An extrusion process based on a floating variable cavity

Abstract

The present invention discloses an extrusion process based on a floating variable cavity, and the steps include: blanking; heating the obtained blank to 1050°C - 1080°C and holding for 30 ± 3 minutes; putting the heated blank into the die cavity; extruding; keeping the upper die, lower die and left and right extrusion dies under pressure for 30 ± 5 seconds; taking out the part and cooling it in the air, and then performing surface cleaning. By adopting the solution of the present invention, complex components with shapes such as narrow ribs, bosses, and branches can be formed by a simple process. The prepared components have high mechanical properties, good internal quality, high material utilization rate, and have the advantages of short production cycle, low implementation cost, and long die life, and are suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of precision plastic forming, and in particular relates to an extrusion process based on a floating variable cavity. Background Art

[0002] Complex parts are widely used in the field of industrial manufacturing, but their plastic forming has always been a common problem in the field of hot working, especially for complex components with shapes such as narrow ribs, bosses, and branches. In order to meet dimensional requirements, traditional process designs often add a large amount of process auxiliary materials (i.e., increase machining allowances), resulting in low material utilization, large cutting allowances, and low machining efficiency. In conventional hot die forging processes, in order to fill these weak locations, multiple forming processes are often added to finally form and prepare the components. However, such process steps are complex, the forming force is large, the mold life is short, and the narrow ribs, process bosses, branches and other parts are still not fully filled, which seriously affects the component qualification rate and increases production costs.

[0003] In addition, for complex components with narrow ribs / bosses (such as Figure 2 Even if the component is finally formed by adding multiple forming processes, there is still a core area corresponding to the narrow rib / boss (the core of the main structure where the narrow rib / boss is located, i.e. Figure 3 The grain size of parts B and C in the middle is poor. If it can be further optimized, it will be of great significance to improve the performance of such complex components. Summary of the Invention

[0004] In view of the problems existing in the background technology, the present invention aims to provide an extrusion process based on a floating variable cavity.

[0005] The object of the present invention is achieved by adopting the following technical solutions.

[0006] An extrusion process based on a floating variable cavity, characterized in that the steps include:

[0007] Step 1: Cutting the bar into blanks with a length not exceeding 360 mm;

[0008] Step 2: heating the blank obtained in step 1 to 1050°C-1080°C and keeping the temperature for 30±3 minutes;

[0009] Step 3, loading, placing the heated blank in step 2 into the mold cavity;

[0010] The die includes an upper die, a lower die, a left extrusion die, and a right extrusion die, which are respectively connected to the extrusion cylinder. The left extrusion die and the right extrusion die are both composed of two semi-cylinders. The upper die, the lower die, the left extrusion die, and the right extrusion die jointly enclose a cavity, and a floating variable cavity is jointly enclosed by the stationary upper die, the downward-moving lower die, and the left and right extrusion dies moving towards each other.

[0011] Step 4, extrusion, is specifically carried out according to the following process.

[0012] Step 41, keep the lower die under pressure at the set upper working position, keep the upper die stationary, and always control the left and right extrusion dies to extrude towards the center respectively until the blank fills the pre-extrusion cavity.

[0013] Step 42, control the upper die to apply pressure (apply an extrusion load to the blank) and move downward. When the extrusion load on the lower die continuously increases to 20 ± 0.2 MPa, control the lower die to retreat (move) downward at a speed of 5 ± 0.5 mm / s. During this process, the blank flows downward to continue filling the mold cavity.

[0014] Step 43, when the stroke of the lower die reaches 68 ± 5 mm, the lower die stops moving, and keep the lower die under pressure at this working position. At the same time, control the upper die to extrude downward. When the blank fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion to obtain a complex component with a narrow rib / ribbed boss shape.

[0015] Step 5, keep the upper die, the lower die, the left extrusion die, and the right extrusion die under pressure for 30 ± 5 seconds.

[0016] Step 6, open the die, take out the part, put it in the air to cool, and perform surface cleaning.

[0017] In order to extrude the required complex component more smoothly, in Step 43, always control the temperature of the lower die to be 410 ± 10 °C, and always control the temperature of the upper die to be 370 ± 0.5 °C.

[0018] In the present invention, the bar stock is 34CrNiMo6 structural steel, and the blank size is

[0019] In order to further optimize the performance of the obtained complex component, in Step 41, first control the upper semi-cylinder body of the left extrusion die and the lower semi-cylinder body of the right extrusion die to move towards the center respectively at a speed of 2 ± 0.5 mm / s for 15 mm; then control the lower semi-cylinder body of the left extrusion die and the upper semi-cylinder body of the right extrusion die to extrude towards the center at a speed of 2 ± 0.5 mm / s until the blank fills the pre-extrusion cavity.

[0020] To further optimize the performance of the obtained complex component, in step 41, first control the lower semi-circular die body of the left extrusion die and the lower semi-circular die body of the right extrusion die to move towards the center respectively at a speed of 2 ± 0.5 mm / s for 20 mm; then control the upper semi-circular die body of the left extrusion die and the upper semi-circular die body of the right extrusion die to extrude towards the center at a speed of 2 ± 0.5 mm / s until the blank fills the pre-extrusion cavity.

[0021] To further optimize the performance of the obtained complex component, step 4 is carried out according to the following process.

[0022] Step 41, keep the lower die under pressure at the set upper working position, keep the upper die stationary, and always control the left and right extrusion dies to extrude towards the center respectively until the blank fills the pre-extrusion cavity;

[0023] Step 42, control the left and right extrusion dies to retract 10 - 15 mm respectively and then keep stationary, and then control the upper die and the lower die to extrude simultaneously until the blank fills the pre-extrusion cavity;

[0024] Step 43, repeat steps 41 - step 42 three times;

[0025] Step 44, control the upper die to apply pressure and move downwards. When the extrusion load on the lower die continuously increases to 20 ± 0.2 MPa, control the lower die to move downwards at a speed of 5 ± 0.5 mm / s. During this process, the blank flows downwards to continue filling the mold cavity;

[0026] Step 45, when the stroke of the lower die reaches 68 ± 5 mm, the lower die stops moving, and keep the lower die under pressure at this working position. At the same time, control the upper die to extrude downwards. When the blank fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion.

[0027] Beneficial effects: Adopting the solution of the present invention, it is possible to form complex components with shapes such as narrow ribs, bosses, and branches by a simple process. The prepared components have high mechanical properties, good internal quality, high material utilization rate, and have the advantages of short production cycle, low implementation cost, and long die life, and are suitable for large-scale production. Brief Description of the Drawings

[0028] Figure 1 is the schematic diagram of the extrusion process in Embodiment 1;

[0029] Figure 2 is the schematic diagram of the outer shape of the complex component obtained in the embodiment;

[0030] Figure 3 is the schematic cross-sectional view of the complex component obtained in the embodiment. Detailed Description of the Invention

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Embodiment 1

[0033] An extrusion process based on a floating variable cavity is used to prepare complex components with narrow ribs. The steps include:

[0034] Step 1, blanking, saw the 34CrNiMo6 structural steel bar into blanks with a size of ; ;

[0035] Step 2, heating, heat the blank obtained in Step 1 to 1050 °C and hold for 30 minutes;

[0036] Step 3, loading, place the blank heated in Step 2 into the die cavity;

[0037] As Figure 1 shown, the die includes an upper die 1, a lower die 2, a left extrusion die 3, and a right extrusion die 4 respectively connected to the extrusion cylinder. The left extrusion die 3 and the right extrusion die 4 are each composed of two semi-cylinders. The upper die 1, the lower die 2, the left extrusion die 3, and the right extrusion die 4 together enclose a cavity, and the static upper die 1, the downward-moving lower die 2, and the left and right extrusion dies moving towards each other together enclose a floating variable cavity; an electric heating wire is installed on the lower die 2;

[0038] Step 4, extrusion, as Figure 1 shown, the specific process is as follows:

[0039] Step 41, keep the lower die 2 at the set upper working position under pressure, keep the upper die 1 stationary, and always control the left and right extrusion dies to synchronously extrude towards the center until the blank 5 fills the pre-extrusion cavity;

[0040] Step 42, control the upper die to apply pressure and move downward. When the extrusion load on the lower die 2 continuously increases to 20 MPa, control the lower die 2 to retreat (move) downward at a speed of 5 mm / s. During this process, the blank 5 flows downward to continue filling the mold;

[0041] Step 43, during the downward movement of the lower die 2, always control the temperature of the lower die to be 410 ± 0.5 °C and the temperature of the upper die to be 370 ± 0.5 °C; when the stroke of the lower die 2 reaches 68 mm, the lower die 2 stops moving and is kept under pressure at this working position. At the same time, control the upper die 1 to extrude downward. When the blank 5 fills the cavity again and extrudes the excess material along the split flash groove, stop extrusion to obtain a complex component with a narrow rib / ribbed boss shape as Figure 2 shown;

[0042] Step 5: The upper die 1, the lower die 2, and the left and right extrusion dies are all kept under pressure for 30 seconds.

[0043] Step 6: Open the die, take out the workpiece, cool it in the air, and perform surface cleaning.

[0044] Example 2

[0045] An extrusion process based on a floating variable cavity for manufacturing complex components with narrow ribs, the steps include:

[0046] Step 1: Cut the material. Cut the 34CrNiMo6 structural steel bar into blanks 5 with dimensions of .

[0047] Step 2: Heat. Heat the blank obtained in Step 1 to 1060 °C and hold for 32 minutes.

[0048] Step 3: Load the material. Place the blank 5 heated in Step 2 into the die cavity.

[0049] Among them, the die includes an upper die 1, a lower die 2, a left extrusion die 3, and a right extrusion die 4 respectively connected to the extrusion cylinder. The left extrusion die 3 and the right extrusion die 4 are both composed of two semi-cylinders. The upper die 1, the lower die 2, the left extrusion die 3, and the right extrusion die 4 jointly enclose a cavity, and the static upper die 1, the downward-moving lower die 2, and the left and right extrusion dies moving towards each other jointly enclose a floating variable cavity; an electric heating wire is installed on the lower die 2.

[0050] Step 4: Extrusion, which is specifically carried out according to the following process.

[0051] Step 41: First, control the upper semi-cylindrical die body of the left extrusion die 3 and the lower semi-cylindrical die body of the right extrusion die 4 to move towards the center part respectively at a speed of 2.5 mm / s for 15 mm; then control the lower semi-cylindrical die body of the left extrusion die 3 and the upper semi-cylindrical die body of the right extrusion die 4 to extrude towards the center part at a speed of 2.5 mm / s until the blank 5 fills the pre-extrusion cavity.

[0052] Step 42: Control the upper die to apply pressure and move downward. When the extrusion load on the lower die 2 continuously increases to 21 MPa, control the lower die 2 to retreat (move) downward at a speed of 5 mm / s. During this process, the blank 5 flows downward to continue filling the mold cavity.

[0053] Step 43: During the downward movement of the lower die 2, always control the temperature of the lower die to be 415 ± 0.5 °C and always control the temperature of the upper die to be 365 ± 0.5 °C; when the stroke of the lower die 2 reaches 73 mm, the lower die 2 stops moving, and keep the lower die 2 under pressure at this working position. At the same time, control the upper die 1 to extrude downward. When the blank 5 fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion to obtain a complex component with a narrow rib / rib boss shape such asFigure 2 as shown;

[0054] Step 5, the upper die 1, the lower die 2, and the left and right extrusion dies are all kept under pressure for 30 seconds;

[0055] Step 6, open the die, take out the workpiece, cool it in the air, and perform surface cleaning.

[0056] Example 3

[0057] An extrusion process based on a floating variable cavity for preparing complex components with narrow ribs, the steps include:

[0058] Step 1, blanking, saw the 34CrNiMo6 structural steel bar into a blank 5 with a size of ; ;

[0059] Step 2, heating, heat the blank obtained in Step 1 to 1070 °C and keep it warm for 30 minutes;

[0060] Step 3, loading, put the blank 5 heated in Step 2 into the die cavity;

[0061] Among them, the die includes an upper die 1, a lower die 2, a left extrusion die 3, and a right extrusion die 4 respectively connected to the extrusion cylinder. The left extrusion die 3 and the right extrusion die 4 are both composed of two semi-cylinders. The upper die 1, the lower die 2, the left extrusion die 3, and the right extrusion die 4 jointly enclose a cavity, and the static upper die 1, the lower die 2 moving downward, and the left and right extrusion dies moving towards each other jointly enclose a floating variable cavity; an electric heating wire is installed on the lower die 2;

[0062] Step 4, extrusion, specifically carried out according to the following process,

[0063] Step 41, first control the lower semi-cylindrical die body of the left extrusion die 3 and the lower semi-cylindrical die body of the right extrusion die 4 to move towards the center part respectively at a speed of 2 mm / s for a distance of 20 mm; then control the upper semi-cylindrical die body of the left extrusion die 3 and the upper semi-cylindrical die body of the right extrusion die 4 to extrude towards the center part at a speed of 2 mm / s until the blank 5 fills the pre-extrusion cavity;

[0064] Step 42, control the upper die to apply pressure and move downward. When the extrusion load on the lower die 2 continuously increases to 20.2 MPa, control the lower die 2 to retreat (move) downward at a speed of 5 mm / s. During this process, the blank 5 flows downward and continues to fill the mold;

[0065] Step 43, during the downward movement of the lower die 2, always control the temperature of the lower die at 420 ± 0.5 °C and always control the temperature of the upper die at 370 ± 0.5 °C; when the stroke of the lower die 2 reaches 70 mm, the lower die 2 stops moving, and the lower die 2 is kept under pressure at this working position. At the same time, control the upper die 1 to extrude downward. When the blank 5 fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion to obtain a complex component with a narrow rib / boss shape as Figure 2 shown;

[0066] Step 5, keep the upper die 1, the lower die 2, and the left and right extrusion dies under pressure for 30 seconds;

[0067] Step 6, open the die, take out the part, put it in the air for cooling, and perform surface cleaning.

[0068] Example 4

[0069] An extrusion process based on a floating variable cavity for preparing a complex component with narrow ribs, the steps include:

[0070] Step 1, blanking, saw the 34CrNiMo6 structural steel bar stock of into a blank 5 with a size of ;

[0071] Step 2, heating, heat the blank obtained in Step 1 to 1080 °C and keep it warm for 33 minutes;

[0072] Step 3, loading, put the blank 5 heated in Step 2 into the die cavity;

[0073] Among them, the die includes an upper die 1, a lower die 2, a left extrusion die 3, and a right extrusion die 4 respectively connected to the extrusion cylinder. The left extrusion die 3 and the right extrusion die 4 are both composed of two semi-cylinders. The upper die 1, the lower die 2, the left extrusion die 3, and the right extrusion die 4 jointly enclose a cavity, and the static upper die 1, the downward moving lower die 2, and the left and right extrusion dies moving towards each other jointly enclose a floating variable cavity; an electric heating wire is installed on the lower die 2;

[0074] Step 4, extrusion, specifically carried out according to the following process,

[0075] Step 41, keep the lower die under pressure at the set upper working position, keep the upper die stationary, and always control the left and right extrusion dies to extrude towards the center until the blank fills the pre-extrusion cavity;

[0076] Step 42, control the left and right extrusion dies to retract 15 mm respectively and then keep stationary (that is, after the end of Step 41, increase the distance between the left and right extrusion dies by 30 mm to make the cavity larger in the transverse direction), and then control the upper die and the lower die to extrude simultaneously until the blank fills the pre-extrusion cavity;

[0077] Step 43: Repeat steps 41 - 42 three times. In this step, by repeatedly squeezing horizontally and vertically, it can ensure that there is no dead zone in the internal area of the blank (no unflowed area during the extrusion process), which is more helpful for optimizing the performance of the workpiece.

[0078] Step 44: Control the upper die to apply pressure and move downward. When the extrusion load on the lower die continuously increases to 20 ± 0.2 MPa, control the lower die to retreat downward at a speed of 5 ± 0.5 mm / s. During this process, the blank flows downward to continue filling the mold cavity.

[0079] Step 45: When the stroke of the lower die reaches 65 mm, the lower die stops moving, and the lower die is held under pressure at this working position. At the same time, control the upper die to squeeze downward. When the blank fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion.

[0080] Step 5: The upper die 1, the lower die 2, and the left and right extrusion dies are all held under pressure for 30 seconds.

[0081] Step 6: Open the mold, take out the workpiece, cool it in the air, and perform surface cleaning.

[0082] Comparative example: Prepare complex space - curved surface components of the same material and the same specifications using the conventional hot forging process, including blanking - Heating (1100 °C) - pre - form blank - Heating (1080 °C) - pre - forming - trimming - Heating (1060 °C) - final forming - cooling (air cooling).

[0083] After sampling and corroding the complex components prepared in each example and the comparative example, perform grain size detection. The detection positions are as shown Figure 3 and the detection results are shown in Table 1.

[0084] Grain size of inspection part A Grain size of inspection part B Grain size of inspection part C Example 1 Grade 8 Grade 8 Grade 7.5 Example 2 Grade 8 Grade 8 Grade 8.5 Example 3 Grade 8.5 Grade 8.0 Grade 9 Example 4 Grade 9 Grade 9 Grade 9 Comparative example Grade 6 Grade 5 Grade 5

[0085] Adopting the scheme in the example has little damage to the mold. Among them, when preparing 524 pieces using the scheme in Example 1, there is significant wear affecting the dimensional accuracy of the product; when preparing 501 pieces using the scheme in Example 2, there is significant wear affecting the dimensional accuracy of the product; when preparing 498 pieces using the scheme in Example 3, there is significant wear affecting the dimensional accuracy of the product; when preparing 460 pieces using the scheme in Example 4, there is significant wear affecting the dimensional accuracy of the product; while when preparing 336 pieces using the scheme in the comparative example, cracks occur in the mold and it cannot be used continuously. In contrast, adopting the scheme in the example can form complex components with space - curved surfaces with only one heating. The forming force is small, the internal quality is good, the material utilization rate is high, the production cycle is short, and the mold life is long.

[0086] In the embodiments, the proposed solution can form difficult-to-deform components with complex shapes such as narrow ribs, bosses, and branches using a simple process. The obtained components have good internal structures, low forming forces, and can significantly simplify the production process (in Example 1, there are a total of 5 process steps, and the processing cycle is approximately 6 hours. In the comparative example, there are a total of 10 process steps, and the processing cycle is approximately 28 hours). It has strong operability and low implementation costs (including die sharing. The total processing and manufacturing cost of using the solution in Example 1 is approximately 160 yuan per piece, the total processing and manufacturing cost of using the solution in Example 2 is approximately 165 yuan per piece, the total processing and manufacturing cost of using the solution in Example 3 is approximately 172 yuan per piece, and the total processing and manufacturing cost of using the solution in Example 4 is approximately 196 yuan per piece; using the solution in the comparative example, the total processing and manufacturing cost is approximately 850 yuan), and is suitable for mass production.

Claims

1. An extrusion process based on a floating variable cavity for preparing complex components with narrow ribs, characterized in that the steps Including: Step 1, blanking: Saw the bar stock into blanks with a length not greater than 360 mm. Step 2, heating: Heat the blank obtained in Step 1 to 1080 °C and hold for 33 minutes. Step 3, loading: Place the heated blank in Step 2 into the mold cavity. Among them, the mold includes an upper mold, a lower mold, a left extrusion mold, and a right extrusion mold respectively connected to the extrusion cylinder. The left extrusion mold and the right extrusion mold are both composed of two semi-cylinders. The upper mold, the lower mold, the left extrusion mold, and the right extrusion mold jointly enclose a cavity, and a floating variable cavity is jointly enclosed by the static upper mold, the lower mold moving downward, and the left and right extrusion molds moving towards each other; an electric heating wire is installed on the lower mold. Step 4, extrusion, which is carried out specifically according to the following process Step 41: Keep the lower mold at the set upper working position under pressure, keep the upper mold stationary, and always control the left and right extrusion molds to squeeze towards the center respectively until the blank fills the pre-extrusion cavity; among them, first control the upper semi-cylinder mold bodies of the left extrusion mold and the lower semi-cylinder mold bodies of the right extrusion mold to move towards the center respectively at a speed of 2 ± 0.5 mm / s for 15 mm; then control the lower semi-cylinder mold bodies of the left extrusion mold and the upper semi-cylinder mold bodies of the right extrusion mold to squeeze towards the center at a speed of 2 ± 0.5 mm / s until the blank fills the pre-extrusion cavity. Step 42: Control the left and right extrusion molds to retract 10 - 15 mm respectively and then keep stationary, and then control the upper and lower molds to squeeze simultaneously until the blank fills the pre-extrusion cavity. Step 43: Repeat Steps 41 - 42 three times. Step 44: Control the upper mold to apply pressure and move downward. When the extrusion load on the lower mold continuously increases to 20 ± 0.2 MPa, control the lower mold to retreat downward at a speed of 5 ± 0.5 mm / s. During this process, the blank flows downward to continue filling the mold. Step 45: When the stroke of the lower mold reaches 68 ± 5 mm, the lower mold stops moving, and keep the lower mold under pressure at this working position. At the same time, control the upper mold to squeeze downward. When the blank fills the cavity again and extrudes the excess material along the split flash groove, stop the extrusion. Step 5: Keep the upper mold (1), the lower mold (2), and the left and right extrusion molds under pressure for 30 seconds. Step 6: Open the mold, take out the part, place it in the air for cooling, and perform surface cleaning. Among them, during the downward movement of the lower mold, always control the temperature of the lower mold to be 420 ± 0.5 °C, and always control the temperature of the upper mold to be 370 ± 0.5 °C.

2. The extrusion process according to claim 1, characterized in that: The bar stock is 34CrNiMo6 structural steel, and the blank size is .

3. The extrusion process according to any one of claims 1-2, characterized in that: In Step 41, first control the lower semi-cylinder mold bodies of the left extrusion mold and the lower semi-cylinder mold bodies of the right extrusion mold to move towards the center respectively at a speed of 2 ± 0.5 mm / s for 20 mm; then control the upper semi-cylinder mold bodies of the left extrusion mold and the upper semi-cylinder mold bodies of the right extrusion mold to squeeze towards the center at a speed of 2 ± 0.5 mm / s until the blank fills the pre-extrusion cavity.

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