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Drive lost capabilities
Drive lost capabilities Experience in using Novikov gearing in locomotive traction transmissions G.I. MIKHAILOV, leading expert, JSC Research and Design and Technological Institute of Rolling Stock (JSC VNIKTI, Kolomna) (Continuation, beginning see “Lokomotiv” No. 9, 2023) NOVIKOV TRANSMISSIONS ON DIESEL locomotives WITH HYDRO TRANSMISSION According to the Order of the Ministry of Heavy and Transport Engineering (Mintyazhmash), in the early 1960s, work was intensified to improve the reliability of diesel locomotives with hydraulic transmission and, first of all, their traction drives. In this regard, more attention was paid to the introduction of the Novikov transmission on mainline diesel locomotives with hydraulic transmission of the TG102 series produced by the Leningrad (Proletarsky) Diesel Locomotive Plant (LenTZ) and shunting diesel locomotives of the TGMZ (A, B) series of the Lyudinovsky Diesel Locomotive Plant (LTZ). Without waiting for the end of testing of the TEZ diesel locomotive, equipped with experimental chevron gears with Novikov gearing, the All-Union Scientific Research Diesel Locomotive Institute (VNITI) began creating similar gears for diesel locomotives with hydraulic transmissions, primarily for the cargo-passenger diesel locomotive TG102. First, Novikov traction transmissions with the original “VVIA-60” circuit were designed and manufactured. Thus, in 1962, a Novikov traction transmission with one line of engagement (OLZ) appeared for the main two-section eight-axle cargo-passenger diesel locomotive TG102 with a power of 3280 hp, which was accepted for mass production at LenTZ in 1959. Experimental traction transmissions were developed in the hydraulic transmission department of VNITI (work supervisor M.P. Troitskaya). Gears with Novikov gearing (according to drawings PR61-68 and PR61-69) were manufactured at VNITI using hob cutters with the original contour “VVIA-60” on a machine model 5K326. The main parameters of the axial gearboxes (experimental and serial involute) of the TP 02 diesel locomotive are presented in Table. 5. During 1962 - 1963. At LenTZ, six sections of two-section diesel locomotives of the TG102 series (No. YuZA, 012B, 154A, 154B, 156A, 156B) were equipped with experimental axial gearboxes with spur traction gears with Novikov gearing, with the original “VVIA-60” circuit (with OLZ). In Fig. Figure 7 shows the gears and wheels of the experimental transmission. For comparison, one section of the TG102 diesel locomotive (No. 103B) was equipped with gearboxes with serial involute gears. In accordance with the test program No. B-04-62, developed by VNITI together with LenTZ specialists and agreed upon with the Main Directorate of Locomotive Facilities (CT) of the USSR Ministry of Railways, comparative tests of axial gearboxes took place on TG102 diesel locomotives registered at the Leningrad-Sortirovochny-Vitebsky depot, which were in the ordinary operation and used on sections from Leningrad to Pskov, Narva and Luga with freight trains weighing 2800 - 3000 tons at speeds of about 50 km/h and passenger trains with speeds up to 100 km/h. Commission inspections during the initial period of operation were carried out after 5, 30, 50, 100 and 150 thousand kilometers. Further, during lifting repairs of diesel locomotives (after runs of 300 ... 350 thousand km). During four years of operation, the mileage of sections No. 154A, 154B, 156A, 156B and 012B of diesel locomotives TP 02 as of 12/01/1967 amounted to 446058, 508076, 461711, 515524, 315558 km, respectively. During this period, 16 commission inspections of experienced gearboxes were carried out, which provided detailed information about the experienced and standard gearboxes. It turned out that after runs of 30 to 70 thousand km, the contact areas of the gear teeth occupied their entire length and 90 - 100% of the height of their working surface, on which no defects (sagging, scuffing, pitting) were observed. During operation, Novikov's transmissions showed fairly high reliability. After a run of 394,747 km, the gear teeth had an average wear of 0.16 mm, and the wheel teeth had an average wear of 0.06 mm (Fig. 8). It was observed that wear mainly occurs in the initial period by smoothing out the hobbing marks. Then the surfaces of the teeth were hardened due to work hardening, and wear increased slowly. The locomotive's involute transmissions did not work so reliably. Their work was accompanied by various damage to the teeth, including fractures, even with runs within 300 thousand km (Fig. 9). On some involute gears, the hardened teeth had damage in the form of pitting with a depth of 0.5 - 1.0 mm in the middle of the tooth and up to 3 mm at the ends. In addition, systemic flaws appeared in the design of serial axial gearboxes, leading to the destruction of ball and roller bearings, and then gear wheels. This required a threefold modernization of the axial gearboxes with a change in the design of the locking flanges, bearings and bevel gears. After runs from 160 to 260 thousand km in several experimental gearboxes, the bearings of the 32230, 176228, 92328 series were destroyed due to rotation of their inner rings and the hexagon of the torsion bar, as a result of which misalignment of the pinion shaft and contact failure of the bevel gears occurred. As a result, the broken teeth of the bevel gears got into the meshes of the cylindrical gears and damaged them, but in one case - in traction gearbox No. 109 of the section of the diesel locomotive TG102 No. 103A, the breakdown of the teeth of the experimental gear was not associated with the destruction of bearings or any other parts, but due to fatigue fracture, as it turned out during metallographic studies at VNITI. By the time of factory repair at the Daugavpils Locomotive Repair Plant (DLRZ) in 1969, TG102 diesel locomotives had a mileage of about 700 thousand km. By this time, they had 10 axial gearboxes in good condition (out of 24 originally installed), the gears of which were in good condition - the teeth were run-in along the entire length. These gearboxes were sent for further operation. The remaining 14 gearboxes were set aside for reasons such as destruction of bearings 32230, 176228 and subsequent damage to bevel and spur gears (7 gearboxes), wear of the pinion shaft splines (on 4 gearboxes) and fatigue failure of teeth (on cylindrical pairs of 3 gearboxes) . Due to the destruction of the bearings of the input shaft and pinion shaft, 10 gearboxes failed during the tests (within ranges of up to 600 thousand km). With increasing mileage of more than 600 thousand km, cases of excessive wear of spline joints became more frequent (9 gearboxes were discarded), despite the satisfactory condition of Novikov’s cylindrical gears. Due to fatigue damage (chipping, fracture) of Novikov’s spur gears, 5 gearboxes were removed (after runs of 700 - 800 thousand km). After reaching a mileage of 800 thousand km and the need for a second factory repair, in 1971, testing of TG102 diesel locomotives with Novikov gears was completed, since spare gears were not provided for in the test program, and also due to the general low reliability of TG102 diesel locomotives (after several years they began to be taken out of service and written off). In addition to the previous developments of traction gears with Novikov gearing on diesel locomotives TG102, according to the plan of new equipment of the Main Directorate of Diesel Locomotive Construction of the Ministry of Heavy Machinery, work was also launched at the Lyudinovsky plant to create Novikov traction gears for shunting diesel locomotives TGMZ (A, B). Experimental cylindrical gears were manufactured at LTZ according to drawings TGM3.35.27.241 and TGM3.35.10.149, developed by the plant designers with the participation of VNITI specialists. The gears were cut in the same place - with hob cutters of the original VVIA-60 contour. The main parameters of Novikov’s cylindrical gears and standard involute diesel locomotive TGMZ are presented in Table. 6. At LTZ in 1965 - 1967. 48 axial gearboxes on 12 shunting diesel locomotives of the TGMZA series, which were sent to various industrial enterprises in different regions of the USSR, were equipped with axial gearboxes with experimental Novikov cylindrical traction gears. They were tested in routine operation in shunting service modes. In accordance with the previously mentioned program No. B-07-64, commission inspections (visual inspections without measurements) of gears were periodically carried out through open hatches with the wheelsets turning without rolling them out. No comments were identified on the operation of gearboxes on diesel locomotives TGMZA No. 870,1252, 1344. In June 1967, on diesel locomotive TGMZA No. 1287 (with a mileage of only 18 thousand km), gears in three axial gearboxes were damaged. Upon inspection, it was found that two gears had broken teeth, and a crack was found on one. All the teeth of these gears had an influx of metal at the top of the tooth. The contact surfaces are smooth, with small traces of scoring. The driven gears were in satisfactory condition. The type of fracture on all teeth is identical and is characteristic of destruction under the influence of cyclic compressive loads. A similar fracture of the teeth occurred on diesel locomotive TGMZA No. 1377. In the conclusion of the Air Force Engineering Academy (VVIA, authors - lieutenant colonel engineers, candidates of technical sciences R.V. Fedyakin and V.A. Chesnokov, one of the first researchers of the Novikov gearing, authors of dissertations and many publications on this topic) it was stated that: “The nature of destruction, when the tip of the tooth breaks off along a plane making an angle of 45° to the axis of the tooth, indicates that the load on the tooth was concentrated at its tip. In this case, from the compression forces of the tooth, maximum tangential stresses arise precisely in the specified plane, which cause shear and rupture of the metal in a local zone. With subsequent loading, a rupture zone develops, leading to failure. The presence of a ridge at the tip of the tooth confirms that a load has been applied to the tip. Load concentration at the tip of a convex tooth may occur due to manufacturing errors. Namely, when the summation of errors in the center distance and the depth of penetration of the tool gives a displacement of the point of initial contact to the top of the convex tooth. This can happen with a significant reduction in the center distance with correctly manufactured gears, and with a significant reduction in the depth of penetration (of the tool) on the gears with the correct center distance.” With this conclusion, experts emphasized the exceptional importance of maintaining the accuracy of tooth processing and maintaining the center distance for gears with Novikov gearing. At the end of 1968, diesel locomotives produced in 1965 - 1967, equipped with Novikov gears with the VVIA-60 circuit, had mileages from 25 to 99 thousand km. On the gear wheels of two gearboxes of diesel locomotives TGMZA No. 870 and 1422, after runs of 87,683 and 48,800 km, respectively, initial chipping was discovered, concentrated on the tooth heads. On diesel locomotive TGMZ No. 1377, the teeth on the gear shaft broke. By the end of 1969, 12 TGMZA diesel locomotives, equipped with 48 axial gearboxes with Novikov spur gears from OLZ, were in trial operation at various enterprises. The diesel locomotives had mileages from 45 to 160 thousand km, while the experimental gears were in normal condition, which was constantly monitored by the operation services and, periodically, by VNITI employees. Researchers obtained the most complete information when opening gearboxes during factory repairs. There, defects and damage to the gears that arose during the last run were discovered. Thus, during a commission inspection at the DLRZ diesel locomotive TGMZA No. 1513, which since 1967 had been used for heavy shunting work at the Chelyabinsk Metallurgical Plant and had a mileage of about 57 thousand km, it was found that in all four axial gearboxes on seven (out of eight ) bevel gears have cracks on the contact area of the convex side of the teeth, and on one there is plastic deformation of the teeth with metal extrusion onto the tops and ends of the teeth. The bearings of these gears (No. 32230, 92230) were rejected due to scoring of the rings and loosening of the cage rivets. In two gearboxes, the teeth of the Novikov cylindrical gear wheels had plastic deformation. One tooth on the gear was broken (Fig. 10). The crushing of the vertices and the fracture of the teeth were the result of their edge contact, which was in effect from the very beginning of operation, the cause of which was the insufficient depth of penetration of the tool into the workpiece. With correct (precise) execution, gear wheels on other diesel locomotives of the TGMZ series reached mileages of 160 thousand km or more. By mid-1971, diesel locomotives had mileage ranges from 75 to 280 thousand km. More than half of them were within time for factory repair. During the repair of diesel locomotives TGMZA No. 870 and 1252, it was found that Novikov’s cylindrical experimental gears were in satisfactory condition and therefore they were left for further operation. All experimental bevel gears were replaced with new ones due to chipping and broken teeth. In only one gearbox of diesel locomotive TGMZA No. 1383 (after a run of 157948 km), fatigue failure of one tooth occurred on a spur gear shaft (made of steel 40X) at a length of 80 mm (Fig. 11). As further studies showed, the beginning of the fracture (focus) was located at a distance of 40 mm from the end, in the middle of the thickness of the tooth, at a depth of 10 - 12 mm from its top. The directions of the cracks (from inside the tooth with development in both directions at angles of 45° to the middle plane) and the type of fracture were characteristic of failure under the influence of cyclic compressive stresses. Small marks were observed on the working surfaces of the teeth pitting spalling. The hardness of the tooth surface was HB 280 - 300 (HB 291 - 320 according to the drawing). By According to the survey participants, the failure was associated with inaccuracies in cutting the teeth. The gear shaft, together with the mating wheel, was replaced with a new pair from a new experimental batch of Novikov transmission, manufactured with a different circuit - “Ural-2N”. A further development of work on the introduction of Novikov gearing was the use of Novikov cylindrical gears with two lines of engagement (DLZ) in the axial gearboxes of diesel locomotives with hydraulic transfer of the TGMZB series. Based on the experience of operating Novikov gears with OLZ on diesel locomotives TP 02 and TGMZA at the Lyudinovsky plant, a batch of TGMZB diesel locomotives was equipped with axial gearboxes with experimental Novikov cylindrical gears with the original Ural-2N meshing circuit. The qualitative difference between this type of engagement was that when it is used, the head and the leg of each convex-concave tooth alternately work, so the teeth have two contact strips each, and this is equivalent to doubling the number of pairs of teeth that are simultaneously in mesh, due to which these gears can transmit large loads. Technical documentation (calculation, drawings) for Novikov spur gears with DLZ for axial gearboxes of diesel locomotives TGMZ, TGM5, TG16 and TP 02 was developed at VNITI. The main parameters of Novikov's experimental gears with the original Ural-2N contour corresponded to those indicated in the table. 6 (except for the sizes indicated in brackets). The height of the teeth in the Novikov gearing was 16.9 mm, in the involute gear - 21.82 mm. Gears were manufactured according to factory drawings TGM3.35.27.243 and TGM3.35.10.153, adjusted in accordance with the recommendations of VNITI and the Central Research Institute of Mechanical Engineering Technology (TsNIIITMASH). The cutting of the teeth of the experimental gears was carried out on “Module” type machines manufactured in the GDR and 5K326 with hob cutters with the original “Ural-2N” contour, manufactured by the Sverdlovsk Tool Plant. The accuracy of cutting teeth was monitored by the depth of cutter cut using a device consisting of a traverse with an indicator pointer. A comprehensive check of the correct installation of the transmission in the assembled gearbox was controlled by the location of two contact strips observed after the gearboxes were run-in on the running-in stand. 6 TGMZB diesel locomotives (No. 2064, 2070, 2090, 2098, 2126 and 2161) were equipped with experimental gearboxes, which contained 24 axial gearboxes with Novikov spur gears. The diesel locomotives underwent run-in tests on the sections of the Lyudinovo - Dyatkovo, Lyudinovo - Fokino, Lyudinovo - Vereshchevka railway stations with trains weighing from 1000 to 2000 tons. Then they were sent into operation at five industrial enterprises in different regions of the country. After runs of 25 - 45 thousand km, inspections and measurements of the experimental and standard (involute) gears were carried out, which recorded their normal condition and the rapid rate of break-in of the teeth of the experimental gears. The most vulnerable turned out to be bevel involute gears, the teeth of which were subjected to fatigue chipping and cracking (as the researchers assumed, due to grinding burns). Also, violations of the integrity of the shaft fastening and damage to bearings No. 2228 and 228 were revealed due to weakening of their fixation, and in axial cylindrical gears, the most damage was found on the driven wheels, which were subject to replacement due to fatigue cracks and cavities from chipping of teeth, while the gear shafts were rejected , mainly due to spline wear. Total from 1962 to 1969 96 axial gearboxes were manufactured and installed on diesel locomotives of the TG102 and TGMZ series, in which the cylindrical pairs were made with Novikov engagement with a post-polar (“VVIA-60”) or sub-polar (“Ural-2N”) initial circuit. Experimental operation of these diesel locomotives has shown that gears with this tooth shape, even those made of 40X steel with a tooth hardness of no higher than HB 320, have performance and service life no lower than serial involute gears made of 20X2N4A alloy steel. Having received generally positive test results and striving for a more complete use of the advantages of the Novikov gearing in relation to the traction transmissions of diesel locomotives, the designers of the Lyudinovsky plant, together with VNITI specialists, began to develop axial gearboxes with Novikov gears with high-hard cylindrical and bevel gears in order to significantly increase their service life on TGMZ B shunting diesel locomotives equipped with hydraulic transmissions. To do this, we had to solve a number of difficult problems, and the main one was the choice of the optimal initial circuit with DLZ, different from the “Ural-2N”, since this circuit (and the circuit developed on its basis in accordance with GOST 15023-69) was developed specifically for gears low and medium hardness, capable of quickly running in contacting teeth. Gears with high hardness required an initial contour with low sensitivity of the gearing to manufacturing errors, especially tooth deformation during heat treatment, along with a sufficient level of contact and bending strength. Another problem was the low productivity and certain complexity of the known gear cutting methods for forming the teeth of bevel wheels with Novikov gearing. This problem was solved using the recommendations, experience and technical assistance of specialists from the Research and Design Institute of Mining and Processing Engineering (NIPIGORMASH) and the Research and Design Technological Institute for Automation and Mechanization of Mechanical Engineering (NIPTIMASH), who developed under the leadership of Ph.D. Techn., Sciences Yu.F. Coubs are a series of initial contours for Novikov’s polar gears with high tooth hardness and have mastered the new effective technology of gear cutting of Novikov’s bevel wheels using the “Riga” system, created at the Riga Polytechnic Institute (RPI) Ph.D. Techn., Science K.K. Paulins. The work was carried out in accordance with the 1970 plan for new equipment of the Ministry of Heavy Machinery on topic G.70.4.02.019. The design of experimental bevel and cylindrical wheels with DLZ for axial gearboxes of diesel locomotives was carried out on the basis of geometric calculations, based on the principle of complete dimensional interchangeability of experimental wheels with standard (serial) ones, and with them being made of the same steel and with the same heat treatment. The operations of final mechanical processing of the teeth (grinding for cylindrical and lapping for bevel wheels) were not used due to the good running-in of the teeth in the Novikov gear. The geometric calculation of conical pairs was carried out according to the method developed by NIPIGORMASH, the calculation of subpolar cylindrical pairs was carried out according to the method laid down by VNITI in the calculation “R-02-66”. In the latter, three parameters were changed that determine the height of the tooth, which became necessary as a result of the introduction of the new initial contour “Ural-1 K” for Novikov’s pole-axial gears with high tooth hardness. The results of the geometric calculation of Novikov’s bevel and cylindrical gears with the original Ural-1K contour for the axial gearbox of the TGMZ diesel locomotive (Fig. 12) are given in Table. 7 and 8. Based on VNITI calculations, LTZ designers developed drawings of gears TGM3.35.10.401, TGM3.35.27.401, TGM3.35.27.402 and TGM3.35.27.403. The development and design of a hob cutter for cutting Novikov cylindrical gears, as well as a special gear cutting head and cutters with a diameter of 240 mm with an 8 mm module for cutting bevel gears using the Riga system were carried out at NIPIGORMASH with the participation of the author of the system K.K. Paulins. Gear cutting heads of the "Riga" system (according to copyright certificates No. 395194,550247) have great advantages over the heads of the "ENIMS-Glisson" system due to their simplicity and versatility (3 standard sizes of "Riga" heads replace 15 standard sizes of "Glisson" heads), since they are round non-backed cutters are easier than backed ones both in manufacturing and in sharpening. It also eliminates the need for a roughing cutter head, which is mandatory with the Glisson system, and also increases productivity by 15 - 20%. For the first experimental cutting of bevel wheels, four- and eight-cutting heads were used. The adjustment of Riga-type cutting heads, as well as calculations for setting up gear cutting machines, were carried out according to the instructions developed by NIPIGORMASH. Spur gears were manufactured according to LTZ drawings (ÒÃÌ3.35.10.401 “Wheel” and ÒÃÌ3.35.27.401 “Gear Shaft”). The hob cutters of the original Ural-1 K contour were manufactured by the Sverdlovsk Tool Plant. Gear shafts were cut with hob cutters on a “Neils” machine made in the GDR, and gear wheels were cut on a model 5861 machine made by the Moscow Machine Tool Plant. After cutting the teeth, the wheels were heat treated and inspected. The teeth were not ground. Due to the lack of appropriate machine equipment at LTZ, gear cutting of bevel wheels using the “Riga” system was carried out at the NIPIGORMASH pilot plant. At the same time, the cutters and blanks for the wheels were supplied by LTZ. The bevel gears were subjected to heat treatment, final machining and measurements. Control after gear cutting showed that all calculated parameters are carried out in the metal with a sufficient degree of accuracy - the errors in the tooth profile did not exceed 0.05 mm, the contact strips after running in bevel gears on a rolling machine were located in areas close to theoretical, with a deviation of no more than 1, 5 mm. Heat treatment did not significantly change the basic meshing parameters of the experimental gears - the degree of accuracy remained within the limits specified in the drawings. After installing the gearboxes on the test bench, the position of the contact strips was finally checked after running in under a load of 5.5 kN-m (25% of the nominal). Their position remained within specified limits. The testing of gearboxes with Novikov gears was carried out according to a program developed in accordance with the standard TsNIITMASH bench testing methodology, which was used at LTZ for testing diesel locomotive axial gearboxes. After running-in at 25% load (5.5 kN-m), the gearboxes were tested at a nominal torque of 22 kN-m on the wheelset axle. The test duration was set to 107 cycles (revolutions) of bevel and cylindrical gears in both directions of rotation. After 680 thousand cycles, damage was discovered to the bevel gear teeth in the first gearbox (chips of the tops of three teeth on the small end side), which, together with the mating wheel, was replaced with another pair that did not have an overhanging section of the tops of the teeth at the inner end (a possible cause of damage) . However, after 1.2-106 cycles, the damage to the teeth in the first gearbox recurred again. The results of metallographic analysis showed no deviations in the composition of the metal and the quality of heat treatment. It was suggested that a possible reason for chipping the tops of bevel gears is the concentration of contact stresses at the edge of the teeth in the area of engagement from the small end, as evidenced by the presence of a significant collapse and an increased width of the contact patch in this place. This is facilitated by the very high hardness (HRC 60 - 62) of the cemented layer, since the hard brittle layer does not withstand high stresses. Next, Novikov’s hardened cylindrical gears were tested in comparison with serial (octoid) bevel gears with the output shaft loaded initially with a torque of 3.5 kN-m (2.04-107 cycles), and then 4 kN-m (1.18-107 cycles) ), when a tooth fracture occurred on the bevel gear. As a result, Novikov’s cylindrical gears passed bench tests, gaining 7.95-106 wheel and 34.03-106 load cycles for the gear shaft, respectively. The condition of the contact surfaces of the teeth (Fig. 13) was quite satisfactory - smooth, shiny stripes of uniform width, with a clear separation along the pole zone, without any damage to the surfaces. Based on the results of bench tests, the conclusions of the VNITI report recommended structural processing of Novikov conical pairs by increasing the modulus and inclination angle of the teeth, reducing the stress concentration at the ends of the teeth by flanking and reducing the hardness of the tooth surface to HRC 50 - 54. In addition, it was planned to conduct comparative bench tests Novikov cylindrical gears with hardened teeth and serial gears (also with hardened teeth) of diesel locomotives of the TGMZ series. (End to follow) Admin äîáàâèë 10.12.2023 â 17:30 [ U ]G.I. MIKHAILOV, leading expert, JSC "Research and Design-Technological Institute of Rolling Stock" (JSC "VNIKTI", Kolomna)[/ U ] [ I ][ COLOR =" Blue "]Solving complex scientific and technical problems cannot be done with any one simple technical solution without appropriate technological support, deep theoretical and experimental research. This was clearly demonstrated by the experience of introducing Novikov gearing in locomotive traction transmissions in the second half of the 20th century. Its widespread use could provide high load-bearing capacity and durability of gears of traction drives of railway rolling stock, and become the basis for further large-scale work in the field of railway engineering. However, the possibilities of the invention were not fully realized. The history of the traction drive with Novikov gearing, the obtained operating results are in the published material.[/ COLOR ][/ I ] In the mid-1950s, a researcher at the Air Force Academy (VVIA) named after. NOT. Zhukovsky engineer-colonel M.L. Novikov theoretically substantiated and experimentally proved the advantages of the transmission he developed with a new type of gearing (Fig. 1), compared to the well-known cylindrical involute transmission of external gearing. [ CENTER ][ IMG ] http :// morepic . ru / images 3/76998708989008990980_5311_3814. jpg [/ IMG ][/ CENTER ] The peculiarity of the new transmission is that in the section by a plane perpendicular to the axes of the wheels, the line of engagement theoretically turns into a point, and the teeth touch each other only at the moment the profiles pass through this point, and the continuity of the transmission of rotational motion is ensured by the helical shape of the teeth, at which the point their contact moves along a line parallel to the axes of the wheels. The point contact of the teeth makes the transmission less sensitive to shaft misalignment. Since the main type of relative movement of teeth is their rolling along their length, friction losses are significantly less than in involute gearing. In the specified section, tooth profiles with a very small difference in radii of curvature can interact, which, in combination with large radii of curvature of the contacting surfaces in the longitudinal section of the teeth, in reality provides large sizes of the contact patch and, therefore, low specific pressure, favorable lubrication conditions, and also leads to increase in transmitted power by 1.7 - 2 times compared to an involute helical gear. Taking into account these advantages, the Decree of the Council of Ministers of the USSR No. 1170 dated November 9, 1960 instructed all ministries and departments to actively introduce new gear into machines and equipment based on departmental specialization. In response to this call, over the next three years, many developments of transmissions with Novikov gearing for various types of machines appeared. According to some data, by that time more than three hundred organizations were already engaged in mastering Novikov’s programs. In addition to the mentioned VVIA named after. NOT. Zhukovsky, the greatest successes were achieved by the Research Institute "Reductor" (NI Reducer), Novokramatorsky Machine-Building Plant (NKMZ), Elektrostal Heavy Engineering Plant (EZTM), Gorlovka, Donetsk and Aleksandrovsky Mining Equipment Plants, Baku Scientific Research Institute of Petroleum mechanical engineering, Gorky Automobile Plant, Research and Design Institute of Mining and Processing Engineering (NIPIGORMASH) and a number of other enterprises and organizations. In the locomotive industry, work was also launched to equip a number of diesel and electric locomotives (Table 1) with traction gears with Novikov gearing. The published material, consisting of three parts, provides a retrospective of development work on the creation of traction gears for diesel locomotives with electric and hydraulic transmissions and electric locomotives. As in the serial version, single-sided experimental traction transmissions were used on diesel locomotives, and double-sided on electric locomotives. [ B ][ CENTER ] EXPERIMENTAL TRANSMISSIONS WITH NOVIKOV MESHING ON DIESEL LOCOMOTIVES WITH ELECTRIC TRANSMISSION[/ CENTER ][/ B ] At the All-Union Scientific Research Diesel Locomotive Institute (VNITI, now JSC VNIKTI, Kolomna), back in 1956 (the first year of the institute’s functioning), they began to study the properties and determine the effectiveness of using a traction transmission with Novikov gearing in the support-axial drive of a freight truck. diesel locomotive At the same time, several goals were pursued at once - increasing the durability of the transmission; replacement of alloy steels, from which gears with an involute contour were made, with cheaper carbon steels, and, accordingly, simplification of their manufacturing technology due to the abandonment of carburization, hardening and grinding due to the absence of the need for high hardness of the teeth. The first experimental traction transmission with Novikov's engagement with the "VVIA-60" circuit with one line of engagement (OLZ) was designed according to the recommendations of the author himself, M.L. Novikov already at the end of 1956 in relation to the TEZ diesel locomotive drive in the dimensions of a standard involute transmission ( aw = 468.8 mm, bw = 140 mm), with an inclination angle p = 32.6°, an end module m = 10.19 mm. The radius of curvature of the convex tooth was 16 mm, the radius of curvature of the concave tooth was 17 mm. Their thicknesses along the initial circumference were 20 and 12 mm, the pressure angle aG = 25°. To avoid axial forces, the transmission was made of a chevron type, made of normalized steel grade 45 with a hardness of HB 180 ... 200. The teeth were cut with finger cutters on a 5A342 machine at the Kolomna Heavy Machine Tools Plant (KZTS). On a stand with a closed loading loop at VNITI, comparative tests were carried out for the contact strength of a serial spur-toothed involute transmission of a TEZ diesel locomotive (10 mm module, 17 and 75 teeth) and an experimental chevron transmission with Novikov gearing (at a constant speed of the driven shaft 270 rpm, which corresponds to a diesel locomotive speed of 60 km/h). The load (circumferential force on the tooth) increased stepwise from the design value (20.5 kN), the limiting contact strength for involute gears of a given hardness, to the stage of progressive chipping of the teeth, leading to their breakage. The duration of the loading stage was 3–5 million cycles. As a result of bench tests, it was revealed that gears with Novikov gearing (the original “VVIA-60” contour) are 5 times higher in contact strength and 2 times higher in wear resistance than involute gears of similar material and hardness. The bending strength indicators of gears of two types of gears (Novikov and involute) were determined by studying in a polarization installation loaded models of the end profiles of teeth made of optically active material, which showed that the stress at the root of the teeth of gears with Novikov gearing is almost two times lower than that of involute. In addition, the teeth of both gears in the Novikov gear turned out to be of equal strength, while the stress concentration at the root of the involute gear turned out to be significantly higher than that of the wheel. In order to clarify the data on the performance of a chevron traction transmission with Novikov gearing in conditions of instability of the interaxle distance due to wear of the motor-axial bearing (MOB) liners, the effects of dynamic loads, tooth misalignments and elastic deformations of the axle were carried out for two years from July 1960 operational tests of Novikov gears on the TEZ diesel locomotive on the North Caucasus Railway. For this purpose, in June 1960, at the Lugansk Diesel Locomotive Plant (LTZ), two experimental chevron traction transmissions with Novikov gearing (normal module 8.6 mm; 17 and 75 teeth; tooth angle 32.12°; steel 45; tooth hardness NV 200 ... 250) were installed in the wheel-motor unit (WMU) on the two outer wheel pairs (WP) of the three-axle bogie of section “B” of the TEZ-2768 diesel locomotive. The experimental gear was compared in terms of performance with a serial spur involute gear (module 10 mm, 17 and 75 teeth, width 140 mm), in which the gears were made of steel 12Õ2Í4À (teeth hardness HB 500 ... 600), wheels were made of steel 45ÕÍ (hardness teeth HB 450). Serial transmissions were in the remaining four KMB sections of the locomotive. All gears had a center distance of 468.8 mm, a gear ratio of 4.412. Before dispatching the diesel locomotive, measurements were taken of the thickness of the teeth, the diameters of the axle journals and the MOS liners to determine their wear and control the gaps during operation. After three months of operation of the TEZ-2768 diesel locomotive in passenger traffic (on the Derbent - Grozny - Mineralnye Vody section) and reaching a mileage of 37,570 km, at the depot In Grozny, the first visual inspection of the gears was carried out, combined with the ongoing repair of the diesel locomotive. The inspection showed that the teeth of the experimental wheels and gears were run-in along the entire length, their condition was good (Fig. 2), as was the condition of all four serial involute gears. After repairs, the TEZ-2768 diesel locomotive was transferred to the Gudermes depot for driving freight trains on the busy Gudermes-Astrakhan and Gudermes-Nevinnomysskaya sections of the North Caucasus Road. During the operational tests, two more commission inspections of the experimental gears were carried out with the necessary measurements of the tooth thicknesses and MOS clearances. Representatives of VNITI (M.P. Troitskaya, A.P. Manshin), Gudermes depot (V.A. Shtilman, L.P. Kravchenko, P.A. Smolyakov), LTZ (R.M. Roberman, S.M. Nikitin, A.S. Rylin) and VVIA im. NOT. Zhukovsky (engineer-lieutenant colonel V.A. Chesnokov). The completion of operational tests was timed to coincide with the scheduled lifting repair of the diesel locomotive. Testing ended in February 1962 after 299,167 km. During the run, the teeth of the driving gears received 400 million load cycles, the teeth of the driven wheels - 91 million cycles (one revolution is taken per cycle). The latter were in good condition: the contact surfaces were smooth, without signs of fatigue damage, and run-in along the entire length of the teeth (Fig. 3). The drive gears had significant wear on the surfaces of the teeth, reaching sharp points at the tops, and metal tearouts were even observed at some of the tops. In these gears, the gaps in the sliding MOS reached 1.2 mm on one side (from the commutator side) and 1.65 mm on the other (Table 2). The straight-toothed involute wheels of serial design were in satisfactory condition, but on the sixth wheel pair the gear teeth had minor damage on 1/3 of their length, and on the mating driven wheel the teeth had small-scale fatigue chipping on half the length and almost the entire height of the teeth (gaps in the MOS amounted to 0.9 ... 1.0 mm). The wear of the teeth on two experimental gears of the drives of the first and third gearboxes was 4.07 and 4.67 mm, on the wheels - about 1 mm, while the wear of the harder involute teeth (on the fourth and sixth gearboxes) was 0.33 and 0.5 mm on gears and 0.32 and 0.17 mm on wheels. As a result of operational tests of the experimental traction transmission on the TEZ diesel locomotive, three main conclusions were made:
After the completion of the first tests on the TEZ diesel locomotive of prototypes of the Novikov transmission with polar engagement (with the “VVIA-60” circuit), work was launched on further research and improvement of traction transmissions, which led to the implementation of a circuit with two lines of engagement (DLZ). Being one of the modifications of the Novikov gearing, the pre-polar transmission, having two lines of engagement, always has an overlap coefficient of more than 2, which is its clear advantage over the transmission with OLZ. Due to their greater height, gear teeth with DLZ are more pliable, which contributes to their better fit in multi-pair gearing and compensation of profile and pitch errors obtained during manufacturing. For the drives of diesel locomotives TEZ and 2TE10L with an axle distance of 468.8 mm, VNITI designers in 1962 performed calculations and developed drawings of a traction gearbox with a gear ratio of 4.93 (two helical wheels with teeth numbers z? = 16 and z2 = 79, normal module tp = 9 mm, tooth angle p = 23.8°, gear width b = 90 mm). Two versions of gearboxes with different initial contours were provided - “VVIA-60” (OLZ) and “Ural-2N” (DLZ). To carry out bench tests, three gearboxes were manufactured: two with the original “VVIA-60” contour and one with the “Ural-2N” contour, containing gears made of steels 45 and 40X, improved to a hardness of HB 300... 320, without grinding teeth Design options for experimental and serial (involute) gearboxes are presented in Table. 3. To unload from the action of axial forces arising in the engagement of helical wheels, special thrust (ridge) washers made of 38ÕÌÓÀ steel were used, installed on both sides of the gear and closing the axial forces upon themselves when interacting with the ends of the wheel (Fig. 4). The contacting surfaces of the washers and the ends of the wheels were made conical (with an angle of inclination y = 0.5...2°) to better ensure hydrodynamic (fluid) friction. Their contacting surfaces were nitrided to a hardness of HRC 60...62. The washers were placed on the gears using the hot-fitting method (heating in an oil bath to 160 °C) with an interference fit of 0.18 ... 0.20 mm. The manufacture of gears was carried out according to drawings developed at VNITI (E4.00.001. Gear and E4.00.002. Wheel). The cutting of teeth was carried out in the VNITI machine shop on a 5K326 machine (ESZ Komsomolets) using hob cutters with the original VVIA-60 contour, manufactured by the Moscow Tool Plant (MIZ) according to VNITI drawings. Cutting was carried out with a rough milling depth of up to 8 mm, finishing - up to 0.6 mm (with a feed of 0.6 mm/rev, cutting speed of 50 ... 60 m/min), and gear cutting (module 9 mm, 17 teeth) took 9 hours, wheels (79 teeth) - about 20 hours of machine time. Bench tests carried out at VNITI on stand ST51 using a closed loop scheme of two kinematically coupled gearboxes, one of which operates in gearbox mode and the other in multiplier mode, were aimed at obtaining data on the performance of thrust washers when absorbing axial forces in the two most severe modes operation of a diesel locomotive - long-term and starting. After 1.3-107 cycles (for a gear) of testing the gearboxes under the action of a circumferential force of 50 kN (80% of the nominal) on the teeth, the contact surfaces of the thrust washers and teeth were in good condition: the contact area was uniform, on the washers it occupied about 50% working height. Tests at a rated load Rocr = 62.7 kN, corresponding to the long-term load of a diesel locomotive, did not change the state of the contacting surfaces of the thrust washers. In this case, the total contact area was about 80%. The wear of the washers (based on their thickness) was determined by the method of cored conical holes (with the apex angle of the core cone equal to 140°). Despite the significant axial forces (about 43.2 kN) absorbed by the thrust washers, there were no cases of violation of the strength of the thermal fit of the thrust washers. No scoring, sticking or other defects were found. During the entire test period (3.43-107 cycles, equivalent to 113,000 km of diesel locomotive mileage), there was no wear on the thrust washers, although they operated under loads significantly exceeding the operating loads on the diesel locomotive. The wear of the contact surfaces of the end of the gears was no more than 0.1 mm. After testing at rated load for 2.2-106 cycles, initial pitting appeared on the tops of the concave teeth of the experimental wheels, spreading over 50...75% of the length of the teeth. The size of individual pits from chipping on the side of the bearings was 1.5 ... 2.0 mm, and as they moved away from the supports, their size decreased to a barely noticeable size; the rest of the working part of the teeth had a shiny, smooth contact surface. The gears had full contact along the length and height of the teeth, but initial chipping shells were found on the legs of the teeth, forming a chain stretching along one edge from the side of the supports, measuring 2 ... 3 mm, gradually decreasing to points. At the same time, two gears (out of six) on the side of the supports had cavities ranging in size from 5 to 12 mm. After increasing the load (circumferential force) by 25% to almost 80 kN (within 80 hours), metal creep appeared on the gears onto the tops of the teeth, smoothing out the pitting. On the wheel teeth, shells measuring 1.0...1.5 mm were concentrated at the tops of the concave sides of the teeth. At a load of 98 kN (160% of the nominal), the tests lasted for 6.3-106 cycles (counting by gear) at the same low-speed shaft speeds of 50 and 350 rpm. By the end of the tests, the temperature of the gearboxes increased to 80... 98 °C, and the noise and vibration of the housings increased noticeably. Inspection showed that their cause was fatigue chipping of the teeth; the resulting cavities reached significant sizes (Fig. 5), provoking the development of fatigue cracks. In 1965, the testing stage of experimental gearboxes with thrust washers was completed. Based on the results, it was concluded that it is advisable to use thrust washers in a one-way traction gear with Novikov gearing, which made it possible to abandon herringbone gears and thrust bearings, significantly simplify the manufacturing technology and increase the accuracy of gears. It was also concluded that the Novikov helical gear with the original “VVIA-60” contour, with the width of the gears reduced from 140 to 90 mm and the hardness of the teeth NV 290 ... 320, has sufficient contact and bending strength when operating in continuous mode locomotive speed (rocr = 6270 KGS' Msh = 495 KGS'M> - Completion of this stage of work coincided with the issuance of the Order of the State Committee of Heavy, Energy and Transport Engineering under the USSR State Planning Committee dated 04/03/1964 No. 79, in which an assessment was made work carried out in the industry, carried out, in particular, at the Central Research Institute of Mechanical Engineering Technology (TsNIITMASH), NIPIGORMASH, Scientific Research and Design and Technological Institute for Automation and Mechanization of Mechanical Engineering (NIPTIMASH), etc., mainly using the primary source contour "VVIA-60", with polarity gearing (with OLZ). In order to intensify and increase the efficiency of work, it was proposed to move on to the development of Novikov gears with more advanced polar gearing and, before developing a single initial circuit, to develop new gears, use the original Ural-2N circuit developed at NIPIGORMASH. In this regard, the Sverdlovsk Tool Plant (SIZ) was tasked with providing enterprises with cutting tools. Funds were allocated for experimental work, including strengthening the mechanical transmission department of NIPIGORMASH. In accordance with the Order and subsequent recommendations of the Scientific Research and Design and Technological Institute of Mechanical Engineering (NIIPTMASH), work on the Novikov transmission was adjusted towards the development of transmissions with DLZ. Soon, another special Resolution of the State Committee on Science and Technology under the Council of Ministers of the USSR dated 02/03/1966 “On the state and prospects for the introduction of gears with Novikov gearing into the national economy of the USSR” was issued, in which, in order to speed up the obtaining of results, it was recommended to “consider “The most important task is to determine the possibility of effective use of Novikov’s polarity gears with hard tooth surfaces instead of involute gears with hard teeth by producing experimental units based on calculations without mandatory long-term comparative tests.” A response to these documents was a new version of Novikov’s traction transmission with the Ural-2N circuit (DLZ), which was developed and manufactured at VNITI, where the gear (drawing RL233.00.000) was made of 40X steel, and the wheel (drawing RL234. 00.000) made of steel 45. The transmission was intended for the 2TE10L freight diesel locomotive. The parameters of the transmission gears are indicated in table. 4. After preliminary machining, the blanks (forgings) were improved to a hardness of HB 290 ... 320. This was followed by final processing and cutting of teeth with hob cutters (from the SIZ plant) on a 5K326 machine at VNITI. Control of the accuracy of cutting teeth was carried out by the depth of penetration of the tool, and the assembled gear was checked by the location of two contact strips (at distances from 0.3 to 0.5 of the working height of the tooth), which appeared during the running-in of the gear (running in to roll up micro-irregularities) for 20 h. Transmission tests, as before, were carried out on the ST51 stand with a closed loading loop, with loads (in fractions of the circumferential force Rocr and the torque on the Msh gear) in the following modes: > rated load corresponding to the long-term speed of the diesel locomotive and allowed by the contact strength of the teeth (at Rocr = 61.1 kN, Msh = 4.82 kN-m); > load corresponding to the starting moment of the diesel locomotive and the maximum contact strength of the teeth (Pokr = '\.25-RN0M = 76.81 kN, Msh = 6.1 kN-m); > Rocr = 1.6-RN0M = 96.1 kN, Msh = 7.6 kN-m. At each loading mode, 3 pairs of gears were tested with a test base (107 cycles per gear, 2-106 cycles per wheel, respectively). As the test results have shown, gear drives with the Ural-2N circuit (Fig. 6) provide reliable, fatigue-free operation at loads 25% higher than the nominal load, corresponding to the starting moment of the diesel locomotive. Based on the test results, the advantage of the transmission with the Ural-2N circuit was confirmed in terms of load-bearing capacity by 1.25 - 1.3 times and in wear rates compared to the transmission with the VVIA-60 (OLZ) circuit. It was also concluded that the transmission with DLZ provides reliable operation under loads corresponding to moments (Msh) of 6.1 and 4.82 kN-m, but the gear and wheel are not equally strong - the gear could not withstand the load at Msh = 7, 6 kN-m. In this regard, it was recommended to increase the module to 11 - 12 mm; high difference in hardness of gear teeth (with nitriding of teeth) and scaffolding (with improvement), as well as continuation of full-scale bench tests to study the load capacity of Novikov transmission options (with OLZ and DLZ) and serial involute gears. However, further work on Novikov traction transmissions on diesel locomotives with electric transmission was not continued, and by order of the Ministry of Heavy and Transport Engineering they were concentrated on diesel locomotives with hydraulic transmission. |
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