Two-high reversing rolling method for diamond-diamond pass system of titanium and titanium alloy bar

Abstract

The rhombus-rhombus pass system two-high reversible rolling method of titanium and titanium alloy rod material has the steps that the titanium and titanium alloy surface is pretreated and transferred into a first rhombus pass after heating and holding, rhombus billets are obtained, the rhombus billets are rolled by one or two times of rhombus pass again, rhombus materials are obtained, the rhombus materials are sequentially rolled by square pass, preforming elliptical pass, preforming round pass, finished product front elliptical pass and finished product round pass, and are straightened, and the rod material with a diameter of 30-45 mm is obtained. The rhombus-rhombus pass system two-high reversible rolling method of titanium and titanium alloy rod material realizes extension pass multi-pass sharing by rhombus-rhombus pass effect, greatly improves the utilization efficiency of the extension pass, increases the total deformation amount of rolling, and is stable in the rolling process, high in production efficiency, high in rolling rod material machining precision, and excellent in the titanium alloy rod material organization and performance prepared, and is suitable for mass production and processing.

Description

Technical Field

[0001] This invention belongs to the field of titanium and titanium alloy processing technology, and relates to a two-roll reversible rolling method for titanium and titanium alloy bars with a rhombus-rhombus hole system. Background Technology

[0002] Titanium and titanium alloys, due to their high specific strength, good corrosion resistance, and excellent biocompatibility, are widely used in aerospace, shipbuilding, medical, and civilian fields. Currently, titanium and titanium alloy bars are generally produced using forging or transverse rolling methods, which involve numerous processing steps and mill runs, resulting in low production efficiency. Transverse rolling mills use manual feeding, and the dwell time between passes and the billet flipping angle are significantly affected by human factors, easily introducing human error into the processing. This makes it difficult to control the product's microstructure and properties, and easily leads to scrap. The two-roll reversible rolling method, applied to titanium and titanium alloy processing, replaces manual feeding with a turner, improving the automation and efficiency of rolling production. However, the limited roll length of two-roll reversible rolling mills restricts the number of possible pass patterns; therefore, improving the commonality of pass patterns is crucial to enhancing mill capacity. Box-square, elliptical-circular, and rhomboid pass patterns are commonly used hot-rolling elongation pass systems for bars. However, continuous multi-pass rolling of material in a single box-square pass can easily lead to instability and desquamation. Elliptical materials entering the round pass rely on the support of rolling guides, allowing for only single-pass rolling. Furthermore, the rolling guides significantly encroach on roll space, further limiting the utilization efficiency of the roll pass. The rhomboid-square pass system can roll square billets in any pair of passes, but requires a larger number of passes and is suitable for tandem rolling mills. Summary of the Invention

[0003] The purpose of this invention is to provide a two-roll reversible rolling method for titanium and titanium alloy bars using a rhombus-rhombus die system, which has the advantages of improving the utilization efficiency of the elongation die, increasing the total rolling deformation, and improving the uniformity of the microstructure of titanium and titanium alloy bars.

[0004] The technical solution adopted in this invention is a two-roll reversible rolling method for titanium and titanium alloy bars with a rhombus-rhombus hole pattern, which specifically includes the following steps.

[0005] Step 1: Pre-treat the surface of titanium and titanium alloys and heat them to maintain their temperature;

[0006] Step 2: Transfer the pretreated titanium and titanium alloy billet from Step 1 into the first diamond-shaped die and roll it continuously for three passes to obtain a diamond-shaped billet.

[0007] Step 3: After flipping the rhomboid billet obtained in Step 2 by 90°, feed it into the second rhomboid die and roll it continuously for three passes. Check if it meets the rolled product specifications. If it does not meet the specifications, transfer it to the third rhomboid die and continue rolling until it meets the standards to obtain rhomboid material.

[0008] Step 4: After flipping the rhomboid material obtained in Step 3 by 90°, put it into a square die rolling mill for one pass to obtain a square material with a regular shape.

[0009] Step 5: The square material obtained in Step 4 is subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling in sequence, and then straightened to obtain a bar with a diameter of Φ30mm~Φ45mm.

[0010] The invention is further characterized by:

[0011] The pretreatment process in step 1 is as follows: the titanium and titanium alloy are forged into a round billet with a size of Φ95mm, the surface of the billet is polished clean, and it is placed in a heating furnace and heated to 900℃~950℃ and held for 70min~120min.

[0012] In step 2, the transfer time is less than 15 seconds. When rolling three passes, the billet is flipped 90° by a turning machine after the previous pass before the next pass.

[0013] In step 2, the apex angle of the first diamond-shaped die is 95° to 102°, the bottom fillet is R20mm to R25mm, the opening fillet is R15mm to R25mm, and the die height is 30mm to 40mm. The average elongation coefficient of the three rolling passes is 1.10 to 1.20, the rolling speed is 0.5m / s to 2.0m / s, and the dwell time between adjacent passes is less than 8 seconds.

[0014] In step 3, the apex angle of the second rhomboid die is 95° to 102°, the bottom fillet is R17mm to R22mm, the opening fillet is R12mm to R18mm, and the die height is 25mm to 35mm. The average elongation coefficient of the three rolling passes is 1.10 to 1.25, the rolling speed is 1.0m / s to 2.0m / s, the dwell time between passes is less than 8 seconds, and after the previous rolling pass, the rhomboid billet is flipped 90° by a turning machine before the next rolling pass.

[0015] In step 3, the apex angle of the third rhomboid die is 95° to 102°, the bottom fillet is R10mm to R15mm, the opening fillet is R10mm to R15mm, and the die height is 20mm to 30mm. The third rhomboid die is rolled in two passes with an average elongation coefficient of 1.15 to 1.25, a rolling speed of 1.0m / s to 2.0m / s, and a dwell time between passes of less than 8 seconds. After the previous pass, the rhomboid billet is flipped 90° using a turning machine before the next pass.

[0016] In step 4, for rolling square holes with diameters of Φ30mm to Φ35mm, the apex angle of the hole is 90°, the bottom fillet is R8mm to R12mm, the opening fillet is R8mm to R15mm, and the hole height is 20mm to 30mm; for rolling square holes with diameters of Φ40mm to Φ45mm, the apex angle of the hole is 90°, the bottom fillet is R8mm to R15mm, the opening fillet is R8mm to R15mm, and the hole height is 30mm to 35mm.

[0017] The elongation coefficient for one pass of square hole rolling is 1.10 to 1.20, and the rolling speed is 1.0 m / s to 2.0 m / s.

[0018] Step 5 is as follows: After the square material obtained in step 4 is rotated 45°, it is fed into the pre-forming elliptical die rolling mill to obtain elliptical material. After that, the elliptical material is rotated 90° and fed into the pre-forming round die rolling mill to obtain round material. Then, the round material is rotated 90° and fed into the pre-finishing elliptical die rolling mill. After that, the material is rotated 90° and fed into the finished round die rolling mill. The residual heat of the bar rolling is used for online straightening to obtain hot-rolled bars with a diameter of Φ30mm~Φ45mm.

[0019] In step 5, the pre-formed elliptical die adopts a double-arc elliptical die with a large arc and a small arc, rolling an elliptical die with a diameter of Φ30mm to Φ35mm. The large arc of the pre-formed elliptical die is R60mm to R70mm, the small arc is R10mm to R15mm, and the die height is 10mm to 15mm. For rolling an elliptical die with a diameter of Φ40mm to Φ45mm, the large arc of the pre-formed elliptical die is R70mm to R80mm, the small arc is R10mm to R20mm, and the die height is 15mm to 20mm.

[0020] The elongation coefficient of a single pass in the pre-formed elliptical roll is 1.10 to 1.25, and the rolling speed is 1.0 m / s to 2.0 m / s.

[0021] In step 5, the pre-rolled elliptical die adopts a double-arc elliptical die with a large arc and a small arc. The elliptical die with a diameter of Φ30mm to Φ35mm is rolled. The large arc of the pre-rolled elliptical die is R55mm to R65mm, the small arc is R5mm to R10mm, and the die height is 8mm to 10mm. The elliptical die with a diameter of Φ40mm to Φ45mm is rolled. The large arc of the pre-rolled elliptical die is R60mm to R70mm, the small arc is R5mm to R10mm, and the die height is 10mm to 15mm.

[0022] The elongation coefficient of one pass of elliptical roll forming before finishing is 1.10 to 1.25, and the rolling speed is 1.0 m / s to 2.0 m / s.

[0023] The beneficial effects of this invention are:

[0024] The present invention relates to a diamond-diamond pass method for rolling titanium and titanium alloy bars using a two-roll reversible rolling mill. This method utilizes the diamond-diamond pass to extend the rolling pass, enabling multiple passes to share the extended pass and improving its utilization efficiency. It achieves the production of bars with a diameter of Φ30mm to Φ45mm on a single roll of a two-roll reversible mill. Compared to tandem mills, the rolling process is automated, stable, and highly efficient, resulting in high precision in the rolled bars. The resulting titanium alloy bars exhibit excellent microstructure and properties, making them suitable for mass production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the first rhombic die in the two-roll reversible rolling method for titanium and titanium alloy bars of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of the second rhombic die in the two-roll reversible rolling method for titanium and titanium alloy bars of the present invention.

[0027] Figure 3 This is a schematic diagram of the third rhomboid hole in Embodiment 1 of the present invention;

[0028] Figure 4 This is a schematic diagram of the square hole type in Embodiment 1 of the present invention;

[0029] Figure 5 This is a schematic diagram of the pre-formed elliptical hole structure in Embodiment 1 of the present invention;

[0030] Figure 6 This is a schematic diagram of the elliptical hole shape of the finished product in Embodiment 1 of the present invention;

[0031] Figure 7 This is a schematic diagram of the square hole type in Embodiment 2 of the present invention;

[0032] Figure 8 This is a schematic diagram of the pre-formed elliptical hole shape in Embodiment 2 of the present invention;

[0033] Figure 9 This is a schematic diagram of the elliptical hole shape of the finished product in Embodiment 2 of the present invention;

[0034] Figure 10 This is a schematic diagram of the microstructure of the TC4Φ35mm rolled bar obtained in Example 1 of the present invention;

[0035] Figure 11 This is a schematic diagram of the microstructure of the TC4Φ45mm rolled bar obtained in Example 2 of the present invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0037] The present invention discloses a rhombic-rhombic-drill two-roll reversible rolling method for titanium and titanium alloy bars, which is implemented according to the following steps:

[0038] Step 1, Billet Preparation:

[0039] TC4 alloy is selected as the raw material and processed into a round billet with a size of Φ95mm by forging or rolling. The surface of the Φ95mm TC4 round billet is repaired by peeling or grinding to remove all defects on the surface of the billet. It is then heated and held at a certain temperature in a heating furnace. The rolling heating temperature of TC4 alloy is 900℃~950℃, and the rolling holding time is 70min~120min.

[0040] Step 2, continuous rolling of a single diamond-shaped die:

[0041] After exiting the furnace, the TC4 round billet is transferred to the first diamond-shaped die and rolled continuously for 3 passes. The transfer time after exiting the furnace is less than 15 seconds. Between passes, the turning machine flips the material 90° before feeding it. That is, after the previous rolling pass, the turning machine flips the billet 90° before the next rolling pass. The dwell time between passes is less than 8 seconds, resulting in a diamond-shaped billet.

[0042] like Figure 1 As shown, the apex angle of the first diamond-shaped die is 95°–102°, the bottom fillet radius is R20mm–R25mm, the opening fillet radius is R15mm–R25mm, and the die height is 30mm–40mm. The average elongation coefficient for three rolling passes is 1.10–1.20, and the rolling speed is 0.5m / s–2.0m / s.

[0043] Step 3, change to diamond-shaped hole rolling:

[0044] After flipping the rhomboid material obtained in step 2 by 90°, feed it into the second rhomboid die and roll it for 3 passes. Then, depending on the specifications of the rolled product, decide whether to transfer it to the third rhomboid die for further rolling. If not, transfer it to the third rhomboid die for 2 more passes until the specifications are met, and obtain the rhomboid material.

[0045] In step 3, the apex angle of the second rhomboid hole is 95°~102°, the bottom fillet is R17mm~R22mm, the opening fillet is R12mm~R18mm, and the hole height is 25mm~35mm. Figure 2 As shown. The average elongation coefficient of the second diamond-shaped hole rolling three passes is 1.10 to 1.25, the rolling speed is 1.0 m / s to 2.0 m / s, the dwell time between passes is less than 8 seconds, and after the previous pass rolling, the diamond-shaped billet is flipped 90° by a turning machine before the next pass rolling.

[0046] The third rhomboid die has a apex angle of 95°–102°, a groove bottom radius of R10mm–R15mm, a groove opening radius of R10mm–R15mm, and a die height of 20mm–30mm. The average elongation coefficient of the third rhomboid die after two rolling passes is 1.15–1.25, the rolling speed is 1.0m / s–2.0m / s, the dwell time between passes is less than 8 seconds, and after each rolling pass, the rhomboid billet is flipped 90° using a turning machine before the next rolling pass.

[0047] Step 4, square rolling:

[0048] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0049] In step 4, for rolling square holes with a diameter of Φ30mm to Φ35mm, the apex angle is 90°, the bottom fillet radius is R8mm to R12mm, the opening fillet radius is R8mm to R15mm, and the hole height is 20mm to 30mm. For rolling square holes with a diameter of Φ40mm to Φ45mm, the apex angle is 90°, the bottom fillet radius is R8mm to R15mm, the opening fillet radius is R8mm to R15mm, and the hole height is 30mm to 35mm. The elongation coefficient for one rolling pass is 1.10 to 1.20, and the rolling speed is 1.0m / s to 2.0m / s.

[0050] Step 5: The square material obtained in Step 4 is sequentially subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling, and then straightened to obtain TC4 alloy bars with a diameter of Φ30mm~Φ45mm.

[0051] Step 5 is as follows: After the square material obtained in step 4 is flipped 45°, it is fed into the pre-formed elliptical die rolling mill to obtain elliptical material. Then, the material is flipped 90° and fed into the pre-formed round die rolling mill to obtain round material. After the round material is flipped 90° and fed into the pre-finished elliptical die rolling mill, the material is flipped 90° and fed into the finished round die rolling mill. The residual heat of the bar rolling is used for online straightening to obtain hot-rolled bars with a diameter of Φ30mm~Φ45mm.

[0052] In step 5, the pre-formed elliptical die adopts a double-arc elliptical die with a large arc and a small arc. When rolling an elliptical die with a diameter of Φ30mm to Φ35mm, the large arc of the pre-formed elliptical die is R60mm to R70mm, the small arc is R10mm to R15mm, and the die height is 10mm to 15mm. When rolling an elliptical die with a diameter of Φ40mm to Φ45mm, the large arc of the pre-formed elliptical die is R70mm to R80mm, the small arc is R10mm to R20mm, and the die height is 15mm to 20mm. The elongation coefficient of the pre-formed elliptical die in one pass is 1.10 to 1.25, and the rolling speed is 1.0m / s to 2.0m / s.

[0053] The pre-finishing elliptical die uses a double-arc elliptical die with a large arc and a small arc. When rolling elliptical dies with diameters of Φ30mm to Φ35mm, the large arc of the pre-finishing elliptical die is R55mm to R65mm, the small arc is R5mm to R10mm, and the die height is 8mm to 10mm. When rolling elliptical dies with diameters of Φ40mm to Φ45mm, the large arc of the pre-finishing elliptical die is R60mm to R70mm, the small arc is R5mm to R10mm, and the die height is 10mm to 15mm. The elongation coefficient for one pass of pre-finishing elliptical rolling is 1.10 to 1.25, and the rolling speed is 1.0m / s to 2.0m / s.

[0054] The principle of the diamond-diamond pass system two-roll reversible rolling method for titanium and titanium alloy bars of the present invention is as follows: The diamond-diamond pass system is used as the main extended pass system of a two-roll reversible rolling mill. By rationally setting the apex angle, bottom fillet, opening fillet, and pass height, a single diamond pass can achieve 2-3 passes of continuous rolling. Through the transition from pre-formed ellipse, pre-formed circle, and pre-finished ellipse, a Φ95mm titanium alloy round billet is rolled into Φ30mm-Φ45mm titanium alloy bars in 11-13 passes.

[0055] The diamond-diamond pass system two-roll reversible rolling method for titanium and titanium alloy bars of the present invention has the following advantages: Using a diamond-diamond pass system as the main extension pass of a two-roll reversible mill, the utilization efficiency of the extension pass is greatly improved through multiple passes sharing the diamond pass, increasing the total rolling deformation and improving rolling production efficiency. It achieves the rolling production of bars with a specification range of Φ30mm to Φ45mm on a single roll of the two-roll reversible mill, which can improve the uniformity of the microstructure of titanium and titanium alloy bars, and the high-magnification microstructure of the rolled bars meets or exceeds the A4 grade of the ETTC2 standard. Compared with tandem mills, the rolling process is automated, stable, and has high production efficiency, high processing precision, and produces titanium alloy bars with excellent microstructure and properties, suitable for mass production.

[0056] Example 1

[0057] This invention discloses a rhombic-rhombic-drill two-roll reversible rolling method for titanium and titanium alloy bars, which prepares Φ35mm TC4 titanium alloy bars. The specific steps are as follows:

[0058] Step 1, Billet Preparation:

[0059] The Φ95mm TC4 round billet is processed by forging or rolling, and surface defects are removed by peeling or grinding. The Φ95mm billet is then heated in a box-type resistance furnace at a temperature of 920℃, with a minimum holding time of 70 minutes.

[0060] Step 2, continuous rolling of a single diamond-shaped hole:

[0061] As attached Figure 1 As shown, the first diamond-shaped hole has a 98° apex angle, a groove bottom radius of R25mm, a groove opening radius of R15mm, and a hole height of 38mm. After the billet exits the furnace, it is attached... Figure 1 The material is continuously rolled in a diamond-shaped hole for three passes, with a turning mill flipping the material 90° between passes. The rolling speed is 1.0 m / s. The roll gap for the first pass is 19 mm, and the elongation coefficient is 1.12. The roll gap for the second pass is 9 mm, and the elongation coefficient is 1.17. The roll gap for the third pass is 5 mm, and the elongation coefficient is 1.11.

[0062] Step 3, change to diamond-shaped hole rolling:

[0063] As attached Figure 2 As shown, the second rhomboid hole has a apex angle of 98°, a groove bottom radius of R20mm, a groove opening radius of R15mm, and a hole height of 31mm. The rhomboid material obtained in step 2 is flipped 90° and then continuously rolled in the second rhomboid hole for three passes. Between passes, a turning machine flips the material 90°, and the rolling speed is 1.5m / s. The roll gap for the fourth pass is 16mm, with an elongation coefficient of 1.17. The roll gap for the fifth pass is 12mm, with an elongation coefficient of 1.11. The roll gap for the sixth pass is 6mm, with an elongation coefficient of 1.15.

[0064] like Figure 3 As shown, the third diamond-shaped die has a 98° apex angle, a groove bottom radius of R15mm, a groove opening radius of R13mm, and a die height of 25mm. After being rolled three times in the second diamond-shaped die, the workpiece is transferred to the third diamond-shaped die for two consecutive passes. Between passes, a turning machine flips the material 90°. The rolling speed is 2.0 m / s. The roll gap for the seventh pass is 12mm, with an elongation coefficient of 1.23. The roll gap for the eighth pass is 5mm, with an elongation coefficient of 1.23.

[0065] Step 4, square rolling:

[0066] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0067] like Figure 4 As shown, the square hole has a 90° apex angle, a groove bottom radius of R10mm, a groove opening radius of R10mm, and a hole height of 24mm. After rolling the workpiece for two passes in the third diamond-shaped hole, it is flipped 90° and transferred to the square hole for the ninth pass. The roll gap is 8mm, the elongation coefficient is 1.12, and the rolling speed is 2.0m / s.

[0068] Step 5: The square material obtained in Step 4 is sequentially subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling, and then straightened to obtain a TC4 alloy bar with a diameter of Φ35mm.

[0069] After flipping the square material obtained in step 4 by 45°, feed it as follows: Figure 5 The material is rolled in the 10th pass of the pre-formed elliptical die to obtain an elliptical material. The material is then flipped 90° and fed into the 11th pass of the pre-formed circular die to obtain a circular material. The circular material is then flipped 90° and fed into the... Figure 6 The 12th pass of the pre-elliptical die rolling mill, as shown, produces an elliptical material. The material is then flipped 90° and fed into the 13th pass of the pre-round die rolling mill. The residual heat from the bar rolling process is used for online straightening to obtain a 35mm TC4 alloy hot-rolled bar. The high-magnification microstructure of the bar is shown in the attached figure. Figure 10 As shown.

[0070] Among them, the pre-formed elliptical hole shape is as follows Figure 5 As shown, the large arc is R65mm, the small arc is R10mm, the die height is 12.5mm, the elongation coefficient of the pre-formed elliptical die for one pass is 1.10, and the rolling speed is 1.0m / s; the elliptical die before finishing is as follows. Figure 6 As shown, the large arc is R60mm, the small arc is R8mm, the die height is 9.15mm, the elongation coefficient of the elliptical die rolling for one pass before finishing is 1.10, and the rolling speed is 1.0m / s.

[0071] Example 2

[0072] The present invention discloses a rhombus-rhombus die two-roll reversible rolling method for titanium and titanium alloy bars, which prepares Φ45mm TC4 titanium alloy bars. The specific steps are as follows:

[0073] Step 1, Billet Preparation:

[0074] The Φ95mm TC4 round billet is processed by forging or rolling, and surface defects are removed by peeling or grinding. The Φ95mm billet is then heated in a box-type resistance furnace at a temperature of 920℃, with a minimum holding time of 70 minutes.

[0075] Step 2, continuous rolling of a single diamond-shaped hole:

[0076] As attached Figure 1 As shown, the first diamond-shaped hole has a 98° apex angle, a groove bottom radius of R25mm, a groove opening radius of R15mm, and a hole height of 38mm. After the billet exits the furnace, it is attached... Figure 1 The material is continuously rolled in a diamond-shaped hole for three passes, with a turning mill flipping the material 90° between passes. The rolling speed is 1.0 m / s. The roll gap for the first pass is 19 mm, and the elongation coefficient is 1.12. The roll gap for the second pass is 9 mm, and the elongation coefficient is 1.17. The roll gap for the third pass is 5 mm, and the elongation coefficient is 1.11.

[0077] Step 3, change to diamond-shaped hole rolling:

[0078] As attached Figure 2 As shown, the second rhomboid hole has a apex angle of 98°, a groove bottom radius of R20mm, a groove opening radius of R15mm, and a hole height of 31mm. The rhomboid material obtained in step 2 is flipped 90° and then continuously rolled in the second rhomboid hole for three passes. Between passes, a turning machine flips the material 90°, and the rolling speed is 1.5m / s. The roll gap for the fourth pass is 16mm, with an elongation coefficient of 1.17. The roll gap for the fifth pass is 12mm, with an elongation coefficient of 1.11. The roll gap for the sixth pass is 8.5mm, with an elongation coefficient of 1.10.

[0079] Step 4, square rolling:

[0080] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0081] As attached Figure 7 As shown, the square hole has a 90° apex angle, a groove bottom radius of R12mm, a groove opening radius of R10mm, and a hole height of 30mm. After rolling the workpiece for 3 passes in the second diamond hole, it is rotated 90° to enter the square hole for the 7th pass. The roll gap is 8mm, the elongation coefficient is 1.14, and the rolling speed is 2.0m / s.

[0082] Step 5: The square material obtained in Step 4 is sequentially subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling, and then straightened to obtain a TC4 alloy bar with a diameter of Φ45mm.

[0083] After flipping the square material obtained in step 4 by 45°, feed it into the feeder. Figure 8 The pre-formed elliptical die shown is rolled in the 8th pass to obtain an elliptical material. The material is then flipped 90° and fed into the pre-formed circular die for the 9th pass at a rolling speed of 2.0 m / s to obtain a circular material. This circular material is then flipped 90° and fed into the pre-formed circular die as shown. Figure 9 The 10th pass of the pre-elliptical die rolling mill, as shown, produces an elliptical material. The material is then flipped 90° and fed into the 11th pass of the pre-round die rolling mill at a rolling speed of 2.0 m / s. The residual heat from the bar rolling process is used for online straightening to obtain a 45mm TC4 alloy hot-rolled bar. The high-magnification microstructure of the bar is shown in the attached figure. Figure 11 As shown.

[0084] Example 3

[0085] This invention discloses a rhombic-rhombic-drill two-roll reversible rolling method for titanium and titanium alloy bars, which prepares Φ30mm TC4 titanium alloy bars. The specific steps are as follows:

[0086] Step 1, Billet Preparation:

[0087] The Φ95mm TC4 round billet is processed by forging or rolling, and surface defects are removed by peeling or grinding. The Φ95mm billet is then heated in a box-type resistance furnace to a temperature of 950℃ and held for 95 minutes.

[0088] Step 2, continuous rolling of a single diamond-shaped hole:

[0089] The first diamond-shaped hole has a apex angle of 102°, a bottom fillet radius of R23mm, an opening fillet radius of R20mm, and a hole height of 30mm. After the billet exits the furnace, it is attached... Figure 1 The material is continuously rolled in a diamond-shaped hole for three passes, with a turning mill flipping the material 90° between passes. The rolling speed is 0.5 m / s. The average elongation coefficient of the three rolling passes is 1.1.

[0090] Step 3, change to diamond-shaped hole rolling:

[0091] The second rhomboid hole has a apex angle of 102°, a bottom fillet radius of R22mm, an opening fillet radius of R18mm, and a hole height of 25mm. The rhomboid material obtained in step 2 is flipped 90° and then continuously rolled in the second rhomboid hole for three passes. Between passes, a turning machine flips the material 90°, and the rolling speed is 2.0 m / s. The average elongation coefficient of the three passes in the second rhomboid hole is 1.1.

[0092] The third diamond-shaped die has a apex angle of 102°, a groove bottom fillet of R10mm, a groove opening fillet of R10mm, and a die height of 20mm. After being rolled three times in the second diamond-shaped die, the workpiece is transferred to the third diamond-shaped die for two consecutive passes. Between passes, a turning machine flips the material 90°. The rolling speed is 1.5m / s. The average elongation coefficient of the third diamond-shaped die after two passes is 1.25.

[0093] Step 4, square rolling:

[0094] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0095] The square hole has a 90° apex angle, a groove bottom radius of R12mm, a groove opening radius of R15mm, and a hole height of 20mm. After rolling the workpiece for two passes in the third diamond-shaped hole, it is flipped 90° and transferred to the square hole for the ninth pass. The roll gap is 8mm, the elongation coefficient is 1.12, and the rolling speed is 2.0m / s.

[0096] Step 4, square rolling:

[0097] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0098] The square hole has a 90° apex angle, a groove bottom radius of R12mm, a groove opening radius of R15mm, and a hole height of 20mm. After rolling the workpiece for two passes in the third diamond-shaped hole, it is flipped 90° and transferred to the square hole for the ninth pass. The roll gap is 8mm, the elongation coefficient is 1.12, and the rolling speed is 2.0m / s.

[0099] Step 5: The square material obtained in Step 4 is subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling in sequence, and then straightened to obtain a TC4 alloy bar with a diameter of Φ30mm.

[0100] The square material obtained in step 4 is flipped 45° and fed into a pre-formed elliptical die for the 10th rolling pass to obtain an elliptical material. Then, the material is flipped 90° and fed into a pre-formed round die for the 11th rolling pass to obtain a round material. The round material is then flipped 90° and fed into a pre-finished elliptical die for the 12th rolling pass to obtain an elliptical material. Finally, the material is flipped 90° and fed into a pre-finished round die for the 13th rolling pass. The residual heat from the bar rolling process is used for online straightening to obtain a 35mm TC4 alloy hot-rolled bar.

[0101] The pre-formed elliptical die has a large arc of R60mm, a small arc of R12mm, a die height of 15mm, an elongation coefficient of 1.18 for one pass of rolling, and a rolling speed of 1.5m / s.

[0102] The large arc of the elliptical die before the finished product is R65mm, the small arc is R10mm, the die height is 8mm, the elongation coefficient of the elliptical die before the finished product is 1.18 for one pass, and the rolling speed is 1.5m / s.

[0103] Example 4

[0104] This invention discloses a rhombic-rhombic-drill two-roll reversible rolling method for titanium and titanium alloy bars, which prepares Φ30mm TC4 titanium alloy bars. The specific steps are as follows:

[0105] Step 1, Billet Preparation:

[0106] The Φ95mm TC4 round billet is processed by forging or rolling, and surface defects are removed by peeling or grinding. The Φ95mm billet is then heated in a box-type resistance furnace to a temperature of 900℃ and held for 120 minutes.

[0107] Step 2, continuous rolling of a single diamond-shaped hole:

[0108] The first diamond-shaped hole has a 95° apex angle, a groove bottom radius of R20mm, a groove opening radius of R25mm, and a hole height of 40mm. After the billet exits the furnace, it is attached... Figure 1 The material is continuously rolled in a diamond-shaped hole for three passes, with a turning mill flipping the material 90° between passes. The rolling speed is 2.0 m / s. The average elongation coefficient of the three rolling passes is 1.2.

[0109] Step 3, change to diamond-shaped hole rolling:

[0110] The second rhomboid hole has a 95° apex angle, a groove bottom radius of R17mm, a groove opening radius of R12mm, and a hole height of 35mm. The rhomboid material obtained in step 2 is flipped 90° and then continuously rolled in the second rhomboid hole for three passes. Between passes, a turning machine flips the material 90°, and the rolling speed is 1.0 m / s. The average elongation coefficient of the second rhomboid hole after three passes is 1.25.

[0111] The third diamond-shaped die has a 95° apex angle, a groove bottom fillet radius of R15mm, a groove opening fillet radius of R15mm, and a die height of 35mm. After being rolled three times in the second diamond-shaped die, the workpiece is transferred to the third diamond-shaped die for two consecutive passes. Between passes, a turning machine flips the material 90°. The rolling speed is 1.0 m / s. The average elongation coefficient of the third diamond-shaped die after two passes is 1.15.

[0112] Step 4, square rolling:

[0113] After flipping the rhomboid material obtained in step 3 by 90°, feed it into a square die for one pass to obtain a square material with a regular shape.

[0114] The square hole has a 90° apex angle, a groove bottom radius of R18mm, a groove opening radius of R18mm, and a hole height of 30mm. After rolling the workpiece for two passes in the third diamond-shaped hole, it is flipped 90° and transferred to the square hole for the ninth pass. The roll gap is 8mm, the elongation coefficient is 1.12, and the rolling speed is 2.0m / s.

[0115] Step 5: The square material obtained in Step 4 is subjected to pre-forming elliptical die rolling, pre-forming round die rolling, pre-finished elliptical die rolling, and finished round die rolling in sequence, and then straightened to obtain a TC4 alloy bar with a diameter of Φ30mm.

[0116] The square material obtained in step 4 is flipped 45° and fed into a pre-formed elliptical die for the 10th rolling pass to obtain an elliptical material. Then, the material is flipped 90° and fed into a pre-formed round die for the 11th rolling pass to obtain a round material. The round material is then flipped 90° and fed into a pre-finished elliptical die for the 12th rolling pass to obtain an elliptical material. Finally, the material is flipped 90° and fed into a pre-finished round die for the 13th rolling pass. The residual heat from the bar rolling process is used for online straightening to obtain a 35mm TC4 alloy hot-rolled bar.

[0117] The pre-formed elliptical die has a large arc of R70mm, a small arc of R15mm, a die height of 10mm, an elongation coefficient of 1.25 for one pass of rolling, and a rolling speed of 2.0m / s.

[0118] The large arc of the elliptical die before the finished product is R55mm, the small arc is R5mm, the die height is 10mm, the elongation coefficient of the elliptical die before the finished product is 1.25 for one pass of rolling, and the rolling speed is 2.0m / s.

Claims

1. A two-roll reversible rolling method for titanium and titanium alloy bars using a rhombus-rhombus die profile, characterized in that: Specifically, the following steps are included: Step 1: Pre-treat the surface of titanium and titanium alloys and heat them to maintain their temperature; Step 2: Transfer the pretreated titanium and titanium alloy billet from Step 1 into the first diamond-shaped die and roll it continuously for three passes to obtain a diamond-shaped billet. Step 3: After flipping the rhomboid billet obtained in Step 2 by 90°, feed it into the second rhomboid die and roll it continuously for three passes. Check if it meets the rolled product specifications. If it does not meet the specifications, transfer it to the third rhomboid die and continue rolling until it meets the standards to obtain rhomboid material. Step 4: Flip the rhomboid material obtained in Step 3 by 90° and place it into a square die for one pass to obtain a square material with a regular shape. Step 5: The square material obtained in Step 4 is sequentially rolled into a pre-formed elliptical die, rolled into a pre-formed round die, rolled into a pre-finished elliptical die, and rolled into a finished round die. After straightening, a bar with a diameter of Φ30mm~Φ45mm is obtained. In step 2, the transfer time is less than 15 seconds. During the three rolling passes, after the previous rolling pass, the billet is flipped 90° by a turning machine before the next rolling pass. In step 2, the apex angle of the first diamond-shaped die is 95°~102°, the bottom fillet is R20mm~R25mm, the opening fillet is R15mm~R25mm, and the die height is 30mm~40mm; the average elongation coefficient of the three rolling passes is 1.10~1.20, the rolling speed is 0.5m / s~2.0m / s, and the dwell time between adjacent passes is less than 8 seconds; In step 3, the apex angle of the second rhomboid die is 95°~102°, the bottom fillet is R17mm~R22mm, the opening fillet is R12mm~R18mm, and the die height is 25mm~35mm; the average elongation coefficient of the three rolling passes is 1.10~1.25, the rolling speed is 1.0m / s~2.0m / s, the dwell time between passes is less than 8 seconds, and after the previous rolling pass, the rhomboid billet is flipped 90° by a turning machine before the next rolling pass; In step 3, the apex angle of the third rhomboid die is 95°~102°, the bottom fillet is R10mm~R15mm, the opening fillet is R10mm~R15mm, and the die height is 20mm~30mm. The third rhomboid die is rolled in 2 passes, with an average elongation coefficient of 1.15~1.25, a rolling speed of 1.0m / s~2.0m / s, and a dwell time between passes of less than 8 seconds. After the previous pass, the rhomboid billet is flipped 90° using a turning machine before the next pass. In step 4, for rolling square holes with a diameter of Φ30mm~Φ35mm, the apex angle of the hole is 90°, the bottom fillet is R8mm~R12mm, the opening fillet is R8mm~R15mm, and the hole height is 20mm~30mm; for rolling square holes with a diameter of Φ40mm~Φ45mm, the apex angle of the hole is 90°, the bottom fillet is R8mm~R15mm, the opening fillet is R8mm~R15mm, and the hole height is 30mm~35mm. The elongation coefficient for one pass of square hole rolling is 1.10~1.20, and the rolling speed is 1.0m / s~2.0m / s.

2. The method for reversible two-roll rolling of titanium and titanium alloy bars using a rhombus-rhombus die system according to claim 1, characterized in that: The pretreatment process described in step 1 is as follows: forge titanium and titanium alloy into a round billet with a size of Φ95mm, grind the surface of the billet clean, put it into a heating furnace and heat it to 900℃~950℃, and hold it at that temperature for 70min~120min.

3. The method for reversible two-roll rolling of titanium and titanium alloy bars using a rhombus-rhombus die system according to claim 1, characterized in that: Step 5 specifically involves: rotating the square material obtained in step 4 by 45° and feeding it into a pre-formed elliptical die for rolling to obtain an elliptical material; rotating the elliptical material by 90° and feeding it into a pre-formed circular die for rolling to obtain a circular material; rotating the circular material by 90° and feeding it into a pre-finished elliptical die for rolling; rotating the material by 90° and feeding it into a finished circular die for rolling; and using the residual heat from the bar rolling process for online straightening to obtain a hot-rolled bar with a diameter of Φ30mm~Φ45mm.

4. The method for reversible two-roll rolling of titanium and titanium alloy bars using a rhombus-rhombus die system according to claim 1 or 3, characterized in that: In step 5, the pre-formed elliptical hole adopts a double-arc elliptical hole with a large arc and a small arc, and rolls an elliptical hole with a diameter of Φ30mm~Φ35mm. The large arc of the pre-formed elliptical hole is R60mm~R70mm, the small arc is R10mm~R15mm, and the hole height is 10mm~15mm. For rolling an elliptical hole with a diameter of Φ40mm~Φ45mm, the large arc of the pre-formed elliptical hole is R70mm~R80mm, the small arc is R10mm~R20mm, and the hole height is 15mm~20mm. The elongation coefficient of one pass of preformed elliptical roll is 1.10~1.25, and the rolling speed is 1.0m / s~2.0m / s.

5. The method for reversible two-roll rolling of titanium and titanium alloy bars using a rhombus-rhombus die system according to claim 1, characterized in that: In step 5, the finished product's elliptical die shape adopts a double-arc elliptical die shape with a large arc and a small arc. For rolling an elliptical die shape of Φ30mm~Φ35mm, the large arc of the finished product's elliptical die shape is R55mm~R65mm, the small arc is R5mm~R10mm, and the die height is 8mm~10mm. For rolling an elliptical die shape of Φ40mm~Φ45mm, the large arc of the finished product's elliptical die shape is R60mm~R70mm, the small arc is R5mm~R10mm, and the die height is 10mm~15mm. The elongation coefficient of one pass of elliptical roll forming before finishing is 1.10~1.25, and the rolling speed is 1.0m / s~2.0m / s.

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