RU2275997C2 - Automatic electric arc surfacing method for parts such as bodies of revolution - Google Patents

Abstract

FIELD: restoration of worn parts or hardening new ones by means of electric arc surfacing.

SUBSTANCE: method comprises steps of welding-on single bead onto the whole surface of part to be surfaced by means of continuous electric arc; using bead having two annular portions and at least one helical portion; at first surfacing first annular portion, then helical portion and second annular portion; surfacing annular portions of bead in such a way that to place them partially on ends of part along its whole perimeter; after termination of surfacing procedure removing coating from part ends by mechanic working.

EFFECT: enhanced quality of surfaced coating, lowered labor consumption of process.

4 dwg, 1 ex

Description

The method relates to methods for electric arc surfacing of products such as bodies of revolution during the restoration of worn out and hardening of new parts. The proposed method is suitable both for coating under a flux layer and for other types of coating processes, in particular, flux-free coating processes.

As products such as bodies of revolution should be considered products (parts) having cylindrical, conical and spherical surfaces, which are coated.

A known method of automatic electric arc welding of products such as bodies of revolution by applying a continuous arc on the deposited surface of the product roll, having at least one weldable in a spiral section (see RF patent No. 2117560, class. 23 K 9/04, 1998).

This method is the closest to the claimed technical essence and the achieved result. A disadvantage of the known method is that it does not allow coating surfacing on the entire surface of the product without the use of additional parts (products). Since the spiral roller in the process of surfacing on the first turn of the spiral is removed from the edge of the deposited surface of the product (from the end of the product), and on the last turn of the spiral it does not come close to the edge of the specified surface, therefore, so that there are no sections on the indicated sections of the surface of the product, free from the deposited coating (flaws), rings are welded to the end of the product. This complicates and increases the cost of the coating method, as it is necessary to manufacture additional parts - rings, and coating involves two operations: welding of rings and surfacing of a spiral roller.

The invention is aimed at achieving a technical result: improving the quality of the deposited coating on products such as a shaft while reducing the cost of surfacing and reducing its complexity.

The specified technical result is achieved by the fact that in the method of coating by automatic electric arc welding of products such as bodies of revolution by continuous arc welding on the deposited surface of the product of the roller having at least one spiral-welded area, the coating on the entire deposited surface of the product is carried out by welding with a continuous arc of a single of a (non-composite) roller having two annular sections and said spiral section located between them; the second roller section is deposited in the following sequence: first, the first annular section is fused, then the indicated spiral section, and after the spiral section is surfaced, the second ring section of the roller is fused, and also, the indicated ring sections of the roller are fused so that they are partially located on the ends of the product around their perimeter, and then remove the coating from the ends of the product.

Due to this, surfacing of the entire surface of the product occurs without the use of additional parts, such as rings. In this case, the coating on the deposited surface of the product is carried out by surfacing with a continuous arc of a single roller (and not a composite one, consisting of separate sections, fused separately, with the initiation of the arc before welding of each of these sections). When surfacing a single bead, surfacing smoothly passes from the ring to the spiral and from the spiral to the ring again, without forming defects of the bead, since arc excitation occurs once - at the beginning of the specified bead. When the said rings and spiral are separately deposited (during the composite roller surfacing), for example, during the initial surfacing of each ring roller individually and then the spiral roller, the electric arc must be excited three times, which leads to the appearance of an increased number of surfacing defects and complicates the welding process, so as in this case, it is necessary to bind the start and end points of the surfacing repeatedly in a known manner. Since the annular sections of the roller during the surfacing process are not removed from the end of the product, no defects are formed during surfacing. In addition, the absence of non-melted sections of the surface of the product (flaws) during surfacing and the required thickness of the deposited coating near the ends of the product is ensured by the fact that these annular sections of the roller are fused so that they are partially located at the ends of the product, around their entire perimeter, and then removed coating from the ends of the product.

Figure 1 shows a device for implementing the proposed method when surfacing the inner cylindrical surface; figure 2 - diagram of the formation of a layer of surfacing of the outer cylindrical surface of the product (shaft); figure 3 - shows a device for implementing the proposed method when surfacing the outer conical surface; figure 4 - shows a device for implementing the proposed method when surfacing the outer spherical surface.

The method is as follows.

The product 1 is fixed in the device (not shown) associated with the block 2 of the rotator, providing a given speed of rotation of the product. The electrode wire is fed through the welding torch 3 to the product with rollers 4, and a flux is supplied from the hopper 5 using the flux-feeding device 6. The power of the welding arc is carried out from a source 7 of welding current. The known unit 8 of the longitudinal movement of the burner 3 provides its longitudinal movement at a given speed (in the direction of the arrow, Fig. 1). The transverse feed of the burner 3 is carried out using a known helical gear 9 (Fig.3, 4).

The product 1 is rotated with simultaneous longitudinal movement of the block 8 while maintaining a given speed of movement of the electrode along the path of surfacing. In this case, the coating on the entire deposited surface (in this case, FIGS. 1, 2, cylindrical surface) of the product 10 is carried out by continuous arc welding of one single roller having two annular sections 11 and 12 and the spiral section 13 located between them, and surfacing of the specified roller is carried out in the following sequence: first the first, its annular section 11 is deposited, then the spiral section 13, and after the welding of the spiral section 13, the second annular roller section 12 is surfaced, the ring sections 11 and 12 of the roller are welded in such a way that they are partially located at the ends 14 and 15 of the product (in those cases when it is required to weld an open surface over its entire length, as shown in figure 1), around the entire perimeter of the ends 14 and 15, and then remove the coating from the ends of the product by machining (for example, in a known manner on a lathe). When surfacing, arc excitation is performed only once, at the beginning of the automatic deposition process. Moreover, due to the fact that after surfacing the first annular section 11 of the roller, the deposition does not stop, but continues by fusing the spiral section 13 of the roller, and then, without stopping it, the second ring section 12 of the roller is fused, the arc is excited only once, at the beginning automatic surfacing process, which improves the quality of the deposited coating.

Due to the fact that in the case of surfacing of open surfaces, the annular sections of the roller are partially located at the ends of the product, it is possible to apply a coating to the entire surface of the product to be surfaced, such as a body of revolution, for example, a cylindrical surface of the product, providing the required thickness of the coating over the entire surface of the product, including sections of this surface near end faces of the product.

Example:

Automatic casting of three cast bearing shields (products such as bodies of revolution) of locomotive traction electric motors made of 35L steel was performed. The landing surface of the bearing shield to be surfaced had a diameter of 465 mm, and the length of the landing diameter was 30 mm. On the one hand the surface is open, on the other it is bounded by a flange. For this reason, an annular flux-retaining device was installed on the open surface, and surfacing was performed from the open surface toward the flange with the angle forward so that the angle of the weld part could be reached. The annular flux-holding device had a diameter of 16 mm less than the deposited diameter, therefore, when surfacing the first bead at the open end, a flux pillow was created, which contributed to the good formation of the first deposited bead. Automatic surfacing with direct current of reverse polarity was carried out in the following mode:

- surfacing speed - 22 m / h

- the number of spirals - 1

- spiral pitch - 5 mm

- surfacing step - 5 mm

- welding wire - Sv08G2S

- diameter of a welding wire - 2 mm

- welding flux - AN348A

- welding current - 250 A

- arc voltage - 36 V.

Test surfacing showed that the slag crust in the selected modes is separated satisfactorily and does not interfere with the surfacing of the adjacent bead.

Surfacing of the first bearing shield was carried out by applying a spiral roller fused with a continuous arc to its surface. The spacing of the electrode from the open end of the deposited surface was chosen so that the influx of the roller on the end was approximately 2 mm, which was cut off flush with the end of the product during further machining. With such surfacing near the open end of the product and near the flange there were flaws - areas without coating that arose due to the displacement of the weld bead by the step of spiral surfacing for the first and last revolutions of the bearing shield.

The second bearing shield was surfaced in the same modes by helical surfacing with ring rollers. In this case, the annular rollers were first deposited, then, starting and ending at the tops of the annular rollers, automatic surfacing was performed by a continuous arc by applying a spiral roller. Due to the fact that the electric arc was excited repeatedly (before the surfacing of each of the three mentioned individual rollers), a defect in the surfacing was detected in the arc excitation site on the second ring roller.

The coating on the entire weld surface of the third bearing shield was carried out by continuous arc welding of a single roller having two annular sections and a spiral section located between them. Surfacing of sections of the specified roller was carried out in the following sequence: first, the first annular section was surfaced, then the spiral section, and after welding of the spiral section, the second ring section of the roller was surfaced. Then, after surfacing the specified roller, the coating was flush-removed from the open end of the product. At the same time, a high-quality coating was obtained on the entire deposited surface of the bearing shield without surfacing defects.

Thus, the use of the proposed method (the method of automatic surfacing in the so-called ring-helix-ring-KSK mode) will improve the quality of the deposited coating on a shaft-type product with a simultaneous increase in the quality of the deposited coating and the cost of the deposition process.

Claims (1)

The method of coating by automatic electric arc surfacing under a flux layer on products such as bodies of revolution, including continuous arc welding on the deposited surface of at least one single roll, characterized in that the single roll is made up of two annular sections and a spiral section located between them, wherein the annular sections of the roller are partially located on the ends of the product along their entire perimeter, with the first annular section being fused first, then the spiral section, after which is fused to the second annular portion of the roller, and after surfacing a single roller coating from the ends of the product is removed.

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