JP2001337020A - Bending tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bending tester capable of always obtaining an accurate test result without causing a slip between a test piece and a fulcrum steel panel even in the case of a long-span test or a test piece with a large bending distortion quantity. SOLUTION: Respective fulcrum steel panels 6a, 6b are divided into upper members 62a, 62b having support surfaces S for supporting the test piece W from the under surface thereof and lower members 61a, 61b supported in a freely revolvable manner by fulcrums 5a, 5b and the upper members 62a, 62b are supported so as to be movable in a span direction with respect to the lower members 61a, 61b to allow the upper members 62a, 62b to move so as to follow the approach of a support position due to the fulcrum steel panels 6a, 6b accompanying the bending of the test piece W to approach mutually to prevent the occurrence of a slip between the test piece W and the fulcrum steel panels 6a, 6b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending test apparatus, and more particularly to a bending test apparatus suitable for performing a test over a relatively long span or a test piece having a large bending deflection.

[0002]

2. Description of the Related Art In bending test of a test piece, generally,
When two fulcrums are fixed at positions separated by a predetermined distance in the horizontal direction, and the lower surface of the test piece is supported by each of the fulcrums, when three points are bent from the upper surface of the test piece between the two fulcrums. Applies a bending load to the specimen by pressing one punch and, in the case of four-point bending, two punches.

[0003] When the test piece is, for example, plywood, a fulcrum steel plate having a flat surface formed in contact with the lower surface of the test piece is interposed between each fulcrum and the test piece. By pivotally supporting each fulcrum about an axis perpendicular to the direction of separation between the two fulcrums,
It is specified that the bending test is performed while the test piece is always supported by the surface.

FIG. 7 shows an example of the configuration of a main part of a conventional bending test apparatus for performing such a bending test. FIG. 7 shows a case where a three-point bending test is performed, and an apparatus frame (not shown).
Two fulcrums 72 on a fulcrum mount 71 fixed to
a and 72b are attached so as to be adjustable in distance from each other, and a punch 73 attached via a mounting boss 73a to a platen (not shown) displaced in a vertical direction by a vertical movement mechanism is disposed above the a and 72b. . And, each fulcrum 72a, 72b
The supporting steel plates 74a and 74b are respectively supported on the top portions. The top of each of the fulcrums 72a and 72b is an R surface having a ridge line in a direction orthogonal to the paper surface, that is, a direction orthogonal to the direction of separation between the two fulcrums 72a and 72b, and the fulcrum steel plates 74a and 74b are provided on the R surface. In the mounted state, the fulcrum fittings 75a and 75b are loosely engaged with the fulcrum 72a and 72b by the fulcrum fittings 75a and 75b, so that the fulcrum steel plates 74a and 74b are connected to the fulcrums 72a and 72b.
With respect to the horizontal axis (the axis in the direction of the ridge line of the R surface) that is orthogonal to the direction in which the two fulcrums 72a and 72b are separated from each other.

[0005] In the test, a test piece W is placed on the two fulcrum steel plates 74a and 74b in a surface contact state, and the punch 73 is lowered in this state to apply a bending load. When the test piece W is bent by the bending load, the supporting steel plates 74a, 74b
Are rotated (inclined) on the R surfaces of the fulcrums 72a and 72b, so that the test piece W is maintained in a state of being supported in surface contact with the fulcrum steel plates 74a and 74b.

[0006]

By the way, in the conventional bending test apparatus as described above, the fulcrums 72a, 72b
If the distance between them is relatively short, that is, in a test with a relatively short span and the amount of bending deflection of the test piece W is relatively small, there is no particular problem. In the case where the amount of bending deflection of W is large, even if each fulcrum steel plate 74a, 74b rotates following the deflection of the test piece W, slippage occurs between each fulcrum steel plate 74a, 74b and the test piece W. Inevitably, there is a problem that the influence of the friction appears in the test results.

The present invention has been made in view of such circumstances, and even when a long-span test or a test piece has a large amount of flexure, no slip occurs between the test piece and the fulcrum plate. It aims to provide a bending test apparatus that can always obtain accurate test results.

[0008]

In order to achieve the above object, a bending test apparatus according to the present invention is provided with two fulcrums arranged at positions separated from each other by a predetermined distance in the horizontal direction, and A fulcrum steel plate having a test piece support surface on the upper surface is rotatably supported on a horizontal axis orthogonal to the separation direction between the two fulcrums, and one or two fulcrum plates are provided above the fulcrum steel plate. A test is performed by pressing one or two punches against the upper surface of the test piece while the punch is provided so as to be movable in the vertical direction and the test piece is supported from below by the test piece support surface of each of the fulcrum steel plates. In the bending test apparatus for performing a three-point or four-point bending test on a piece, a lower member in which each of the fulcrum steel plates is rotatably supported with respect to the fulcrum, and a test piece support surface that contacts the lower surface of the test piece are formed. Top And a timber, the upper member is characterized by being movably supported in the spacing direction of the two pivot relative to the lower member (claim 1).

Here, in the present invention, when two punches are used to perform a four-point bending test on a test piece, each of the punches is moved with respect to the vertical moving mechanism by the two fulcrums. A punch upper member rotatably supported around a horizontal axis orthogonal to the separation direction, a test piece pressing surface abutting against an upper surface of the test piece, and the punch upper member is It is desirable to have a structure having a punch lower member supported so as to be movable in a direction of separating the two fulcrums (claim 2).

According to the present invention, each of the fulcrum plates contacting and supporting the lower surface of the test piece is provided with both a function of rotating around a horizontal axis orthogonal to the span direction and a function of moving in the span direction. The goal is to achieve the intended purpose.

That is, the fulcrum steel plate is divided into an upper member having a test piece support surface in contact with the test piece and a lower member rotatably supported with respect to the fulcrum. By supporting the upper member movably in the span direction, when the test piece is bent in a long span test or a bending test of a test piece having a large bending deflection, the fulcrum steel plate is turned according to the bending angle of the test piece. Simultaneously, the fulcrum plate moves in accordance with the amount of the support position by the fulcrum plate in the horizontal direction due to the bending of the test piece, and no slip occurs at the contact position between the test piece surface and the fulcrum plate. It is possible to obtain a test result without the influence of friction with the test piece.

In the case of a long span test or a bending test of a test piece having a large bending deflection, the two punches used in the four-point bending test cause slippage between the test piece and the fulcrum plate as described above. The effect of the friction will be included in the test results. Therefore, as in the invention according to claim 2, the two punches used in the four-point bending test are respectively divided into a punch upper member and a punch lower member. The lower part of the punch, which is rotatably supported around the horizontal axis in the same direction as the above and has a test piece pressing surface in contact with the upper surface of the test piece, is movably supported in the span direction with respect to the upper part of the punch. By doing so, the punch rotates as a whole according to the bending angle of the test piece, and at the same time, the punch upper member moves according to the amount of approach of the pressed portion by the punch due to the bending of the test piece, and the test piece and the punch The occurrence of slip at the contact position can be suppressed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing the entire configuration of the embodiment of the present invention, and FIG. 2A is a left side view in which the punch 9 is omitted to avoid complication of the drawing. () Is a left side view of the punch 9.

The portal frame 1 and the auxiliary frames 2a,
A fulcrum mounting beam 3 is fixed to 2b, and two fulcrum mounting stands 4a and 4b are provided on the fulcrum mounting beam 3 so that the distance (span) between them in the horizontal direction can be adjusted. The fulcrum mounts 4a and 4b have fulcrums 5a and 5 respectively.
b is fixed, and each of the fulcrums 5a and 5b has an apex T which has a ridge line in a direction perpendicular to the span direction.
It is formed in a plane or wedge shape. At the tops of the fulcrums 5a and 5b, fulcrum steel plates 6a and 6b are provided so as to be rotatable around axes along the respective ridge lines.

A crosshead 7 that is vertically displaced by a load mechanism (not shown) is supported on the portal frame 1, and a punch mounting beam 8 is fixed to the crosshead 7. I have. A punch 9 for three-point bending is attached to the center of the punch mounting beam 8, and two punches for four-point bending are provided on both sides thereof.
The two punches 10a and 10b are provided so that the distance between them in the horizontal direction can be adjusted.

The left and right fulcrums 5a and 5b and the fulcrum steel plates 6a and 6b have the same structure, and the right side is shown in FIGS. 3 and 4 as an enlarged front view and the right side. FIG. The fulcrum steel plate 6a has a lower member 61a whose lower surface is placed on the top T of the fulcrum 5a,
It is divided into an upper member 62a having a support surface S for supporting the test piece W formed on the upper surface, and the upper member 62a is supported movably in the span direction with respect to the lower member 61a.

That is, the upper member 62a is supported by the lower member 61a via a plurality of stroke bearings 63a that allow only linear movement in the span direction, and the lower member 61a has a plurality of extending members extending in the same direction. A guide bar 64a is provided, and the upper member 62a is moved by the stroke bearing 63 while being guided by the guide bar 64a.
a allows movement in the span direction.

With the lower surface of the lower member 61a placed on the top T of the fulcrum 5a as described above, the movement in the same direction is restricted by the guide plates 65a arranged on both sides of the fulcrum 5a in the ridge direction. In addition, two tension coil springs 66a are interposed between each of the guide plates 65a on both sides thereof and the lower member 61a, and the lower member 61a is moved in the span direction by a total of four tension coil springs 66a. Pulled on both sides. As a result, the lower member 61a is rotatably supported around the horizontal axis along the ridge line of the fulcrum 5a perpendicular to the span direction with respect to the fulcrum 6a, and in the no-load state, the upper member 6a.
The rotational position of the support surface S is elastically restricted so that the support surface S is always substantially horizontal. The above configuration is the left fulcrum 5
The same applies to b and the fulcrum steel plate 6b.

Next, the punches 9, 10a and 10b which move in the vertical direction to apply a bending load to the test piece W will be described. FIG. 5 is an enlarged front view of a main portion near the punch mounting beam 8, and FIG. 6 is a left side view of the punch 10a.

The punch 9 for three-point bending is a roller-shaped member as in the prior art, and is mounted on the punch mounting beam 8 via a punch mounting base 91.

On the other hand, punches 10a and 10b for four-point bending
Have the same structure as each other, and each of the fulcrums 5
a, 5b and fulcrum steel plates 6a, 6b are turned upside down. That is, the punch 10a on the left side will be described as a representative. The punch mounting beam 8 has a shape in which the fulcrum 5a is turned upside down, that is, an R surface or a bottom surface having a downward ridge line in a direction orthogonal to the span direction. A punch fulcrum 100a formed in a wedge shape is mounted via a punch mounting base 11a. Punch fulcrum 10
In FIG. 0a, the punch fulcrum steel plate 101 is rotatable about an axis along the ridge line with the upper surface in line contact with the downward ridge line.
a is supported. And this punch fulcrum steel plate 10
1a is a punch upper member 102a whose upper surface is in line contact with the lower edge of the punch fulcrum 100a, and a punch lower member 103a whose lower surface is formed with a pressing surface P which contacts the test piece W.
The punch lower member 103a is supported movably in the span direction with respect to the punch upper member 102a.

The relationship between the punch upper member 102a and the punch lower member 103a is based on the fulcrum 5a and the fulcrum steel plate 6 described above.
This is exactly the same as the relationship a, and the punch lower member 103a is supported by the punch upper member 102a via a plurality of stroke bearings 104a and a guide bar 105a that allow only linear movement in the span direction.

The relationship between the punch upper member 102a and the punch fulcrum 100a is the same as the relationship between the lower member 61a of the fulcrum steel plate 6a and the fulcrum 5a.
The position of the punch upper member 102a in the direction of the ridge line 0a is
The guide plates 106a are arranged on both sides of the punch fulcrum 100a in the direction of the ridge line.
By means of two tension coil springs 107a interposed between the core member 06a and the punch upper member 102a, the rotational position thereof is elastically regulated so that the upper surface of the punch upper member 102a always extends substantially horizontally in a no-load state. Have been.
The above configuration is exactly the same for the punch fulcrum 100b and the punch fulcrum steel plate 101b on the right side.

In the above embodiment of the present invention, the punch 9 is attached in the case of the three-point bending test, and the punch 9 is detached in the case of the four-point bending test.
The crosshead 7 is lowered while being placed on the supporting surface S of the a and 6b. In any of the tests, when the test piece W bends with the progress of the test, the fulcrum plate 6 depends on the amount of the bend.
a, 6b are rotated (inclined) as a whole to support surface S and test piece W
And the upper members 62a and 62b of the fulcrum steel plates 6a and 6b move closer to each other following the approach of the two support positions of the test piece W due to the bending. I do. Therefore, the test piece W and the fulcrum steel plates 6a, 6
No slippage occurs between b.

In the case of the four-point bending test, 2
When the test piece W is bent by the lowering of the two punches 10a, 10b, the punch fulcrum steel plates 101a, 101a,
The whole of 101b rotates to maintain the close contact with the upper surface of the test piece W, and the punch lower member of each punch fulcrum steel plate 101a follows the approach of two pressing positions of the test piece W due to the bending. 103a and 103b move so as to approach each other. Therefore, the test piece W and the punch fulcrum steel plate 101
No slippage occurs between a and 101b.

In the above embodiment, the lower members 61a and 61b and the upper members 6 of the fulcrum steel plates 6a and 6b are used.
2a, 62a, and the punch fulcrum steel plate 101a,
Although a plurality of stroke bearings 63a or 104a and a plurality of guide bars 64a or 105a are interposed between the punch upper members 102a and 102b and the punch lower members 103a and 103b of 101b, only the stroke bearings may be used. However, in order to withstand a heavy load test under a compact configuration, it is desirable to use both a stroke bearing and a guide bar as in the above example.

[0027]

As described above, according to the present invention, the fulcrum steel plate which comes into surface contact with the test piece disposed between the two fulcrums and the test piece in the bending test apparatus is brought into close contact with the test piece. The upper member having a surface is divided into a lower member rotatably supported with respect to a fulcrum, and the upper member is supported movably in the span direction with respect to the lower member. Test and test piece with large bending deflection
Even in a point or four-point bending test, slippage occurs between the fulcrum steel plate and the test piece as in the past, and the influence of the friction is not included in the test result, so that it is possible to always perform an accurate bending test It became.

The two punches used in the four-point bending test also include a punch lower member having a pressing surface for pressing the test piece and a punch pivot point, as in the second aspect of the present invention. When the punch is divided into a freely supported upper punch member and the lower punch member is movably supported in the span direction with respect to the upper punch member, a four-point bending test over a long span and a large bending deflection of the test piece are performed. In the point bending test, no slip occurs between the punch and the test piece, and the influence of the friction is not included in the test result, so that an accurate four-point bending test can always be performed.

[Brief description of the drawings]

FIG. 1 is a front view showing an overall configuration of an embodiment of the present invention.

FIGS. 2A and 2B are left side views of FIG. 1, in which FIG. 1A is a left side view of the entirety with the punch 9 omitted, and FIG. 2B is a left side view of the punch 9;

FIG. 3 is an enlarged front view of the vicinity of a fulcrum steel plate 6a on the right side according to the embodiment of the present invention.

FIG. 4 is a right side view of FIG. 3;

FIG. 5 is an enlarged front view of a main part near a punch mounting beam 8 according to the embodiment of the present invention.

FIG. 6 is a left side view of the punch 10a in FIG.

FIG. 7 is a diagram showing a configuration example of a main part of a bending test device using a conventional fulcrum steel plate.

[Explanation of symbols]

 1 portal frame 3 fulcrum mounting beam 4a, 4b fulcrum mounting base 5a, 5b fulcrum 6a, 6b fulcrum steel plate 61a, 61b Lower member 62a, 62b Upper member 63a Stroke bearing 64a Guide bar 65a Guide plate 66a Tension coil spring 7 Crosshead 8 Punch mounting beam 9 Punch (for three-point bending) 10a, 10b Punch (for four-point bending) 100a, 100b Punch fulcrum 101a, 101b Punch fulcrum steel plate 102a Punch upper member 103a Punch lower member 104a Stroke bearing 105a Guide bar 106a Guide plate 107a Extension coil spring S Support surface P Press surface

Claims (2)

[Claims] 1. A fulcrum steel plate having two fulcrums disposed horizontally apart from each other by a predetermined distance, and each of the fulcrums having a fulcrum plate having a test piece support surface on an upper surface thereof. Are supported so as to be rotatable about an axis perpendicular to the separation direction, and one or two
One punch is provided movably in the vertical direction, and in a state where the test piece is supported from below by the test piece supporting surface of each of the fulcrum steel plates, the one or two punches are pressed against the upper surface of the test piece, In a bending test apparatus for performing a three-point or four-point bending test on a test piece, a lower member in which each of the fulcrum steel plates is rotatably supported with respect to the fulcrum, and a test piece support surface that abuts on a lower surface of the test piece. A bending test apparatus comprising: a formed upper member; and the upper member is supported by the lower member so as to be movable in a direction in which the two fulcrums are separated from each other. 2. Two punches for performing a four-point bending test on a test piece are each rotatable about a horizontal axis orthogonal to a separating direction of the two fulcrums with respect to a moving mechanism in a vertical direction. A punch upper member supported by the punch and a test piece pressing surface abutting against the upper surface of the test piece are formed, and the punch is movably supported by the punch upper member in a direction in which the two fulcrums are separated from each other. The bending test device according to claim 1, further comprising a lower member.