A method for forming a blank by die forging

Abstract

The present invention discloses a method for forging blanks, which obtains the area of each cross section of a part along the axial direction and obtains a distribution diagram of the part area along the axis; designs a blank according to the distribution diagram of the part area along the axial direction and adds a processing allowance; when blanking, uses a bar with a diameter equal to the maximum diameter of the blank, and then obtains a blank for processing the part based on the volume of the blank; blanks are blanked after blanking; when blanking the blank after blanking: first, the first end of the blank is heated, and then the first end of the blank is extruded into a first frustum; then, the second end of the blank is heated, and then the second end of the blank is extruded into a second frustum. The present invention uses existing equipment and simple dies to realize the blanking of stepped shafts, and has the advantages of high efficiency compared to free forging blanking. Compared with roll forging and wedge cross rolling blanking, it does not require special equipment and complex dies, and has the characteristics of simplicity, high efficiency, and high material utilization.

Description

Technical Field

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

[0002] With the rise of energy conservation and emission reduction, and the need for manufacturing upgrades, the forging industry is facing new demands, moving away from the crude, primitive, and extensive production models of the past. Die forging technology, a mass production method used to manufacture critical parts such as shafts, offers advantages such as high efficiency, high dimensional accuracy, and excellent product quality, and is increasingly being used in forging production.

[0003] As the shapes of die forgings become more and more complex, in order to improve material utilization and prevent forging defects, the billet making process is becoming more and more important in die forging. At this stage, the billet making methods include free forging, roll forging, wedge cross rolling, etc. These methods have their own advantages and disadvantages. Since the batch size of die forgings is usually not large or small, free forging has good flexibility, but the efficiency is obviously too low, and there is a lack of skilled operators. Roll forging and wedge cross rolling require special equipment and billet making molds. The design and manufacture of billet making molds are relatively complex. For billet making with small batch size, the efficiency and cost are not significantly improved. Therefore, a simple and easy billet making method is urgently needed. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a method for forging blanks, which is simple and easy to implement and can improve material utilization.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for forging a blank, comprising the following steps:

[0007] Obtain the area of each cross section of the part along the axis and obtain the distribution diagram of the part area along the axis;

[0008] According to the distribution diagram of the part area along the axial direction and adding the processing allowance, the blank is designed;

[0009] When cutting, a bar with a diameter equal to the maximum diameter of the blank is used. Then, according to the volume of the blank, a blank for processing parts is obtained. The middle part of the blank is a middle cylinder, and the two ends are frustums. The frustums at the two ends are respectively recorded as the first frustum and the second frustum.

[0010] The blank is formed into a blank after being cut, wherein one end of the blank is recorded as a first end, and the other end of the blank is recorded as a second end, the first end of the blank corresponds to the position of the first truncated cone, and the second end of the blank corresponds to the position of the second truncated cone;

[0011] When blanking the blank:

[0012] First, the first end of the blank is heated, and the length of the heating section is determined according to the volume of the first truncated cone of the blank. Then, the first end of the blank is extruded into the first truncated cone to obtain the intermediate piece.

[0013] The second end of the blank is then heated, and the length of the heating section is determined according to the volume of the second truncated cone of the blank. The second end of the blank is then extruded into the second truncated cone, and the die forging process is completed.

[0014] Preferably, the processing allowance includes flash and machining allowance.

[0015] Preferably, when the first truncated cone and the second truncated cone are extruded from the blank, the heated blank and the preheated mold are sprayed with water-based graphite and then placed in the mold for extrusion.

[0016] Preferably, when the first and second frustums are extruded from the blank, if the free middle cylindrical section of the intermediate piece is upset, the single deformation amount is reduced and the necking extrusion is performed multiple times.

[0017] Preferably, when the first end of the blank is extruded into a first frustum, the extrusion die used includes a first upper die and a first lower die, the first upper die is provided with a positioning groove for positioning the second end of the blank, and the first lower die is provided with a through hole coaxially opposite to the positioning groove, the through hole includes a first introduction section, a first forming section and a first ejection section in sequence, the diameter of the first introduction section is larger than the diameter of the blank; the first forming section is a frustum, used for processing the first frustum, and the diameter of the first ejection section is smaller than the diameter of the small end of the first forming section.

[0018] Preferably, the length of the first introduction section is greater than the length of the heating section at the first end of the blank.

[0019] Preferably, when the second end of the blank is extruded into a second frustum, the extrusion die used includes a second upper die and a second lower die, the second upper die is provided with a first positioning section for positioning the first frustum, the shape of the first positioning section includes a frustum hole for positioning the first frustum and a circular hole section for positioning the upper end of the intermediate cylinder, the frustum hole is adapted to the shape of the first frustum, and a vent hole is provided on the small end surface of the frustum hole;

[0020] The second lower die has a through hole coaxially opened at a position opposite to the first positioning section. The through hole includes a second introduction section, a second forming section and a second ejection section in sequence. The diameter of the second introduction section is larger than the diameter of the blank; the second forming section is a frustum, used for processing the second frustum, and the diameter of the second ejection section is smaller than the diameter of the small end of the second forming section.

[0021] Preferably, the length of the second introduction section is greater than the length of the heating section at the second end of the blank.

[0022] The present invention has the following beneficial effects:

[0023] The present invention adopts existing equipment and simple molds to realize the blanking of stepped shafts. Compared with free forging, it has the advantage of high efficiency. Compared with roll forging and wedge cross rolling, it does not require special equipment and complex molds. It has the characteristics of simplicity, high efficiency and high material utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A photograph of a part (eccentric shaft) machined in an embodiment of the present invention;

[0025] Figure 2 The distribution diagram of the cross-sectional area of the eccentric shaft along the axis in an embodiment of the present invention;

[0026] Figure 3 This is a diagram of a blank in an embodiment of the present invention;

[0027] Figure 4 This is a diagram of the blank obtained after blanking in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of heating the first end of the blank in an embodiment of the present invention;

[0029] Figure 6 Schematic diagram of the structure of the first upper mold in an embodiment of the present invention;

[0030] Figure 7 Schematic diagram of the structure of the first lower mold in an embodiment of the present invention;

[0031] Figure 8 Schematic diagram of a blank-making mold for processing the first end in an embodiment of the present invention;

[0032] Figure 9 Schematic diagram of the intermediate piece obtained after the first end is deformed in an embodiment of the present invention;

[0033] Figure 10 This is a schematic diagram of heating the second end of the middle piece in an embodiment of the present invention;

[0034] Figure 11 Schematic diagram of the structure of the second upper mold in an embodiment of the present invention;

[0035] Figure 12 Schematic diagram of the structure of the second lower mold in an embodiment of the present invention;

[0036] Figure 13 Schematic diagram of a blank-making mold for processing the second end in an embodiment of the present invention;

[0037] Figure 14 Schematic diagram of the blank obtained after the second end is deformed in an embodiment of the present invention.

[0038] In the figure, 1-blank, 1-1-middle section cylinder, 1-2-first frustum, 1-3-second frustum, 2-blank, 3-first upper die, 3-1-positioning groove, 4-first lower die, 4-1-first introduction section, 4-2-first forming section, 4-3-first ejection section; 5-first heating section, 6-second upper die, 6-1-first positioning section, 6-2-vent, 7-second lower die, 7-1-second introduction section, 7-2-second forming section, 7-3-second ejection section, 8-second heating section. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] The die forging method of the present invention can improve the material utilization rate, which specifically includes determining the size of the blank according to the distribution of the forging volume + flash margin along the axial direction of the forging, blanking the bar according to the volume of the blank, and then blanking the blank after blanking, first heating one end of the blank by medium frequency induction heating, and the length of the heating section is determined according to the volume of the deformed end of the blank, after the heated blank and the preheated mold are sprayed with water-based graphite, the blank is placed in the blanking mold at one end and extruded into the shape of one end to obtain the intermediate piece. During the extrusion process, if the intermediate piece is free When upsetting occurs in the middle section, the single deformation amount is reduced, and the necking extrusion is performed multiple times. After one end of the billet to be made is extruded, the other end of the middle piece is heated by medium-frequency induction heating. The length of the heating section is determined according to the volume of the deformation of one end of the billet. After the heated billet and the preheated mold are sprayed with water-based graphite, the shape of the other end is extruded in the billet mold at the other end. Also during the extrusion process, if upsetting occurs in the free middle section of the middle piece, the single deformation amount is reduced, and the necking extrusion is performed multiple times. Finally, the heated billet is sent into the forging die for die forging to obtain the final forging.

[0041] See also Figures 1-14 The die forging method of the present invention comprises the following steps:

[0042] Obtain the area of each cross section of the part along the axis and obtain the distribution diagram of the part area along the axis. For details, refer to Figure 1 and Figure 2 ;

[0043] According to the distribution diagram of the part area along the axial direction and adding the processing allowance, the blank 1 is designed, see Figure 3 , where the machining allowance should take into account the flash and machining allowance;

[0044] When cutting, use a bar with a diameter equal to the maximum diameter of the blank, and then obtain the blank 2 for processing parts according to the volume of the blank, see Figure 4The middle part of the blank 1 is a middle section cylinder 1-1, and the two ends are frustums, which are respectively denoted as the first frustum 1-2 and the second frustum 1-3; the diameter of the middle section cylinder 1-1 is the same as the diameter of the blank 2;

[0045] The blank 2 after blanking is formed into a blank, wherein one end of the blank is recorded as the first end, and the other end of the blank is recorded as the second end. The first end of the blank corresponds to the position of the first truncated cone, and the second end of the blank corresponds to the position of the second truncated cone.

[0046] When blanking the blank:

[0047] First, the first end of the blank is heated, and the length of the heating section is determined according to the volume of the first truncated cone of the blank. Then, the first end of the blank is extruded into the first truncated cone to obtain the intermediate piece.

[0048] The second end of the blank is then heated, and the length of the heating section is determined according to the volume of the second truncated cone of the blank. The second end of the blank is then extruded into the second truncated cone, and the die forging process is completed.

[0049] The blank prepared above is then forged to obtain a final forging.

[0050] In the above-described embodiment of the present invention, when extruding the first and second frustums from the billet, the heated billet and die are sprayed with water-based graphite before being placed into the die for extrusion. If, during the extrusion of the first and second frustums from the billet, the free intermediate cylindrical section 1-1 of the intermediate piece experiences upset, the single deformation is reduced, and multiple necking extrusions are performed.

[0051] See also Figure 6-Figure 8 When the first end of the blank is extruded into the first truncated cone, the extrusion die used includes a first upper die 3 and a first lower die 4. The first upper die 3 is provided with a positioning groove 3-1 for positioning the second end of the blank 1. The first lower die 4 is provided with a through hole coaxially opposite to the positioning groove 3-1. The through hole includes a first introduction section 4-1, a first forming section 4-2 and a first ejection section 4-3 in sequence. The diameter of the first introduction section 4-1 is larger than the diameter of the blank 1, and is generally a clearance fit; the first forming section 4-2 is a truncated cone, which is used to process the first truncated cone 1-2. When the blank is extruded downward, the first forming section 4-2 is used to extrude the first truncated cone 1-2. The diameter of the first ejection section 4-3 is smaller than the diameter of the small end of the first forming section 4-2. The blank with the processed first truncated cone 1-2 can be ejected upward by the first ejection section 4-3 to achieve demolding. The length of the first introduction section 4-1 is greater than the length of the heating section at the first end of the blank (i.e. Figure 8 The first heating section 5) is shown in the figure to prevent the upper end of the heating section from being exposed, which may cause the strength of the exposed section to decrease after being heated and thus fail to perform extrusion normally.

[0052] See also Figure 11-13When the second end of the blank is extruded into a second frustum, the extrusion mold used includes a second upper mold 6 and a second lower mold 7. The second upper mold 6 is provided with a first positioning section 6-1 for positioning the first frustum 1-2. The shape of the first positioning section 6-1 includes a frustum hole for positioning the first frustum 1-2 and a circular hole section for positioning the upper end of the middle section cylinder 1-1. The frustum hole is adapted to the shape of the first frustum 1-2, and a vent hole 6-2 is provided on the small end face of the frustum hole; the first frustum 1-2 should be tightly pressed against the frustum hole of the first positioning section 6-1, and the frustum hole tightly wraps the first frustum 1-2 to prevent the first frustum 1-2 from deforming during the extrusion process. There is a gap fit between the cylindrical section on the first positioning section 6-1 and the middle section cylinder 1-1 to prevent the first frustum 1-2 from becoming unstable and deforming during the extrusion process. The second lower die 7 has a through hole coaxially formed at a position opposite to the first positioning section 6-1. The through hole includes a second introduction section 7-1, a second forming section 7-2 and a second ejection section 7-3 in sequence. The diameter of the second introduction section 7-1 is larger than the diameter of the blank 1; the second forming section 7-2 is a truncated cone, which is used to process the second truncated cone 1-3. When the blank is extruded downward, the second forming section 7-2 is used to extrude the second truncated cone 1-3. The diameter of the second ejection section 7-3 is smaller than the diameter of the small end of the second forming section 7-2. The blank with the processed second truncated cone 1-3 can be ejected upward by the second ejection section 7-3 to achieve demoulding. The length of the second introduction section 7-1 is larger than the length of the heating section at the second end of the blank (i.e. Figure 13 The second heating section 8 shown in the figure prevents the upper end of the heating section from being exposed, which may cause the strength of the exposed section to decrease after being heated and thus fail to perform extrusion normally.

[0053] Example

[0054] This embodiment Figure 1 The figure shows the eccentric shaft to be formed in this embodiment. The center of the eccentric shaft has two large eccentric masses, requiring more material, while the ends are smaller than the center, requiring less material. If bar stock were used for forming, the bar diameter would be determined based on the material required for the two large eccentric masses. This would result in significant material waste at the ends and could also cause other defects such as folding during forming.

[0055] By slicing the part along the axial direction, the area of each cross section is obtained, as shown in the following figure: Figure 2 The distribution of the part area along the axis is shown.

[0056] According to the distribution diagram of the part area along the axial direction, and adding the allowance such as flash, the design is as follows Figure 3 When cutting, use a bar with a diameter equal to the maximum diameter of the blank (i.e. the middle section of the cylinder 1-1). According to the volume of the blank, the following is obtained: Figure 4 The blank diagram is shown.

[0057] The first end of the blank is heated by medium frequency induction heating. The length of the heating area is determined according to the volume of one end of the blank. After the heated blank and the blank mold at one end are sprayed with water-based graphite, the blank is quickly placed on the blank mold at the first end (such as Figure 8 ) is formed in the middle, if the middle cylindrical section 1-1 of the middle piece is upset during the forming process, the single deformation amount is reduced, the necking and extrusion are performed multiple times, and the middle piece is ejected by the ejector rod after forming.

[0058] Figure 8 In the mold shown, the diameter of the positioning groove 3-1 is 0.5-1mm larger than the diameter of the bar and the depth is 5-10mm, and the clearance fit is sufficient; in the first lower mold, the diameter of the first introduction section 4-1 is 0.5-1mm larger than the diameter of the bar, the depth of the first introduction section 4-1 is 5-10mm larger than the length of the first heating section 5, and the diameter of the first ejection section 4-3 is 0.5-1mm smaller than the diameter of the small end of the first forming section 4-2.

[0059] The second end of the intermediate piece is heated by medium frequency induction. The length of the heating area at the second end is determined according to the volume of the second cone of the blank. After the heated intermediate piece and the blank mold used to process the second end are sprayed with water-based graphite, the intermediate piece is quickly placed in the blank mold at the other end for forming. If the middle section of the intermediate piece is upset during the forming process, the single deformation amount is reduced, and the necking and extrusion are performed multiple times. After forming, the intermediate piece is ejected by the ejector pin.

[0060] like Figure 13 As shown, in the second end blanking mold, the size of the first positioning section 6-1 matches the size of the first end of the blank, and the depth is 5-10mm larger than the length of one end of the blank. In the second lower mold, the diameter of the second introduction section is 0.5-1mm larger than the diameter of the bar, the depth of the second introduction section is 5-10mm larger than the length of the heating section, and the diameter of the second ejection section 7-3 is 0.5-1mm smaller than the diameter of the small end of the second forming section 7-2.

Claims

1. A method for forging a blank, characterized in that: The process includes the following: Obtain the area of each cross section of the part along the axis and obtain the distribution diagram of the part area along the axis; According to the distribution diagram of the part area along the axial direction and adding the machining allowance, the blank (1) is designed; When cutting, a bar having a diameter equal to the maximum diameter of the blank is used, and then a blank (2) for processing parts is obtained according to the volume of the blank. The middle part of the blank (1) is a middle section cylinder (1-1), and the two ends are frustums, and the frustums at the two ends are respectively recorded as a first frustum (1-2) and a second frustum (1-3); The blank (2) after blanking is formed, wherein one end of the blank is recorded as a first end, and the other end of the blank is recorded as a second end, the first end of the blank corresponds to the position of the first truncated cone, and the second end of the blank corresponds to the position of the second truncated cone; When blanking the blank: First, the first end of the blank is heated, and the length of the heating section is determined according to the volume of the first truncated cone of the blank. Then, the first end of the blank is extruded into the first truncated cone to obtain the intermediate piece. The second end of the blank is then heated, with the length of the heating section determined according to the volume of the second truncated cone of the blank, and the second end of the blank is extruded into the second truncated cone, completing the die forging process. When the first end of the blank is extruded into a first truncated cone, the extrusion die used comprises a first upper die (3) and a first lower die (4); the first upper die (3) is provided with a positioning groove (3-1) for positioning the second end of the blank (2); the first lower die (4) is provided with a through hole coaxially opposite to the positioning groove (3-1); the through hole comprises a first introduction section (4-1), a first forming section (4-2) and a first ejection section (4-3) in sequence; the diameter of the first introduction section (4-1) is larger than the diameter of the blank (2); the first forming section (4-2) is in a truncated cone shape and is used to process the first truncated cone (1-2); the diameter of the first ejection section (4-3) is smaller than the diameter of the small end of the first forming section (4-2); When the second end of the blank is extruded into a second truncated cone, the extrusion die used includes a second upper die (6) and a second lower die (7); the second upper die (6) is provided with a first positioning section (6-1) for positioning the first truncated cone (1-2); the shape of the first positioning section (6-1) includes a truncated cone hole for positioning the first truncated cone (1-2) and a circular hole section for positioning the upper end of the intermediate cylinder (1-1); the truncated cone hole is adapted to the shape of the first truncated cone (1-2); and a vent hole (6-2) is provided on the small end face of the truncated cone hole; The second lower die (7) is coaxially provided with a through hole at a position directly opposite to the first positioning section (6-1), the through hole sequentially comprising a second introduction section (7-1), a second forming section (7-2) and a second ejection section (7-3), the diameter of the second introduction section (7-1) being larger than the diameter of the blank (2); the second forming section (7-2) being in the shape of a truncated cone and being used for machining the second truncated cone (1-3), the diameter of the second ejection section (7-3) being smaller than the diameter of the small end of the second forming section (7-2).

2. A die forging method according to claim 1, characterized in that: The processing allowance includes flash and machining allowance.

3. The die forging method according to claim 1, characterized in that: When the first truncated cone and the second truncated cone are extruded from the blank, the heated blank and the preheated extrusion die are sprayed with water-based graphite and then placed in the extrusion die for extrusion.

4. The method for forming a blank by die forging according to claim 1, wherein: When the first and second truncated cones are extruded from the blank, if the free middle section cylinder (1-1) of the intermediate piece is upset, the single deformation amount is reduced and multiple necking extrusions are performed.

5. The method for forming a blank by die forging according to claim 1, wherein: The length of the first introduction section (4-1) is greater than the length of the heating section at the first end of the blank.

6. The die forging method according to claim 1, characterized in that: The length of the second introduction section (7-1) is greater than the length of the heating section at the second end of the blank.

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