The device and method that is used for the electric fusion joint disbonded test
Technical field
The present invention relates to a kind of disbonded test method and cover corresponding experimental rig, particularly a kind of device and method for the electric fusion joint disbonded test of checking high strength electric fusion joint adhesion strength and convenient objective quantitative assessment.
Background technology
Polyethylene pipe good toughness, shock resistance, corrosion-resistant, and long service life, operation energy consumption and maintenance cost are low, have obtained increasing application in fields such as oil, chemical industry, municipal administrations.Electric fusion joint is polyethylene pipe one of the most widely used connected mode, also is the weak link of pipe-line system safety.The main failure cause that studies show that electric fusion joint is that the adhesive property of weld interface between tubing and the sleeve does not reach requirement.
Disbonded test is the analog electrical welded joint process of being stripped from effectively, can reflect the joint peeling resistance, is considered to one of effective means of estimating polyvinyl piping materials/electric smelting bellmouth welding quality.ISO13954-1997 Peel decohesion test for PE electrofusion assemblies of nominal outside diameter greater than or equal to 90mm and domestic GB/T 19808-2005 " plastic pipe and the pipe fitting that is equal to it, nominal outside diameter is more than or equal to the stretch release test of the polyethylene electric smelting assembly of 90mm ", be the main reference standard of carrying out the stretch release test at present.Standard describes the stretch release test method in detail: from the test bars that electric fusion joint cuts down, vertically fixing, under the effect of tensile load, sample fusion face is stripped from gradually.
Once effectively peel off require sample along or near losing efficacy on the melting zone plane.But studies show that the power that the solder bond face can bear is higher than the power that sleeve and tubing itself can bear.When therefore the stretch release test method of stipulating according to existing standard detected the high-strength joint welding quality, tubing can rupture before fusion face is by strip off, and very difficult realization is effectively peeled off.Concrete reason is: in the stripping process, sample bears tensile load; Tensile force hour because high-strength joint makes melting zone have very high bulk strength, weld interface can not destroy; Meanwhile, serious flexural deformation and stretcher strain take place in the less relatively tubing of intensity; Tensile load continues to increase, and tubing place polyethylene is compared the polyethylene of welding region and preferentially surrendered, and before be stripped from the fusion plane ductile failure takes place.So conventional disbonded test method can't detect the melting zone quality of high-strength joint.
In addition, the destructive characteristics after existing standard is peeled off by tube wall, pipe wall or fusion face and fragility are peeled off the peel strength that percentage characterizes assembly.On the one hand, the specimen surface destructive characteristics is subject to experimental enviroment and test operation influence, is unfavorable for guaranteeing the degree of accuracy of testing result; On the other hand, fragility is peeled off percentage and is depended on human eye to the subjective judgement of failure mode, is unfavorable for guaranteeing the precision of testing result.Therefore, the disbonded test method according to the existing standard regulation is difficult to develop the peel strength that an objective quantitative target characterizes the electric smelting assembly, has restricted the further popularization of standard.
Along with the development of electric fusion joint technology, detected strength of joint improves constantly, need a kind of at high-strength joint the disbonded test method of effective and convenient objective its adhesion strength of quantitative assessment.But, still do not have the disbonded test method that satisfies above-mentioned requirements both at home and abroad.
Summary of the invention
The technical problem to be solved in the present invention is, overcomes deficiency of the prior art, and a kind of peel test device and method that can be used for checking high-strength joint welding quality and convenient objective quantitative assessment is provided.
Be the technical solution problem, solution of the present invention is:
A kind of device for the electric fusion joint disbonded test is provided, comprises the mechanics cupping machine, also comprise carrying platform, end pressing plate, afterbody pressing plate, detachable connector and chain; The zone line of carrying platform upper surface, end pressing plate lower surface and afterbody pressing plate lower surface all have staggered lines in length and breadth; Be connected by bolt between end pressing plate, afterbody pressing plate and the carrying platform and be used for fixedly sample; Loading plate also is connected with detachable connector by bolt, and detachable connector and cupping machine lower clamp link by pin; Anchor clamps link on one end of chain and the testing machine, and the other end links to each other with towing pad on being located at sample by pin.
As a kind of improvement, have 8 tapped through holes that run through on the described carrying platform, its lower surface has 4 tapped blind holes around the platform center; The end pressing plate has two unthreaded holes that run through, and afterbody presses off four unthreaded holes that run through; Described detachable connector comprises flange and cylindrical seat, and flange has four unthreaded holes at the relative position of four screwed holes of corresponding carrying platform lower surface, and cylindrical seat has horizontal pin-and-hole.
As further goal of the invention, be used for the method for electric fusion joint disbonded test among the present invention, may further comprise the steps:
(1) according to the processing sample that requires of GB/T 19808-2005, then at groove that is deep to the resistive heater upper surface of Surface Machining of sample electric smelting sleeve, to reduce the effective length at place, weld seam composition surface; And offer towing pad at the sleeve elongation end of sample, the center line up and down that is centered close to sleeve of towing pad, and equate with distance between first resistance wire, the sleeve root;
(2) sample is placed on carrying platform central authorities, with the fixing sample tubing extension and prop up the root of sample sleeve of afterbody pressing plate as far as possible; According to the position of towing pad on the length of sample blank area and the sample, determine to clamp behind the position of end pressing plate the joint of sample;
(3) anchor clamps on an end of chain and the testing machine are linked, the other end links to each other with the towing pad of sample by pin;
(4) confirm that sample is fixed, tubing is close to carrying platform, and towing pad center, carrying platform center are all on the central axis of last lower clamp;
(5) disbonded test of beginning sample; In the whole stripping process, external applied load is mainly carried by melting zone perpendicular to weld interface, and the inefficacy of high-strength joint sample is located on or near the welding plane, and tubing and sleeve remain intact, for once effectively peeling off; Stop test, preserve data;
(6) obtain the stretch release energy of whole stripping process by the power-displacement integration at external load function point place, be used for characterizing joint bonding intensity.
Disbonded test method of the present invention is that with the sample horizontal fixed, fusion face is realized effectively peeling off under vertical force by a cover stripping off device, characterizes the adhesion strength of joint by mechanics cupping machine record related data.
Sample of the present invention at groove of Surface Machining of sample sleeve part, is deep to the resistive heater upper surface then according to the requirement processing of GB/T 19808-2005, thereby reduces the effective length at place, weld seam composition surface.
In the peel test device of the present invention, the end pressing plate can be adjusted according to different joint samples with the relative position that the afterbody pressing plate is connected with carrying platform.
The principle of disbonded test method of the present invention is, the mechanics cupping machine vertically acts on joint fusion face by the tensile load that chain applies, because batten is by horizontal fixed firmly, external applied load is mainly born by weld interface.Along with the continuous increase of external applied load, the weld seam indentation, there is opened gradually, and the place tears up to the weld seam composition surface.In the whole stripping process, power and the displacement at external load function point place are recorded.
Now for prior art, beneficial effect of the present invention is:
Utilize the present invention the inefficacy of high-strength joint sample can be guided to or close welding plane, thereby realize effectively peeling off high-strength joint.Be embodied in:
(1) specimen surface open channels is divided into two parts with whole melting zone.The effective length at weld seam faying face place reduces, and intensity reduces, and helps to realize effectively peeling off of high-strength joint sample.The polyethylene of whole melting zone evenly distributes, and axially mechanical property is consistent, and the adhesion strength of Gu Bufenrongrongqu can represent the adhesion strength level of the preceding whole melting zone of fluting;
(2) increase the roughness on apparatus parts surface, can prevent that sample from skidding or hauled out, and strengthened the fixing of sample under the effect of external applied load;
(3) link position of pressing plate and carrying platform can be adjusted, and assurance device is to the applicability of different size high-strength joint sample;
(4) detachable connector links the device main body part with the cupping machine lower clamp, peels off the joint sample by the tensile load of mechanical test machine, greatly facilitates the use of disbonded test method of the present invention;
(5) sample horizontal positioned, two ends firmly are clamped between carrying platform and the pressing plate, can prevent bending, the stretcher strain of sample in the stripping process, thereby avoid the tubing part of sample because of large deformation ductile failure to take place, help to realize effectively peeling off of high-strength joint sample;
(6) whole disbonded test process, external applied load is vertical all the time with the joint release surface, can prevent that on the one hand sample from being hauled out by level, be conducive to the fixing of sample, external applied load is mainly carried by melting zone on the other hand, not only help to realize effectively peeling off of high-strength joint sample, also can get rid of the tubing carrying to the influence of testing result;
(7) the relevant mechanics data of testing machine system log (SYSLOG) have embodied the complexity of peeling off joint sample melting zone, are subjected to such environmental effects less, and do not rely on the subjective judgement of testing crew, can be used for objective quantitative assessment joint bonding intensity.
Description of drawings
Fig. 1 electric fusion joint sample structure schematic diagram;
The carrying platform schematic diagram of Fig. 2 specific embodiment of the invention;
The end pressing plate schematic diagram of Fig. 3 specific embodiment of the invention;
The afterbody pressing plate schematic diagram of Fig. 4 specific embodiment of the invention;
The detachable connector schematic diagram of Fig. 5 specific embodiment of the invention;
The apparatus main body schematic diagram of Fig. 6 specific embodiment of the invention;
The test assembling schematic diagram of Fig. 7 specific embodiment of the invention.
Reference numeral among Fig. 1: electric smelting sleeve 1, resistive heater 2, groove 3, towing pad 4, polyethylene pipe 5, actual stripping area 6;
Reference numeral among Fig. 6: carrying platform 7, end pressing plate 8, packing ring 9, afterbody pressing plate 10, hexagon socket head cap screw 11, detachable connector 12.
The specific embodiment
Sample to be detected: require the sample to be detected make according to GB/T 19808-2005, be deep to the narrow groove 3 of resistive heater 2 upper surfaces in one of the Surface Machining of sample electric smelting sleeve 1, groove 3 is between the 6th and the 7th resistance wire.Sleeve elongation end at sample is offered towing pad, the center line up and down that is centered close to sleeve of towing pad, and equate with distance between first resistance wire, the sleeve root.As Fig. 1.
The carrying platform 7 of peel test device as shown in Figure 2, carrying platform 7 has 8 tapped through holes, lower surface has 4 tapped blind holes around the platform center, the upper surface central area is processed with staggered lines in length and breadth.End pressing plate 8 as shown in Figure 3, end pressing plate 8 has two unthreaded holes, its lower surface is processed with lines.Afterbody pressing plate 10 as shown in Figure 4, afterbody pressing plate 10 has four unthreaded holes, its lower surface is processed with lines.Detachable connector 12 comprises flange and cylindrical seat such as Fig. 5, and flange has four unthreaded holes at the relative position of four screwed holes of corresponding carrying platform 7 lower surfaces, has pin-and-hole on the cylindrical seat.
End pressing plate 8, afterbody pressing plate 10 and detachable connector 12 are connected with carrying platform 7 by hex bolts, the assembling of finishing device main body, as shown in Figure 6.Utilize pin that detachable connector is linked to each other with the mechanics cupping machine, device installs.
In the present embodiment, the disbonded test of electric fusion joint is implemented according to following steps:
(1) sample is placed on the rough region of carrying platform 7 central authorities, with fixing polyethylene pipe 5 extensions of sample of afterbody pressing plate 10, to prop up the root of electric smelting sleeve 1 as far as possible, according to the length of blank area and the position of towing pad 4, determine that the position of end pressing plate 8 clamps the joint of sample, as shown in Figure 7;
(2) end of chain links to each other with sample by pin, and the other end directly connects the last anchor clamps of testing machine;
(3) confirm that the device installation is correct, sample is fixed, input test parameters, beginning disbonded test;
(4) for the sample of Fig. 1 form, the sample welding plane is finally as follows by the basic process of strip off fully: along with the increase that adds tensile load, slight flexural deformation takes place in the sample batten at towing pad 4 places.Then in efficient melting district towing pad one side, open in the gap between electric smelting sleeve 1 and the polyethylene pipe 5, and melting zone begins to be torn.Along with the continuation increase of external applied load, the weld seam breach opens gradually, and electric fuse comes off gradually, and the place tears up to the whole welding line composition surface.In the whole stripping process, external applied load is mainly carried by melting zone perpendicular to weld interface, and the inefficacy of high-strength joint sample is located on or near the welding plane, and polyethylene pipe 5 and electric smelting sleeve 1 remain intact, for once effectively peeling off.Stop test, preserve data;
(5) obtain the stretch release energy of whole stripping process by the power-displacement integration at external load function point place, be used for characterizing joint bonding intensity.
It is also to be noted that what more than enumerate only is specific embodiments of the invention.Obviously, the present invention does not limit above embodiment, and many distortion can also be arranged.Those of ordinary skill in the art can all should think protection scope of the present invention from all distortion that content disclosed by the invention directly derives or contact is expected.