CN105081692A - Machining method for tapered strength structure of oil hole of piston pin of large-powder diesel engine - Google Patents
Machining method for tapered strength structure of oil hole of piston pin of large-powder diesel engine Download PDFInfo
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- CN105081692A CN105081692A CN201510469795.5A CN201510469795A CN105081692A CN 105081692 A CN105081692 A CN 105081692A CN 201510469795 A CN201510469795 A CN 201510469795A CN 105081692 A CN105081692 A CN 105081692A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J1/00—Pistons; Trunk pistons; Plungers
- F16J1/10—Connection to driving members
- F16J1/14—Connection to driving members with connecting-rods, i.e. pivotal connections
- F16J1/16—Connection to driving members with connecting-rods, i.e. pivotal connections with gudgeon-pin; Gudgeon-pins
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
The invention relates to the technical field of piston pins of large-powder diesel engines, in particular to a machining method for a tapered strength structure of an oil hole of a piston pin of a large-powder diesel engine. The method includes the steps that firstly, the oil hole is precisely machined in advance before being carburized, and the margin of an outer circle strengthened layer of the piston pin is reserved; secondly, the piston pin is thoroughly carburized, and the depth of a carburization layer on the outer surface and the diffusion stage are controlled; thirdly, machining is performed, the oil hole is expanded, and the proportion of the smooth transient phase penetration face of a hole opening to the depth of the carburization layer reserved in advance is controlled; and fourthly, quenching is performed, wherein a hardening layer extending from the outer surface of the oil hole is formed in the preset position, and the effective hardening layer starting from a round corner R is kept; the strength is gradually changed along the contour of a chamfer of the round corner R to the inner portion; and after a certain size of a high-strength region is kept, and toughness is in transition to tenacity. By the adoption of the method, a tapered strength layer is obtained by the oil hole structure, high strength and high abrasion resistance of the outer circle of the piston pin are kept, and meanwhile, the hardening layer with the strength and the tenacity gradually changed along the contour of the chamfer in the inner extending direction of the oil hole is obtained.
Description
Technical field
The present invention relates to piston of high power diesel engine pin technical field, especially a kind of processing method of piston of high power diesel engine pin oilhole gradual change type strength structure.
Background technology
Piston of high power diesel engine pin, due to the high request of its military service operating mode, generally has very high surface abrasion resistance, core structure mechanical property and a series of requirement such as processing structure, dimensional accuracy.In use, often there is the problems of serious failure such as Local Cracking in this vitals, its cylindrical position oilhole intersection easily causes stress concentrate and become formation of crack.
Conventional method generally adopts and improves selection, strengthens the structure such as oilhole intersection chamfering or rounding, or adopts carburizing and quenching to obtain local strengthening, and reinforced structure and tenacity effect are as shown in Figure 1, 2.These methods especially drawback: under the material property limit and processing cost limit, chamfering only can be eliminated part stress and concentrate, and strongly limit the nominal power of diesel engine; Quench-hardened case, along the continuity continuity of oilhole surface, unavoidably increases fragility, reduces toughness and plasticity, under high-power alternate load stress concentrates condition, very easily produces quench-hardened case crackle.
Summary of the invention
In order to overcome the deficiency of existing technology, the invention provides a kind of processing method of piston of high power diesel engine pin oilhole gradual change type strength structure.
The technical solution adopted for the present invention to solve the technical problems is: a kind of processing method of piston of high power diesel engine pin oilhole gradual change type strength structure:
Step 1: first carry out pre-fine finishining to the oilhole before carburizing, reserves piston pin cylindrical strengthening layer surplus;
Step 2: comprehensive carburizing is carried out to piston pin, after full case-carbonizing, carburized layer is uniformly distributed along oilhole all outer surfaces, now controls the case depth of outer surface, makes carburized (case) depth reach piston pin depth of penetration technical requirement; Carry out the control of diffusion phase, the cooling in diffusion phase mainly carburizing later stage, the carburizing temperature of more than 900 DEG C is reduced to the tapping temperature of 750-880 DEG C, the time is no less than 30min, carries out carburizing post drop simultaneously; Then follow procedure is carried out to the carburized layer of oilhole periphery rounding profile;
Step 3: machined: the internal diameter of oilhole is expanded, after making processing, oilhole forms aperture rounding off and passes through face mutually, and such face of passing through mutually can reserve certain remaining infiltration layer, and the depth of penetration of its degree of depth and outer round surface keeps certain ratio;
Step 4: quenching: the quench-hardened case forming the continuity of oilhole outer surface in precalculated position, keeps effective quench-hardened case that the fillet R place at piston pin cylindrical and the oilhole place of passing through mutually obtains along the internally intensity gradual change of fillet R rounding profile; After intensity region keeps some scale, tough ratio is excessively leading to toughness.
According to another embodiment of the invention, comprise further, described pass through mutually face depth of penetration be the 0.4-0.8 of outer round surface depth of penetration doubly.
According to another embodiment of the invention, comprise further, the pre-fine finishining degree of depth of described oilhole is that drawing technical requirement specifies the 1.5-4.5 of depth of penetration doubly.
The invention has the beneficial effects as follows, the present invention adopts the technological process of cold and hot Combined process, oil hole structure is made to obtain gradual change strength layer, while piston pin cylindrical keeps high strength, high-wearing feature, oilhole extend inward direction obtain along the gradual change of rounding profile, strength and toughness by become quench-hardened case, can effectively solve the problem.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the present invention is further described.
Fig. 1 is the schematic diagram of the common reinforced structure of piston pin oilhole.
Fig. 2 is that the common reinforced structure of oilhole is from surface to the intensity in heart portion and change in toughness figure.
Fig. 3 is the schematic diagram of gradual change type strength structure of the present invention.
Fig. 4 is that gradual change type strength structure of the present invention is from surface to the intensity in heart portion and change in toughness figure.
In figure 1, oilhole, 2, stress concentrates (inefficacy) point, 3, alternate stress district, 4, quench-hardened case, R, fillet, a, intensity, b, toughness.
Detailed description of the invention
Oil hole machine processing entire flow before carburizing is mainly as follows:
A) rough turn: turning and both ends of the surface φ 110-125 × 200-219, equipment: C630 lathe, regular turning tool;
B) finish turning: turning and both ends of the surface φ 105-123 × 200-215, rounding R1, equipment: CK7525 numerically controlled lathe, regular turning tool, frock: R advises (R0.5--8); Boring central through hole φ 34-38, Common boring cutter, orifice chamfer, frock: φ 35 stop-pass rule (GE84-JE8-01).
C) hole: (it is finally shaping see Fig. 3 in processing excircles hole, the i.e. piston pin oilhole with gradual change type strength structure of this real invention indication): cylindrical bores 12-φ 8-10 hole, normal drill bit, aperture milling fillet R2-4.5, special molding milling cutter, HSV1150 vertical machining centre, transverse holes frock GE84-JE71-21, φ 8-11 stop-pass rule GE84-JE8-03R rule (R0.5--8).
Machined only (indoor, 0-40 DEG C) can need be carried out under normal temperature condition, and the time cycle has no special requirements (completing by normal work step).Above-mentioned for GE84-JE series, other similar frock figure number is identical with above-mentioned processing method with unit type, does not repeat them here.
The present invention adopts the technological process of cold and hot Combined process, makes oil hole structure obtain gradual change strength layer, while piston pin cylindrical keeps high strength, high abrasion, hole extend inward direction obtain along the gradual change of rounding profile, strength and toughness is by the quench-hardened case become.
As follows for obtaining quench-hardened case a kind of processing method of the present invention:
(1) before carburizing, pre-fine finishining is carried out to oilhole, machine-tooled method As mentioned above.
(2) carburizing is carried out to the full surface of piston pin.After completing pre-fine finishining, workpiece is carried out full case-carbonizing: carburizing temperature 900-920 DEG C, carburizing cycle 12-18h, carbon potential 1.0-1.3, equipment: the common well formula with carbon-potential control or case-hardening furnace.
Full case-carbonizing, carburized layer is uniformly distributed along oilhole all outer surfaces, now controls the case depth of outer surface, makes carburized (case) depth reach piston pin depth of penetration technical requirement; Carry out the control of diffusion phase: the tapping temperature carburizing temperature of more than 900 DEG C being reduced to 750-880 DEG C, the time is no less than 30min simultaneously, then carries out carburizing post drop, comes out of the stove.
(3) carburized layer of oilhole periphery rounding R profile is controlled after comprehensive carburizing, by follow-up machined--expand limit and the processing to the oilhole degree of depth along piston pin radial direction, change the residual of carburized layer.
Expand limit technique: equipment: HSV1150 machining center, bore 12-φ 8.5-12 hole, normal drill bit, aperture milling fillet R2-3, profile milling cutter, transverse holes frock GE84-JE71-23, φ 8.5-12 stop-pass rule GE84-JE8-05.
When being expanded by the internal diameter of machined to oilhole, control oilhole mouth rounding off passes through face mutually reserves depth of penetration ratio, depth of penetration ratio is gradual change, the proportion controlling gradual change is: the pre-fine finishining degree of depth of oilhole is that drawing technical requirement specifies the 1.5-4.5 of depth of penetration doubly, with reaming and the deep processing of the follow-up oilhole of carburizing, the remaining carburized layer of hole sidewall keeps at certain size (in the reserved pre-fine finishining degree of depth of oilhole) and is gradually reduced to elimination subsequently.Form aperture rounding off after processing and pass through face mutually, such face of passing through mutually can reserve certain remaining infiltration layer, and the depth of penetration of its degree of depth and outer round surface keeps certain ratio, is 0.4-0.8 times of outer round surface depth of penetration.
(4) quenching process is carried out.Adopt common batch-type furnace or shaft furnace to carry out entirety heating, 800-820 DEG C of insulation 2.5-3.5h, adopts oil quenchinng (overall quenching), 150-250 DEG C of insulation 2.5-4h tempering subsequently.
Specify to require that the piston pin outer round surface that hardens forms the quench-hardened case of outer surface at drawing, keep effective quench-hardened case that rounding R place obtains along the internally intensity gradual change of rounding R profile.Position of hardening after quenching obtains intensity region, as shown in Figure 3.After intensity region keeps some scale (referring to that the 1.5-4.5 of effective depth of hardening doubly), tough ratio is excessively leading to toughness, as shown in Figure 4.
The present invention carries out pre-fine finishining to oilhole before machined, reserves the surplus of cylindrical strengthening layer.And Conventional processing methods oilhole is in the processing of carburizing front portion, or only retain location dimples, size is not limit and is not had depth requirements.Oilhole periphery rounding profile carburized layer of the present invention changes the residual of carburized layer by follow-up processing, like this, can obtain the carburized layer of oilhole week edge rounding profile gradual change, obtain the quench-hardened case of gradual change after quenching.The present invention effectively can solve high-power alternate load condition lower piston pin and be easy to the problems of serious failure such as the Filleted angle on oil hole Local Cracking occurred.
Claims (3)
1. a processing method for piston of high power diesel engine pin oilhole gradual change type strength structure, is characterized in that:
Step 1: first carry out pre-fine finishining to the oilhole before carburizing, reserves piston pin cylindrical strengthening layer surplus;
Step 2: comprehensive carburizing is carried out to piston pin, after full case-carbonizing, carburized layer is uniformly distributed along oilhole all outer surfaces, now controls the case depth of outer surface, makes carburized (case) depth reach piston pin depth of penetration technical requirement; Carry out the control of diffusion phase: the tapping temperature carburizing temperature of more than 900 DEG C being reduced to 750-880 DEG C, the time is no less than 30min simultaneously, carries out carburizing post drop; Then follow procedure is carried out to the carburized layer of oilhole periphery rounding profile;
Step 3: machined: the internal diameter of oilhole is expanded, after making processing, oilhole forms aperture rounding off and passes through face mutually, and such face of passing through mutually can reserve certain remaining infiltration layer, and the depth of penetration of its degree of depth and outer round surface keeps certain ratio;
Step 4: quenching: the quench-hardened case forming the continuity of oilhole outer surface in precalculated position, keeps effective quench-hardened case that the fillet R place at piston pin cylindrical and the oilhole place of passing through mutually obtains along the internally intensity gradual change of fillet R rounding profile; After intensity region keeps some scale, tough ratio is excessively leading to toughness.
2. the processing method of piston of high power diesel engine pin oilhole gradual change type strength structure according to claim 1, is characterized in that, described pass through mutually face depth of penetration be the 0.4-0.8 of outer round surface depth of penetration doubly.
3. the processing method of piston of high power diesel engine pin oilhole gradual change type strength structure according to claim 1, is characterized in that, described some scale refers to that drawing technical requirement specifies the 1.5-4.5 of depth of penetration doubly.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105583083A (en) * | 2015-12-29 | 2016-05-18 | 艾尼科环保技术(安徽)有限公司 | Machining technological method for cathode vibrating and hitting pin wheel pin of electric dust collector |
| CN107825087A (en) * | 2017-12-12 | 2018-03-23 | 盛瑞传动股份有限公司 | A kind of piston pin roughing technique |
| CN107955874A (en) * | 2017-11-22 | 2018-04-24 | 株洲市九洲传动机械设备有限公司 | A kind of axial workpiece and its process for machining equipped with surface selective hardening transition region |
| CN109339971A (en) * | 2018-12-10 | 2019-02-15 | 广西玉柴机器股份有限公司 | Laser hardens main beating cap and its manufacturing method |
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| CN104481719A (en) * | 2014-11-21 | 2015-04-01 | 余姚市舒春机械有限公司 | Cold-extruded high-precision gasoline engine piston pin |
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| EP0269422A2 (en) * | 1986-11-28 | 1988-06-01 | Ford Motor Company Limited | Engine crankshaft |
| CN101358269A (en) * | 2008-09-05 | 2009-02-04 | 潍坊潍柴零部件机械有限公司 | Carburizing quenching pipeline and technique thereof |
| CN102776471A (en) * | 2012-07-10 | 2012-11-14 | 镇江中船设备有限公司 | Carburizing quenching technology for low-carbon alloy steel parts |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105583083A (en) * | 2015-12-29 | 2016-05-18 | 艾尼科环保技术(安徽)有限公司 | Machining technological method for cathode vibrating and hitting pin wheel pin of electric dust collector |
| CN107955874A (en) * | 2017-11-22 | 2018-04-24 | 株洲市九洲传动机械设备有限公司 | A kind of axial workpiece and its process for machining equipped with surface selective hardening transition region |
| CN107825087A (en) * | 2017-12-12 | 2018-03-23 | 盛瑞传动股份有限公司 | A kind of piston pin roughing technique |
| CN109339971A (en) * | 2018-12-10 | 2019-02-15 | 广西玉柴机器股份有限公司 | Laser hardens main beating cap and its manufacturing method |
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| CN105081692B (en) | 2017-07-11 |
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