CN100544526C

CN100544526C - Piston manufacturing method

Info

Publication number: CN100544526C
Application number: CNB2003801072172A
Authority: CN
Inventors: C·里贝罗; T·埃格雷尔; R·盖泽
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 2002-11-06
Filing date: 2003-11-05
Publication date: 2009-09-23
Anticipated expiration: 2023-11-05
Also published as: CN101629629A; CN1729718A; CN101629629B

Abstract

A piston particularly adapted for use in heavy duty diesel engines is constructed from separate components having circumferentially extending joining surfaces which are heated to an elevated temperature sufficient to cause them to bond together prior to bonding, and thereafter the joining surfaces are brought into contact with one another and twisted to effect a permanent metallurgical weld at the interface of the joining surfaces.

Description

A kind of method for making piston

Technical field

The present invention relates to the method for a kind of piston and this piston of manufacturing.

Background of invention

Being used in conjunction with the piston each several part that forms separately is known with the whole bag of tricks that produces piston structure.A kind of such method is the friction welding (FW) connection, and wherein piston part presses to cover on another part with high speed rotating simultaneously, and resulting frictional energy produces enough heats and two parts are combined.Other technology comprises resistance welding method, induction heating welding etc., wherein, after two parts are contacted with each other, enables flux and passes composition surface, and this is fully heated it and two surfaces are engaged with each other.

United States Patent (USP) the 5th, 150, No. 517 is an example of friction welding (FW) connection, and United States Patent (USP) is for the 6th, No. 291806 another example of typical induction heating, wherein coil configuration in contact composition surface side with inductive energy, thereby induce heat at the interface.The side of this induction coil disposes a kind of tendency, and near the composition surface zone rate of heat addition the edge of materials of proximity sensing coil is faster than those zones away from coil, thereby the generation hot-fluid changes and heat affected zone in the material area of adjacent interface.In piston needs, high capacity application scenario such as Diesel engine, need provide across welding point uniformly in the heat affected area, interface, so that reduce any variation of the strength of materials and globality as far as possible.

United States Patent (USP) the 6th, 155 discloses a kind of piston No. 157, and this piston has first and second parts, and these two parts engage across the composition surface group that two spaced radials come by the friction welding (FW) connection.As can be seen, this structure shows for engaging two-part challenge by the induction heating welding, this is owing to the approaching of zone for the composition surface place is restricted, and in the situation of internal cooling channel, can not be near position adjacent to any induction coil of the composition surface that cooperates.In the piston field on the basis of known prior art, people also do not know to exist a kind of proper technology that is used for induction heating welding the sort of complicated piston structure as shown in No. 642 patent of above-mentioned ', and, owing to this induction heating technique is applicable to have the practical difficulty of the complicated piston structure of the composition surface that a plurality of spaced radials come, and does not know to use such proper technology.

Beyond heavy piston field, induction heating is used to engage simple structure, for example, and the butt welding metal tube of carrying oil product.This pipeline is that simple single wall is columnar structured, has planar end.For with an end joined in the other end, an induction coil is directed between the both ends of the surface, end face is heated to the temperature of rising, thereafter coil is extracted out, and end face is engaged with each other to form weld seam.When making the end face contact, preferably make it reverse an a small amount of (several years) to obtain the closer combination of face of weld.Surprisingly, the inventor has been found that, up to now the induction heating solder technology that is confined to engage simple single wall cylindrical shape petroleum pipeline can be modified, thereby be successfully used to engage complicated piston structure, realize firm, high globality joint, have evenly and very little heat affected area across the interface of composition surface.

Summary of the invention

According to a first aspect of the present invention, a kind of aspect of making piston comprises first and second parts of making piston, and each part has at least two composition surfaces.Described part is supported with the relation that each interval comes by described surface.When being spaced apart when coming, composition surface is heated to the temperature of a raising, stop heating thereafter, composition surface is contacted with each other cross the metallurgical binding of composition surface with formation.

According to another aspect of the present invention, a kind of method of making piston is provided, and wherein the composition surface of piston first is bearing on the composition surface of piston second portion, when spaced apart with spaced apart relationship, described surface is heated, and it is contacted with each other to form metallurgical binding.

According to another aspect of the present invention, a kind of piston is provided, this piston has first and second parts, these two composition surfaces that are partly with by the cooperation of induction heating welded joint combination, and have the uniform heat affected area of crossing the junction surface.

Advantage of the present invention is that a kind of method of welding the multi-piece type piston simply, cheaply can be provided.

The present invention also has the advantage that a kind of high globality welding point is provided, and contiguous welding point has little and uniform heat affected area.

The present invention also has the advantage of the induction heating method of the heating that a kind of composition surface that can accurately control two-piston part is provided, thereby in the process in conjunction with temperature that composition surface is heated to raising, the composition surface of each piston portion can overheated or underheat.

Another advantage of the present invention is, the composition surface of heating piston portion when each interval comes is compared with the back area of heating surface that is engaged with each other, and the heating on surface is more accurate, even and be controlled.For example, when friction welding, piston has upper and lower bizet, be provided with at the end face of the inside and outside wall portion that the spaced radial of piston portion comes and connect the surface, this must cause outer wall than the relative heating more fully of inwall, this is because outer diameter is bigger, thereby rotates with the angular speed bigger than inwall, thereby produces frictional heat with the speed bigger than inwall.Different with friction welding, according to the present invention, induction heating can accurately be controlled the relative heating of the inside and outside wall of this piston, thereby forms more uniform welded joint between inside and outside wall.

Control can be avoided exceedingly heating outer wall by the heating of the inside and outside wall of the piston of method joint of the present invention, forms annular groove on outer wall, so that compare with friction welding, is controlled at the hot-fluid in the ring belt area better.

Another advantage according to induction heating of the present invention is, compare with friction welding, engage piston portion with induction heating and need lower pressure, in friction welding the required heat of welding be by piston portion under higher relatively compressive load, relatively rotate produce (approximately 1000psi is to 20 of friction welding, 00opsi).Therefore, fixing and support required anchor clamps of the part of induction welding and equipment according to the present invention, to need not to resemble friction welding needed so firm.In addition, because structure needn't be born the sort of weight load that often surpasses suffered load in the piston use in the friction welding, thereby piston structure is more free.Therefore, use the induction heating welding to make the piston each several part thinner, weight is lighter, has saved manufacturing cost, and makes the user of such piston approve fuel oil and discharging usefulness.

Description of drawings

When considering, will be more readily understood above and other features and advantages of the present invention in conjunction with following detailed description and accompanying drawing.

Fig. 1 is the stereogram of the upper and lower parts of welding secondary piston;

The view of Fig. 2 and Fig. 1 is seemingly represented the parts and the heated composition surface thereof that are fixed;

Fig. 3 is the plane graph of employed heater coil among Fig. 2;

Fig. 4 is the cross-sectional figure of Fig. 2 parts;

The view of Fig. 5 and Fig. 2 seemingly moves into the parts that contact with each other and reversed but be illustrated in the heating back;

Fig. 6 is the stereogram of the piston of last processing;

Fig. 7 is the profile along 7-7 line intercepting among Fig. 6;

Fig. 8 is that amplification profile represents that heater coil is arranged to from one of piston element nearer than another parts.

Embodiment

Piston according to preferred embodiment body plan of the present invention is represented with Reference numeral 10 in the accompanying drawings, make by at least two parts, these two parts form independent of one another, at least one group, the best composition surface that cooperates that circumferentially extends of at least two groups are provided, the initial each interval of described composition surface comes, and is heated to the temperature that is enough to welding assembly, thereafter, the heating on surface is terminated, and the surface is engaged with each other to realize the permanent weld between parts.

In the illustrated embodiment, piston 10 comprises first parts 12 and second parts 14.Two parts 12,14th, by metal, preferably made by steel alloy, but, the present invention is not limited to these materials.First and second parts can cast, forge, made or made by any other method that is used to make metal parts by powdered-metal.First and second parts, 12,14 used alloys can be identical or different, and therefore, for the required heating-up temperature of welding first and second parts that realizes material can be identical or different, this depends on the needs of concrete application scenario.

In the illustrated embodiment, first parts 12 comprise the upper crown of piston 10, and second parts 14 are the following bizet of piston 10 among the figure, and with upper-part 12 complementations, thereby when engaging,

parts

12,14 constitute piston 10.

First parts 12 have a upper wall 16, and this upper wall is formed with a burning bowl 18, and can select to be provided with one or more valve pools 20.Burning bowl 18 can be around the longitudinal axis A symmetry of piston 10, and it is asymmetric perhaps can resembling according to concrete application scenario the diagram.Valve pool 22 is asymmetric about lower member 14.In other words, valve pool 20 and burning bowl 18 are formed to such an extent that have certain location or orientation with respect to following parts 14, thereby if non-symmetrical features is formed on the piston 10, the position that makes valve pool 20 and burning bowl 18 is conclusive with respect to the position, angle of lower member 14 for the operation of piston 10.

Upper-part 12 is formed with an annular inner wall 22 and annular outer wall or endless belt 24, and described internal ring wall is in 18 times extension that face down of burning bowl, and described outer wall or endless belt are spaced apart outside radially at inwall 22, and dangles downwards from upper wall 16.Inside and

outside wall

22,24 is formed with

composition surface

26,28 separately near its end or

end.Composition surface

26,28 circumferentially extends, and is preferably continuous, form symmetrically with respect to longitudinal axis A, thereby

composition surface

26,28 is concentric around axis A.

Before being welded on first parts 12 on second parts 14, first parts are preferably processed, what more recommend is finally to process, so that to burning bowl 18, any valve pool 20,

composition surface

26,28 and be arranged on inside and outside wall 22, the 16 annular cooling grooves 30 that extend upwardly to the outside of burning bowl 18 between 24 and from

composition surface

26,28 towards upper wall, and an interior vault 32 that extends within radially at inwall 22 provides the polishing surface.To talk about below, piston 10 is formed with the annular groove on a series of externally endless belt 24, and still, these annular grooves process on piston 10 after being preferably in the joint that will describe.

Second parts 14 of the bottom of piston 10 are formed with pair of pin bosses 34, and described pin hub extends downwards from a neck 36, and are formed with one group along the coaxillay aligned pin-and-hole of pin-and-hole axis B.Neck 36 is formed with an annular inner wall 40 and an annular outer wall 42.Inside and

outside wall

40,42 is formed with

composition surface

44,46 separately, and described composition surface circumferentially extends, and is preferably continuous, aims at the

composition surface

26,28 of the inside and

outside wall

22,24 of the crown part 12 on top respectively and cooperates.As shown in Figure 2, the

composition surface

44,46 of the

composition surface

26,28 of the crown part 12 on top and the crown part 14 of bottom preferably is comprised in separately the common plane, introduces between parts and removes heater coil being convenient to, and this will talk about hereinafter.Though recommend the composition surface on plane to arrange,, the present invention is not limited to this layout, composition surface can be arranged in the different planes, and has multiple shape, as long as these surfaces (for example are fitted to each other, the surface that cooperates is conical, step-like etc.).

Before welding following crown part 14 on the superincumbent crown part 12, preferably following crown part 14 is processed, what more recommend is finally to process, thereby, comprise being located between the inside and

outside wall

40,42 from composition surface 44 at pin hub 38,

neck

36,46 extend downwardly on the cooling groove 48 of a diapire 50 and form finished machined, above-mentioned diapire 50 extends between the lower end of inside and

outside wall

40,42 and connects, and preferably makes it become a member.Below crown part 14 also comprise a piston skirt 52, the structure of this piston skirt and following crown part 14 is made single, not movable structure, and is not fixed on movably on the pin hub 34.Inside and outside surperficial 54,56 of piston skirt 52 is finally processed before welding, and inside and outside surperficial 58,60 of pin hub 34 also is like this.Pin-and-hole 38 also can be by final processing to comprise an annular groove 62, and it is used in piston 10 work a crosshead pin being remained in the pin-and-hole 38.

The

outer wall

24,42 of the

crown part

12,14 of upper and lower part can be adjacent to its free end and be formed with a neck region that radially reduces 64,66, and there is thin cross section in described

neck region

64,66 in the zone of

wall

24,42 near it.According to preferred embodiment, composition surface is formed on neck region 64, on 66 the free end, thereby attachment 12 as shown in Figure 4,, on piston, form a drain pan 68 near pin hub 34 tops, at 14 o'clock respectively at composition surface 26, cross drain pan 68 on 44 and 28,46 the position and form welded joint 70.

Describe welding operation now in detail, Fig. 2 represents the

crown part

12,14 of upper and lower part formation separately, that process in advance, and these two parts are fixed, and its

composition surface

26,28 and 44,46 is separately axially aligned, but each interval come.Heater coil, preferably load coil 72 stretches between the upper and

lower crown part

12,14, and coil 72 is energized with the induction heating composition surface, and it is risen to is enough to make composition surface by the induction heating welded joint temperature of metallurgical binding each other.In case be heated to sufficiently high temperature, heater coil 72 is removed fast, as shown in Figure 4, upper and

lower crown part

12,14 is axially moved each other in opposite directions, make its composition surface separately be enough to consistent each other joint the under the temperature of combination.According to the present invention, the composition surface of inside and outside wall in by the once-through operation of heater coil 72, be heated to simultaneously suitable one in conjunction with temperature or different in conjunction with temperature.Heater coil 72 preferably includes a load coil, when energising, in inside and outside wall, induce electron stream, make the composition surface localized heating to raise in conjunction with temperature, and the influence that most of inside and outside wall material still is not induction heated substantially (that is, not rising to the temperature that causes that material microstructure changes).Therefore, induction heating can produce the heat affected area (HAZ) 74 of well-controlled, and the width that inside and outside wall is crossed in this zone is uniform substantially.

When upper and

lower crown part

12,14 have been heated and when it is contacted with each other, preferably make

parts

12,14 reverse a less relatively amount, so that mix or smear composition surface, so that cross the very high metallurgical binding of globality that weld interface 70 is realized upper and lower crown part.Upper and

lower crown part

12,14 is preferably in the scope intort than the little about 2-4 degree of a commentaries on classics at the scope intort than the little several years of commentaries on classics.Last or down crown part comprise non-symmetrical features, in the situation as the burning bowl 18 of valve pool 20 or biasing, importantly make them suitably directed with respect to pin-and-hole axis B in final piston.Therefore, the position of

crown part

12,14 and anchor clamps will be controlled meticulously, thereby make these features and amount of axis B mis-alignment before joint, thereby make these features enter suitable orientation with respect to pin-and-hole axis B after reversing.

As shown in Figure 6, after welding, on piston 10, finally process, so that in endless belt 24, form a series of annular grooves 76.Annular groove 76 is preferably in drain pan 68 tops, thereby welded joint 70 is arranged in the

outer wall

24,42.

As the result of upper and

lower crown part

12,14 welding, between

crown part

12,14, form the oil duct 78 of sealing, this oil duct is with inside and

outside wall

22,40; 24,42, upper wall 16 and diapire 50 are the boundary, and welded joint is exposed to oil duct 78.

Crown part

12,14 can form or be processed with fuel feeding or the draining passage that enters oil duct 78, and it forms with other above-mentioned final finished surface before being preferably in welding.

As can be seen,, before engaging these surfaces, heat by heater coil 72 owing to

composition surface

26,28 and 44,46th, rather than after engaging these surfaces, heat, thereby can obtain and highly control the direct of composition surface and uniform heating.In the situation that Fig. 8 represents, owing to different materials, geometry etc., if the equidistant setting of each composition surface on coil and each set of bond surface, so, the composition surface of upper and lower crown part can evenly not heated.In example shown in Figure 8, the

composition surface

26,28 of last crown part 12 needs bigger, stronger heating than the composition surface of following crown part, thereby induction coil 72 is towards

composition surface

26,28 biasings or skew are so that relatively more close last crown part but not following crown part.Like this, in addition when different or parts in conjunction with temperature of two parts more multipotency is to reach certain during in conjunction with temperature than another parts needs, can guaranteeing also that the composition surface that cooperates suitably is heated to, they are required separately in conjunction with temperature.By towards the parts, the parts moving coil 72 that deviates from the less heating of needs that need more add heat, can reach suitable equilbrium position, so that minimizing is in conjunction with the overheated of forepiece and prevent underheat.The ability of the relative heating of the upper and lower crown part of this control makes the upper and

lower crown part

12,14 can be by having different made in conjunction with temperature, or have same structure or a different materials, need different heating, so that reach the suitable temperature that combines at appropriate time with the complementary part joint.

Parts 12,4 preferably are formed from steel, and what more recommend is to be made for 4140 grades by SAE.Before welding,

parts

12,14 by tempering so that the tempered martensite structure of the hardness that has in the 28-34Rc scope to be provided.Welded joint in 35 to 50 scope, preferably is partial to the low side of this scope in the hardness of central authorities.Owing to by induction coil the controlled of composition surface preheated, the hardness of welded joint can be controlled in the scope of 38-42Rc.This " soaking into " composition surface that preheats effectively enters under the surface heat.This benefit of bringing is to reduce " quenching " effect behind joint of weld zone material, its objective is and avoids forming untempered martensite in central authorities, but form bainite.The advantage of above-mentioned 4140 materials is the TTT curves that are suppressed, and makes controlled cooling (that is, to calculate second) in the rational time.

Obviously can make many modifications and variations to the present invention according to top technology contents.Therefore, obviously can different with specific descriptions within the scope of the claims modes implement the present invention.The present invention is defined by the claims.

Claims

1. A method of manufacturing a piston, comprising:

preparing a first portion of the piston having at least two associated circumferentially extending engagement surfaces spaced apart from each other;

preparing a second portion of the piston having at least two associated circumferentially extending engagement surfaces spaced apart from each other;

supporting the first and second parts of the piston such that the engagement surface of the first part is disposed out of contact with the engagement surface of the second part;

The joining surfaces of the first and second parts are heated to an elevated bonding temperature, after which the joining surfaces of the first and second parts are brought into contact with each other to form a metallurgical bond therebetween.

2. A method as claimed in claim 1, characterized in that the joining surfaces are heated by means of induction heating.

3. The method of claim 2, wherein when the first and second parts of the piston are supported out of contact with each other, their respective engagement surfaces are arranged in spaced relation to each other, the A gap is formed between the forming surface and the forming surface of the second portion.

4. A method as claimed in claim 3, characterized in that an induction coil is inserted into said gap and the coil is energized for inductive heating to heat the joining surfaces, after which the first and second parts The coil is withdrawn from the gap before the mating surfaces come into contact.

5. A method as claimed in claim 4, characterized in that during contact of the engaging surfaces, the first and second parts are twisted relative to each other to slide the engaging surfaces relative to each other.

6. The method of claim 5, wherein the twisting occurs over less than 360°.

7. The method of claim 5, wherein the twisting occurs over less than 180°.

8. The method of claim 5, wherein the twisting occurs over less than 90°.

9. The method of claim 5, wherein the twisting occurs over less than 45°.

10. The method of claim 5, wherein the twisting occurs over less than 30°.

11. The method of claim 5, wherein the twisting occurs over less than 20°.

12. The method of claim 5, wherein the twisting occurs over less than 10°.

13. The method of claim 5, wherein the twisting occurs over less than 5°.

14. A method as claimed in claim 4, characterized in that the induction coil is positioned closer to the engagement surface of one of the first and second parts than away from the engagement surface of the other.

15. A method as claimed in claim 14, characterized in that the first and second parts are made of different materials.

16. The method of claim 1, wherein a combustion bowl is finalized in a first part and a pin hub and pin hole are finalized in a second part prior to heating and joining said joint surfaces.

17. The method of claim 1, wherein the obtained piston is provided with an induction heating welded joint in the annulus of the piston, and the induction heating welded joint is provided on any ring provided in the annulus. Below the lowest ring groove in the groove.

18. The method of claim 1, wherein the valve slot is machined in the first part prior to heating the joining surfaces of the first part and the second part and bonding the first part to the second part.

19. The method of claim 1, wherein an engagement surface is formed on cooperating wall portions of the first and second parts.

20. The method of claim 19, wherein the wall portion is annular.

21. A method as claimed in claim 20, characterized in that the engagement surface is provided in the necked end region of the wall.

22. The method of claim 1, wherein any heating required to raise the temperature of the joining surfaces to the joining temperature is stopped after bringing the joining surfaces into contact with each other.

23. The method of claim 1, wherein an annular cooling trench is formed between the first and second portions, the annular cooling trench consisting of a pair of radially spaced side walls, a top wall and A bottom wall is defined.

24. The method of claim 23, wherein joint surfaces are formed on the side walls such that a weld joint is formed on each side wall at the joint surface exposed to the cooling trench.

25. The method of claim 1, wherein the first portion is formed with a combustion bowl and the second portion is formed with a pair of pin hubs, a piston skirt being immovably secured to the pin hubs.

26. The method of claim 1, wherein the first portion is machined with features that are asymmetric about a plane containing the longitudinal axis of the first portion.

27. A method of making a piston comprising:

manufacturing a piston first part with at least one associated mating surface;

manufacturing a second part of the piston separate from the first part, the second part having at least one associated mating surface;

spacing the mating surface of the first part of the piston from the mating surface of the second part of the piston;

When mating surfaces are spaced apart, heating the surfaces to a temperature sufficient to weld those surfaces; and

The heated mating surfaces are brought into contact with each other and the two parts of the piston are welded across the engaged mating surfaces.

28. A method as claimed in claim 27, characterized in that the joining surfaces are heated by means of induction heating.