外文翻譯--礦井提升機繩索的失效分析

1、<p><b>　　外文資料與中文翻譯</b></p><p><b>　　外文資料：</b></p><p>　　FAILURE ANALYSIS OF A MINE HOIST ROPE</p><p>　　Astarte--An extensive investigation was carried out

2、 to determine the cause of the early retirement of an inservicehoist rope. The rope was retired earlier than expected because it met the criteria for removal based on the number and distribution of wire breaks. Its chemi

3、stry, strength and ductility compared favorably to standards for new ropes. Metallography revealed minor anomalies, but these appeared indiscriminately in both the good and the bad segments, and in both broken and unbrok

4、en wires.</p><p>　　1. INTRODUCTION</p><p>　　Wire ropes transmit large axial loads, and exhibit extreme flexibility. In addition, a wire rope is designed so that it can withstand some wire breaks

5、 without a loss of integrity. These characteristics make wire rope a versatile component in many systems. Wire ropes are used in many industries,with applications that include mining, offshore oil production, and towing

6、or mooring of ships. The Albany Research Center has been studying the degradation mechanisms of wire ropes with the goal of more a</p><p>　　2. BACKGROUND</p><p>　　Wire ropes are composed of wire

7、s wound into bundles called "strands", which are then wound into the final rope (Fig. 1). The centermost wire of a strand, known as the king wire, provides support for the wires wrapped around it. One or more l

8、ayers may be wrapped around the king wire to form the strand. The last layer of wires forms the outside of the strand, and, hence, the wires are called outside wires. The number, size and arrangement of wires in a strand

9、, and the number of strands in a rope, </p><p>　　Fig. 1. The three basic components of a wire rope are the wire, the strand, and the core. The wire is a single, continuous length of metal that is drawn from

10、a rod. The strand is a symmetrically arranged and helically wound assembly of wires. The core is the central member of a wire rope, about which the strands are laid. It can be made of a fiber, a wire strand, or an indepe

11、ndent wire rope. </p><p>　　rope can be wound in either a right or a left helix. Wire rope terminology refers to a right regular lay or left lang lay. The terms right and left refer to the helix of the strand

12、 within the rope, while the lay refers to the relationship between the helix of the wires in the strand and the helix of the strand in the rope. A regular lay rope has the wires in the strand wound in the opposite direct

13、ion to the strands in the rope, whereas a lang lay rope has the wires in the strand and the strands </p><p>　　The wear that occurs within ropes used in mine hoisting operations usually occurs as the result o

14、f one of three types of contact: (1) contact of the outer strands of the rope with an external member, such as a sheave, drum, or layer of rope on the drum, a contact that is often called crown wear; (2) line contact bet

15、ween wires within a single strand or between strands; and (3) point contact between wires within a single strand or between strands. Actual wear of the wires results from the combinat</p><p>　　3. EXPERIMENTA

16、L PROCEDURE </p><p>　　The two rope segments were approximately 10 ft in leng.The bad segment contained numerous breaks, and was in the vicinity of the location requiring retirement. The good segment containe

17、d no breaks, and came from the dead wrap on the drum (Fig. 4). During service, the bad segment of the rope experienced cyclic bending stresses from both the head sheave and the drum, as well as varying tensile stress fro

18、m the weight of the rope and the counterweight. The good segment of the rope experienced some t</p><p>　　All wires were disassembled and labeled by rope segment, layer (outside strands = layer 1 to core = la

19、yer 5), strand, and wire position, as shown in Fig. 5. Broken wires were only found in the bad rope segment. In this segment, all breaks were contained within two outside layer strands, and one strand from the third laye

20、r. These three strands also contained the construction anomaly referred to as a "dive". These were named dives because, while visually following outside wires around a strand, it</p><p>　　During a

21、dive, a king wire and an outside wire physically change position within the strand. This presented a difficulty in labeling the wires and performing statistical comparisons. For labeling purposes, king wires were initial

22、ly identified by strand position referenced to one end of the rope segment. However, many of the planned evaluations were based on groupings of nominally identical wires. Therefore, for analyses, both king and outside wi

23、res were determined solely by diameter. Implicit in</p><p>　　The chemistry of all groups of wires in the rope segments were examined. Since the alloying composition of a wire can have a large affect on the m

24、echanical response, (1) the alloying composition of broken and unbroken wires in the bad segment were evaluated for significant differences, and (2)the overall alloying composition of each individual layer was evaluated.

25、 The alloying composition of the good segment was assumed to be identical to that of the bad segment: therefore, chemical analyses of </p><p>　　Fig. 3. (a) Abrasive wear is commonly seen as the principal mod

26、e of damage in wires that are exposed to external surfaces. (b) Fretting results from the relative motion between wires, such as is seen at nicks. Fracture craters due to delamination are present. Some material has been

27、extruded from the area of contact.</p><p>　　same steel heat. Therefore, t,he chemistry of the king wires was evaluated separately from the outside wires. The following elements were determined: carbon, sulfu

28、r, silicon, phosphorus, manganese, chromium and nickel. Carbon and sulfur were determined by gas analysis, and silicon, manganese, phosphorus and chromium by wet chemistry methods. In order to obtain a statistical repres

29、entation of the alloying composition, multiple samples from each layer were analyzed. The results are reported in Tab</p><p>　　Torsion tests were performed according to the American Petroleum Institute (API)

30、 Specification for Wire Rope [3]. Table 2 lists the requirements for the minimum number of torsions (i.e. the number of twists to failure) to be attained by wires made out of electric furnace steel after fabrication into

31、 wire rope. In addition to the API requirements for minimum torsions, Table 2 also lists the average number of experimentally determined torsions for wires in the good segment and the bad segment, and</p><p>

32、;　　Fig. 4. Schematic of hoisting operation. The rope in question came from the counterweight of a double drumhoist. The segment requiring removal was at the location marked "bad" section. The comparison sample(

33、"good" segment) came from the dead wraps on the drum.</p><p>　　torsions drops to 30% of the initial reference value, and recommend that ropes be retired when the number of torsions drops below 15%

34、[4].</p><p>　　Tensile tests were performed according to the API Specification for Wire Rope [3]. Table 3 lists the requirements for the average minimum breaking strength to be attained by wires made out of e

35、lectric furnace steel after fabrication into wire rope. In addition to the API requirements for minimum tensile strength, Table 3 also lists the experimentally determined average breaking strength for wires in the good s

36、egment, the bad segment, and broken wires in the bad segment ()?GOOD, XBAD, "~BROKEN, r</p><p>　　Metallographic and fractographic investigations were carried out in order to identify the cause(s) of fai

37、lure of individual wires. For the metallographic investigation, one outside and one king wire from each strand layer of both the good and the bad segments were evaluated in the transverse direction at sites of general we

38、ar, crown wear, and nicks between adjacent strands. These samples</p><p>　　Fig. 5. Construction ofretired hoist rope. Wires in the rope were examined as a function oflayer (outside=layer 1, core = layer 5) a

39、nd strand position (wires 1~5 = outside wires, wire 7 = king wire). Strands in each layer were labeled in a clockwise relationship to strand 1, an arbitrarily chosen reference strand. For illustration purposes, the two s

40、trands from layer 1 that contained wire breaks (strands 2 and 13) are shown.</p><p>　　Fig. 6. Appearance of a dive. A dive is a location where an outside wire and a king wire switch positions in the strand s

41、tructure. White arrows indicate positions where an outside wire moves into the interior of the strand to assume the function of a king wire.</p><p>　　were evaluated for decarburization, cracks, martensite, a

42、nd the appearance of the wear scar. In addition, wires involved with dives were also evaluated.</p><p>　　4. EXPERIMENTAL RESULTS AND DISCUSSION</p><p>　　4.1. Rope construction</p><p&g

43、t;　　The construction anomalies were named dives, and are locations where an outside wire and a king wire switch position in the strand structure. Along the strand axis, the interchange of the two wires will take place ov

44、er a length of several centimeters, and results in a larger than normal strand diameter (Fig. 7). Unusual and unexpected wear and/or deformation will take place between the wires within the strand. In some cases, as also

45、 shown in Fig. 7, this is observed as deep nicks (gouges). In ot</p><p>　　During disassembly, 12 dives were identified in three different strands in the bad segment. All wire breaks were found in these three

46、 different strands (Figs 9-11), and were often located at or between dives. In contrast, only one dive was found in the good segment (Fig. 12), and there was no associated wire break. In wire rope design, king wires typi

47、cally have a larger diameter than outside wires. Overall, the king wires (wire 7) had a diameter of approximately 2.95 mm, in comparison with </p><p>　　Fig. 7. Dive from layer 1, strand 2. The strand diamete

48、r at the location of the dive is larger than elsewhere, as is shown by the two white arrows. The gouge produced as a result of this expanded diameter is shown by the black arrow.</p><p>　　Fig. 8. Dive from l

49、ayer 1, strand 13. A total of four wire fractures are visible, and two are matching fractures. The location where the king wire switches position and becomes an outside wire is at the location marked "'dive.&quo

50、t; This wire shows extensive flattening and crown wear just prior to its fracture location. The two gray arrows point out differences in the severity of the crown wear. As the location of the dive is approached, the crow

51、n wear of the surrounding wires becomes more severe.</p><p>　　Fig.9. Wire diameters and location of wire breaks for layer 1, strand 2, bad rope segment. The shaded portion of the wire has a significantly lar

52、ger diameter. The bottom illustration shows the relationship of dives and wire breaks in the assembled strand. (Dimensions are in mm.)</p><p>　　2.82 mm for the outside wires. In attempting to group like wire

53、s/sizes, it was found that a continuous king wire could not be identified in strands 2 and 13 from layer 1 as illustrated in Figs 9 and 10 . This, in addition to the difficulty unwinding strands containing dives, suggest

54、s that the anomaly was not created during service.</p><p>　　Fig. 10. Wirc diameters and location of wire breaks for layer 1, strand 13, bad rope segment. The shaded portion of the wire has a significantly la

55、rger diameter. The bottom illustration shows the relationship of dives and wire breaks in the assembled strand. (Dimensions are in mm.)</p><p>　　4.2. Chemical analysis</p><p>　　Wire ropes used i

56、n the United States are not required to meet alloying standards. However, the API does require that the wire be produced from: (1) acid or basic open-hearth, (2) basic oxygen, or (3) electric furnace steelmaking processe

57、s; and that the wire so produced meets certain mechanical property specifications, e.g. breaking strength and torsional requirements, dependent upon the steelmaking process used. Breaking strength and torsional requireme

58、nts are highly dependent on alloying compos</p><p>　　The chemistries of the wires in Table 1 are typical of an electric furnace steel [5]. Residual alloying elements (manganese, chromium and nickel) and impu

59、rities (sulfur and phosphorus) are generally higher in electric furnace steel than in open-hearth or basic oxygen steel. In general, higher levels of alloying elements result in lower ductility and higher strength. This

60、is reflected in the API specifications, where the electric furnace steel has the highest requirement for tensile strength and </p><p>　　A multivariate analysis of the chemical analysis data was performed to

61、determine if differences in chemical composition exist between the different layers of wires. The analysis revealed that there is a significant difference in the chemistries between the first three layers and the two lay

62、ers that comprise the independent wire rope core. The results can be summarized as follows:</p><p>　　(1) Layers 1 3 contain wires with very similar composition, and are probably obtained from the same heat o

63、f steel. Furthermore, the outside wires from layers I-3 were obtained from one heat of steel, and the king wires from the same layers were obtained from another heat. It should be noted that layer 2 appears to be produce

64、d from the same steel heats as layers 1 and 3, yet contains no wire breaks of either king or outside wires.</p><p>　　(2) Layers 4 and 5 have significantly different composition from the first three layers, a

65、nd are probably not obtained from the same heat as layers 1 3.</p><p>　　(3) Layers 4 and 5 differ significantly from each other, and probably do not come from the same heat. Again, the king wires appear to b

66、e from a different heat than the outside wires.</p><p>　　In all, it appears that there are six distinct heats of steel represented in this rope.</p><p>　　Independent of the type of steelmaking p

67、rocess used, one of the primary questions to be addressed is whether the wire material itself is responsible for premature failure of the wires. As can be seen in Table 1, the chemical analyses of broken and unbroken wir

68、es in the bad rope segment are very similar. A multivariate analysis of variance shows no significant difference between the chemistries,with the possible exception of the nickel content of the layer 1 king wires. Althou

69、gh the statistical a</p><p>　　It appears that the steel used for this wire rope came from six distinct heats from an electric furnace. All of the broken wires were found in layers 1 and 3, which would compri

70、se only two of six distinct steelmaking heats identified. No significant difference was found between the broken and unbroken wires. It can, therefore, be concluded that it is highly unlikely that the overall chemistry o

71、f the wires was responsible for the wire breaks.</p><p>　　4.3. Torsion results</p><p>　　For the rope segments examined, the number of torsions may reasonably be expected to be lower than those i

72、n the API specifications, due to fatigue and wear degradation during service. However,as can be seen from Table 2, the torsions generally met or exceeded the AP! specifications. It should be noted that the API specificat

73、ion evaluates the individual torsions, not the averages, whereas Table 2 lists the averages. When individual torsion results are evaluated, more than 90% of outside wires fro</p><p>　　For the rope segments e

74、xamined, the number of torsions may reasonably be expected to be lower than those in the API specifications, due to fatigue and wear degradation during service. However, as can be seen from Table 2, the torsions generall

75、y met or exceeded the AP! specifications. It should be noted that the API specification evaluates the individual torsions, not the averages, whereas Table 2 lists the averages. When individual torsion results are evaluat

76、ed, more than 90% of outside wires fr</p><p>　　(1) The outside wires of a strand experience crown wear and/or trellis contact, a cumulative process that affects the surface quality of the wire and lowers the

77、 overall torsions.</p><p>　　(2) King wires do not experience crown wear or trellis contact, and no appreciable difference in the torsion values was seen.</p><p>　　The torsion test is geared towa

78、rds testing ductility. The API specifications provide for a minimum ductility to be present in a newly fabricated rope. On the other hand, the Ontario Ministry of Labour recommendations provide guidelines for removing a

79、rope based on a decrease in ductility. The initial ductility is primarily a function of the steel chemistry and the wire drawing process. After a rope is put into service, the ductility will change as a function of fatig

80、ue and wear. As can be seen,t</p><p>　　All the torsion results met or exceeded the API requirements for wires removed from newly fabricated wire rope, even though the wires were removed from a used rope. The

81、 number of torsions of wires removed from the good rope segment was significantly greater than for those removed from the bad rope segment, but was limited to the outside wires of a strand. These differences are most lik

82、ely a result of crown wear and/or trellis patterns. There was virtually no difference in the number of torsions </p><p>　　4.4. Tensile results</p><p>　　The breaking strengths listed in Table 3 g

83、enerally do not meet the minimum requirements for wires produced from electric furnace steel. Breaking strength requirements should more accurately be called breaking load requirements because the requirements list the m

84、inimum load-carrying ability of a given diameter wire. Minimum breaking loads will depend on the cross-sectional area as well as the material property known as the ultimate tensile strength. When crown wear and trellis p

85、atterns are presen</p><p>　　The differences in breaking load between the king wires in the good and bad segments for the first three layers was found to be highly significant. An effect similar to this has b

86、een seen by the Bureau of Mines Pittsburgh Research Center when testing rope segments [6]. They have noted that the rope breaking strength may initially increase, and then drop off significantly as the rope approaches th

87、e end of its useful life. For ropes, the initial increase in breaking strength is generally attribute</p><p>　　The tensile test is used to evaluate the minimum strength of the wires. Wires that are not of th

88、e minimum strength run the risk of being overloaded during normal use, and will also have shorter fatigue lives. Signs of overloading, such as ductile cup-cone failures, were not seen. The average strength of the wires i

89、s generally acceptable when compared with the strengths listed for other steelmaking processes. With the exception of results for the broken wires in the outside layer (which appears t</p><p>　　The average b

90、reaking strength of the wires removed from both the good and bad segments failed to meet the minimum API specifications for wires made out of electric furnace steel. With a few exceptions, the average breaking strengths

91、exceeded those required for basic oxygen steel. The loss of strength of broken outside wires from layer 1 is attributed to the presence of crown wear and trellis patterns. King wires showed an unexplained increase in str

92、ength between the good segment and the bad segm</p><p>　　4.5. Metallography</p><p>　　Decarburization was observed on wires from layers 1-3. The full depth of decarburization was approximately 15

93、-20/tm, or a little over 1% of the diameter of the wire. Although decarburization detrimentally affects fatigue, the effect is much smaller in magnitude than that of a surface blemish such as crown wear or trellis contac

94、t. The amount measured should not have a noticeable effect on the fatigue life of the rope [7].</p><p>　　Two types of cracks were observed in the metallographic samples. The first type of crack was radial, l

95、ess than 50 pm, and generally emanated from a surface pit. The pits and cracks appear to ollow the incursion of decarburization into the wire. This is not unexpected since the ferrite resulting rom the decarburization wi

96、ll pit preferentially during the pickling process. Since the cracks appear n almost all of the samples from layers 1 3, regardless of location, it is highly unlikely that the adi</p><p>　　The second type of

97、crack propagated parallel to the surface of the wire, and was located at both rown wear and nick sites. The size and appearance of this type of crack took a variety of forms.At crown wear scars, various degrees of abrasi

98、on were found, many samples having wedge formation nd heavy plastic deformation. Some cracks were seen separating the wedge from the main body of he wire. Smaller cracks often appeared in the middle of the crown wear sit