Method of manufacturing harrow disks

Abstract

FIELD: agricultural equipment.SUBSTANCE: invention relates to a method for manufacturing harrow discs. The process involves feeding the strip, forming the sphere, obtaining petals and cutting edges of the disk petals, separating the disk from the strip and heat treating it. The cut disk, heated to forging temperature, is placed on the spherical surface of the matrix, identical to the sphere of the disk. By compressing an elastic element made at the end of the punch in the form of a disk spring with a support surface, the upper edges of the disk petals are deformed by the side wall of the cavity of the elastic element, equal in size to the length of the bevel of the cutting edge of the disk petal. The supporting surface of the elastic element contacts the spherical surface of the matrix and simultaneously performs radial sliding towards the periphery of the side wall of the cavity along the metal upper edges of the disk petals. By fully compressing the cavity of the elastic element, the upper base of the cavity of the elastic element comes into contact with the sphere of the disk. The cutting edges of the disk petals are formed in wedge-shaped cavities by stamping on the side wall of the elastic element cavity.EFFECT: efficiency of the harrow disc manufacturing process increases.1 cl, 3 dwg, 1 ex

Description

[0001] The invention relates to metal pressure processing and can be used for the manufacture of harrow discs and other soil-cultivating units, as well as for sharpening blunt cutting edges of discs.

[0002] A known method for manufacturing harrow disks includes feeding a strip, separating the blank from the strip by thermal cutting, heating it to forging temperature, forming petals and an annular section of the cutting edge of the disk by rolling, molding the disk sphere and heat treating. The disks obtained by this method have improved quality, since the petals and cutting edges of the disks are formed by plastic deformation, which creates a favorable fibrous structure of the metal (Patent of the Russian Federation No. 20225181. B21H 7 / 00. Cherkasova I.N., Cherkasov M.M. Method for Manufacturing Harrow Disks. Published December 30, 1994).

[0003] The disadvantages of the known method of manufacturing harrow discs are the production of blanks by thermal cutting, which inevitably results in burns and a coarse-grained structure of the metal around the perimeter of the blank, as well as the complexity of the rolling device, high labor intensity and cost of the process, which reduces the efficiency of the known method of manufacturing harrow discs.

[0004] A known method for manufacturing harrow discs involves feeding a strip, separating the workpiece from the strip, forming a sphere, producing petals and cutting edges of the disc, and heat treating. Discs produced by this method have improved quality, as the disc petals are cut while the disc is simultaneously separated from the strip on an inclined spherical die surface, creating high tensile stresses in the metal. This improves the fibrous structure of the metal. Cutting the metal at an angle to the disc surface brings the peripheral portion of the petal closer to the working profile of its cutting edge, significantly reducing shear stress. As a result, the efficiency and quality of products are increased (RU Patent No. 2770808. B21H 7 / 00 (2006.1). Poksevatkin M.I. Method for manufacturing harrow discs. Published April 21, 2022, Bulletin No. 12).

[0005] The disadvantage of the known method of manufacturing harrow discs is the need to sharpen the cutting edges of the disc petals after they are cut, which reduces the efficiency of the harrow disc manufacturing process by this method.

[0006] The invention is based on the task of increasing the efficiency of the harrow disc manufacturing process.

[0007] To solve the problem in the method for manufacturing harrow disks, which includes feeding a strip, forming a sphere, obtaining petals and cutting edges of the disk petals, separating the disk from the strip and heat treatment, the cut disk, heated to forging temperature, is placed on the spherical surface of the matrix, identical to the sphere of the disk, and by compressing an elastic element made on the end of the punch in the form of a disk spring with a support surface (GOST 3057-90.The disc springs deform the upper edges of the petals with the side wall of the cavity of the elastic element, equal in magnitude to the length of the bevel of the cutting edge of the disk petal, and with the supporting surface of the elastic element they contact the spherical surface of the matrix and create wedge-shaped cavities closed on the outside, adjacent to the disk petals, simultaneously performing radial sliding towards the periphery of the side wall of the cavity along the upper edge metal of the disk petals and activating, thereby, contact friction forces, by means of which they displace the upper edge metal of the disk petals into the aforementioned wedge-shaped cavities (Levanov A.N., Kolmogorov V.L., Burkin S.P. et al. Contact friction in metal forming processes. Publ. "Metallurgy". 1976, 410 pp., p. 339), then complete compression of the cavity of the elastic element, the height of which is set equal to the thickness of the disk according to the condition.

[0008]

[0009] where h вп- the height of the cavity of the elastic element, equal to twice the thickness of the disk, mm; h сж - the height of the full compression of the cavity of the elastic element under cyclic loading, mm (GOST 3057-90. Disc springs. Page 21, Table 8), contact the upper base of the cavity of the elastic element, which is set equal in size to the diameter of the contour of the bases of the cutting edges of the disk petals, with the sphere of the disk and at the same time the side wall of the cavity of the elastic element is stamped to form the cutting edges of the disk petals in wedge-shaped cavities.

[0010] Obtaining cutting edges of the disk petals by making an elastic element in the form of a disk spring with a supporting surface and a side wall of the cavity equal to the length of the bevel of the cutting edge of the disk petal on the punch end makes it possible to deform the upper edges of the disk petals by compression of the elastic element with its side wall of the cavity, and to contact the spherical surface of the matrix with its supporting surface, and to create wedge-shaped cavities closed on the outside, adjacent to the disk petals, simultaneously performing radial sliding to the periphery of the side wall of the cavity along the upper edge metal of the disk petals and activating, thereby, contact friction forces, by means of which to displace the upper edge metal of the disk petals into the wedge-shaped cavities, and to exclude, due to the influence of lateral sink marks, the exit of metal into the sides of the petals, and to contact the upper base of the cavity by full compression of the cavity of the elastic element,which is set equal in size to the diameter of the contour of the bases of the cutting edges of the disk petals, with the sphere of the disk and at the same time the side wall of the cavity of the elastic element by stamping to form the cutting edges of the disk petals in wedge-shaped cavities.

[0011] As a result of the implementation of the described technological methods for obtaining cutting edges of disc petals, the efficiency of the proposed method for manufacturing harrow discs is significantly increased.

[0012] The proposed invention is explained by drawings, where Fig. 1 shows the moment of deformation of the upper edges of the disk petals by the side wall of the cavity of the elastic element; Fig. 2 shows the moment of creation of wedge-shaped cavities closed on the outside and displacement of the upper edge metal of the disk petals in them; Fig. 3 shows the moment of contact of the upper base of the cavity of the elastic element with the sphere of the disk and obtaining cutting edges of the disk petals.

[0013] A method for manufacturing harrow discs, including feeding a strip, forming a sphere, obtaining petals and cutting edges of the disc petals, separating the disc from the strip and heat treating the cut disc heated to forging temperature is placed on the spherical surface of the matrix identical to the sphere of the disc, and by compressing an elastic element made at the end of a punch in the form of a disk spring with a supporting surface, the side wall of the cavity of the elastic element is deformed, equal in magnitude to the length of the bevel of the cutting edge of the disc petal, the upper edges of the petals, and the supporting surface of the elastic element contacts the spherical surface of the matrix and creates closed wedge-shaped cavities on the outside adjacent to the disc petals, simultaneously performing radial sliding to the periphery of the side wall of the cavity along the upper edge metal of the disc petals and activating, thereby, contact friction forces,by means of which the upper edge metal of the disk petals is displaced into the aforementioned wedge-shaped cavities, then by fully compressing the cavity of the elastic element, the height of which, according to condition (1), is set equal to the thickness of the disk, the upper base of the cavity of the elastic element, which is set equal in size to the diameter of the contour of the bases of the cutting edges of the disk petals, is contacted with the sphere of the disk and at the same time the side wall of the cavity of the elastic element is stamped to form the cutting edges of the disk petals in the wedge-shaped cavities.

[0014] The method for manufacturing harrow discs is implemented as follows. The disk 1 heated to forging temperature is placed on the spherical surface 2 of the matrix 3, identical to the sphere 4 of the disk 1, and by compression of the elastic element 5, made on the end 6 of the punch 7 in the form of a disk spring 8 with a supporting surface 9 (Fig. 1), the side wall 10 of the cavity 11 of the elastic element 5 (Fig. 2) is deformed, equal in magnitude to the length of the bevel 12 of the cutting edge 13 of the petal 14 of the disk 1 (Fig. 3), the upper edges 15 of the petals 14, and the supporting surface 9 of the elastic element 5 are in contact with the spherical surface 2 of the matrix 3, and wedge-shaped cavities 16 closed on the outside are created, adjacent to the petals 14 of the disk 1 (Fig. 2), and at the same time a radial sliding is performed to the periphery of the side wall 10 of the cavity 11 along upper edge metal 17 of petals 14 of disk 1 (Fig.2) and thereby activate the contact friction forces by means of which the upper edge metal 17 of the petals 14 of the disk 1 is displaced into the aforementioned wedge-shaped cavities 16, and at the moment of complete compression of the cavity 11 of the elastic element 5, the height of which, according to condition (1), is set equal to the thickness of the disk 1, they contact the upper base 18 of the cavity 11 of the elastic element 5, which is set equal in size to the diameter of the contour 19 of the bases of the cutting edges 13 of the petals 14 of the disk 1, with the sphere 20 of the disk 1 and, at the same time, the side wall 10 of the cavity 11 of the elastic element 5 is formed in the wedge-shaped cavities 16 by stamping the cutting edges 13 of the petals 14 of the disk 1 (Fig. 3).

[0015] Example. Prototypes of a spherical disc for the BDM 560x6 "Romashka" harrow with nine 130 mm wide petals were manufactured; the bevel length of the petal cutting edge is 12 mm, the sharpening angle of the cutting edge is 34°. The height of the disc is H = 67 mm, the radius of the sphere is 560 mm, the strip is 6 mm thick made of 65G steel according to GOST 14959-79 and GOST 1577-81, the tensile strength is σ в =750 MPa, yield strength σ т =440 MPa, during hot processing of steel at T=1100°C, σ в =52 MPa, σ т =43 MPa.

[0016] The elastic element is made of 60S2A steel according to GOST 14959-69 and GOST 14963-78 based on the technical specifications of GOST 3057-90. Disc springs, type 2, with inclined edges and a supporting surface; the tensile strength of steel is σ в =1570 MPa, yield strength σ т =1400 MPa; 12 - relative elongation in percent, relative contraction ψ=20%.

[0017] Technological calculations are performed in the following order.

[0018] 1. The volumes of the displaced upper edge metal of the disk petal and the wedge-shaped cavity are established (Fig. 2).

[0019] From the construction in Fig. 2 and Fig. 3 it is established that, for the volumes to be equal, the angle of inclination of the side wall of the elastic element cavity (α in Fig. 1) must be equal to 45°, and to form a cutting edge in a wedge-shaped cavity, the length of the side wall of the elastic element must be equal to the length of the bevel of the cutting edge of the disk petal.

[0020] 2. Determine the maximum compression force of the elastic element under cyclic loading (GOST 3057-90. Disc springs, Table 8, F (5)):

[0021]

[0022] where R сж - compression force of the elastic element, N;

[0023] E=2.06⋅10 5 , MPa – modulus of elasticity of steel;

[0024] S3=h сж - the height of the full compression of the cavity of the elastic element, equal to 6 mm according to condition (1);

[0025] t уэ- thickness of the side wall of the cavity of the elastic element; take t уэ =16 mm (GOST 3057-90. Disc springs, table 9);

[0026] μ=0.3 - Poisson's ratio;

[0027] γ - parameter selected based on the ratio A=D1 / D2 according to GOST 3057-90. Disc springs, table 2;

[0028] D1=560 mm - diameter of the lower base of the elastic element cavity;

[0029] D2- the diameter of the hole in the upper base of the disc spring, equal to zero in the elastic element; then at A=D1 / D2=A max =1.30, γ=0.773;

[0030] b=5 mm - width of the support plane of the elastic element (GOST 3057-90. Disc springs, table 9);

[0031]

[0032] 3. Determine the stamping force of the metal displaced into the wedge-shaped cavities by means of the side wall of the cavity of the elastic element:

[0033] R шт =k⋅σ m ⋅S кп / 2, MN;

[0034] where R шт- stamping force of metal displaced into wedge-shaped cavities, MN;

[0035] k=9 - number of wedge-shaped cavities;

[0036] S кп - contact area of ​​the side wall of the elastic element with the surface of the wedge-shaped cavity, mm 2 ;

[0037] R шт =9⋅43⋅130⋅12 / 2=301860 N=0.302 MN.

[0038] 4. Determine the total compression force of the elastic element when stamping the cutting edges of the disk petals:

[0039] R сум =R сж +R шт =0.009+0.302=0.311 MN.

[0040] 5. Determine the magnitude of tensile stresses in the most heavily loaded section of the elastic element at the junction of the side wall of the cavity with its upper base. Under cyclic loading of the elastic element in accordance with GOST 3057-90. Disc springs, Table 9, f. (11):

[0041]

[0042] where σ p- the value of tensile stresses in the most loaded section of the elastic element, MPa;

[0043] S - the height of the elastic element, equal to S=h вп +t уэ =12+16=28 mm;

[0044] C1=1.426 and C2=1.738 - parameters selected from Table 9 of GOST 3057-90. Disc springs with A=1.30 and cyclic loading of the elastic element;

[0045] t сж =6 mm – calculated compression height of the elastic element cavity;

[0046]

[0047] which does not exceed the permissible tensile stress according to GOST 3057-90. Disc springs, Table 2, equal to σ p =1360 MPa, recommended for cyclic loading of a disc spring made of 60C2A steel, i.e. the established parameters of the elastic element are quite satisfactory.

[0048] The obtained disk samples had geometrically correctly formed cutting edges of the petals; no metal egress onto the sides of the disk petals was observed.

Claims

A method for manufacturing harrow discs comprising feeding a strip, forming a sphere, producing petals and cutting edges of the disc petals, separating the disc from the strip and heat treating, characterized in that the cut disc heated to forging temperature is placed on the spherical surface of a matrix identical to the sphere of the disc, and by compressing an elastic element made on the end of a punch in the form of a disk spring with a supporting surface, the upper edges of the disc petals are deformed with the side wall of the cavity of the elastic element equal in magnitude to the length of the bevel of the cutting edge of the disc petal, and the supporting surface of the elastic element contacts the spherical surface of the matrix, creating wedge-shaped cavities closed on the outside adjacent to the disc petals, and simultaneously performing radial sliding to the periphery of the side wall of the cavity along the metal upper edges of the disc petals and activating contact friction forces,by means of which the upper edge metal of the disk petals is displaced into the mentioned wedge-shaped cavities, then by complete compression of the cavity of the elastic element, the height of which is set equal to the thickness of the disk according to the condition:, h сж ≤(0.3-0.6)h вп , where h вп - the height of the cavity of the elastic element, equal to twice the thickness of the disk, mm; h сж - the height of the complete compression of the cavity of the elastic element during its cyclic loading, mm, is in contact with the upper base of the cavity of the elastic element, which is set equal in size to the diameter of the contour of the bases of the cutting edges of the disk petals, with the sphere of the disk and at the same time the side wall of the cavity of the elastic element is stamped to form the cutting edges of the disk petals in wedge-shaped cavities.

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