CN214622449U - Palm tree type blade root ultrasonic flaw detection device of large-scale steam turbine - Google Patents

Abstract

The utility model provides a large-scale steam turbine palm type blade root ultrasonic inspection device, including ultrasonic flaw detector, bimorph probe and test block, be connected through the shielded wire between ultrasonic flaw detector and the bimorph probe, the test block includes straight board section and arc board section, straight board section lower part is equipped with along the arc wall that leads to long setting down along straight board section, even interval is equipped with the blind hole in the arc wall, the face upper portion that straight board section is close to the protection board section is equipped with the through-hole, the arc board section includes that the radius is 100 mm's outer arc board and radius is 50 mm's inner arc board, the thickness of inner arc board is greater than the thickness of outer arc board, just, the cambered surface contained angle of outer arc board and inner arc board is 90. The utility model discloses the cooperation of bimorph probe and test block is used to test, adjustment instrument, definite sensitivity do benefit to and detect the arc blade root.

Description

Palm tree type blade root ultrasonic flaw detection device of large-scale steam turbine

Technical Field

The utility model belongs to the technical field of nondestructive test ultrasonic inspection, concretely relates to large-scale steam turbine palm type blade root ultrasonic inspection device.

Background

Along with the rapid development of science and technology, the capacity of a thermal power generating unit is larger and larger, and a 600-plus-one 1000MW unit is put into operation at present and becomes a main unit of thermal power generation. Along with the increase of the unit, the size of the turbine blade is correspondingly increased as shown in figure 1, the requirement on safety is higher, and therefore the quality control in the manufacturing and service processes of the turbine is stricter.

The turbine blade belongs to a high-speed rotating part, and along with the increase of a unit, the length of the turbine blade can reach more than 1 meter, and the width of the turbine blade also reaches more than 300mm, which is shown in figure 2. The blade roots of the blades bear large alternating stress, torsion and shearing stress in the service process and are easy to generate fatigue cracks. Once a crack is generated in a turbine blade or blade root, the crack length reaches a limit value, which causes the blade root to break and the blade to fly out. After the blade root is broken and flies out, the lighter will knock all the moving and static blades of the machine, and the heavier will cause serious accident of machine damage and death. Therefore, the detection of the turbine blade and the blade root is enhanced.

The blade to be detected of each unit is nearly thousands, the blade root type of the steam turbine is fork type, T type, bacterial type and palm tree type, the palm tree type also has arc shape and straight tooth shape, the blade root width is large, the effective detection surface is small, the purpose of comprehensive detection cannot be adapted according to the conventional ultrasonic detection method, and therefore the requirement of comprehensively detecting the blade root cracks is met by people aiming at the series problem of the palm tree type blade root.

For the detection of the blade root of an installation and in-service inspection unit, the MT is adopted as a common conventional flaw detection method, only surface cracks can be detected, but cracks generated inside cannot be detected, a special probe and a test block are developed to better solve the problem, and a satisfactory effect is achieved through field application.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a large-scale steam turbine palm type blade root ultrasonic inspection device, solve prior art and can only detect the surface crack, then the technical problem that can't detect to the crackle that inside produced.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the utility model provides a large-scale steam turbine palm type blade root ultrasonic inspection device which characterized in that: comprises an ultrasonic flaw detector, a double-crystal probe and a test block. The test block comprises a straight plate section and an arc plate section, the lower part of the straight plate section is provided with an arc groove which is arranged along the straight plate section and along the through length, blind holes are arranged in the arc groove at uniform intervals, the upper part of the surface of the straight plate section, which is close to the arc plate section, is provided with a through hole, the arc plate section comprises an outer arc plate with the radius of 100mm and an inner arc plate with the radius of 50mm, the thickness of the inner arc plate is larger than that of the outer arc plate, and the arc included angles of the outer arc plate and the inner arc plate are 90 degrees.

Further preferably, the shielding line comprises a main line directly connected with the ultrasonic flaw detector, and the end of the main line is connected with the double-crystal probe.

Furthermore, the size of the blind holes is phi 1 multiplied by 6mm, the distance between every two adjacent blind holes is 40mm, and the distance between the first blind hole far away from the arc plate section and the left side plate edge of the straight plate section is 10 mm.

Furthermore, the bimorph probe comprises a rectangular shell, a segmentation layer arranged in the rectangular shell and two piezoelectric wafers with inclination angles, wherein the two piezoelectric wafers are arranged in spaces on two sides of the segmentation layer in parallel.

In addition, the upper right corner of the rectangular shell is an inclined plane parallel to the piezoelectric wafer, and the inclined plane forms a unfilled corner of the rectangular shell.

More preferably, the diameter of the through hole is 10mm, and the distance from the top surface of the straight plate section is 30 mm.

Compared with the prior art the utility model has the following characteristics and beneficial effect:

the utility model relates to a blind hole can reflect the acoustic pressure and draw apart from the amplitude curve, the cambered surface contained angle of outer arc board and inner arc board is 90, utilize outer arc board and inner arc board to carry out the sound journey and mark, the display value that makes the instrument equals with actual sound journey, utilize and carry out the survey of refraction angle to the probe apart from upper surface 30mm phi 10 through-hole, the through-hole sets up in the upper right corner, avoid the influence to phi 1X 6mm blind hole reflection acoustic energy, phi 1X 6mm blind hole reflection acoustic pressure through different distances draws apart from the amplitude curve, with the test, the adjusting instrument, the certainty sensitivity, the straight-through arc groove that adopts R5 is in order to overcome the boundary effect and to ensure that phi 1X 6mm short transverse hole different distance reflection acoustic pressures accord with linear law, whole device is favorable to detecting the arc blade root.

The utility model discloses a bimorph probe include two piezoelectric wafer, therefore the transmission wafer separates with the receipt wafer, has eliminated the reflection between piezoelectric wafer and the delay block, has eliminated organic glass and steel interface effectively and has got the clutter that the reflection caused, again because the initial pulse can not get into the amplifier all the time and enlarge, thereby overcome blocking phenomenon and make the blind area of detecting a flaw reduce greatly and do benefit to and detect near surface defect.

Drawings

Fig. 1 is a schematic structural view of a palm tree type blade root ultrasonic flaw detection device of a large-scale steam turbine of the present invention;

FIG. 2 is a schematic structural view of the twin probe of the present invention;

fig. 3 is a side view of fig. 2.

Reference numerals: 1-ultrasonic flaw detector; 2-a twin crystal probe; 21-a rectangular housing; 22-a split layer; 23-a piezoelectric wafer; 3-test block; 31-straight plate section; 32-arc plate segment; 33-blind holes; 34-a through hole; 35-outer arc plate; 36-inner arc plate; 37-an arc-shaped slot; 4-shielded wire.

Detailed Description

In order to make the technical means, innovative features, objectives and functions realized by the present invention easy to understand, the present invention will be further described below.

The embodiments described herein are specific embodiments of the present invention, and are intended to be illustrative of the concepts of the present invention, which are intended to be illustrative and exemplary, and should not be construed as limiting the scope of the embodiments of the present invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include technical solutions which make any obvious replacement or modification for the embodiments described herein.

An ultrasonic flaw detection device for palm tree type blade roots of a large-scale steam turbine is shown in figure 1 and comprises an ultrasonic flaw detector 1, a bimorph probe 2 and a test block 3, wherein the ultrasonic flaw detector 1 (both an analog machine and a digital machine) is connected with the bimorph probe 2 through a shielding wire 4, the test block 3 comprises a straight plate section 31 and an arc plate section 32, an arc-shaped groove 37 is arranged at the lower part of the straight plate section 31 along the through length, blind holes 33 are uniformly arranged in the arc-shaped groove 37 at intervals, a through hole 34 is arranged at the upper part of the plate surface of the straight plate section 31 close to the arc plate section 32, the arc plate section 32 comprises an outer arc plate 35 with the radius of 100mm and an inner arc plate 36 with the radius of 50mm, and the thickness of the inner arc plate 36 is larger than that of the outer arc plate 35, moreover, the arc surfaces of the outer arc plate 35 and the inner arc plate 36 belong to the same circle center, the included angles are both 90 degrees, the shielding wire 4 comprises one wire which is directly connected with the ultrasonic flaw detector 1, and the end part of the main wire is connected with the bicrystal probe 2. The blind hole 33 size is phi 1 x 6mm (diameter 1mm, degree of depth 6 mm), and adjacent blind hole 33 interval is 40mm, and the first blind hole 33 of keeping away from arc board section 32 is 10mm apart from straight board section 31 left side board along, and the through-hole 34 diameter is 10mm, is 30mm apart from straight board section 31 top surface.

As shown in fig. 2 and 3, the bimorph probe 2 includes a rectangular housing 21, a dividing layer 22 disposed in the rectangular housing 21, and two piezoelectric wafers 23 disposed in parallel in the dividing layer 22, wherein the two piezoelectric wafers are not interfered with each other in the spaces on both sides, the upper right corner of the rectangular housing 21 is an inclined plane parallel to the piezoelectric wafers 23, and the inclined plane forms a notch 24 of the rectangular housing 21.

The prior art is easier to solve straight-tooth blade roots and is difficult to solve arc blade roots, the effective detection distance of the probe is greatly limited, a detection surface can be selected at an exposed part, the size of the part is only about 60-80mm, and a small-angle longitudinal wave probe is needed. Because the blade root is a cambered surface, the inspection of all the blade roots on one side is impossible, the inspection of the whole blade root on two sides is difficult to be comprehensively detected on one side, and the inspection of each side is half of the arc length; in actual detection, although a single-crystal ultrasonic probe can meet the detection requirement, when the probe needs to use a phi 1 multiplied by 6mm blind hole with the thickness of 150 plus 170 mm as a reference sensitivity, a large amount of noise reflection occurs at a position 10-20mm away from the probe, which can affect the detection of cracks on the near surface of a blade root. And because the initial pulse can not enter the amplifier for amplification all the time, the blocking phenomenon is overcome, so that the flaw detection blind area is greatly reduced, and the detection of the near-surface defect is greatly facilitated. In addition, the two piezoelectric chips form a diamond area, which is beneficial to detecting near-surface defects, the near field can only change a conventional longitudinal wave probe into a small-angle longitudinal wave probe with 6-10 degrees, and the focusing point f of the probe is 10-15 mm. Since the ultrasonic wave is emitted by an elliptic cylinder, the two piezoelectric chips intersect to form a rhombic cylinder abcd (as shown in fig. 2), and the detection sensitivity is highest at the focus f. Since the transmitting wafer is separated from the receiving wafer, the reflection between the piezoelectric wafer and the delay block is eliminated, and the problems are solved, so that after the reflected wave of a blind hole with the diameter of 1 multiplied by 6mm is increased by 14dB by the distance of 175mm, no disordered reflected wave appears on the near surface after the wave is started.

The basic principles and the main features of the invention and the advantages of the invention have been shown and described above, it will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, but that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (6)

1. The utility model provides a large-scale steam turbine palm type blade root ultrasonic inspection device which characterized in that: including ultrasonic flaw detector (1), bimorph probe (2) and test block (3), be connected through shielded wire (4) between ultrasonic flaw detector (1) and bimorph probe (2), test block (3) are including straight plate section (31) and arc plate section (32), straight plate section (31) lower part is equipped with along arc wall (37) that straight plate section (31) set up down along leading to long, even interval is equipped with blind hole (33) in arc wall (37), the face upper portion that straight plate section (31) are close to arc plate section (32) is equipped with through-hole (34), arc plate section (32) are including radius outer arc board (35) that are 100mm and radius are 50 mm's inner arc board (36), inner arc board (36) are thick to be greater than outer arc board (35) and thick, just, the cambered surface contained angle of outer arc board (35) and inner arc board (36) is 90.

2. The ultrasonic flaw detection device for the palm-tree-shaped blade root of the large-scale steam turbine according to claim 1, wherein: the shielding wire (4) comprises a main wire directly connected with the ultrasonic flaw detector (1), and the end part of the main wire is connected with the double-crystal probe (2).

3. The ultrasonic flaw detection device for the palm-tree-shaped blade root of the large-scale steam turbine according to claim 1, wherein: the size of the blind holes (33) is phi 1 x 6mm, the distance between every two adjacent blind holes (33) is 40mm, and the first blind hole (33) far away from the arc plate section (32) is 10mm away from the left side plate edge of the straight plate section (31).

4. The ultrasonic flaw detection device for the palm-tree-shaped blade root of the large-scale steam turbine according to claim 1, wherein: the bimorph probe (2) comprises a rectangular shell (21), a segmentation layer (22) arranged in the rectangular shell (21) and two piezoelectric wafers (23) arranged in spaces on two sides of the segmentation layer (22) in parallel.

5. The ultrasonic inspection device for palm-type blade roots of large-scale steam turbines according to claim 4, wherein: the upper right corner of the rectangular shell (21) is an inclined plane parallel to the piezoelectric wafer (23), and the inclined plane forms a unfilled corner (24) of the rectangular shell (21).

6. The ultrasonic flaw detection device for the palm tree type blade root of the large-scale steam turbine according to any one of claims 1 to 5, wherein: the diameter of the through hole (34) is 10mm, and the distance from the top surface of the straight plate section (31) is 30 mm.

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