RU2607108C1 - Method of radial forging hexagonal hollow profiles - Google Patents

Abstract

FIELD: metal processing.

SUBSTANCE: invention relates to metal forming and can be used in radial forging of hexagonal hollow profiles. Round hollow workpiece is subjected to reduction simultaneously with two mutually perpendicular pairs of strikers in not less than three passes. Strikers of one pair have smooth working surface. Strikers of second pair have cutout grooves with surfaces inclined to each other at an angle of 120°. Working surfaces of mutually perpendicular strikers are offset relative to each other along forging axis by a value exceeding length of working surface of striker. After each pass, workpiece is turned about forging axis through an angle which is a multiple of 60°, to change faces hexagonal hollow profile pressed by pairs of strikers.

EFFECT: higher quality of hollow profiles.

1 cl, 8 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure, and in particular to methods for producing hexagonal hollow profiles.

Known methods for producing hexagonal hollow profiles / Technology and equipment for pipe production; textbook for universities. V.Ya. Osadchy, A.S. Vavilin, V.G. Zimovets, A.P. Kolikov. - M .: "Engineer Engineering", 2007. - p. 506; Roller mills for cold rolling pipes. Verderevsky V.A. - M.: Metallurgy, 1982. - p. 228 .; Rolling production. Polukhin P.I., Fedosov N.M. Korolev A.A. Metveev Yu.M. - M.: Metallurgy, 1968 .-- p. 297-298 /.

Using these methods, hexagonal mandrel in a cold state from a round hollow billet or on a round rod in a hot state from a square billet with a round hole by crimping, respectively, on a rolling mill or in a conventional longitudinal rolling mill, obtain hexagonal hollow profiles.

The main disadvantages of these methods are the high complexity of obtaining hexagonal hollow profiles due to the need to use mandrels or rods, as well as the impossibility of obtaining such profiles from special low-plastic and hard-to-deform steels and alloys, which require, as you know, special methods of metal forming in hot condition with special deformation schemes providing the required profiles without cracks and flaws. The latter limits the technological capabilities of these methods according to the vintage assortment of the resulting hexagonal hollow profiles.

Thus, the disadvantages of these analogues are the high complexity of obtaining hexagonal hollow profiles and limited technological capabilities for vintage assortment of the resulting hexagonal hollow profiles.

Closest to the proposed solution for the technical nature and the achieved effect is a method of multi-pass radial forging of hollow profiles / U.S. Radyuchenko. Rotational forging - M .: State. nt publishing house literature, 1962. - p. 137; Forging on radial crimping machines. V.A. Tyurin, V.A. Lazorkin, I.A. Pospelov et al. - M.: Mechanical Engineering, 1990. - p. 18-19 /. Using this method without a mandrel, it is possible to obtain similar profiles from a round hollow billet (pipe) with a change in the outer and inner diameters. When two pairs of strikers are used to implement this method, one pair of which has a smooth working surface, the second pair has cut grooves with surfaces inclined to each other at an angle of 120 degrees, the working surfaces of mutually perpendicular strikers are offset relative to each other along the forging axis by an amount exceeding the length of the working surface of the striker / Forging on radial crimping machines. V.A. Tyurin, V.A. Lazorkin, I.A. Pospelov et al. - M.: Mechanical Engineering, 1990. - p. 26-27 /, you can get a hollow hexagonal profiles.

The use of such a combination of well-known technological methods significantly reduces the laboriousness of obtaining hollow products due to the absence of mandrels and rods inside them, and technological possibilities appear for producing hollow products from special grades of steel and alloys without the formation of cracks and tears.

However, the use of such a combination of known technological methods does not allow obtaining hexagonal hollow profiles of the required quality due to the absence of technological methods that ensure uniform filling of the outer ribs of the hexagonal hollow profile and the formation of a regular symmetrical internal cavity. This is due to the fact that during radial forging by pairs of strikers having different shapes of the working surface, the same conditions of metal forming are not provided. When forging by strikers with cut grooves having working surfaces inclined to each other at an angle of 120 degrees, there is a high-altitude metal contraction from the ribs formed by the vertices of these streams, with its movement to the ribs formed by the strikers with a smooth working surface. This leads to asymmetric conditions for the formation of hexagonal profile ribs formed at the top of the working surface of the strikers with cut streams and strikers with a smooth working surface. As a result of this, the ribs formed by the tops of the notched streams turn out to be unfilled with metal, and on the ribs formed by the strikers with a smooth working surface, burrs (whiskers) are formed, which are transformed into casks and captives upon further forging. This position also negatively affects the shape of the internal cavity of the hexagonal hollow profile. It is obtained in the form of an oval (irregular lancet hexagon), elongated in the direction of the ribs formed by the strikers with notched streams. Because of this, hexagonal hollow profiles will have different wall thicknesses. On the part of the strikers with a smooth working surface, the thickness of these walls will significantly exceed the thickness of the walls formed by the strikers with cut-out streams.

Uneven filling of the ribs of a hexagonal hollow profile and the formation of an asymmetric internal cavity is a criterion of low quality.

Thus, the main disadvantage of this method, in which a combination of known technological methods is used to obtain hexagonal hollow profiles, is the low quality of the hexagonal hollow profiles.

The objective of the invention is to improve the quality of hexagonal hollow profiles obtained using radial forging.

The problem is achieved in that in the inventive method of multi-pass radial forging of hexagonal hollow profiles, comprising crimping a round hollow billet simultaneously with two mutually perpendicular pairs of dies, one pair of which has dies with a smooth working surface, the second pair of dies has cut grooves with surfaces inclined to each other to each other at an angle of 120 degrees, the working surfaces of mutually perpendicular strikers are offset from each other along the forging axis by an amount exceeding the length of the working surface According to the invention, the compression of a round hollow billet is performed in no less than three passes; after each pass, the billet is rotated around the forging axis by an angle multiple of 60 degrees with a change in the faces of the hexagonal hollow profile crimped by pairs of strikers.

Fulfillment of three conditions simultaneously: obtaining a hollow hexagonal profile by crimping a round hollow billet in at least three passes; rotation of the workpiece after each pass around the forging axis by an angle multiple of 60 degrees; changing the faces of the hexagonal hollow profile crimped by pairs of strikers - allows you to create uniform conditions for the formation of ribs on the outer surface of the hexagonal hollow profile and the symmetrical inner cavity of the hexagonal hollow profile.

The fulfillment of the second condition means that after each pass, the workpiece must be rotated to one of the following angles 60 degrees, 120 degrees, 180 degrees, 240 degrees, 300 degrees, 360 degrees. etc. degrees. Of the listed series of rotation angles, the simultaneous fulfillment of the third condition provides only rotation angles of 60 degrees. and 120 degrees. At a rotation angle of 180 degrees. and 360 degrees. the position of the pairs of strikers relative to the workpiece does not change with respect to their initial position at a rotation angle of 0 deg. With an angle of rotation of 240 degrees. the position of the pairs of strikers relative to the workpiece is similar to the position of the pairs of strikers relative to the workpiece with a rotation angle of 60 degrees. With an angle of rotation of 300 degrees. the position of the pairs of strikers relative to the workpiece is similar to the position of the pairs of strikers relative to the workpiece at an angle of rotation of 120 degrees.

Thus, for the simultaneous fulfillment of three conditions for the implementation of the proposed method, for example, when performing three passes, two technological options are possible. According to the first variant, after the first pass, the workpiece is rotated around the forging axis by an angle of 60 degrees. After the second pass, the workpiece is turned around the axis of the forging in the same direction by an angle of 60 degrees. According to the second variant, after the first pass, the workpiece is rotated around the forging axis by an angle of 120 degrees, after the second pass into the workpiece, it is turned around the axis of the forging in the opposite direction by an angle of 60 degrees.

The achievement of metal forming conditions under which uniform conditions for the formation of ribs of the outer surface of the hexagonal hollow profile and the symmetric internal cavity of the hexagonal hollow profile are created is explained by the fact that as a result of a minimum of three reductions, accompanied by two turns of the workpiece around the forging axis, all edges and faces of the resulting hexagonal profile undergo deformation by different elements of the caliber formed by the strikers with a smooth working surface and with notched streams.

Creating uniform conditions for the formation of ribs on the outer surface of the hexagonal hollow profile and its symmetrical internal cavity allows obtaining the outer surface of the hexagonal hollow profile with uniform filling of its ribs with metal, without the formation of burrs (whiskers) and obtaining an internal cavity of a symmetrical shape with respect to the forging axis and the same wall thickness formed by all the strikers.

Obtaining hexagonal hollow profiles with the outer surface of the hexagonal profile without burrs (whiskers) on the ribs with filling them with metal with an internal cavity of a symmetrical shape with respect to the forging axis and the same wall thickness are criteria for their high quality.

Thus, the application of the proposed method improves the quality of hexagonal hollow profiles obtained using radial forging.

The proposed method of radial forging of hexagonal hollow profiles is illustrated in the drawings.

In FIG. 1 shows a section through double-head strikers with cut-out streams, a view of a double-stroke striker with a smooth working surface and clamping jaws of manipulators during compression of a round hollow workpiece to obtain a hollow profile in the first pass.

In FIG. 2 shows a section BB with the cross section of the strikers, a round hollow billet and the resulting hollow profile during compression in the first pass.

In FIG. Figure 3 shows a section through double-head strikers with cut-out streams, view of a double-stroke striker with a smooth working surface and clamping jaws of the manipulators after crimping the round initial billet to obtain a hollow profile in the first pass and after turning the hollow profile with the manipulator B at an angle of 60 degrees. before crimping in the second pass.

In FIG. 4 shows a section through double-head strikers with cut-out streams, view of a double-run striker with a smooth working surface and clamping jaws of manipulators during compression of the hollow profile and obtaining a hollow profile in the second pass.

In FIG. 5 shows a section GG with a cross-section of the strikers, the hollow profile defined in the strikers, and the resulting hollow profile during compression in the second pass.

In FIG. Figure 6 shows a section through double-head strikers with cut-out streams, view of a double-stroke striker with a smooth working surface and clamping jaws of the manipulators after crimping the hollow profile, obtaining a hollow profile in the second pass and after it is rotated by the manipulator A at an angle of 60 degrees. before crimping in the third pass.

In FIG. 7 shows a section through two-way strikers with cut-out streams, a view of a two-way striker with a smooth working surface and the clamping jaws of the manipulators during compression of the hollow profile and to obtain the finished hexagonal hollow profile in the third passage.

In FIG. 8 shows a section DD with the cross section of the strikers, the finished hexagonal hollow profile, obtained in the third passage.

Using FIG. 1 ... 8, we will consider the process of obtaining a hexagonal hollow profile from a round hollow workpiece in three passes with the most rational implementation of the proposed method with successive rotation of the workpiece after each pass at an angle of 60 degrees.

Radial forging is carried out by two pairs of double-entry strikers, in which each striker has two working surfaces, allowing deformation both during direct and reverse movement of the workpiece. One pair of strikers 1, 2 has a smooth work surface. Another pair of strikers 3, 4 has cut grooves with surfaces inclined to each other at an angle of 120 degrees. The working surfaces of the pair of strikers are shifted along the forging axis by an amount S exceeding the length of the working surface of the striker L (Fig. 1). The initial workpiece and hexagonal profiles are held along the forging axis, fed into the strikers and rotated around the forged axis by two manipulators A and B (the clamping jaws of the manipulators are shown in the drawings for simplicity). The working surfaces of the clamping jaws of the manipulators in order to eliminate the "stall" (turn) of the workpiece during its deformation are made in accordance with the shape of the hexagon.

Radial forging of hexagonal profiles is carried out in several passes. The number of passes is determined by the maximum possible compression for the passage based on the angle of inclination of the crimping sections of the strikers and the force conditions of the radial forging process. In this example, the implementation of the process of obtaining a hexagonal hollow profile from a round hollow billet in three passes is shown.

Round hollow billet 5 in this example has an outer diameter D, an inner diameter d (Fig. 2). Before the first pass, the round hollow billet 5 is clamped by the jaws of manipulator A, fed by this manipulator into the strikers, and the first pass begins (Fig. 1). Due to the reciprocating movement of the strikers (shown by vertical arrows), the round hollow billet is crimped to obtain a profile with six flats on the outer surface. On the inner surface of the hollow billet, a profile with six rounded faces is obtained (Fig. 2). In the part of the cross section obtained in the first pass of the hollow profile located at the top of the strikers 3, 4 with notched streams, there is a height contraction of Δh _{ut of} metal from the ribs formed by the vertices of these streams, with its movement to the ribs formed by the strikers 1, 2 with a smooth working surface. In these ribs, metal broadening by Δb will take place.

In the process of the first pass, the workpiece 5 from the manipulator A is transferred to the manipulator B, which finishes the implementation of the first pass (Fig. 3). Then begins the second pass (Fig. 3), before which, using the manipulator B, a hollow profile obtained in the first pass is rotated with six flats around the forging axis by an angle of 60 degrees. As a result, points a and c (FIG. 2) are in the position shown in FIG. 5, i.e. the hollow profile ribs with six flats will move from the tops of the strikers 3, 4 with grooves to the slots between the mutually perpendicular strikers 1, 2 and 3, 4.

Next, with the manipulator B, the rotated hollow profile 5 with six flats is fed into the strikers 1-4 and the second pass is carried out (Fig. 4). Due to the reciprocating movement of the strikers (shown by vertical arrows), the hollow profile with six flats is compressed, obtained in the first pass and rotated through an angle of 60 degrees, with the formation of a new hollow profile with six flats (Fig. 5). On the inner surface of the hollow profile with flats, a profile with six rounded faces is obtained (Fig. 5). In the part of the cross section obtained in the second pass of the hollow profile with flats located at the top of the strikers 3, 4 with notched streams, there is a height contraction by Δh _{ut of} metal from the ribs formed by the vertices of these streams, with its movement to the ribs formed by the strikers 1 , 2 with a smooth work surface. In these ribs, the metal broadens by Δb.

In the process of making the second pass, the hollow profile with flats 5 from the manipulator B is transferred to the manipulator A, which ends the implementation of the second pass (Fig. 6).

Then begins the third pass (Fig. 7), before which, using the manipulator A, a hollow profile obtained in the second pass is rotated with six flats around the forging axis by an angle of 60 degrees. in a direction similar to turning a profile with six flats after the first pass (Fig. 6). As a result, points a and c (FIG. 5) are in the position shown in FIG. 8, i.e. the hollow profile ribs with six flats will move from one connector between the mutually perpendicular strikers 1, 2 and 3, 4 to other connectors between these strikers.

Next, with the manipulator A, the rotated hollow profile 5 with six flats is fed into the strikers 1-4 and the third pass is carried out (Fig. 7). Due to the reciprocating movement of the strikers (shown by vertical arrows), a hollow profile with six flats is compressed, obtained in the second pass and rotated through an angle of 60 degrees to obtain a finished hexagonal hollow profile (Fig. 8). On the inner surface of the hollow hexagonal profile, a profile with six rounded edges is obtained (Fig. 8). In the part of the cross section obtained in the third pass of the hollow profile located at the top of the strikers 3, 4 with notched streams, there is also a high-altitude metal contraction from the ribs formed by the vertices of these streams, with the metal moving into the ribs formed by the strikers 1, 2 with a smooth working surface . In these ribs there will be a broadening of the metal. In FIG. 8, due to the filling of the ribs of the hexagonal hollow profile with metal, the parameters of tightening and broadening are not indicated.

In the process of making the third pass, the hollow profile with flats 5 from the manipulator A is transferred to the manipulator B, which ends the implementation of the third pass (not shown in the drawings).

In the described example of the implementation of the proposed method for three passes from a round hollow billet by radial forging, a finished profile is obtained in the form of a hexagonal hollow profile.

To achieve the required quality characteristics of a hexagonal hollow profile, a prerequisite is the approximate equality of the conditions of the formation of all its faces and edges. This is ensured when radially forging a round hollow billet in at least three passes when it is rotated after each pass by an angle multiple of 60 degrees around the forging axis with alternating compression of the faces of the hexagonal hollow profile in pairs of strikers. To obtain a high-quality hexagonal hollow profile, a larger number of passes can be applied while ensuring the same conditions for the formation of faces and edges of the hexagonal hollow profile, which is possible when the hollow workpiece is rotated after each pass by an angle multiple of 60 degrees around the forging axis.

Thus, the use of the proposed method using radial forging allows you to get high-quality hex hollow profiles,

One of the options for the practical use of hexagonal hollow profiles is to obtain nuts from them. In this regard, the proposed method was used in the development of the technology for producing M48 nuts according to GOST 15521-70 and GOST 15522-70. To do this, hot radial forging of a hexagonal hollow profile “with a key size” of 70 mm was made from a hollow round billet (pipe) with an outer diameter of 83 mm and an inner diameter of 45 mm on a SKK-14 radial forging machine of the Austrian company GFM installed on one of enterprises of Chelyabinsk. Obtaining a hexagonal hollow profile was carried out in three passes in two pairs of two-way strikers with a rotation of the hollow billet at an angle of 60 degrees. after each pass in one direction. One pair had strikers with a smooth working surface, the second pair of strikers had cut-out streams with surfaces inclined to each other at an angle of 120 degrees. The strikers had calibrating sections parallel to the forging axis, and crimping sections inclined at an angle of 12 degrees. to the forging axis. The supply of the workpiece in one stroke of the strikers was 5 mm. The number of strokes of the strikers per minute is 800. The displacement of the working surfaces of the pairs of strikers along the forging axis was S = 64 mm. The length of the working surface of the striker L = 58 mm. As a result, we obtained a six-sided hollow profile with external “turnkey dimensions” of 70 mm according to GOST 2879-2006 with filling all the ribs with metal and without burrs (mustaches). The internal cavity of this hexagonal hollow profile was in the form of a regular symmetrical lancet hexagon (a hexagon with rounded convex sides) with a diameter of the circumscribed circle of about 40.5 mm. M48 nuts are made of this hexagonal profile in accordance with GOST 15521-70. Saving metal with this technology of manufacturing nuts is about 30%.

In order to comparatively evaluate the effectiveness of the proposed method in the same strikers with the same technological conditions (only without the use of turning the workpiece through an angle of 60 degrees after each pass), hot radial forging of a hexagonal hollow profile “with a key size” of 70 mm from hollow was carried out round billets (pipes) with an outer diameter of 83 mm, an inner diameter of 45 mm. As a result, a hexagonal hollow profile with external “turnkey dimensions” of 70 mm was obtained with non-filling in metal of two opposite edges of the hexagon located at the tops of the notched streams. The four other hexahedral ribs located in the connectors of the working surfaces of the strikers with a smooth working surface and strikers with notched streams, had sharp corners with signs of defects in the form of captives, zakov because of burrs (whiskers) formed during radial forging. The presence of captives, shackles and metal non-filling of the ribs of hexagonal profiles is their rejection sign. Such profiles are not accepted by the consumer.

Moreover, the internal cavity of the hexagonal hollow profile had the shape of an oval (irregular lancet hexagon), elongated in the direction of the ribs formed by the strikers with notched streams. The walls of such a hexagonal hollow profile had different thicknesses.

The resulting external hexagonal profile did not meet the requirements of GOST. The uneven wall thickness of such a six-sided hollow profile does not allow cutting the internal thread in it with a rational consumption of metal.

Experimental studies have confirmed the effectiveness of the proposed method, namely the receipt of high-quality hexagonal hollow profiles, which can be blanks for the manufacture of nuts.

When forming a hexagonal profile in strikers with notched strikers and with a smooth working surface, there is a simultaneous tightening and transverse flow of metal, affecting the formation of ribs of the hexagonal profile. As a result of additional experimental studies, it was found that for the formation of hexagonal profile ribs that meet the requirements of GOST 2879-2006, the outer diameter of a round hollow billet (pipe) should be 1.18-1.22 times greater than the "turnkey size" of the hexagonal hollow profile.

Additional experimental studies also found that when a hollow hexagonal profile is formed from a round hollow billet (pipe), not only does the shape of their cavity change, but the wall thickens. In this regard, to obtain the minimum sufficient wall thickness of the hexagonal hollow profile necessary to form the desired profile of the nut thread, the inner diameter of the round hollow profile (pipe) should be no more than 1.1 of the inner diameter of the nut thread.

The proposed method is planned to be used for hot forging on a SKK-14 radial forging machine with six-sided hexagonal hollow profiles “with turnkey sizes” 41, 46, 50, 55, 60, 65, 70 and 75 mm for the subsequent manufacture of nuts M 30, 36 , 42, 48 according to GOST 15521-70, 15522-70, 5915-70 and 5916-70.

Claims (1)

A method of multi-pass radial forging of hexagonal hollow profiles, comprising crimping a round hollow billet simultaneously with two mutually perpendicular pairs of strikers, of which one pair has strikers with a smooth working surface, and the working surfaces of the strikers of the second pair are made with cut brooks with surfaces angled to each other 120 °, moreover, the working surfaces of mutually perpendicular strikers are offset relative to each other along the forging axis by an amount exceeding the length of the working surface of the striker, distinguishing by the fact that compression produces at least three passes, with each pass after the workpiece is rotated about the forging axis at an angle that is a multiple of 60 °, with the change in shingled pairs of strikers hexagonal faces of the hollow profile.

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