surface of the concrete structure 10, and use the Schmidt hammer ( When 20 is pushed toward the concrete structure 10, the Schmidt hammer 20 moves toward the concrete structure 10 and the plunger 22 enters the inside of the Schmidt hammer 20.

At this time, the hammer holder (30) bitten by the Schmidt hammer (20) is guided in a straight direction along the spline shaft (50) by the spline bush (51), and the rotation prevention action of the spline shaft (50) and spline bush (51) As a result, the hammer holder 30 and the Schmidt hammer 20 cannot rotate around the spline axis 50.

When the Schmidt hammer 20 and the hammer holder 30 advance along the spline shaft 50, the rear end of the spline shaft 50 protrudes rearward, and the rear end of the spline shaft 50 is inside the protection tube 60. Since it is located in, injuries caused by the spline shaft 50 can be prevented by the protection tube 60 to protect the worker.

While the spline shaft 50 enters the protective tube 60, the air remaining in the protective tube 60 is exhausted through the through hole 63 formed in the stopper 62, resulting in air compression inside the protective tube 60. No resistance occurs.

When the Schmidt hammer 20 is moved backwards in a direction away from the concrete structure 10, the stop ring 53 installed at the rear end of the spline shaft 50 is caught on the spline bush 51 as shown in FIG. The bush 51 can be prevented from being separated from the spline shaft 50.

On the other hand, when the steel wire ring 34r provided on the cicada ring 34 is separated from the latch 35, the opening and closing clamp 32 can be opened by rotating around the hinge pin 33. At this time, the Schmidt hammer 20 ) can be separated from the hammer holder (30).

When remounting the Schmidt hammer (20), which has been separated from the hammer holder (30), to the hammer holder (30), open the opening and closing clamp (32) and move the Schmidt hammer (20) into the lower semicircle formed on the moving clamp (31). After putting it in close contact with the groove (31g), closing the opening and closing clamp (32) and hanging the steel wire ring (34r) installed on the cicada ring (34) on the latch (35), the Schmidt hammer (20) is firmly installed in the hammer holder (30). .

10: Concrete structure 20: Schmidt hammer
21: Recording paper cover 30: Hammer holder
31: moving clamp 31a, 32a: dowel
31g: Lower semicircular groove 32: Opening/closing clamp
32g: Upper semicircular groove 33: Hinge pin
34: Cicada hook 35: Clasp
36: Pinhead 36h: Press-fit hole
37: buffer spacer 37b: boss
40: Shaft holder 41: Base plate
50: Spline shaft 51: Spline bush
53: Stop ring 60: Protection tube
61: hollow flange 62: stopper
63: Hole 70: Handle
71: Rotating holder 72: Open hole
73: lever bolt

Claims (4)

Hammer holder (30) for attaching and detaching the Schmidt hammer (20);
A base plate (41) in close contact with the surface of the concrete structure (10);
A shaft holder (40) installed on the base plate (41);
In the Schmidt hammer guidance device for structural safety diagnosis including,

A spline shaft (50) whose one end is fixed to the shaft holder (40) and whose other end extends in a direction away from the base plate (41) so that its body is perpendicular to the base plate (41);
A pair of spline bushes (51) moving along the spline shaft (50) and installed in a straight line at both front and rear ends of the hammer holder (30);
A hollow flange (61) fixed in close contact with the spline bush (51) located at the rear;
A protective tube (60), one end of which is inserted and fixed to the center of the hollow flange (61), and which accommodates the spline shaft (50);
It is installed on the other end of the spline shaft 50 located inside the protection tube 60, and meets the spline bush 51 located at the rear to stop the movement of the hammer holder 30, thereby forming the spline bush 51. Stop ring (53) to prevent separation;
A stopper (62) installed at the other end of the protective tube (60) and having a through hole (63) at the center;
Schmidt hammer guidance device for structural safety diagnosis comprising a. According to clause 1,
A rotating holder (71) that has an open hole (72) into which the spline shaft (50) is inserted and changes its position by rotating around the spline shaft (50);
A handle (70) installed on the rotating holder (71);
A lever bolt (73) that bites the spline shaft (50) by disengaging the open hole (72) or reducing the inner diameter of the open hole (72);
Schmidt hammer guidance device for structural safety diagnosis comprising a. According to clause 1,
The hammer holder (30) is,
A moving clamp (31) having a lower semicircular groove (31g) in close contact with the lower portion of the outer peripheral surface of the Schmidt hammer (20);
An opening/closing clamp (32) having an upper semicircular groove (32g) covering the upper outer peripheral surface of the Schmidt hammer (20);
Dowel (31a) (32a) formed on one side of the moving clamp (31) and the opening/closing clamp (32) and meeting each other in the form of a tenon joint;
A hinge pin (33) installed to penetrate the dowel (31a) (32a) and serving as the center of rotation when opening and closing the opening and closing clamp (32);
A cicada ring (34) installed on the other side of the moving clamp (31);
A latch (35) installed on the other side of the opening and closing clamp (32) and caught by the cicada hook (34);
Schmidt hammer guidance device for structural safety diagnosis comprising a. According to clause 3,
A pin head (36) formed at one end of the hinge pin (33) and having a press-fit hole (36h) at the center;
a buffer spacer (37) positioned between the recording paper cover (21) of the Schmidt hammer (20) and the pin head (36);
a boss (37b) formed at the center of the other end of the buffer spacer (37) and inserted into the press-fit hole (36h);
Schmidt hammer guidance device for structural safety diagnosis comprising a.

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