Blank design method for casing forge piece

Abstract

The invention relates to a blank design method for a casing forge piece and belongs to the technical field of forging, and the section graph of a blank is defined by a top edge, two side edges, a first line segment, a second line segment, a first bevel edge and a second bevel edge. The design method comprises the steps that the length C of the top edge is preset according to the width B of an upper mold cavity, and C is larger than or equal to B; the vertical distance K between the top edge and the bottom edge is obtained according to the sectional areas S and C of the casing forge piece; obtaining a theoretical maximum side length value Z'of the blank in contact with the lower die cavity; the length a of the first line segment, the length a'of the second line segment, the included angle alpha between the first bevel edge and the extension line of the first line segment and the included angle alpha 'between the second bevel edge and the extension line of the second line segment are preset, the total length Z of the bottom edge is obtained according to a, a', alpha and alpha ', Z is smaller than Z', the sectional area S'of the blank is obtained according to a, a ', alpha, alpha', C and K, S 'and S are compared, and when S' is larger than S, it is judged that the values of a, a ', alpha, alpha' and C are preset to be appropriate.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and in particular relates to a blank design method for a casing forging. Background Art

[0002] Casing forgings are load-bearing components of the outer wall of the high-pressure compressor stator, and are widely used in the field of aerospace engines. Due to the complex morphology of casing forgings, in order to ensure the performance of the forgings, they must be formed by prefabricated billets + final forging. During the early forging process, prefabricated slabs (also known as billets) are used for die forging. The probability of folding defects in the four corners of the forgings is greater than 90%, which not only seriously affects the production cycle of the forgings, but also increases the production cost.

[0003] The shape of the billet currently used is a square plate. Through analysis, it is known that the reason for the folding of the billet during die forging is that the billet width is too large and directly overlaps at the flash bridge. During die forging, the cavity is filled first, and then the flash is extruded, resulting in folding at this location. If the billet size is simply reduced and the billet thickness is increased, there will be a risk of underfilling at the four corners of the forging, and the excessive billet thickness will cause the hardness and mechanical properties of the forging to exceed the standard requirements.

[0004] Therefore, when designing the blank of the casing forging, it is very important to reasonably select the size of the blank to eliminate folding. In the prior art, there is no suitable design method to assist designers in reasonably selecting the size of the blank of the casing forging. Summary of the invention

[0005] The invention provides a blank design method for a casing forging, which is used to solve the technical problem that there is no suitable design method to design the blank size of the casing forging, so that the blank is prone to folding during the die forging process.

[0006] The present invention is implemented by the following technical scheme: a blank design method for a casing forging, wherein the cross-sectional figure of the blank is surrounded by a top edge close to an upper die, a bottom edge close to a lower die, and two side edges, the bottom edge includes a middle section, a first bevel edge, and a second bevel edge, the middle section is divided into a first line segment and a second line segment through a perpendicular midline of the top edge, the first line segment is connected to one of the side edges through the first bevel edge, the second line segment is connected to the other side edge through the second bevel edge, and the first bevel edge and the second bevel edge are both inclined from the bottom edge toward the top edge;

[0007] The design approach includes:

[0008] The length C of the top edge is preset according to the width B of the upper mold cavity, so that C≥B;

[0009] According to the cross-sectional area S of the casing forging and the preset C, a vertical distance K between the top edge and the bottom edge is obtained;

[0010] Obtain the theoretical maximum side length Z' of the blank in contact with the lower mold cavity;

[0011] Preset the length a of the first line segment, the length a' of the second line segment, the angle α between the first hypotenuse and the extension line of the first line segment, and the angle α' between the second hypotenuse and the extension line of the second line segment, and obtain the total length Z of the base according to a, a', α and α', so that Z<Z';

[0012] According to the preset a, a', α, α', C and K, the cross-sectional area S' of the blank is obtained;

[0013] Determine the size relationship between S' and S. When S'>S, determine that the preset values ​​of a, a', α, α', and C are appropriate.

[0014] Further, in order to better implement the present invention, the vertical distance K between the top edge and the bottom edge is obtained according to the cross-sectional area S of the casing forging and the preset C, which is specifically:

[0015] The vertical distance between the top edge and the bottom edge is K=mS / C, m is the material-to-labor ratio, and 1<m≤2.

[0016] Further, in order to better realize the present invention, the bottom of the lower model cavity has a curved surface protrusion, and the curved surface protrusion is provided with three protrusions, so that the cross-sectional figure of the lower model cavity has a curve located at the cavity bottom and three vertices located on the curve, the three vertices are respectively a first point close to one side of the lower model cavity, a third point close to the other side of the lower model cavity, and a second point located between the first point and the third point, the radius of the circumscribed circle of the first point, the second point and the third point is r, the arc between the two points where the circumscribed circle connects with the bottom of the lower model cavity is the first arc, the arc length of the first arc is s, and the two points where the circumscribed circle connects with the bottom of the lower model cavity are respectively a fourth point close to the first line segment and a fifth point close to the second line segment, the angle between the tangent of the first arc at the fourth point and the horizontal plane is β, and the angle between the tangent of the first arc at the fifth point and the horizontal plane is β';

[0017] The theoretical maximum side length Z' of the blank in contact with the lower mold cavity is obtained as follows:

[0018] Z'=s+A-2r×sin(β+β'), where A is the width of the lower mold cavity.

[0019] Further, in order to better implement the present invention, the arc between the first point and the third point on the circumscribed circle is a second arc, and the arc length of the second arc is s';

[0020] The preset length a of the first line segment and the preset length a' of the second line segment are specifically:

[0021] Such that a+a'>s'.

[0022] Furthermore, in order to better implement the present invention, the preset angle α between the first hypotenuse and the extension line of the first line segment and the preset angle α′ between the second hypotenuse and the extension line of the second line segment are specifically:

[0023] When C<A, the values ​​of α and α' are not affected by β and β';

[0024] When C≥A, α≥β, α'≥β'.

[0025] Further, in order to better implement the present invention, the length a of the first line segment is equal to the length a' of the second line segment;

[0026] The included angle α between the first hypotenuse and the extended line of the first line segment is equal to the included angle α′ between the second hypotenuse and the extended line of the second line segment.

[0027] Further, in order to better implement the present invention, the total length Z of the bottom edge is obtained according to a, a', α and α', specifically:

[0028] Z=a+a'+(0.5Ca) / cosα+(0.5C-a') / cosα'.

[0029] Further, in order to better implement the present invention, the cross-sectional area S' of the blank is obtained according to the preset a, a', α, α', C and K, specifically:

[0030] S'=(a+a')×K+[2K-(0.5Ca)tanα]×(0.5Ca) / 2+[2K-(0.5C-a')tanα']×(0.5C-a') / 2.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The blank design method for a casing forging provided by the present invention designs the blank of the casing forging as a blank whose cross-sectional figure is surrounded by a top edge close to an upper die, a bottom edge close to a lower die, and two side edges, wherein the bottom edge includes a middle section, a first beveled edge, and a second beveled edge, and the middle section is divided into a first line segment and a second line segment through a perpendicular bisector of the top edge, the first line segment is connected to one of the side edges through the first beveled edge, and the second line segment is connected to the other side edge through the second beveled edge, and both the first beveled edge and the second beveled edge are inclined from the bottom edge toward the top edge, and in the design process, by presetting the length of the top edge, the length of the first line segment, the length of the first line segment, and the second beveled edge, the blank is designed to have a cross-sectional figure surrounded by a top edge close to an upper die, a bottom edge close to a lower die, and two side edges, wherein the bottom edge includes a middle section, a first beveled edge, and a second beveled edge, and the middle section is divided into a first line segment and a second line segment through a perpendicular bisector of the top edge, and the first line segment is connected to one of the side edges through the first beveled edge, and the second line segment is connected to the other side edge through the second beveled edge, and both the first beveled edge and the second beveled edge are inclined from the bottom edge toward the top edge. The length of the two line segments, the angle between the first hypotenuse and the extension of the first line segment, and the angle between the second hypotenuse and the extension of the second line segment, obtain two key values, as well as the total length of the bottom edge and the cross-sectional area of ​​the blank. The preset value makes the total length of the bottom edge smaller than the theoretical maximum side length of the contact between the blank and the lower mold cavity. In this way, when the blank is forged by the upper die and the lower die, the folding of certain parts of the blank can be avoided. The cross-sectional area of ​​the blank is then compared with the cross-sectional area of ​​the casing forging to determine whether all the above preset values ​​meet the requirements.

[0033] The blank of the casing forging designed by this design method will not have folding defects during die forging, which is not only beneficial to improving the forming quality of the casing forging, but also helps to save the manufacturing cost of the casing forging. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 is a flow chart of a blank design method for a casing forging provided by an embodiment of the present invention;

[0036] Figure 2 is a cross-sectional view of an upper mold in an embodiment of the present invention;

[0037] Figure 3 is a cross-sectional view of a blank in an embodiment of the present invention;

[0038] Figure 4 It is a cross-sectional view of the lower mold in an embodiment of the present invention.

[0039] In the figure:

[0040] 100-blank, 200-upper die, 300-lower die, 301-first point, 302-second point, 303-third point. DETAILED DESCRIPTION

[0041] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0042] Example:

[0043] This embodiment provides a blank design method for a casing forging to determine the shape and appropriate size of the blank 100 of the casing forging, thereby preventing the blank 100 from folding during the die forging process. Specifically, Figure 3 As shown, the blank 100 of the casing forging is designed to have a block structure with length, width and height. The longitudinal cross-sectional figure of the blank 100 in its width direction is surrounded by the top edge close to the upper die 200, the bottom edge close to the lower die 300 and two side edges. The bottom edge includes a middle section, a first bevel and a second bevel. The middle section is divided into a first line segment and a second line segment through the perpendicular bisector of the top edge. The first line segment is connected to one of the side edges through the first bevel, and the second line segment is connected to the other side edge through the second bevel. The first bevel and the second bevel are both inclined from the bottom edge to the top edge. During die forging, the top edge is connected to the cavity wall of the upper die 200, the bottom edge is connected to the cavity wall of the lower die 300, and the top edge and the bottom edge are arranged in parallel. The vertical distance between the top edge and the bottom edge is the thickness of the blank 100, the length of the top edge is the width of the blank 100, and the two side edges are perpendicular to the top edge.

[0044] The design method is as follows Figure 1 As shown, including:

[0045] Step 1: According to the width B of the cavity of the upper mold 200 (such as Figure 2 As shown) to preset the length C of the top edge so that C ≥ B;

[0046] Step 2: According to the cross-sectional area S of the casing forging and the preset C, the vertical distance K between the top edge and the bottom edge is obtained. In this step, the following formula is specifically used: K = mS / C, m is the material-to-work ratio, and 1 < m ≤ 2. Optionally, the value of m is 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2. Through this step, the thickness K of the blank 100 can be obtained.

[0047] Step 3: Obtain the theoretical maximum side length Z' of the blank 100 in contact with the cavity of the lower die 300. Figure 4 As shown, in this step, the theoretical maximum side length Z' (specifically Figure 4The dotted lines in the figure are obtained from the cavity size of the lower die 300. The specific method of obtaining the data is to perform digital model analysis through software. In fact, the bottom of the cavity of the lower die 300 has a curved surface protrusion located in the middle, and the curved surface protrusion has three convex strips along the length direction of the blank 100, so that the cross-sectional figure of the cavity of the lower die 300 has a curve located at the bottom of the cavity and three vertices located on the curve, and the three vertices are a first point 301 close to one side of the cavity of the lower die 300, a third point 303 close to the other side of the cavity of the lower die 300, and a second point 302 located between the first point 301 and the third point 303. Define the radius of the circumscribed circle of the first point 301, the second point 302 and the third point 303 as r, the arc between the two points where the circumscribed circle touches the bottom of the cavity of the lower mold 300 is the first arc, the arc length of the first arc is s, and the two points where the circumscribed circle touches the bottom of the cavity of the lower mold 300 are the fourth point close to the first line segment and the fifth point close to the second line segment, respectively, the angle between the tangent of the first arc at the fourth point and the horizontal plane is β, and the angle between the tangent of the first arc at the fifth point and the horizontal plane is β'. The above r, s, β, β' are determined after the lower mold 300 is determined. After the digital model of the lower mold 300 is drawn in the software, the above r, s, β, β' can be obtained by using the software. In addition, the width A of the cavity of the lower mold 300 can also be obtained in the software. In this step, Z'=s+A-2r×sin(β+β'). It should be noted that the theoretical maximum side length Z' of the blank 100 in contact with the cavity of the lower mold 300 is the sum of the arc length of the first arc and the horizontal distance between the fourth point and the corresponding side edge of the cavity of the lower mold 300, as well as the horizontal distance between the fifth point and the corresponding side edge of the cavity of the lower mold 300.

[0048] Step 4: Preset the length a of the first line segment, the length a' of the second line segment, the angle α between the first hypotenuse and the extension of the first line segment, and the angle α' between the second hypotenuse and the extension of the second line segment, and obtain the total length Z of the base according to a, a', α and α', so that Z < Z'. In this step, Z = a + a' + (0.5Ca) / cos α + (0.5C-a') / cos α', that is,:

[0049] a+a'+(0.5Ca) / cosα+(0.5C-a') / cosα'<s+A-2r×sin(β+β').

[0050] In this way, it can be ensured that the blank 100 obtained by the above preset C, a, a', α and α' will not have folding defects during the process of die forging into a casing forging.

[0051] In this step, the sum of the length of the first line segment and the length of the second line segment is equal to the length of the intermediate segment. In the actual die forging process, the intermediate segment needs to correspond to the area between the first point 301 and the third point 303. Therefore, in this embodiment, the arc between the first point 301 and the third point 303 on the circumscribed circle is defined as the second arc, and the arc length of the second arc is s'. When the length a of the first line segment and the length a' of the second line segment are preset, a+a'>s' is required, that is, the length of the intermediate segment is greater than the arc length of the second arc.

[0052] In addition, the preset angle α between the first hypotenuse and the extension line of the first line segment and the angle α′ between the second hypotenuse and the extension line of the second line segment must satisfy:

[0053] When C<A, the values ​​of α and α' are not affected by β and β';

[0054] When C≥A, α≥β, α'≥β'.

[0055] In order to avoid the blank 100 being asymmetric in the cavity of the lower mold 300 and causing incorrect orientation when placed, the best implementation scheme of this embodiment is to preset a=a' and α=α'.

[0056] Step 5: According to the preset a, a', α, α', C and K, the cross-sectional area S' of the blank 100 is obtained. Specifically:

[0057] S'=(a+a')×K+[2K-(0.5Ca)tanα]×(0.5Ca) / 2+[2K-(0.5C-a')tanα']×(0.5C-a') / 2

[0058] Step 6: Determine the size relationship between S' and S. When S'>S, determine that the preset values ​​of a, a', α, α', and C are appropriate. If S'≤S, it is necessary to reset the above C and / or a and / or a' and / or α and / or α'. It is worth noting that only when S'>S can it be guaranteed that the blank 100 can completely fill the upper cavity of the upper die 200 and the lower cavity of the lower die 300 during the die forging process.

[0059] The above design method can help designers design a suitable blank 100 for a casing forging and determine the shape and size of the blank 100 so that no folding defects will occur during the process of die forging the blank 100 into a casing forging, which is not only conducive to improving the molding quality of the casing forging, but also helps to save the manufacturing cost of the casing forging. Of course, the design length of the blank 100 must be greater than or equal to the length of the casing forging.

[0060] Embodiment 2:

[0061] This embodiment is a specific implementation of Embodiment 1. In this embodiment:

[0062] Step 1: The width B of the cavity of the upper die 200 is 570 mm, and the length C of the top edge of the blank 100 is preset to be 590 mm, so that C>B. And the total length of the blank 100 in the overall length direction is preset to be 910 mm. In fact, the total length of the casing forging in the length direction is 895 mm, which satisfies that the length of the blank 100 in the overall length direction is greater than the length of the casing forging in the length direction. The cross-sectional area S of the casing forging is 29580 square millimeters, and the material-to-work ratio m is 1.8. According to the formula K=mS / C, K=90 mm is obtained, that is, the vertical distance between the top edge and the bottom edge of the blank 100 is 90 mm, which can also be understood as the thickness of the blank 100 is 90 mm.

[0063] Step 2: The cross-sectional area of ​​the casing forging is S = 29580 square millimeters, and the material-to-work ratio m is 1.8. According to the formula K = mS / C, we get K = 90 mm, that is, the vertical distance between the top and bottom edges of the blank 100 is 90 mm, which can also be understood as the thickness of the blank 100 is 90 mm.

[0064] Step 3: Use software to obtain the arc length s=356.5mm of the first arc, the radius r=485mm of the first arc, the width A=580mm of the cavity of the lower die 300, the angle between the tangent of the first arc at the fourth point and the horizontal plane is β=9°, the angle between the tangent of the first arc at the fifth point and the horizontal plane is β'=11°, and the theoretical maximum side length Z'=604.7mm of the contact between the blank 100 and the cavity of the lower die 300 is obtained through the formula Z'=s+A-2r×sin(β+β').

[0065] Step 4: Preset the length of the first line segment to be equal to the length of the second line segment, the angle between the first hypotenuse and the extension of the first line segment, and the angle between the second hypotenuse and the extension of the second line segment, specifically, a=a'=180mm, α=α'=15°, a+a'=360mm, which is greater than the arc length of the first arc. Since the second arc is a segment of the first arc, the value of a+a' is greater than the arc length of the second arc, and α>β, α'>β'. Z<Z' calculated by the formula Z=a+a'+(0.5Ca) / cosα+(0.5C-a') / cosα'.

[0066] Step 5, according to the formula:

[0067] S'=(a+a')×K+[2K-(0.5Ca)tanα]×(0.5Ca) / 2+[2K-(0.5C-a')tanα']×(0.5C-a') / 2:

[0068] S' = 49556 square millimeters.

[0069] Step 6: S'=49556 square millimeters, S=29580 square millimeters, so S'>S, thereby confirming that the preset values ​​of the length C of the top edge of the cross-sectional figure of the blank 100, the length a of the first line segment in the cross-sectional figure of the blank 100, the length a' of the second line segment in the cross-sectional figure of the blank 100, the angle α between the first hypotenuse in the cross-sectional figure of the blank 100 and the extension line of the first line segment, and the angle α' between the second hypotenuse and the second line segment are appropriate.

[0070] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for designing a blank for a casing forging, characterized in that: The cross-sectional figure of the blank is surrounded by a top edge close to the upper die, a bottom edge close to the lower die, and two side edges, the bottom edge includes a middle section, a first oblique edge, and a second oblique edge, the middle section is divided into a first line segment and a second line segment through a perpendicular midline of the top edge, the first line segment is connected to one of the side edges through the first oblique edge, the second line segment is connected to the other side edge through the second oblique edge, and both the first oblique edge and the second oblique edge are inclined from the bottom edge toward the top edge; The design approach includes: The length C of the top edge is preset according to the width B of the upper mold cavity, so that C≥B; According to the cross-sectional area S of the casing forging and the preset C, a vertical distance K between the top edge and the bottom edge is obtained; Obtain the theoretical maximum side length Z' of the blank in contact with the lower mold cavity; Preset the length a of the first line segment, the length a' of the second line segment, the angle α between the first hypotenuse and the extension line of the first line segment, and the angle α' between the second hypotenuse and the extension line of the second line segment, and obtain the total length Z of the base according to a, a', α and α', so that Z<Z'; According to the preset a, a', α, α', C and K, the cross-sectional area S' of the blank is obtained; Determine the size relationship between S' and S. When S'>S, determine that the preset values ​​of a, a', α, α', and C are appropriate.

2. The blank design method for a casing forging according to claim 1, characterized in that: According to the cross-sectional area S of the casing forging and the preset C, the vertical distance K between the top edge and the bottom edge is obtained, which is specifically: The vertical distance between the top edge and the bottom edge is K=mS / C, m is the material-to-labor ratio, and 1<m≤2.

3. The blank design method for a casing forging according to claim 2, characterized in that: The bottom of the lower mold cavity has a curved surface protrusion, and the curved surface protrusion is provided with three protrusions, so that the cross-sectional figure of the lower mold cavity has a curve located at the cavity bottom and three vertices located on the curve, the three vertices are respectively a first point close to one side of the lower mold cavity, a third point close to the other side of the lower mold cavity, and a second point located between the first point and the third point, the radius of the circumscribed circle of the first point, the second point and the third point is r, the arc between the two points where the circumscribed circle connects with the bottom of the lower mold cavity is the first arc, the arc length of the first arc is s, and the two points where the circumscribed circle connects with the bottom of the lower mold cavity are respectively a fourth point close to the first line segment and a fifth point close to the second line segment, the angle between the tangent of the first arc at the fourth point and the horizontal plane is β, and the angle between the tangent of the first arc at the fifth point and the horizontal plane is β'; The theoretical maximum side length Z' of the blank in contact with the lower mold cavity is obtained as follows: Z'=s+A-2r×sin(β+β'), where A is the width of the lower mold cavity.

4. The method for designing a blank for a casing forging according to claim 3, characterized in that: The arc between the first point and the third point on the circumscribed circle is a second arc, and the arc length of the second arc is s'; The preset length a of the first line segment and the preset length a' of the second line segment are specifically: Such that a+a'>s'.

5. The method for designing a blank for a casing forging according to claim 4, characterized in that: The preset angle α between the first hypotenuse and the extension line of the first line segment and the preset angle α′ between the second hypotenuse and the extension line of the second line segment are specifically: When C<A, the values ​​of α and α' are not affected by β and β'; When C≥A, α≥β, α'≥β'.

6. The method for designing a blank for a casing forging according to claim 5, characterized in that: The length a of the first line segment is equal to the length a' of the second line segment; The included angle α between the first hypotenuse and the extended line of the first line segment is equal to the included angle α′ between the second hypotenuse and the extended line of the second line segment.

7. The method for designing a blank for a casing forging according to claim 1, characterized in that: The total length Z of the bottom edge is obtained according to a, a', α and α', specifically: Z=a+a'+(0.5Ca) / cosα+(0.5C-a') / cosα'.

8. The method for designing a blank for a casing forging according to claim 1, characterized in that: According to the preset a, a', α, α', C and K, the cross-sectional area S' of the blank is obtained, specifically: S'=(a+a')×K+[2K-(0.5Ca)tanα]×(0.5Ca) / 2+[2K-(0.5C-a')tanα']×(0.5C-a') / 2.

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