CN101639430A - Repeated bending testing equipment under constant load and method - Google Patents

Abstract

The invention relates to repeated bending testing equipment under constant load and a method, belonging to the field of detection technique. The equipment comprises a drawing system and a bending system, wherein the drawing system is provided with a second clamping device connected with an elastic device and a drawing loading platform capable of rotating freely so as to realize the purposes of applying constant load to the sample and ensuring that bilateral bending occurs at effective parts; the bending system comprises a bending die, a bending working platform and a sliding groove with special track, realizes the equal-amplitude reciprocating movement of the bending working platform along the sliding groove and drives the sample to occur repeated bending at the arc of the bending die. Theinvention also discloses a testing method for carrying out repeated bending under constant load by the equipment, which can carry out repeated bending performance test under constant load on even materials and materials with welding seams.

Description

Repeated bending test equipment under the permanent load and method

Technical field

The invention belongs to the detection technique field, particularly relate to repeated bending test equipment and method under a kind of permanent load, be used for the compound bending performance test of material under permanent load.

Background technology

Alternating bending test is a kind of important method of evaluating material plastic deformation ability.

Mostly traditional alternating bending test is to adopt fixes an end of sample 94, remainder penetrates in the projection on the rocking arm, wherein rocking arm is fixed on the worktable and can rotates around stationary shaft, arm is shaken in the process of the test transfer makes the bearing bending of sample around predetermined radius, rotate the repeated flex test method of rocking arm more in opposite direction, this method can be measured the plastic deformation ability in the material alternating bending process.

The deficiency of said method is that it only can the bending property of test material under free state.Material usually is the alternating bending of carrying out under loading in the engineering.And under loading, the repeated bending performance of material can change a lot.

Be the compound bending performance of test material under load condition, recently certain methods attempts to load at the sample two ends, for example application number is that 200720074944.9 utility model patent has been described a kind of band steel bend test device, it realizes the alternating bending test of band steel under the load by the acting in conjunction of gravity and spring force.

The deficiency of said method is when bending under the effect of steel band in dancer roll, because being subjected to the length of tension force effect spring can change, the crooked loading is carried in mutual interference mutually in the process of the test with stretching, can not realize the repeated bending performance test under the permanent load.

Summary of the invention

The object of the present invention is to provide the repeated bending test equipment under a kind of permanent load, overcome crooked loading and be carried in the process of the test deficiency of mutual interference mutually with stretching, made alternating bending test can accurately provide the performance of test material under the permanent load condition.Realized: tensile load and bending load can independently load; The tensile load of sample can be set and be changed before test; Sample tensile force in BENDING PROCESS keeps constant.

Equipment of the present invention comprises tensioning system and bending system.Wherein, an end of tensioning system is loaded on the bending table of bending system, and adopts the mode of rotating freely to connect, to realize that sample is positioned on the extended line of the second clamp device bare terminal end all the time in the process of the test.

The present invention, described tensioning system comprises second clamp device that links with elastic device and the stretching loading bench that can rotate freely, and with realization sample is applied permanent load and guarantees that compound bending occurs in active component.Described bending system comprises bending die, bending table and has the chute of special track, realizes bending table along the to-and-fro movement of chute constant amplitude, drives sample alternating bending takes place at bending die circular arc place.

Some B (X on the chute _B, Y _B) satisfy following funtcional relationship with the distance of the mid point O of two bending die circle center line connectings, to realize bending table on the optional position of chute, the suffered tension force of sample is constant:

$X_B=(R-R\cos \mathrm{\θ})+(L-\frac{\mathrm{\π\θ}}{180}R)\·\sin \mathrm{\θ}$

$Y_B=R\sin \mathrm{\θ}+(L-\frac{\mathrm{\π\θ}}{180}R)\·\cos \mathrm{\θ}$

Wherein, R is the bending die radius, and L is the length of sample stretch section behind the imposed load, and the point of contact of sample and bending die is A, and θ is the pairing central angle of circular arc OA.

Tensioning system comprises second clamp device that links with elastic device and the stretching loading bench that can rotate freely, and with realization sample is applied permanent load and guarantees that compound bending occurs in active component.Bending system comprises bending die, bending table and has the chute of special track, realizes bending table along the to-and-fro movement of chute constant amplitude, drives sample alternating bending takes place at bending die circular arc place.

Preferably, an end of tensioning system is loaded on the bending table of bending system, and adopts the mode of rotating freely to connect, so that sample is positioned on the extended line of the second clamp device bare terminal end all the time in the process of the test.

Preferably, chute is the curve of special function relation, so that bending table is on the optional position of chute, the suffered tension force of sample is constant.

Another object of the present invention provides a kind ofly carries out the test method that alternating bending takes place simulation material by above-mentioned bending apparatus under permanent load, it may further comprise the steps:

(1) specimen preparation: measured material is processed into the sample that is fit to length, and the specimen preparation process need guarantee that tested part is positioned at the zone that can be bent the mould bending;

(2) sample is inserted bending die after, an end is fixed with first clamp device;

(3) second clamp devices clamp the other end of sample;

(4) regulate stationary installation, make sample bear required load, locking and fixing device;

(5) promote bending table left and right constant amplitude swing in chute, make sample closely contact, bend with the arc section of bending die;

(6) sample is carried out alternating bending, until satisfying the end of test (EOT) condition, as sample fracture or reach and specify bending number of times etc.

Preferably, described sample is uniform single material.

Preferably, described sample is the material that has weld seam.

Preferably, this method is used for the compound bending performance test of material under permanent load.

Description of drawings

Fig. 1 is the tradition synoptic diagram of bending method repeatedly.Wherein, the projection 92 on bearing 91, the rocking arm, rocking arm 93, sample 94.

Fig. 2 is the synoptic diagram according to the repeated bending test equipment of the embodiment of the invention.Wherein, first clamp device 11, second clamp device 12, elastic device 13, stationary installation 14, stretching loading bench 15, bending die 21, bending table 22, chute 23, sample 94.

Fig. 3 is that chute 23 center line tracks calculate synoptic diagram.

Fig. 4 is the total system parts relative position synoptic diagram when arriving leftward position of the bending table 22 in the repeated bending test equipment of Fig. 2.Wherein, first clamp device 11, second clamp device 12, elastic device 13, stationary installation 14, stretching loading bench 15, bending die 21, bending table 22, chute 23.

Fig. 5 is the total system parts relative position synoptic diagram when arriving right positions of the bending table 22 in the repeated bending test equipment of Fig. 2.First clamp device 11, second clamp device 12, elastic device 13, stationary installation 14, stretching loading bench 15, bending die 21, bending table 22, chute 23, sample 94.

Embodiment

Be described further below in conjunction with accompanying drawing 2:

Alternating bending equipment under the permanent load comprises tensioning system 1 and bending system 2 two parts.

Tensioning system comprises first clamp device 11, second clamp device 12, elastic device 13, stationary installation 14, stretching loading bench 15.

First clamp device 11, second clamp device 12 are separately fixed at the two ends of sample 94.First clamp device 11 is fixed on the matrix, remains static in the process of the test.Second clamp device 12 links by elastic device 13 and stationary installation 14.Elastic device 13 is in the test load scope, and the relation of tension force and elongation satisfies Hooke's law.Stationary installation 14 is installed on the stretching loading bench 15, and stationary installation 14 can move on stretching loading bench 15 upper edge samples 94 length directions, and lockable fixing.After clamp device 11,12 clamped, according to testing requirements, mobile fixture 14 made sample 94 be subjected to the effect of required load F, and in process of the test the position of locking and fixing device 14, keep in the process of the test load constant.Stretching loading bench 15 is fixed on the bending table 22, and can rotate freely on bending table 22.The purpose of rotation is: in carrying out the bending test process, bending table 22 is on any position of chute 23, by rotating freely of stretching loading bench 15, remain on the extended line that sample 94 is positioned at second clamp device, 12 bare terminal ends, guarantee that sample 94 does not bend at the bare terminal end of second clamp device 12.

Bending system comprises bending die 21, bending table 22 and chute 23.

The quantity of bending die 21 is two, lays respectively at the both sides of sample 94, and having radius on it is 1/4 circular arc of R.Bending table 22 can carry stretching loading bench 15 and slide on chute 23.The track of chute 23 makes bending table 22 on any position of chute 23 through particular design, and the suffered tension force of sample 94 is identical.

As mentioned before, under the permanent load situation, when satisfying any position of sample 94 in BENDING PROCESS, suffered tension force is identical, must make that the length L in sample 94 processs of the test is constant.Therefore, the track of chute 23 need pass through particular design.Because chute 23 left and right sides symmetries are calculated for simplifying, and only provide the computing method of chute 23 right side tracks.In Fig. 3, OF is 1/4 circular arc of right lateral bending mould, and C is the center of circle of circular arc.OAB is a bending table 22 when moving to chute 23 right side B points, the state of sample 94.At this moment, the A point is the point of contact of B and circular arc OF.Under loading, the part of sample 94 overlaps with circular arc OA, and another part AB and A point are tangent to the line AC in the center of circle.Definition, the central angle ∠ OCA of circular arc OA correspondence is θ, the O point is an initial point.

At this moment, the track of chute 23 is calculated as follows:

EC＝Rcosθ

EA＝Rsinθ

OE＝R-EC＝R-Rcosθ

The length of circular arc OA, $\mathrm{OA}=\frac{\mathrm{\π\θ}}{180}R$

$\mathrm{AB}=L-\frac{\mathrm{\π\θ}}{180}R$

∠ABD＝∠CAD＝∠OCA＝θ

$\mathrm{AD}=\mathrm{AB}\·\sin \mathrm{\θ}=(L-\frac{\mathrm{\π\θ}}{180}R)\·\sin \mathrm{\θ}$

$\mathrm{DB}=\mathrm{AB}\·\cos \mathrm{\θ}=(L-\frac{\mathrm{\π\θ}}{180}R)\·\cos \mathrm{\θ}$

The B point coordinate:

$X_B=\mathrm{OE}+\mathrm{AD}=(R-R\cos \mathrm{\θ})+(L-\frac{\mathrm{\π\θ}}{180}R)\·\sin \mathrm{\θ}$

$Y_B=\mathrm{EA}+\mathrm{DB}=R\sin \mathrm{\θ}+(L-\frac{\mathrm{\π\θ}}{180}R)\·\cos \mathrm{\θ}$

Therefore, the some B coordinate on the chute center line need satisfy X _B, Y _B

The residing position of entire equipment parts when Fig. 4 and Fig. 5 show bending table 22 respectively and reach leftward position and right positions.

The step of alternating bending test method is under the permanent load described in the invention:

(1) specimen preparation: measured material is processed into the sample 94 that is fit to length, and the specimen preparation process need guarantee that tested part is positioned at the zone that can be bent mould 21 bendings;

(2) with behind the sample 94 insertion bending dies 21, an end is fixing with first clamp device 11;

(3) second clamp devices 12 clamp the other end of sample 94;

(4) regulate stationary installation 14, make sample 94 bear required load, locking and fixing device 14;

(5) promote bending table 22 left and right constant amplitude swing in chute 23, make sample 94 closely contact, bend with the arc section of bending die 21;

(6) sample 94 is carried out alternating bending, until satisfying the end of test (EOT) condition, as sample 94 fractures or reach and specify bending number of times etc.

Equipment of the present invention can be realized even sample and the sample that has a weld seam are detected in the repeated bending performance under the permanent load, when the sample that has weld seam is tested, advantageously, weld seam need be placed can with the contacted zone of crease die 21 arc sections in.

Although described the present invention by example, but what it will be apparent to those skilled in the art that is, the only also unrestricted the present invention for explaination purpose of the present invention of above present embodiment, those skilled in the art can make various modifications, change and replacement under the situation that does not depart from the spirit and scope of the invention that is defined by the following claims.

Claims (7)

1, the repeated bending test equipment under a kind of permanent load comprises tensioning system and bending system; It is characterized in that, one end of tensioning system (1) is loaded on the bending table (22) of bending system (2), and adopt the mode of rotating freely to connect, to realize that sample (94) is positioned on the extended line of second clamp device (12) bare terminal end all the time in the process of the test.

2, equipment as claimed in claim 1, it is characterized in that, described tensioning system (1), comprise second clamp device (12) that links with elastic device (13) and the stretching loading bench (15) that can rotate freely, sample (94) is applied permanent load and guarantees that compound bending occurs in active component with realization.

3, equipment as claimed in claim 3, it is characterized in that, described bending system (2), comprise bending die (21), bending table (22) and have the chute (23) of special track, realize bending table (22) along chute (23) constant amplitude to-and-fro movement, drive sample (94) alternating bending takes place at bending die (21) circular arc place.

4, equipment as claimed in claim 1 is characterized in that, the some B (X on the described chute (23) _B, Y _B) for satisfying the curve of following special function relation, to realize bending table (22) on the optional position of chute, the suffered tension force of sample (94) is constant;

$X_B=(R-R\cos \mathrm{\θ})+(L-\frac{\mathrm{\π\θ}}{180}R)\·\sin \mathrm{\θ}$

$Y_B=R\sin \mathrm{\θ}+(L-\frac{\mathrm{\π\θ}}{180}R)\·\cos \mathrm{\θ}$

Wherein, R is bending die (a 21) radius, and L is the length of sample (94) stretch section behind the imposed load, and sample (94) is A with the point of contact of bending die, and θ is the pairing central angle of circular arc OA.

5, a kind of method that adopts the described equipment of claim 1 to carry out alternating bending test under the permanent load is characterized in that, may further comprise the steps:

(1) specimen preparation: measured material is processed into the sample (94) that is fit to length, and the specimen preparation process need guarantee that tested part is positioned at the zone that is bent mould (21) bending;

(2) with behind sample (94) the insertion bending die (21), an end is fixing with first clamp device (11);

(3) second clamp devices (12) clamp the other end of sample (94);

(4) regulate stationary installation (14), make sample (94) bear required load, again locking and fixing device (14);

(5) promote bending table (22) left and right constant amplitude swing in chute (23), make sample closely contact, bend with the arc section of bending die (21);

(6) sample (94) is carried out alternating bending, until satisfying the end of test (EOT) condition.

6, method as claimed in claim 5 is characterized in that, described sample (94) is uniform single material.

7, method as claimed in claim 5 is characterized in that, described sample (94) is the material that has weld seam.

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