UA134004U - METHOD OF RESTORATION OF WASHED MACHINE PARTS - Google Patents

Abstract

A method of repairing worn surfaces of machine parts in which an electrode wire is automatically fed to the rotating surface of the rotating part by a tangent at a small angle. Outside the combustion zone, an arc is pressed into the workpiece with a certain force by a roller strip. Due to the destruction of the oxide film on the surface of the strip, it is stretched, lengthening in front of the welding zone.

Description

A useful model belongs to the field of mechanical engineering and can be used in the restoration of the surfaces of parts that require overlaying a strip on them by welding.

A known method of electric arc surfacing (||), in which the relative movement of the surface of the part and the electrode is carried out by its oscillations perpendicular to the surfacing strip and the introduction of the filler tape into the arc combustion zone with its constant contact with the guide surface.

The disadvantage of this method is the uneven melting of the tape, which causes uneven movement of the arc across the width of the tape and affects the stability of arc burning.

There is a known method of restoring worn surfaces of machine parts (21, in which a strip of metal of small thickness, which is pressed by a roller, is welded to a rotating part, and a heat source is placed between the part and the strip, forming a welding bath on the surface of the restored part by melting the electrode with an electric arc and of the surface layer of the part, the strip is heated by the same source, and in the process of pressing it, the resulting metal layer is plastically deformed.

The disadvantage of this method is the limited possibility of ensuring a high-quality connection of the strip with the surface of the part.

The essence of a useful model is to improve the quality of welding parts due to the destruction of the oxide film on the surface of the strip.

The task is solved by the method of restoration of worn surfaces of machine parts, in which an electrode wire is automatically fed tangentially at a small angle to the restored surface of the rotating part, and also behind the arc burning zone, a strip is pressed against the part with a determined force with a roller, according to a useful model, due to the destruction of the oxide film on the surface of the strip, it is stretched, lengthening in front of the welding zone.

An electrode wire is automatically fed tangentially at a small angle to the restored surface of the rotating part, and the strip is pressed with a roller to the part with a determined force behind the burning zone of the arc, and the welding bath is formed due to the melting of only the surface of the part and the metal of the welding bath under the action the arc is thrown onto the surface of the strip and covers it in front of the welding zone with a solid layer. When self-tightening, the strip is stretched, lengthening it in front of the welding zone, in the process of which

The oxide film on its surface is destroyed. With joint plastic deformation in the welding zone of the strip and the layer of the metal of the welding bath, an increase in the quality of the connection is achieved.

The proposed useful model is confirmed by the drawing, which shows the welding scheme of the strip on the surface of the worn part.

The method is carried out as follows.

An electrode wire 2 is fed to the surface of the rotating part 1 automatically tangentially at a small angle, and an electric arc 3 burns between them.

Directly behind the burning zone of the arc Z to the part 1 with a determined force, the strip 5 is pressed by the roller 4, placed at an angle B, during the self-tightening feed of which, its tension is formed with the force P. The part 1 is rotated with a linear speed (welding speed) of 45-70 mm/ with.

The arc 3 burning between the electrode wire 2 and the part 1 forms a welding bath on the surface of the part 1 and provides a directed emission of drops 6 of liquid metal into the zone 7 of the surface of the strip 5, which adhere to it and cover it with a continuous layer. As a result of this, as well as the thermal interaction of the arc Z burning at a distance from the surface of the self-tightening strip 5, which is determined by the angle y, the latter in zone 7 is heated. During the rotation of the part 1, the metal layer formed on the surface of the self-tightening strip 5 contacts the molten surface of the part 1, and under the action of the force of the roller 4, a welding zone 8 is formed. The strip 5 in the heated zone 7, which belongs to the welding zone 8, is pulled out under the tension force P (elongation), in which due to the longitudinal flow of metal, the surface area of strip 5 in zone 7 increases. At the same time, the surface area of the oxide film remains unchanged due to its fragility, as a result of which the film is destroyed. Since the surface, which is connected to the strip 5 in zone 7, has a continuous coating of drops 6, the destroyed oxide film on it is not restored. The strip 5 enters the welding zone 8, where it passes along the height and expands with the formation of a layer 9 of the metal of the welding bath.

During the joint plastic deformation of strip 5 and layer 9 in the welding zone 8, the metals move mainly in the longitudinal direction, causing their movement (shift) relative to each other, as a result of which the surface oxide films are further destroyed and conditions are created to accelerate the formation of physical contact and activation of contact surfaces and increasing the intensity of development of the interaction of connecting metals both in the plane of contact with the formation of strong metal connections, and in the volume of the contact zone.

Thus, lengthening the strip in front of the welding zone allows to improve the quality of its connection with the interlayer.

A strip of metal with a thickness of 1 mm and a width of 10 mm was welded to samples made of steel 45 with a diameter of 55 mm with an electrode wire Sv-15GSTYUCA with a diameter of 1. mm using a special device mounted on the base of a lathe.

The VDH-60 U welding rectifier is used as a power source. The diameter of the pressure roller is 50 mm, the width is 10 mm. The tension force of the self-tightening strip was created by friction braking.

Welding is carried out with the reverse polarity of the current with a voltage on the arc of 26 V, current

Z00 A.

Angles а, ВД, у, 20 at the same time are equal to 10, 20 and 20", respectively, the pressing force of the roller is 800 N, the rotation frequency of the part is 16 min. 7", the speed of feeding the electrode wire is 88 min./s.

To obtain comparative results when examining the strength of the connection of the strip with the base, all the parameters of the welding process regime listed above, except for the strip tension force, which was changed in the range of 250-350 N every 20 N, were left constant. The strip was also welded without its tension. The number of samples, taking into account the three-fold repeatability of experiments on each mode, was 21, including C samples without strip tension. At the same time, the elongation of the welded strip was determined. The quality of the connection of the strip with the base was determined by metallographic analysis of the sections and by the peeling method.

Experiments confirmed the improvement of the quality of the connection during the process of welding the strip with its tension. The best connection was observed at a tensile strength of 310

H, in which the elongation of the strip was 18 95, while when welding the strip without tension it was equal to 11 95 and the quality of the connection was noticeably low.

The method ensures high quality when welding strips of small thickness.

Sources of information: 1. Author's certificate 50 Mo 524636, IPC V2ZK 9/04, 1976. 2. Author's certificate 50 Mo 1433739, IPC V2ZR 6/02, 1988.

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Claims (1)

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