CN111173638A

CN111173638A - Penetration welding type forged steel piston and machining method thereof

Info

Publication number: CN111173638A
Application number: CN202010055209.3A
Authority: CN
Inventors: 张伟斌; 张新华
Original assignee: Binzhou Donghailong Piston Co ltd
Current assignee: Binzhou Donghailong Piston Co ltd
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2020-05-19

Abstract

The invention relates to a penetration welding type forged steel piston and a processing method thereof, wherein the piston comprises: the piston head is formed by forging, the bottom of the piston head defines a first plug-in part, and the top of the piston head forms a combustion chamber; the piston skirt is forged, a second inserting part matched with the first inserting part is limited at the top of the piston skirt, a main welding seam is formed at the first inserting part and the second inserting part through high-energy penetration welding, and an auxiliary welding seam is formed between the outer wall of the combustion chamber and the top and/or the cylindrical surface of the piston skirt; the piston head and the piston skirt are welded to form a closed cooling oil cavity. The piston head and the piston skirt blank are forged separately, so that the forging process is simplified, the requirement on the tonnage of equipment is reduced, and the equipment investment is reduced. Piston head and piston skirt portion pass through the high energy welding in the middle of the combustion chamber, and the welding seam does not have the arch, has reduced because of the welding seam drops to cause the danger of drawing the jar, high energy to pierce through the welding mode and is connected, and welding speed is fast, and the cooling is rapid, can play the effect that the crystalline grain refines, and welding seam intensity is greater than body intensity.

Description

Penetration welding type forged steel piston and machining method thereof

Technical Field

The invention relates to the technical field of piston manufacturing, in particular to a penetration welding type forged steel piston and a machining method thereof.

Background

The piston is the 'heart' of an automobile engine, bears alternating mechanical and thermal loads, and is one of the most severe key parts in the engine under severe working conditions. The piston has the function of bearing gas pressure and is transmitted to the connecting rod through the piston pin shaft to drive the crankshaft to rotate, and the failure of the piston can cause the engine to lose power and even cause the whole engine to be scrapped. In recent ten years, the design and manufacturing technology of engines are rapidly improved, especially diesel engines are developed towards high power and high load, the strengthening degree is continuously improved, the explosive force exceeds 20MPa, meanwhile, the emission requirement is more and more strict, and the aluminum material can not meet the emission requirement of the engines with high power, high strength gradually. Therefore, many manufacturing companies select steel materials to replace aluminum alloy materials, and particularly the development of forged steel piston materials represents the current piston development direction.

There are two main types of steel pistons today: one is a hinged pendulum body, and the other is integrally forged steel. The hinged pendulum body type structure is characterized in that the head part of the piston is forged steel, the skirt part of the piston is aluminum, the piston is connected through a piston pin after being separately processed, a closed cooling oil cavity is difficult to form in the piston, the cooling effect of the piston is poor, meanwhile, the piston pin needs to be longer to be connected, the total weight is also increased, and the piston is gradually eliminated in developed countries. The integral forged steel piston is formed by forging the head and skirt separately, rough machining and combining them in some way.

Chinese patent CN 1610601 a discloses a method for manufacturing forged steel piston, which is to forge the head and skirt separately, the inner cooling oil cavity is formed by friction welding after the head and skirt are processed separately, the two end welds of the head and skirt are welded at one time, the welding area is large, and the large-bore piston cannot be welded normally due to the influence of the precision and capacity of the equipment. In addition, high power friction welding consumes a large amount of electricity, wasting energy. Chinese patent CN 407431B discloses a manufacturing process of a hot-spinning pressed forged steel integral piston with an internal cooling oil cavity. The blank required by the process is of an integrated structure, the forging process is complex, and the hot spinning pressing efficiency is low due to the fact that the wall thickness of the piston blank is thick. In the hot spinning process, the invention mentions that a spinning die is needed, because an inner cooling oil channel is closed, how the spinning die works and is taken out is not explained, and in addition, because the material in the hot spinning process is plastically deformed, the oil channel needs to be closed or a small gap is needed, and the machining precision of the shielding part of the machined oil channel is needed to be higher. Thus, the above-mentioned manufacturing methods have certain disadvantages.

Therefore, how to provide a penetration welded forged steel piston to solve the above-mentioned shortcomings is a problem that needs to be solved by those skilled in the art.

Disclosure of Invention

Therefore, the invention aims to provide a penetration welding type forged steel piston, which simplifies the forging process, reduces the investment on equipment and tools in blank forging, has no bulge in main welding line welding, and reduces the risk of cylinder drawing caused by welding line falling.

The invention provides a penetration welded forged steel piston, comprising:

the piston head is formed by forging, a first inserting part is limited at the bottom of the piston head, and a combustion chamber is formed at the top of the piston head;

the piston skirt is forged, a second inserting part matched with the first inserting part is limited at the top of the piston skirt, a main welding seam is formed at the first inserting part and the second inserting part through high-energy penetration welding, and an auxiliary welding seam is formed between the outer wall of the combustion chamber and the top and/or the cylindrical surface of the piston skirt; the piston head and the piston skirt are welded to form a closed cooling oil cavity.

According to the technical scheme, compared with the prior art, the penetration welding type forged steel piston disclosed by the invention has the advantages that the head part and the skirt part blank of the piston are separately forged, the forging process is simplified, the requirement on the tonnage of equipment is reduced, the equipment investment is reduced, the head part and the skirt part are separately processed, and the requirements on the equipment and a cutter are reduced. The piston head and the piston skirt are welded in the middle of the combustion chamber through high energy, and a welding line is not bulged, so that the danger of cylinder pulling caused by falling of the welding line is avoided. The piston head and the skirt part are connected in a high-energy penetration welding mode, the welding speed is high, the cooling is rapid, the effect of grain refinement can be achieved, and the strength of a welding seam is greater than that of the body.

The auxiliary welding line between the outer wall of the combustion chamber and the top of the skirt part of the piston is preferably welded in an advanced electron beam welding mode due to the severe working environment. The auxiliary welding line of the piston excircle mainly plays a supporting role, and argon arc welding can be selected for welding in order to reduce the cost.

Further, the cooling oil chamber is one, or two communicated with each other.

Furthermore, the first inserting part is a step platform, a concave ring groove or a convex ring step, and the second inserting part is correspondingly a step platform, a convex ring step or a concave ring groove. Different plug-in part structures are adopted according to the welding thickness of penetration welding.

Furthermore, the fit clearance between the first plug part and the second plug part is 0.05mm-0.2 mm; the interference fit interference range at the auxiliary welding line for installation is 0.03-0.1 mm. The fit clearance between the first inserting part and the second inserting part is 0.05mm-0.2mm, so that a larger welding depth can be achieved, the welding depth is determined according to the distance between the fit surface and the inner wall of the combustion chamber, and the welding depth is much deeper than the interference fit under the condition of certain voltage when the clearance exists. The auxiliary welding seam is in interference fit so as to prevent the head part and the skirt part from generating welding deformation in the welding process.

The invention also provides a penetration welding type forged steel piston processing method, which comprises the following steps:

s1, respectively forging the piston head and the piston skirt; respectively machining the piston head and the piston skirt according to the machining process requirements;

s2, assembling the piston skirt after being heated with the piston head;

s3, performing high-energy penetration welding on the first inserting part and the second inserting part through the combustion chamber;

s4, slowly cooling the welded parts obtained in the step S3;

s5, welding auxiliary welding seams on the outer wall of the combustion chamber and the top surface or the outer circular surface of the piston skirt;

s6, carrying out modulation or post-welding annealing treatment on the piston according to different materials; and (4) machining and surface treating the piston to obtain a finished product.

According to the technical scheme, compared with the prior art, the invention discloses the processing method of the penetration welding type forged steel piston, the head part and the skirt part blank of the piston are forged separately, the forging process is simplified, the requirement on the tonnage of equipment is reduced, the equipment investment is reduced, the head part and the skirt part are processed separately, and the requirements on the equipment and a cutter are reduced. The piston head and the piston skirt are welded in the middle of the combustion chamber through high energy, and a welding line is not bulged, so that the danger of cylinder pulling caused by falling of the welding line is avoided. The piston head and the skirt part are connected in a high-energy penetration welding mode, the welding speed is high, the cooling is rapid, the effect of grain refinement can be achieved, and the strength of a welding seam is greater than that of the body.

Further, the fit clearance of the first plug part and the second plug part in the S2 is 0.05mm-0.2 mm.

Furthermore, the interference fit interference range at the auxiliary welding line is 0.03-0.1 mm.

Further, after welding in the welding chamber in S3, the welding chamber is taken out and put into a heat preservation furnace in S4, and after the welding chamber is cooled to 200 ℃ along with the furnace, the welding chamber is taken out and air is cooled.

Furthermore, when the welding thickness of the penetration welding is less than 6mm, the first plug-in part and the second plug-in part are matched in a step mode; when the welding thickness is larger than 6mm, the matching surfaces of the first inserting part and the second inserting part are matched in a concave-convex mode.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a sectional view of a front view of an embodiment of a penetration welded forged steel piston (an embodiment in which the first and second mating parts are male and female) according to the present invention;

FIG. 2 is a side cross-sectional view of FIG. 1;

FIG. 3 is a schematic structural view of another embodiment of a penetration welded forged steel piston (an embodiment in which a first socket and a second socket are connected in a stepped manner) according to the present invention;

FIG. 4 is a schematic structural view of a double cooling gallery penetration welded forged steel piston according to the present invention;

in the figure: 100-piston head, 101-first plug-in part, 200-piston skirt, 201-second plug-in part, 300-main weld, 400-auxiliary weld, 500-cooling oil cavity.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Referring to fig. 1 and 2, the present invention provides a penetration welded forged steel piston comprising:

the piston head 100 is formed by forging the piston head 100, the bottom of the piston head 100 defines a first plug-in part 101, and the top of the piston head forms a combustion chamber;

the piston skirt 200 is formed by forging the piston skirt 200, the top of the piston skirt 200 is provided with a second plug-in part 201 matched with the first plug-in part 101, the first plug-in part 101 and the second plug-in part 201 form a main welding seam 300 through high-energy penetration welding, and the outer wall of the combustion chamber and the top or the cylindrical surface of the piston skirt 200 form an auxiliary welding seam 400; the piston head 100 and skirt 200 are welded to form a closed cooling gallery 500.

The invention discloses a penetration welding type forged steel piston, which has the advantages that a piston head blank and a piston skirt blank are separately forged, the forging process is simplified, the requirement on the tonnage of equipment is reduced, the equipment investment is reduced, the head and the skirt are separately processed, and the requirements on the equipment and a cutter are reduced. The piston head and the piston skirt are welded in the middle of the combustion chamber through high energy, and a welding line is not bulged, so that the danger of cylinder pulling caused by falling of the welding line is avoided. The piston head and the skirt part are connected in a high-energy penetration welding mode, the welding speed is high, the cooling is rapid, the effect of grain refinement can be achieved, and the strength of a welding seam is greater than that of the body.

Referring to fig. 1 and 3, one cooling oil chamber 500 is provided, and referring to fig. 4, two cooling oil chambers are provided to communicate with each other, thereby increasing the cooling effect.

Advantageously, different plug-in part configurations are used depending on the weld thickness of the penetration weld. When the welding thickness is more than 6mm, the matching surfaces of the first inserting part and the second inserting part are matched in a concave-convex mode, and the attached drawing 1 is shown. The first insertion part 101 is a step, and the second insertion part 201 is a step. When the welding thickness of the penetration welding is less than 6mm, the first inserting part and the second inserting part are matched in a step-and-step mode, and refer to the attached drawing 3.

More advantageously, the fit clearance between the first mating part 101 and the second mating part 201 is 0.05mm to 0.2 mm; the auxiliary welding line is arranged in an interference fit mode, and the interference magnitude is 0.03-0.1 mm. The fit clearance between the first inserting part and the second inserting part is 0.05mm-0.2mm, so that a larger welding depth can be achieved, the welding depth is determined according to the distance between the fit surface and the inner wall of the combustion chamber, and the welding depth is much deeper than the interference fit under the condition of certain voltage when the clearance exists. The auxiliary welding seam is in interference fit so as to prevent the head part and the skirt part from generating welding deformation in the welding process.

s2, assembling the piston skirt after being heated with the piston head;

s4, slowly cooling the welded parts obtained in the step S3;

The invention discloses a processing method of a penetration welding type forged steel piston, which is characterized in that a piston head blank and a piston skirt blank are separately forged, so that the forging process is simplified, the requirement on the tonnage of equipment is reduced, the equipment investment is reduced, the head and the skirt are separately processed, and the requirements on the equipment and a cutter are reduced. The piston head and the piston skirt are welded in the middle of the combustion chamber through high energy, and a welding line is not bulged, so that the danger of cylinder pulling caused by falling of the welding line is avoided. The piston head and the skirt part are connected in a high-energy penetration welding mode, the welding speed is high, the cooling is rapid, the effect of grain refinement can be achieved, and the strength of a welding seam is greater than that of the body.

Wherein, the fit clearance of the first plug part and the second plug part in the S2 is 0.05mm-0.2 mm.

Advantageously, the interference fit interference range at the auxiliary welding line for installation is 0.03-0.1 mm.

And (S4) after welding in the welding chamber in S3, taking out the welding chamber, putting the welding chamber into a heat preservation furnace, cooling the welding chamber to 200 ℃ along with the furnace, and taking out the welding chamber for air cooling.

In the method, when the welding thickness of penetration welding is less than 6mm, the first plug-in part and the second plug-in part are matched in a step-platform mode; when the welding thickness is larger than 6mm, the matching surfaces of the first inserting part and the second inserting part are matched in a concave-convex mode.

The high-energy penetration welding mainly comprises electron beam welding and laser welding, materials needing welding are instantly melted through high energy density, the electron beam and the laser penetrate through the head of the piston to weld matching surfaces, and then the piston is rapidly cooled to achieve the purpose of welding. Welding requires that the melting points of the two materials do not differ significantly. The specific welding step is as follows: electron beam welding: putting a workpiece into a welding chamber, vacuumizing the welding chamber, adjusting welding parameters (focusing, high pressure, bias voltage, beam current, welding speed and the like), welding, inflating the welding chamber, and taking out the workpiece.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A penetration welded forged steel piston, comprising:

the piston head (100) is forged, the bottom of the piston head (100) defines a first plug part (101), and the top of the piston head forms a combustion chamber;

the piston skirt (200) is forged, a second plug-in part (201) matched with the first plug-in part (101) is defined at the top of the piston skirt (200), a main welding seam (300) is formed at the positions of the first plug-in part (101) and the second plug-in part (201) through high-energy penetration welding, and an auxiliary welding seam (400) is formed between the outer wall of the combustion chamber and the top or the cylindrical surface of the piston skirt (200); the piston head (100) and/or the piston skirt (200) are welded to form a closed cooling gallery (500).

2. A penetration welded forged steel piston as claimed in claim 1, wherein said cooling gallery (500) is one, or two in communication with each other.

3. A penetration welded forged steel piston according to claim 1, wherein said first spigot (101) is a step, a recessed ring groove or a raised annular step and said second spigot (201) is a step, a raised annular step or a recessed ring groove.

4. A penetration welded forged steel piston according to claim 1, wherein the fit-up clearance between said first spigot (101) and said second spigot (201) is 0.05mm-0.2 mm; the auxiliary welding line is arranged in an interference fit mode, and the interference magnitude is 0.03-0.1 mm.

5. A penetration welding type forged steel piston machining method is characterized by comprising the following steps:

s2, assembling the piston skirt after being heated with the piston head;

s4, slowly cooling the welded parts obtained in the step S3;

6. The method of processing a penetration welded forged steel piston as claimed in claim 5, wherein the fitting clearance between the first and second spigots in S2 is 0.05mm-0.2 mm.

7. The method for processing the penetration welding type forged steel piston as claimed in claim 5, wherein the auxiliary welding seam is in interference fit, and the interference is 0.03-0.1 mm.

8. A penetration welding type forged steel piston as claimed in claim 5, wherein after welding in the welding chamber in S3, it is taken out in S4 and put in a holding furnace, and after furnace cooling to 200 ℃, it is taken out to be air-cooled.

9. The penetration welding type forged steel piston processing method as claimed in claim 5, wherein when the penetration welding thickness is less than 6mm, the first plug part and the second plug part are matched in a step-and-step manner; when the welding thickness is larger than 6mm, the matching surfaces of the first inserting part and the second inserting part are matched in a concave-convex mode.