Method for forming irregular inner diameter rolling rings

Abstract

This invention relates to a method for forming irregularly shaped inner diameter rings, comprising the following steps: blanking: cutting the raw material to a specified length on a saw to obtain a billet; pre-forging heating: heating the billet to the forging temperature and holding it at that temperature; upsetting and punching: upsetting the billet to a set height on a press, and punching holes in the billet using a punch to obtain a ring blank; pre-rolling: rolling the ring blank using a ring mill, with the first working part of the mandrel rolling the straight wall inside the through hole of the ring part to obtain a rectangular cross-section ring part; final rolling: moving the mandrel down to the second station position, rolling the rectangular cross-section ring part using a ring mill, with the second working part of the mandrel rolling the groove inside the through hole of the ring part to obtain an irregularly shaped cross-section ring part. In this invention, the ring rolling process only requires one heating and holding time, and the continuous rolling of the ring blank using a dual-station mandrel greatly shortens the processing time and improves processing efficiency. Furthermore, by eliminating multiple heating cycles, energy is saved, and the impact of repeated heating on the quality of the ring part is avoided, ensuring product quality.

Description

Technical Field

[0001] This invention relates to the field of rolling technology, and in particular to a method for forming irregularly shaped rolling rings with different inner diameters. Background Technology

[0002] Ring forgings are one of the important types of forgings, and they are widely used in petrochemical, machinery, wind power, thermal power, aviation, aerospace and other fields.

[0003] As the industry develops, the cross-sectional shapes of rings are becoming increasingly complex. Conventional rectangular cross-section ring rolling processes lead to waste of raw materials and processing time. Rolling irregularly shaped rings can achieve cross-sectional contouring, saving raw materials and reducing processing time waste. This represents a technological trend and is an important technological direction for energy conservation and emission reduction.

[0004] In the forming methods of irregular-shaped inner diameter rings, most processes employ two or more heating cycles. For example, after the first heating and holding at the processing temperature, a rectangular cross-section ring is pre-rolled. After the second heating and holding at the processing temperature, the irregular-shaped mandrel is replaced, and the ring is finally rolled to form the irregular cross-section. While two heating cycles ensure the formation of the irregular cross-section, the processing time is long, and the irregular-shaped mandrel mold needs to be changed midway. This is not only time-consuming and labor-intensive, increasing production costs, but the repeated heating also has an adverse effect on the quality of the ring itself. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for forming irregular inner diameter rolling rings to solve one or more problems in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] The method for forming irregularly shaped inner diameter rolling rings includes the following steps:

[0008] Cutting: Cutting the raw material to a specified length on a saw to obtain a blank;

[0009] Pre-forging heating: heating the billet to the forging temperature and holding it at that temperature;

[0010] Upsetting and punching: The billet is upset to a set height on a press, and then punched with a punch to obtain a ring billet;

[0011] Pre-rolling: The mandrel moves to the first station position and the ring blank is rolled by the ring mill. The first working part of the mandrel rolls the straight wall inside the through hole of the ring to obtain a ring with a rectangular cross section.

[0012] Final rolling: The mandrel moves to the second station position and rolls the rectangular cross-section ring through the ring mill. The second working part of the mandrel rolls the groove in the through hole of the ring to obtain the irregular cross-section ring.

[0013] Furthermore, the outer diameter D1, inner diameter d1, and height H1 of the ring billet before pre-rolling satisfy the following relationship:

[0014] ;

[0015] Where k is the proportionality coefficient that the outer diameter and inner diameter of the ring blank should satisfy, 0.25≤k≤0.35; V1 is the volume of the irregular cross-section ring, D3 is the outer diameter of the irregular cross-section ring, d3 is the inner diameter of the irregular cross-section ring, and H3 is the height of the irregular cross-section ring.

[0016] Furthermore, the outer diameter D2, inner diameter d2, and height H2 of the pre-rolled rectangular cross-section ring satisfy the following relationship:

[0017] ;

[0018] Where m is the ratio of the wall thickness reduction of the rectangular cross-section ring in the final rolling stage to the total wall thickness reduction, 25%≤m≤35%, and n is the ratio of the height reduction of the rectangular cross-section ring in the final rolling stage to the total height reduction, 5%≤n≤15%.

[0019] Furthermore, the step of moving the mandrel to the second work station position includes:

[0020] The mandrel first moves horizontally a distance L. x Then move vertically downwards a second distance L y L x L y The following relationship must be satisfied:

[0021] ;

[0022] Among them, D max D is the maximum outer diameter of the second working part of the mandrel. min L1 is the outer diameter of the first working part of the mandrel; L2 is the minimum vertical distance between the working surface of the second working part of the mandrel and the material support plate during pre-rolling; L2 is the safe distance range between the mandrel mold and the ring mill so that they will not collide, 50mm≤L2≤150mm.

[0023] Furthermore, the upsetting direction is the axial direction of the billet, and the total upsetting ratio is >3.5.

[0024] Furthermore, the pre-rolled ring speed increase is 10~20mm / s.

[0025] Furthermore, the final rolling process has three stages; the first stage is when the outer diameter of the ring increases by [0%, 20%), with a ring growth rate of 3~10 mm / s; the second stage is when the outer diameter of the ring increases by [20%, 80%), with a ring growth rate of 10~20 mm / s; and the third stage is when the outer diameter of the ring increases by [80%, 100%), with a ring growth rate of 2~5 mm / s.

[0026] Furthermore, the ring mill includes a support plate for placing the billet, a main roller, a conical roller, and a mandrel; the outer diameter surface of the main roller rolls the outer diameter surface of the billet; there are two conical rollers, symmetrically arranged on the upper and lower end surfaces of the billet, and the outer surfaces of the two conical rollers respectively roll the upper and lower end surfaces of the billet. The conical roller located on the lower end surface of the billet has no displacement along the axial direction of the billet, and the conical roller located on the upper end surface of the billet rolls the upper end surface of the billet downward along the axial direction of the billet to achieve deformation in the height of the billet; the outer surface of the mandrel has a first working part and a second working part, the first working part is located at the lower end of the second working part, the first working part is a cylinder of equal diameter, and the second working part is a cylinder of variable cross-section, the outer diameter profile of its radial section is the same as the inner diameter profile of the radial section of the irregular cross-section ring.

[0027] Compared with the prior art, the beneficial technical effects of the embodiments of the present invention are as follows:

[0028] The method for forming an irregularly shaped inner diameter ring according to the present invention includes the following steps: blanking: cutting the raw material to a specified length on a saw to obtain a billet; pre-forging heating: heating the billet to the forging temperature and holding it at that temperature; upsetting and punching: upsetting the billet to a set height on a press, and punching the billet with a punch to obtain a ring blank; pre-rolling: rolling the ring blank with a ring mill, and rolling the straight wall inside the through hole of the ring part with the first working part of the mandrel to obtain a ring part with a rectangular cross-section; final rolling: moving the mandrel down to the second station position, rolling the rectangular cross-section ring part with a ring mill, and rolling the groove inside the through hole of the ring part with the second working part of the mandrel to obtain an irregularly shaped cross-section ring part. The inner diameter irregular-shaped rolling ring forming method of the present invention is the first to discover that by heating and holding to the processing temperature in one heating process, an irregular-shaped mandrel with two working parts is used to continuously roll the ring blank to form a ring with an irregular cross section, which greatly shortens the processing time and improves the processing efficiency. Moreover, since multiple heating processes are eliminated, energy is saved, and the impact of repeated heating on the quality of the ring is avoided, thus ensuring product quality. Attached Figure Description

[0029] Figure 1 This diagram illustrates the structure of the punched ring blank in the inner diameter irregular-shaped rolling ring forming method provided in Embodiment 1 of the present invention.

[0030] Figure 2A schematic diagram of the mandrel structure in the inner diameter irregular-shaped rolling ring forming method provided in Embodiment 1 of the present invention is shown.

[0031] Figure 3 The diagram shows the structure of the pre-rolling ring mill and the ring blank in the inner diameter irregular ring forming method provided in Embodiment 1 of the present invention.

[0032] Figure 4 The diagram shows the structure of the pre-rolling ring mill and the rectangular cross-section ring in the inner diameter irregular ring forming method provided in Embodiment 1 of the present invention.

[0033] Figure 5 The diagram shows the structure of the ring mill and the irregular cross-section ring in the inner diameter irregular ring forming method provided in Embodiment 1 of the present invention.

[0034] Figure 6 (a) is a metallographic image of the end face of the irregularly shaped ring with an inner diameter obtained in Comparative Example 1. Figure 6 (b) is a metallographic image of the end face of the irregular-shaped ring with inner diameter produced in Example 1.

[0035] Marked in the attached diagram:

[0036] 1. Mandrel; 11. First working section; 12. Second working section; 2. Main roller; 3. Conical roller; 4. Material support plate; 5. Ring blank; 51. Through hole; 52. Groove. Detailed Implementation

[0037] To make the objectives, features, and advantages of this invention more apparent and understandable, please refer to the accompanying drawings. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the implementation conditions of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed in this invention.

[0038] In the description of this invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0039] Example 1

[0040] Please refer to Figures 1-5 The method for forming irregularly shaped inner diameter rolling rings includes the following steps:

[0041] Step S1, material cutting: Cut the raw material to a specified length on a saw to obtain a blank.

[0042] Specifically, the height-to-diameter ratio of the billet before upsetting is ≤3. The smallest specification of raw material that meets the height-to-diameter ratio requirement is selected according to the required blank weight of the product. For example, in this embodiment, continuously cast round billets of S355NL material are used as raw materials. Of course, steel ingots or square billets and other raw materials can also be used. This invention does not impose further restrictions on this.

[0043] Step S2, Pre-forging heating: Heat the billet to the forging temperature and hold it at that temperature.

[0044] Specifically, cold material is fed into the furnace and heated to 850±30℃ at the maximum power of the furnace, and held for 2~3 hours. Then, the temperature is increased to 1250±15℃ at a heating rate of ≤100℃ / h, and held for 7~8 hours.

[0045] Step S3, upsetting and punching: Upset the billet to a set height on a press, and punch holes in the billet to obtain a ring billet.

[0046] Please refer to Figure 1 , Figure 2 and Figure 3 Specifically, the billet is upset to a set height H1 on the press, with the upsetting direction being the billet's axial direction. The total upsetting ratio is greater than 3.5, and the total upsetting ratio is the sum of the upsetting ratios of each iteration. A punch with a diameter of d1 is used to punch holes in the billet, resulting in a billet with outer diameter D1, inner diameter d1, and height H1 after punching.

[0047] Specifically, the outer diameter D1, inner diameter d1, and height H1 of the ring billet before pre-rolling satisfy the following relationship:

[0048] ;

[0049] Where k is the proportionality coefficient that the outer diameter and inner diameter of the ring blank should satisfy, 0.25≤k≤0.35, and k is taken as 0.35 here; V1 is the volume of the irregular cross-section ring, which can be obtained by modeling and calculation in 3D software. D3 is the outer diameter of the irregular cross-section ring, d3 is the inner diameter of the irregular cross-section ring, H3 is the height of the irregular cross-section ring, and d1 is the punch diameter, all of which are known parameters. The first formula represents Figure 1 rectangular cross-section ring blank and Figure 5 For irregularly shaped cross-section rings, the height-to-wall-thickness ratio is constant across the cross-section. The second formula reflects the principle of constant volume. Figure 1 rectangular cross-section ring blank and Figure 5The irregularly shaped cross-section rings have equal volumes. By simultaneously solving three equations containing three unknowns D1, d1, and H1, the outer diameter D1 and inner diameter d1 can be calculated. 1、 The specific value of height H1.

[0050] Step S4, pre-rolling: The mandrel is moved to the first station position and the ring blank is rolled by the ring mill. The first working part of the mandrel rolls the straight wall inside the through hole of the ring to obtain a rectangular cross-section ring.

[0051] Please refer to Figure 4 Specifically, the rolling mill includes a support plate for placing the billet, a main roll, a conical roll, and a mandrel; the outer diameter surface of the main roll rolls the outer diameter surface of the billet; there are two conical rolls, symmetrically arranged on the upper and lower end surfaces of the billet, and the outer surfaces of the two conical rolls respectively roll the upper and lower end surfaces of the billet. The conical roll located on the lower end surface of the billet has no displacement along the axial direction of the billet, and the conical roll located on the upper end surface of the billet rolls the upper end surface of the billet downward along the axial direction of the billet. During rolling, as the outer diameter of the billet increases, the two conical rolls move in the same direction along the direction of increasing outer diameter of the billet, so that the outer surfaces of the two conical rolls always contact the upper and lower end surfaces of the billet, thereby achieving deformation in the height of the billet.

[0052] The outer surface of the mandrel has a first working part and a second working part. The first working part is located at the lower end of the second working part. The first working part is a cylinder with a constant diameter, and the second working part is a cylinder with a variable cross-section. The outer diameter profile of its radial section is the same as the inner diameter profile of the radial section of the irregular cross-section ring.

[0053] Specifically, the outer diameter profile of the radial section of the second working part includes a trapezoid that mates with the groove of the irregular cross-section and straight walls at the upper and lower ends of the trapezoid. When the mandrel moves to the first working position, the first working part aligns with the inner wall of the rectangular cross-section ring blank. When the mandrel moves to the second working position, the second working part aligns with the inner wall of the rectangular cross-section ring. The groove of the irregular cross-section and the second working part are not limited to the trapezoid in this embodiment; they can also be arc-shaped, rectangular, or protruding, etc., as long as they can satisfy the mutual cooperation between the second working part and the inner wall of the irregular cross-section ring. The present invention does not impose further limitations on this.

[0054] Furthermore, the pre-rolling ring speed increase is 10~20 mm / s. A larger ring speed increase during the pre-rolling stage can improve the forging penetration of the ring, increase the degree of plastic deformation of the core metal of the ring, and contribute to a more uniform overall performance of the ring.

[0055] The outer diameter D2, inner diameter d2, and height H2 of the pre-rolled rectangular cross-section ring satisfy the following relationship:

[0056] ;

[0057] Where m is the ratio of the wall thickness reduction of the rectangular cross-section ring in the final rolling stage to the total wall thickness reduction, 25%≤m≤35%, and n is the ratio of the height reduction of the rectangular cross-section ring in the final rolling stage to the total height reduction, 5%≤n≤15%. Within this range, m is preferentially taken as the maximum value of 35%, and n is preferentially taken as the minimum value of 5%. The first formula represents the ratio of the wall thickness reduction in the final rolling stage to the total wall thickness reduction. The second formula represents the ratio based on the principle of constant volume. Figure 4 rectangular cross-section ring and Figure 5 The volumes of the irregularly shaped cross-section rings are equal. The third formula represents the ratio of the height reduction during the final rolling stage to the total height reduction. The height H2 can be calculated using the third formula, and the outer diameter D2 and inner diameter d2 can be calculated by combining the first and second formulas.

[0058] Step S51: The mandrel is moved to the second working position.

[0059] Please refer to Figure 4 and Figure 5 Specifically, the mandrel first moves horizontally a distance L. x Then move vertically downwards a second distance L y L x L y The following relationship must be satisfied:

[0060] ;

[0061] Among them, D max D is the maximum outer diameter of the second working part of the mandrel. min L1 is the outer diameter of the first working part of the mandrel; L2 is the minimum vertical distance between the working surface of the second working part of the mandrel and the material support plate during pre-rolling; L2 is the safe distance range between the mandrel mold and the ring mill so that they will not collide, 50mm≤L2≤150mm. The value of L2 is adjusted according to the actual situation.

[0062] In step S52, the second working part of the mandrel rolls the groove inside the through hole of the ring to obtain a ring with an irregular cross-section.

[0063] Furthermore, the ring speed increase in the first stage of final rolling is 3~10 mm / s. This first stage is the die biting stage, specifically the stage where the outer diameter of the ring increases by [0%, 20%) of the outer diameter increase (D3-D2) during final rolling. This is beneficial for the stable formation of irregular grooves in the inner diameter of the ring. However, excessively rapid ring speed increases can lead to severe deformation and ring deviation. The ring speed increase in the second stage of final rolling is 10~20 mm / s. This second stage is the stable rolling expansion stage, specifically the stage where the outer diameter of the ring increases by [20%, 80%) of the outer diameter increase (D3-D2) during final rolling. A faster ring speed increase can improve the overall deformation uniformity of the ring. The ring speed increase in the third stage of final rolling is 2~5 mm / s. This third stage is the finishing stage, specifically the stage where the outer diameter of the ring increases by [80%, 100%) of the outer diameter increase (D3-D2) during final rolling.

[0064] Comparative Example 1

[0065] The steps of Comparative Example 1 are mostly the same as those of Example 1, except that there are two core rods, one of which has a first working part on the outside and the other core rod has a second working part on the outside.

[0066] Step S4 Pre-rolling: The ring billet is rolled and expanded by a ring mill. The first working part of the first mandrel rolls the straight wall inside the through hole of the ring to obtain a ring with a rectangular cross section.

[0067] Step S51: Heat the rectangular cross-section ring to the forging temperature and hold it at that temperature, while replacing the first mandrel with the second mandrel.

[0068] In step S52, the second working part of the mandrel rolls the groove inside the through hole of the ring to obtain a ring with an irregular cross-section.

[0069] The same inner diameter irregular ring parts were produced using the methods of Example 1 and Comparative Example 1, respectively. The dimensions of the inner diameter irregular ring parts produced by Example 1 and Comparative Example 1 are shown in Tables 1 and 2.

[0070] Table 1 Dimension Calculation Factors

[0071]

[0072] Table 2 Dimensions of Irregularly Shaped Rings with Inner Diameter

[0073]

[0074] The method in Example 1 only requires one pre-forging heating, resulting in low gas consumption. In contrast, the method in Comparative Example 1 requires reheating and heat preservation in the furnace midway, increasing gas consumption.

[0075] The method in Example 1 directly forms the target irregular cross-section ring through dual-station linkage, and the time required depends on the size, usually 8 to 15 minutes. In contrast, the method in Comparative Example 1 requires additional time for mandrel changing, ring insulation, feeding, and ring machine adjustment, adding at least 2.5 hours of extra time.

[0076] The method in Example 1 involves a large deformation per rolling cycle, which facilitates full deformation of the billet, resulting in finer grains and better microstructure and properties. In contrast, the method in Comparative Example 1 involves a smaller deformation per rolling cycle, resulting in less grain refinement. Furthermore, reheating and holding in the furnace will increase the grain size, leading to a more significant negative impact on microstructure and properties.

[0077] The grain size of Example 1 and Comparative Example 1 was tested. The testing standard was ISO 643, and the testing equipment was a Zeiss AXIO Observer metallurgical microscope from Germany. Figure 6 (a) is a metallographic image of the end face of the irregularly shaped ring with an inner diameter obtained in Comparative Example 1. Figure 6 (b) is a metallographic image of the end face of the irregular-shaped ring with inner diameter produced in Example 1. The end face grain size of the irregular-shaped ring with inner diameter produced in Example 1 is grade 8, while the end face grain size of the irregular-shaped ring with inner diameter produced in Comparative Example 1 is grade 6.5.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method of forming an inner profiled mill ring, characterised in that, Includes the following steps: Cutting: Cutting the raw material to a specified length on a saw to obtain a blank; Pre-forging heating: heating the billet to the forging temperature and holding it at that temperature; Upsetting and punching: The billet is upset to a set height on a press, and then punched with a punch to obtain a ring billet; The outer diameter D1, inner diameter d1, and height H1 of the ring billet before pre-rolling satisfy the following relationship: ； Where, k is the proportionality coefficient that the outer diameter and inner diameter of the ring blank should satisfy, 0.25≤k≤0.35; V1 is the volume of the irregular cross-section ring, D3 is the outer diameter of the irregular cross-section ring, d3 is the inner diameter of the irregular cross-section ring, and H3 is the height of the irregular cross-section ring. Pre-rolling: The mandrel moves to the first station position and the ring blank is rolled by the ring mill. The first working part of the mandrel rolls the straight wall inside the through hole of the ring to obtain a ring with a rectangular cross section. The outer diameter D2, inner diameter d2, and height H2 of the pre-rolled rectangular cross-section ring satisfy the following relationship: ； Where m is the ratio of the wall thickness reduction of the rectangular cross-section ring in the final rolling stage to the total wall thickness reduction, 25%≤m≤35%; and n is the ratio of the height reduction of the rectangular cross-section ring in the final rolling stage to the total height reduction, 5%≤n≤15%. Final rolling: The mandrel moves to the second station position and the rectangular cross-section ring is rolled and expanded by the ring mill. The second working part of the mandrel rolls the groove in the through hole of the ring to obtain the irregular cross-section ring. The step of moving the mandrel to the second working position includes: The mandrel moves horizontally first distance L x , then moves vertically downward second distance L y ; L x , L y satisfy the following relationship: ； wherein D max is the maximum outer diameter of the second working portion of the mandrel, D min is the outer diameter of the first working portion of the mandrel; L1 is the minimum vertical distance from the working surface of the second working portion of the mandrel to the material supporting plate during pre-rolling, and L2 is the safe distance range in which the mandrel mold and the ring machine will not collide, 50mm≤L2≤150mm.

2. The method of claim 1 wherein: The upsetting direction is the axial direction of the billet, and the total upsetting ratio is >3.

5.

3. The method of claim 1 wherein: The pre-rolled ring speed increase is 10~20mm / s.

4. The method of claim 1 wherein: The final rolling process has three stages; the first stage is when the outer diameter of the ring increases by [0%, 20%), with a ring growth rate of 3~10 mm / s; the second stage is when the outer diameter of the ring increases by [20%, 80%), with a ring growth rate of 10~20 mm / s; and the third stage is when the outer diameter of the ring increases by [80%, 100%), with a ring growth rate of 2~5 mm / s.

5. The method of claim 1 wherein: The ring mill includes a support plate for placing the billet, a main roller, a conical roller, and a mandrel. The outer diameter surface of the main roller rolls the outer diameter surface of the billet. There are two conical rollers, symmetrically arranged on the upper and lower end surfaces of the billet. The outer surfaces of the two conical rollers respectively roll the upper and lower end surfaces of the billet. The conical roller located on the lower end surface of the billet has no displacement along the axial direction of the billet, while the conical roller located on the upper end surface of the billet rolls the upper end surface of the billet downward along the axial direction of the billet to achieve deformation in the height of the billet. The outer surface of the mandrel has a first working part and a second working part. The first working part is located at the lower end of the second working part. The first working part is a cylinder of constant diameter, and the second working part is a cylinder of variable cross-section. The outer diameter profile of its radial section is the same as the inner diameter profile of the radial section of the irregular cross-section ring.

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