RU2457061C1 - Method of producing forgings - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in production of forgings from various steels, alloys and nonferrous metals at hydraulic forging presses. Press four-hammer forging device is used to forge ingot heated to its forging point. Forging includes roughing, broaching in several passes and gaging. Broaching is performed by quadrilateral reduction with additional metal macro shears in transverse plate at every pass. Every hammer has working section consisting of central and two lateral sections. The latter adjoin the former at obtuse angle. In broaching, multi-faceted cross-section billet is formed. In every new pass, billet is formed with cross-section turned relative to previous pass through 30-60°. At least in one pass, except for final one, unit reductions are performed. At this reductions, width of billet surface of contact with hammer exceeds width of hammer central section and is smaller than that of working section.

EFFECT: higher quality and efficiency.

9 cl, 3 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of metal forming, and in particular to methods for producing forgings from ingots and pre-deformed billets on forging complexes consisting of hydraulic forging presses with one or two manipulators and equipped with one or more four-sided forging devices.

The invention can be used in the machine-building and metallurgical industries in the manufacture of forgings from various steels, alloys and non-ferrous metals in forging workshops having hydraulic forging presses equipped with one or more four-forging forging devices.

A known method of manufacturing forgings, including billeting of the ingot and subsequent forging on a press with one or two manipulators in several passes by pulling in four-forging forging devices and calibrating the workpiece, feeding, tilting and cutting of the forging. Billet ingot is carried out in a four-sided forging device for billet ingots, while the ingot is squeezed during each single compression in a vertical plane with a greater degree of deformation than in a horizontal plane (RU 2288065 C2, IPC (2006.01) B21J 1/04, 9/02, 13 / 02, published on November 20, 2006).

The known method of forging allows forging ingots of large cross sections in four-sided forging devices.

The disadvantage of this method is that for the operation of billing of the ingot, a special four-sided forging device is required, which allows compressing the ingot in a vertical plane with a greater degree of deformation than in the horizontal plane with each single crimping.

Closest to the proposed method of manufacturing forgings is a method that includes heating an ingot, forging it in several passes by four-side crimping in four-side forging devices with additional macroshifts of metal in the transverse plane of the workpiece with each single compression, feeding between the crimping and turning the workpiece. In this case, forging is carried out during one heating of the ingot in the allowable range of forging temperatures with a coefficient of yield of 2.0: 1-32.0: 1 in two stages, first, rough forging in one or more four-die forging devices for rough forging, and then calibrated forging in a four-side forging device for calibrating forging with a pitch coefficient of 1.05: 1-1.8: 1 and coverage of the perimeter of the cross section of the workpiece for each single compression of each pair of working sections of the strikers by 40-100%. The working surface of each striker consists of a central plane parallel to the support plane of the striker, and two lateral planes adjacent to it from two sides at an angle of 135-170 ° (RU 2220020 C1, IPC ⁷ B21J 1/04, 9/02, 5/02 , Op. 27.12.2003).

In the known method, the ingot is heated and forged during one heating, gradually transferring from one four-forging device to another. Due to this, in the known method, an increase in the production productivity of forgings with high surface quality and high accuracy is achieved.

The disadvantages of this method is that in it the possibility of forging during one heating of the ingot and, accordingly, an increase in productivity are achieved due to forging in several four-forging forging devices installed simultaneously in the same forging complex. In addition, the technological modes of the known method do not provide high productivity of the process and high quality metal obtained forgings.

The objective of the invention is to provide a method for the manufacture of forgings, in which by changing the deformation, feeding and tilting the workpiece, firstly, more intensive deformation processing of the metal structure and metal drawing, as well as reducing the number of passes, which leads to an improvement in the quality of metal forgings and increase process productivity, and, secondly, a more intense deformational heating of the metal, which leads to compensation of heat losses of the workpiece into the surrounding space and the possibility of complements forging operations per heating the ingot in a Four-die forging device, which also improves the process performance.

To achieve the named technical result in a method of manufacturing forgings, which includes heating the ingot to the forging temperature, its subsequent forging in a four-side forging device on the forging press, including billet ingot, broaching in several passes by four-sided crimping with additional macroshifts of the metal in the transverse plane of the workpiece for each unit compression by four strikers, each of which has a working section, consisting of a central and two side, adjacent to both sides central at an obtuse angle, with the formation of a contact surface of the workpiece with a striker during each crimping, calibration of the forging, feeding between the crimps and the groove, it is new that when drawing, a workpiece with a multifaceted cross section is formed, and at each new pass, a workpiece is formed, the cross section of which is rotated relative to the previous cross section at an angle of 30-60 °, with at least one pass, in addition to the last, produce single compression, in which the width of the contact surface of the workpiece with a striker exceeds the width of the central working section of the striker, but less than the width of the entire working section.

The achievement of the technical result is also facilitated by the fact that, depending on the parameters of the ingot and forging, as well as on the composition of the equipment:

- after heating the ingot, before trimming it, forging of the trunnion can be performed, while forging of the trunnion, billing of the ingot, broaching and calibration of the forgings is carried out in a four-forging forging device;

- with an increase in the number of the passage during broaching, the feed rate of the workpiece can be increased in comparison with the feed rate in the previous pass;

- with an increase in the number of the passage during broaching, the degree of deformation of the workpiece with each single compression can be increased in comparison with the degree of deformation of the workpiece in the previous pass;

- after each single crimping, the workpiece can be turned over at an angle of 30-60 °;

- during calibration of the forgings, the feed rate and the degree of deformation of the workpiece with each single compression can be kept constant at each pass;

- after heating the ingot before it is forged in a four-sided forging device, the ingot can be forged by two strikers, while the ingot can be forged by two combined strikers, of which the upper is flat and the lower is rhombic, or by two flat strikers by forming a square cross section on each the passage, and the subsequent forging in the four-sided forging device to perform by four-sided compression ribs of the workpiece.

The inventive method of manufacturing forgings is illustrated in figures 1-3.

Figure 1 presents the drawing scheme of the ingot with the formation of a multifaceted cross section of the workpiece, rotated relative to the previous cross section by an angle α;

figure 2 is a diagram of the compression of the workpiece, in which the width b _{k the} contact surface of the workpiece with the striker exceeds the width b _{c of the} Central working section of the striker, but less than the width b of the entire working section;

figure 3 is a diagram of the compression along the ribs in a four-sided forging device blanks of square cross section obtained by forging two strikers.

β is the angle between the central and lateral sections of the striker.

A patented method of manufacturing forgings is as follows.

The ingot heated to the forging temperature is taken out of the heating furnace and, using the manipulator, is fed into the working area of the hydraulic forging press, where it is forged in a four-side forging device, which is previously installed on this press. Compression of the workpiece 1 is carried out simultaneously by four strikers 2-5, each of which has a working section consisting of a central section 6 and two side sections 7, 8 adjacent to the central section at an obtuse angle β (Fig. 1). The four-side forging device is made in such a way that during compression of the workpiece 1, the upper hammer 3 moves vertically downward in the direction of arrow 9, and two side strikers 2, 4 in the direction of arrows 10, 11. Due to such movements of the strikers, the workpiece is crimped with additional macroshifts metal in its transverse plane.

At the beginning of the forging, the ingot is billed (aligned) in several passes, then the broaching itself is carried out, and at the end of the forging, the forging is calibrated. All these forging operations are carried out in one heating of the ingot, which provides an increase in the productivity of the process of manufacturing forgings. When drawing in each pass, a blank 1 of a multifaceted cross section is formed, and in each new pass, a blank is formed, the cross section of which is rotated by an angle of 30-60 ° (angle α (Fig. 1). During the formation of a multifaceted cross section, turned by an angle of 30 -60 ° relative to the previous cross-section, compresses are made along the edges and faces of the workpiece, which contributes to the deep penetration of deformations into the body of the workpiece.Multiple repetitions of such compressions over several passes allow intensive deformation study of the metal structure, which improves its quality. When forming a multifaceted cross section, rotated relative to the previous cross section by an angle of less than 30 ° and more than 60 °, intense deformation study of the metal structure is not achieved. besides the last one, single reductions are made in which the width b _{k of the} contact surface of the workpiece with the striker exceeds the width b _{c of the} central working section of the striker, but less than the width b of the entire working area of the striker (figure 2). After such a passage, a preform is obtained in which there are four depressed sections and four protruding sections in cross section. In the next pass, after turning the workpiece at an angle of 30-60 °, these protruding sections are crimped. The formation of four depressed and four protruding sections on the workpiece, and then after turning the workpiece through an angle α = 30-60 °, pressing these protruding sections into the central zone of the workpiece, leads to intensive deformation study of the metal structure and due to this, high metal quality is achieved. In addition, due to such intense compression of the workpiece, a more intensive drawing of the workpiece is ensured and the number of passes is reduced, which ultimately leads to an increase in the process productivity.

Before billetization of the ingot, trunnion forging is sometimes performed, while trunnion forging, ingot billing, broaching and forging calibration are performed in a four-forging forging device for one ingot heating.

After each feed, a value of "s" is used to compress a portion of the workpiece by a value of "Δh". In this case, it is possible to carry out a broaching mode in which, with an increase in the passage number, the feed rate s is increased in comparison with the feed amount at the previous pass. In this way, the heat loss of the workpiece into the surrounding space is partially or completely compensated for due to a more intense deformational heating of it at each subsequent pass. This allows you to perform all forging in one heat ingot.

It is possible to carry out such a forging mode, in which, in the process of broaching the workpiece, with an increase in the passage number, the degree of deformation of the workpiece "ε" at each single reduction is increased compared with the degree of deformation of the workpiece in the previous pass. It also allows you to partially or fully compensate for the heat loss of the workpiece into the surrounding space due to more intense deformation heating it in each subsequent pass. This allows you to complete all forging in one heat. The degree of deformation at each single compression of the workpiece is determined by the formula

,

,

where Δh is the amount of compression of the workpiece per pass;

h _o - the size of the cross section of the workpiece before compression.

After each single compression, the blank is tilted at an angle α = 30-60 °. At such corners of the tilting, the most effective deformation study of the metal structure is achieved by pressing the protruding sections of the workpiece into the central zone of the workpiece (Figs. 1, 2). When the pitching angles are less than 30 ° and more than 60 °, the effective deformation study of the metal structure is not ensured, since the volumes of metal moved in the direction of the central zone during compression of the workpiece are significantly reduced.

Forgings are also calibrated in a four-forging forging device. In this case, the feed rate and the degree of deformation of the workpiece with each single compression are kept constant in each pass. This ensures uniformity of the properties of the metal along the entire length of the forging.

When forging ingots of large cross-section in a four-sided forging device, the press force in the first passes is not always enough. In this regard, before forging in a four-flange forging device, the ingot is sometimes forged with two dies to reduce the size of the cross section of the workpiece, since when forged by two dies, a significantly lower technological effort is required compared to forging four dies with the same deformation modes. The resulting billet is then continued to be forged in a four-forging device without additional heating. Due to this, a high productivity of the process and the possibility of forging ingots with large transverse dimensions are achieved.

Before forging in a four-sided forging device, the ingot can be forged by two combined strikers, of which the upper is flat and the lower is rhombic. Compared to forging in a four-sided forging device, the forging force is reduced, and the intermediate workpiece in the cross section has the shape of a polyhedron, which is optimal for further forging in a four-sided forging device.

Before forging in a four-sided forging device, forging of the ingot with two strikers can also be carried out by forming a square cross-section blank in each pass, and subsequent forging in the four-side forging device in the first pass by four-sided crimping of the workpiece ribs (Fig. 3). This provides a significant reduction in the forging force compared to forging in a four-sided forging device. In addition, this method provides high productivity of the process of drawing the workpiece and intensive deformation study of the metal structure due to the deep penetration into the axial zone of the workpiece of the volumes of metal under the strikers.

An example implementation of the method.

Before forging, a four-side forging device with four strikers was installed in the press working space with a force of 25 MN. The working section of each striker consisted of a central width b _c = 120 mm and two lateral ones adjoining from both sides at an angle β = 135 ° to the central section. The 25 MN press was equipped with two manipulators.

An ingot weighing 1100 kg of open arc smelting from P6AM5 steel was heated in a gas chamber furnace to a temperature of 1150 ° C and forged on a hydraulic forging press with a force of 25 MN in a four-forging forging device for forging with a diameter of 122 mm. The maximum size of the cross section of the ingot in its head was 450 mm, and the minimum was 350 mm (in the bottom). Forging was carried out in one set of strikers for one ingot heating. At the same time, the ingot was first captured at the bottom by the first manipulator and the axle was forged from the side of the head of the ingot. Then, holding the ingot by the pin in the jaws of the second manipulator, the ingot was billed to a size of 350 mm. After that, using the same manipulator, the billeted ingot was forged according to the scheme:

⌀350 mm → 290 mm → 290 mm → 250 mm → 240 mm → 195 mm → 170 mm → 128 mm → 128 mm → ⌀122 mm → ⌀122 mm.

Up to a size of 250 mm, the workpiece was forged with feeds “into strikers” and “from strikers” without idle passages. Then, forging was carried out only “from the strikers”, with idle passages after each pass with reductions. After each pass to a second size of 128 mm, the workpiece was tilted at an angle of 45 °, and the feed of the workpiece between reductions in these passages was 220-400 mm. In addition, with an increase in the number of passes, the feed rate of the billet was increased, starting from 220 mm and ending in the eighth pass (forging to a size of 128 mm) with 400 mm feeds. During broaching, on each pass, a blank of multifaceted cross section was formed, and on each next new pass, a blank, the cross section of which was rotated by an angle of 45 ° relative to the previous cross section. At the same time, in the first pass, when compressing to a size of 290 mm, on the third pass, when compressing to a size of 250 mm, and on the fifth pass, when compressing to a size of 195 mm, the width of the contact surface of the workpiece with the striker exceeded the width of the central working section, but was less than the width of the entire working area. Due to such reductions, part of the metal was squeezed into the space between the strikers, and in the next pass, this metal was pressed (like a wedge) into the axial zone of the workpiece, thereby providing intense shear deformation in the cross section of the workpiece. The resulting preform of a multifaceted cross section with dimensions in the cross section of 128 mm was calibrated to 0.122 mm with tolerances of ± 1 mm. In this case, after each crimping, the workpiece was rotated through an angle of 12–16 ° (in one circumferential direction). The supply of the workpiece was performed "out of the strikers." When calibrating the forgings, the feed rate and the degree of deformation of the workpiece at each single compression were kept constant at each pass. In the first pass, when calibrating the forgings, the feed rate was 45 mm, and the degree of deformation was 4.0%; in the second pass, the feed rate was 35 mm, and the degree of deformation was 1%.

The productivity of the forging process was 2620 kg / h.

The quality of the metal was assessed by a carbide inhomogeneity score in three zones of the forging cross section (GOST 19265-73):

1st - 5 mm from the forging surface;

2nd - the middle of the radius of the cross section of the forging (1 / 2R);

3rd - axial zone of forging.

At the surface, carbide heterogeneity corresponded to 3 points, to 1 / 2R - 5 points, and in the axial - 6 points.

Comparison day, as a basic object adopted a method of manufacturing forgings according to the prototype.

The performance of the forging process by the prototype method was 2030 kg / h, and the quality of the metal, assessed by the carbide inhomogeneity score:

- at the forging surface - 5 points;

- at half the radius of the cross section of the forgings - 7 points;

- in the axial zone of the forgings - 8 points.

The experimental results for other process parameters are presented in the table.

Experiment number
that Angle of rotation, α ° The ratio b _k / b _c , unit B.C. on 1 / 2R Productivity, kg / h Note one thirty 1.27 5 2580 Before forging in a four-sided forging device, two combinations were forged. brisk 2 45 1.35 5 2620 Before forging in a four-side forging device, two flat strikers were forged 3 60 1.38 5 2510 four 45 1.18 5-6 2400 5 45 1.22 5-6 2440 6 (pro-type) 7 2030

Note: B.C. - point carbide heterogeneity. Analysis of the data given in the table shows that the quality of the metal forgings obtained by the claimed method (estimated by the carbide inhomogeneity score) is higher than the quality of the metal forgings obtained by the prototype method. For a specific example of the manufacture of forgings from high-speed steel P6AM5, a decrease in carbide heterogeneity was 1-2 points.

The productivity of the forging process according to the patented method increased by 18.2-29.0%.

Claims (9)

1. A method of manufacturing forgings, including heating the ingot to the forging temperature, its subsequent forging in a four-side forging device on the forging press, including billet ingot, broaching in several passes by four-side crimping with additional macroshifts of the metal in the transverse plane of the workpiece with each single crimping by four strippers, each of which has a working section, consisting of a central section and two lateral, adjacent to the central on both sides at an obtuse angle, with the formation m each compression of the contact surface of the workpiece with the striker, calibration of the forgings, the feed between the compressions and the tilting, characterized in that during broaching form a workpiece with a multifaceted cross section, and at each new pass form a workpiece, the cross section of which is rotated relative to the previous cross section by an angle of 30 -60 °, with at least one pass, in addition to the last, produce single compression, in which the width of the contact surface of the workpiece with the striker exceeds the width of the Central section ka striker and less than the width of the entire working area. 2. The method according to claim 1, characterized in that after heating the ingot before billing, the forging of the trunnion is performed, which is produced in a four-forging forging device. 3. The method according to claim 1, characterized in that with the increase in the number of the passage during broaching, the feed rate of the workpiece is increased compared with the feed rate of the workpiece in the previous pass. 4. The method according to claim 1, characterized in that with an increase in the number of the passage during broaching, the degree of deformation of the workpiece with each single compression is increased compared with the degree of deformation of the workpiece in the previous pass. 5. The method according to claim 1, characterized in that after each single crimping, the blank is tilted at an angle of 30-60 °. 6. The method according to claim 1, characterized in that when calibrating the forgings, the feed rate and the degree of deformation of the workpiece with each single compression are kept constant at each pass. 7. The method according to claim 1, characterized in that after heating the ingot before forging it in the four-side forging device, the ingot is forged in two strikers. 8. The method according to claim 7, characterized in that the ingot is forged by two combined strikers, of which the upper is flat and the lower is rhombic. 9. The method according to claim 7, characterized in that the ingot is forged with two flat dies by forming a square cross-section blank in each pass, and the subsequent forging in the four-side forging device is performed by quadrilateral compression of the blank ribs.

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