Method for producing medium-large step shaft through large continuous casting billet

Abstract

The invention discloses a method for producing a medium-large step shaft through a large continuous casting billet, and belongs to the technical field of metal hot working. According to the large step forging process in large continuous casting billet production, the continuous casting billet is adopted, and compared with traditional steel ingot forging, the steps of forging a pressure jaw and chamfering through a steel ingot are omitted, the situation that the cutting amount of a water riser is large is avoided, the heating time is shortened, burning loss is reduced, and the metal yield is effectively increased. The upper V-shaped anvil and the lower V-shaped anvil with the arc bottoms are adopted for drawing out, the size precision of the step shaft is improved, machining excess materials are reduced, and the metal yield is remarkably increased. Compared with an existing traditional production process for forging medium-large stepped shafts through steel ingots, the method has the advantages that the production heating number is small, the production process is simple, the production efficiency is high, the production cost is greatly reduced, and better application prospects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal hot working, and specifically to a method for producing large stepped shafts during continuous casting billet production in Dalian. Background Art

[0002] Traditional medium and large stepped shafts are forged from ingots, with multiple forging heats and low material yield. The traditional medium and large steps usually adopt the following process: Production process of medium and large stepped shafts: Press the clamp mouth - chamfer - (rounding) - heating - upsetting and drawing - (rounding) - heating - upsetting and drawing - (rounding) - (press the step) - heating - drawing out - heating - draw to the forging size.

[0003] The disadvantages of traditional medium and large stepped shaft forging are also obvious. When forging medium and large stepped shafts with ingots, a large amount of the water riser material of the ingot needs to be cut off. The process uses multiple heating heats, so the burning loss is large. The forging size accuracy with ordinary V-shaped anvils is low, resulting in low metal yield and low material yield of the ingot forging. Therefore, the cost is relatively high and the market competitiveness declines. Summary of the Invention

[0004] The present invention provides a method for producing large stepped shafts during continuous casting billet production in Dalian, which solves the problems of multiple forging heats, large burning loss, large water riser cutting amount, low finished product accuracy, and too low material yield when using ingots to forge medium and large stepped shafts. The medium and large stepped shafts manufactured by the process method of the present invention not only have excellent performance in all aspects, but also have a simple process, high production efficiency, high metal material yield, reduced energy consumption, and greatly reduced production costs.

[0005] The present invention is realized through the following technical solutions: A method for producing large stepped shafts during continuous casting billet production in Dalian, comprising the following steps: S1: Heat the continuous casting billet in Dalian; S2: First upset and draw the continuous casting billet in Dalian. Upset the heated continuous casting billet on a forging press, then lay it down on the upsetting platform. Use a flat anvil on top and the upsetting platform below. Use the upsetting platform to draw out longitudinally with the upset surface perpendicular to the flat anvil for longitudinal forging, and then rotate the upsetting platform so that the upset surface is parallel to the upper flat anvil, and use the upper and lower flat anvils to draw out for transverse forging; S3: Reheat the forging blank in the furnace and perform the second upset and draw. Use the same method as the first upset and draw, and then use a triangular knife to pinch the platform to forge the preliminary step; S4: Replace the upper and lower V-shaped anvils to draw out the maximum cross-sectional size and step size. The V-shaped anvils are designed with a circular arc at the bottom, and the rest is the same as the V-shaped anvil, that is, the upper and lower V-shaped anvils with a circular arc at the bottom; S5: Perform final heat treatment on the forging.

[0006] Preferably, in steps S2 and S3, after upsetting, the drawing process is carried out longitudinally by the FM method. After upsetting, the large diameter of the forging stock enables the FM method to meet the requirements that a narrow anvil can forge and weld the central porosity and central cracks of the continuous casting billet. When the size of the forging stock meets the requirements of the WHF forging penetration stock, transverse WHF forging is carried out to further compact the core of the continuous casting billet. Changing the forging direction longitudinally and transversely is beneficial to forging and solidifying the central defects of the continuous casting billet.

[0007] Preferably, for the steps of the medium-sized stepped shaft, upsetting and drawing are carried out once in step S2, which can meet the requirements of forging and welding the central porosity and cracks of the large continuous casting billet; for the large-sized stepped shaft, upsetting and drawing are carried out twice in step S3 to ensure the forging and welding of the central porosity and cracks of the large continuous casting billet.

[0008] Preferably, in step S4, drawing is carried out using a V-shaped anvil with a circular arc at the bottom, which combines the advantages of the three-way compressive stress deformation on the side of the V-shaped anvil and the high dimensional accuracy of the rounding die. The forging size of the V-shaped anvil with a circular arc at the bottom is close to the requirements of the rounding die.

[0009] Preferably, the heat treatment in step S5 is normalizing treatment.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: In the large stepped forging process for the production of large continuous casting billets in the present invention, large continuous casting billets are used. Compared with the traditional ingot forging, the steps of forging the clamping jaws and chamfering of the ingot are reduced, the large amount of water riser cutting is avoided, the heating time is reduced, the burning loss is reduced, and the metal yield is effectively improved.

[0011] The problems of central cracks and central porosity in large continuous casting billets are more serious than those in small continuous casting billets. To solve this problem, it is necessary to ensure that the forging ratio is greater than 4.5, and there must be multiple large three-way compressive stresses in the core to weld the central cracks and central porosity of the large continuous casting billet. Generally, continuous casting billets with a diameter of φ800 - φ1200 are used for forging medium-sized stepped shafts, and continuous casting billets with a diameter of φ1200 - φ1300 are used for large-sized stepped shafts. The larger the direct size of the large continuous casting billet, the more serious the central porosity and central cracks are. Only by adopting the special forging process of the present invention can the flaw detection requirements be met. By using the FM method of longitudinal drawing, that is, a narrow anvil can penetrate the core of the large-diameter material. At the same time, when the diameter is less than 1600 (anvil width 900), the WHF method is used for transverse forging. The large deformation amounts longitudinally and transversely make the core deformation penetrate completely. Upsetting and drawing of medium-sized stepped shafts are completed in 2 heats with fewer heats, and forging of large stepped shafts is completed in 3 heats. Therefore, the risk of grain size increase or mixed grains due to multiple heating times is reduced, and the excellent mechanical properties are comprehensively improved.

[0012] The present invention uses upper and lower V-shaped anvils with a circular arc at the bottom for drawing, which improves the dimensional accuracy of the stepped shaft, reduces the machining surplus material, and significantly improves the metal yield.

[0013] Compared with the existing traditional production process of large and medium-sized stepped shafts by ingot forging, the production process in the present invention has fewer heating times, a simpler production process, higher production efficiency, significantly lower production costs, and better application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a forging drawing of a stepped shaft with a diameter of φ870mm; Figure 2 It is a broken line graph of time and temperature of the heating process in Step S1 of Embodiment 1 of the present invention; Figure 3 It is a V-shaped anvil with an arc (arc φ950) in Step S3 of Embodiment 1 of the present invention; Figure 4 It is a forging process drawing of continuously cast billet forging a stepped shaft in Step S2 and Step S3 of Embodiment 1 of the present invention; Figure 5 It is a broken line graph of time and temperature of the final heat treatment in Step S4 of Embodiment 1 of the present invention; Figure 6 It is a forging drawing of a stepped shaft with a diameter of φ1200mm; Figure 7 It is a broken line graph of time and temperature of the heating process in Step S1 of Embodiment 2 of the present invention; Figure 8 It is a V-shaped anvil with an arc (arc φ1300) in Step S3 of Embodiment 2 of the present invention; Figure 9 It is a forging process drawing of continuously cast billet forging a stepped shaft in Step S2, Step S3 and Step S4 of Embodiment 2 of the present invention; Figure 10 It is a broken line graph of time and temperature of the final heat treatment in Step S5 of Embodiment 2. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be further described below with reference to the accompanying drawings: A method for producing large and medium-sized stepped shafts from large continuous cast billets includes the following steps: S1: Heat the large continuous cast billet; S2: Perform one-time upsetting and drawing of the large continuous cast billet. Upset the heated large continuous cast billet on a forging press, place the upset billet on the upsetting platform, use a flat anvil on the top and the upsetting platform on the bottom, and use the upsetting platform to draw longitudinally with the upset surface perpendicular to the flat anvil, then rotate the upsetting platform so that the upset surface is parallel to the upper flat anvil, and use the upper and lower flat anvils to draw transversely; S3: Reheat the forged billet in the furnace, perform the second upsetting and drawing, use the same method as the first upsetting and drawing, and then use a triangular knife to cut the platform to forge the preliminary steps; S4: Replace the upper and lower V-shaped anvils to draw the maximum cross-sectional dimension and the step dimension. The V-shaped anvil is designed with a bottom arc, and the rest is the same as the V-shaped anvil, that is, the upper and lower V-shaped anvils with a bottom arc; S5: Perform final heat treatment on the forging.

[0016] Preferably, in steps S2 and S3, after upsetting, the drawing is carried out by the longitudinal FM method. After the material is upset, the large diameter can meet the requirements of forging the center porosity and center cracks of the continuous casting billet by using the FM method. When the size of the forging material meets the requirements of the WHF forging penetration material, then carry out the transverse WHF forging to further compact the core of the continuous casting billet. Changing the forging direction in the longitudinal and transverse directions is beneficial to forging and eliminating the center defects of the large continuous casting billet.

[0017] Preferably, for the steps of the medium-sized stepped shaft, upsetting and drawing are carried out once in step S2, which can meet the requirements of forging and eliminating the center porosity and cracks of the large continuous casting billet. The medium-sized stepped shaft is φ600 - 1000mm; for the large stepped shaft, upsetting and drawing are carried out twice in step S3 to ensure that the center porosity and cracks of the large continuous casting billet are forged and eliminated. The large stepped shaft is φ > 1000mm.

[0018] Preferably, in step S4, drawing is carried out with a V-shaped anvil with an arc at the bottom, which combines the advantages of the three-way compressive stress deformation on the side of the V-shaped anvil and the high dimensional accuracy of the rounding die. The forging size with a V-shaped anvil with an arc at the bottom is close to the requirements of the rounding die.

[0019] Preferably, the heat treatment in step S5 is normalizing treatment. Example 1

[0020] The process route for producing a medium-sized step φ870 from a large continuous casting billet of the present invention is as follows: The structure of the forging drawing of the φ870 stepped shaft is as shown in the appendix Figure 1 A continuous casting billet of φ1000mm * 3.08m with the material grade of 35CrMo is used to forge a stepped shaft of φ870.

[0021] The processing method is as follows: heating - upsetting and drawing - heating - drawing and finishing with a V-shaped anvil - normalizing - straightening - flaw detection - sawing off the head and tail - machining - flaw detection - warehousing.

[0022] S1: Put the φ1000mm * 3.08m into the furnace for heating, and the heating process parameters are as shown in the appendix Figure 2 as shown.

[0023] S2: Upset the continuously cast billet after heating to Φ1960*0.8m. After upsetting, lay it down on the upsetting platform. Use a flat anvil on top and the upsetting platform below. Use the upsetting platform to draw out the upset surface perpendicular to the flat anvil, press 250mm, turn it over 180 degrees and press 250mm, then turn it over 90 degrees and press 280mm, turn it over 180 degrees and press another 280mm. Trim it to 1550mm*1550mm using the upper flat anvil and the large platform. Then rotate the upsetting platform so that the upset surface is parallel to the upper flat anvil, and draw out using the upper and lower flat anvils (anvil width 900mm). The reduction ratio is 20%-25%, and the feeding amount of the anvil is controlled between 0.5-0.8 (anvil width / material height) for large reduction ratio drawing. Finally, trim it to chamfer and forge it into a φ950mm circle; then use a triangular knife to pinch the steps and first press the size of the step part to φ700mm.

[0024] S3: Return the workpiece to the furnace for reheating. First press both ends using a V-shaped anvil with an arc, draw out both ends to φ625mm, draw out the middle part with the V-shaped anvil to φ870mm, then press out the sizes of each section of the steps, and finally finish the sizes of each step. Measure that the outer diameter and length of each step section meet the requirements of the forgings. The figure of the V-shaped anvil with an arc is as attached Figure 3 as shown.

[0025] S4: Conduct final heat treatment on the final forgings. The normalizing process parameters are as attached Figure 5 as shown. After normalizing, the operations are straightening - qualified black skin flaw detection - sawing off the head and tail - qualified sampling performance - machining - qualified flaw detection after turning smooth - warehousing. Example 2

[0026] The process route for producing a large stepped φ1200mm from a large continuously cast billet of the present invention is as follows: The structure of the Φ1200mm stepped shaft forging drawing is as attached Figure 6 as shown. Forge a stepped shaft of φ1200mm using a continuously cast billet of φ1200mm*3.1m with the material grade 60CrMnMo.

[0027] The processing method is as follows: heating - upsetting and drawing - heating - upsetting and drawing - heating - drawing and finishing with a V-shaped anvil - normalizing - straightening - qualified black skin flaw detection - sawing off the head and tail - qualified sampling performance - machining - qualified flaw detection after turning smooth - warehousing.

[0028] S1: Put the φ1200mm*3.1 into the furnace for heating. The heating process parameters are as attached Figure 7 as shown.

[0029] S2: Upset the heated large continuous casting billet to Φ2140mm * 0.95m. After upsetting, lay it down on the upsetting platform, use a flat anvil on top and the upsetting platform below. Use the upsetting platform to draw out the upset surface perpendicular to the flat anvil, press 280mm, turn it over 180 degrees and press 280mm, then turn it over 90 degrees and press 300mm, turn it over 180 degrees and press another 300mm. Trim it to 1580mm * 1580mm on the upper flat anvil and the large platform. Then rotate the upsetting platform so that the upset surface is parallel to the upper flat anvil, and use the upper and lower flat anvils (anvil width 900mm) to draw out with a reduction of 20% - 25%, and control the feeding amount of the anvil between 0.5 - 0.8 (anvil width / material height) for large reduction drawing. Finally, trim it to a chamfer and forge it into a forged billet of φ1250mm * 2.8m.

[0030] S3: Heat the forged billet of φ1250mm * 2.8m and upset it to Φ2200mm * 0.9m. After upsetting, lay it down on the upsetting platform, use a flat anvil on top and the upsetting platform below. Use the upsetting platform to draw out the upset surface perpendicular to the flat anvil, press 280mm, turn it over 180 degrees and press 280mm, then turn it over 90 degrees and press 300mm, turn it over 180 degrees and press another 300mm. Trim it to 1580mm * 1580mm on the upper flat anvil and the large platform. Then rotate the upsetting platform so that the upset surface is parallel to the upper flat anvil, and use the upper and lower flat anvils (anvil width 900mm) to draw out with a reduction of 20% - 25%, and control the feeding amount of the anvil between 0.5 - 0.8 (anvil width / material height) for large reduction. Finally, trim it to a chamfer and forge it into a circle of φ1250mm. Then use a triangular tool to pinch the step, and first press the size of the step part to 1000mm.

[0031] S4: Reheat in the furnace. First, use a V - shaped anvil with an arc to press both ends, draw out both ends to φ600mm, draw out the middle part with the V - shaped anvil to φ1200mm, then press out the sizes of each section of the step, and finally finish the size of each step. Measure that the outer diameter and length of each step section meet the requirements of the forging. The figure of the V - shaped anvil with an arc is as attached Figure 8 as shown.

[0032] S5: Conduct final heat treatment on the final forging. The normalizing process parameters are as attached Figure 10 as shown. After normalizing treatment, the operations are straightening - qualified black - skin flaw detection - sawing off the head and tail - qualified sampling performance - machining - qualified flaw detection after turning smooth - warehousing.

[0033] After forging the large continuous casting billet by the forging method of the present invention, normalizing and then rough turning, the internal ultrasonic flaw detection of the forging meets the Class II standard in JB / T 5000.15 - 2007. The grain size of the forging is inspected according to the GB / T 6394 standard, and the result is ≥ 6.0 grades, without mixed - grain phenomenon.

[0034] In summary, the above are only the preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Any equivalent changes and modifications made to the shape, structure, features and spirit described in the scope of the claims of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A method for producing large stepped shafts in continuous casting billets in Dalian, characterized in that: It includes the following steps: S1: Heat the Dalian bloom. S2: Perform the first upsetting and drawing of the Dalian bloom. After heating the Dalian bloom, upset it on a forging press. After upsetting, place it on the upsetting platform. Use a flat anvil on top and the upsetting platform below. Use the upsetting platform to draw out longitudinally with the upsetting surface perpendicular to the flat anvil for longitudinal forging. Then rotate the upsetting platform so that the upsetting surface is parallel to the upper flat anvil, and use the upper and lower flat anvils to draw out for transverse forging. S3: Reheat the forged billet in the furnace and perform the second upsetting and drawing. Use the same method as the first upsetting and drawing. Then use a triangular knife to cut the platform to forge a preliminary step. S4: Replace with upper and lower V-shaped anvils to draw out the maximum cross-sectional dimension and step dimension. The V-shaped anvils are designed with a circular arc at the bottom, and the rest is the same as the V-shaped anvil, that is, the upper and lower V-shaped anvils with a circular arc at the bottom. S5: Perform final heat treatment on the forgings.

2. The method for producing large and medium-sized stepped shafts in continuous casting billets in Dalian according to claim 1, characterized in that: In steps S2 and S3, after upsetting, the drawing is carried out by the longitudinal FM method. After the material is upset, the large diameter can meet the requirements of forging the center porosity and center cracks of the continuous casting billet by the FM method with a narrow anvil. When the size of the forging material meets the requirement of the penetrative material of WHF, perform transverse WHF forging to further compact the core of the continuous casting billet. Changing the forging direction in the longitudinal and transverse directions is conducive to forging out the center defects of the continuous casting billet.

3. A method for producing large and medium-sized stepped shafts in continuous casting billets in Dalian, as claimed in claim 1, wherein: Performing the first upsetting and drawing in step S2 on the steps of the medium-sized stepped shaft can meet the requirements of forging out the center porosity and cracks of the Dalian bloom. For the stepped shaft of the large-sized stepped shaft, the second upsetting and drawing in step S3 should be carried out to ensure that the center porosity and cracks of the Dalian bloom are forged out.

4. A method for producing large and medium-sized stepped shafts in continuous casting billets according to claim 1, characterized in that: The heat treatment in step S5 is normalizing treatment.

Images