WO2013075625A1

WO2013075625A1 - Method for heat bulge forming rectangular ring rolled piece of stainless steel

Info

Publication number: WO2013075625A1
Application number: PCT/CN2012/084949
Authority: WO
Inventors: 夏欲民; 邹伟; 吴涛; 雷静越
Original assignee: 贵州安大航空锻造有限责任公司
Priority date: 2011-11-24
Filing date: 2012-11-21
Publication date: 2013-05-30
Also published as: CN102489616B; CN102489616A

Abstract

Disclosed is a method for heat bulge forming a rectangular ring rolled piece of stainless steel. The method comprises the steps of: mounting the hot-rolled rectangular ring rolled piece of stainless steel (10) over the periphery of a pre-heated bulge-forming block (3) in a bulge-forming machine; starting the bulge-forming machine to press the bulge-forming block radially from the inner circumferential surface of the ring rolled piece against the ring rolled piece to complete a first bulge-forming step, the bulge-forming temperature being 890°C-950°C, the bulge-forming duration being 15 s-25 s, the duration for pressure maintenance being 7 s-8 s, and the deformation amount being 0.9%-1.2%; then rotating the ring rolled piece at 45° about the central axis to complete a first rotation; completing a second bulge-forming step according to the abovementioned operation, the bulge-forming temperature being 850°C-910°C, the bulge-forming duration being 15 s-25 s, the duration for pressure maintenance being 9 s-10 s, and the deformation amount being 0.7%-1%; rotating the ring rolled piece again in the direction of the first rotation to complete a second rotation; and conducting a third bulge-forming step according to the abovementioned operation, the bulge-forming temperature being 800°C—870°C, the bulge-forming duration being 25 s-35 s, the duration for pressure maintenance being 13 s-15 s, and the deformation amount being 0.5%-0.8%. The dimensional accuracy of the bulge-formed ring rolled piece can reach 1‰-2‰ of the corresponding dimensions.

Description

Hot bulging method for stainless steel rectangular ring rolling parts

The present invention relates to a method of bulging a ring member, and more particularly to a method of thermal bulging of a stainless steel rectangular ring. Background technique

Stainless steel rectangular ring rolling parts (referring to ring-shaped rolling parts with a longitudinal section of rectangular section), after rolling with a ring rolling mill, due to the influence of the rolling process and equipment limitations, the dimensional accuracy is generally not high; only in the shape of the ring rolling piece When the ideal and the performance of the equipment are excellent, the dimensional accuracy can reach 3% of the corresponding size. ~ 5%. (Three thousandths to five thousandths), and the rolled ring rolling parts have large stresses, and if they are not well controlled in the subsequent processing steps, defects such as warpage, deformation, and even cracking may occur.

The Chinese invention patent specification CN 101367104A disclosed on February 18, 2009 discloses a hydraulic bulging strengthening process for the external refilling of the steam turbine generator retaining ring, which passes the high-pressure pump of the peripheral high-pressure pump and passes the high-pressure liquid generated by the high-pressure cylinder. The inner passage is then injected into the closed space formed by the fixed upper cone mold and the moving lower cone mold and the retaining ring via the passage in the force reducing column in the mold portion, so that the retaining ring is plastically deformed under the action of liquid pressure. The retaining ring is used for the purpose of strengthening the retaining ring and improving the forming precision of the retaining ring. As can be seen from the drawings of the patent specification, the retaining ring is a rectangular ring member. The method does not disclose in detail how to improve the dimensional accuracy of the ring member by bulging, but only for the purpose of improving the forming precision of the retaining ring in a general manner, that is, the method cannot solve the problem of low dimensional accuracy of the ring rolling piece existing in the prior art. The problem. Summary of the invention

The technical problem to be solved by the present invention is to provide a thermal expansion method for a stainless steel rectangular ring rolling piece by using a bulging block, which is obtained by bulging the stainless steel rectangular ring rolling piece by three small deformations in succession. A bulging ring rolling piece with high dimensional accuracy.

In order to solve the above technical problem, the thermal expansion method of the stainless steel rectangular ring rolling piece of the present invention comprises the following steps:

The hot-rolled stainless steel rectangular ring rolling piece is set into the bulging machine, and the inner ring surface is sleeved on the outer circumferential surface of the bulging block preheated to 255 ° C ~ 305 ° C. At this time, the radial slider is at Closed state The bulging machine applies an axial pulling force F to the mandrel slider to move it downward in the axial direction and press the radial sliding block along the inner hole taper surface of the radial sliding block to make the radial sliding blocks radially Simultaneous movement and diffusion, the bulging block mounted on the outer circumferential surface of the radial slider presses the ring rolling piece radially from the inner circumferential surface of the ring rolling piece, and the inner and outer diameters of the ring rolling piece are enlarged and the wall thickness is thinned. The plastic deformation, the first bulging is completed; in the bulging process, the bulging temperature of the ring rolling piece is 890 ° C ~ 950 ° C, the bulging time is 15 s ~ 25 s, the dwell time is 7 s ~ 8s, the amount of bulging deformation is 0.9% ~ 1.2%;

The bulging machine drives the mandrel slider to move upward in the axial direction in the radial slider, and drives the radial slider to move synchronously in the radial direction to close the bulging block away from the bulging ring rolling piece, and start the bulging machine. The guide roller on the table drives the ring rolling member to rotate 45° along the central axis to complete the first rotation of the ring rolling member; according to the first bulging operation described above, the ring after the first bulging The rolling piece undergoes a second bulging. In this bulging process, the bulging temperature of the ring rolling piece is 850 ° C ~ 910 ° C, the bulging time is 15 s ~ 25 s, and the dwell time is 9 s ~ 10 s. , the amount of bulging deformation is 0.7% ~ 1%;

Performing the second rotation after the second bulging after the first rotation operation, the rotation of the ring rolling element is rotated 45° in the same direction as the first rotation direction;

According to the first bulging operation described above, the second bulging of the ring rolling piece after the second bulging is performed, and in the bulging process, the bulging temperature of the ring rolling piece is 800 ° C ~ 870 ° C, bulging time is 25s ~ 35s, dwell time is 13s ~ 15s, bulging deformation is 0.5% ~ 0.8%;

After the bulging is finished, move the mandrel slider up, close the radial slider, and take out the bulged ring rolling piece.

The above stainless steel is preferably made of stainless steel having a grade of 1 Mn 18Cr 18N.

The axial pulling force applied by the bulging machine to the mandrel slider F is determined by the following formula:

F = ξ X σ 0.2 S

In the formula:

ξ——The bulging coefficient of the bulging machine, the invention takes 1.26 ~ 1.52;

σ ₀ . ₂ —— the yield strength (MPa) of stainless steel material at bulging temperature, 180 MPa ~ 200 MPa for lMnl8Crl8N stainless steel;

S——The longitudinal cross-sectional area (mm ² ) of the ring-rolled piece.

The bulging size of the ring-rolled piece in the hot state is determined by the following formula: D = Do ( 1 + β ₍ ) +d

In the formula:

D——the inner diameter dimension (mm) of the ring rolling piece after being inflated in a hot state;

Do—the inner diameter of the final product (mm) in the cold state after the lap is rolled;

β ₍ the temperature compensation coefficient (%) of the ring rolling piece at the bulging temperature, lMnl8Crl8N stainless steel is 1.2% ~ 1.65%;

d——The rebound amount of the inner diameter of the ring rolling piece after bulging (mm), lMnl8Crl8N stainless steel takes 2mm ~ 4mm.

The stainless steel rectangular ring rolling piece which is bulged by the thermal expansion method of the present invention has an inner diameter ranging from C»400 mm to Φ 4500 mm, a wall thickness of 10 mm to 200 mm, and a height of 40 mm to 750 mm.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The invention directly bulges by rigid contact between the bulging block on the bulging machine and the stainless steel rectangular ring rolling piece, and the required bulging size and the dimensional accuracy can be obtained.

The invention bulges through three small deformations, and by selecting suitable process parameters such as bulging temperature, bulging time and holding time, it can ensure that the stainless steel rectangular ring rolling piece does not generate dynamic recrystallization during the bulging process. , does not affect the structure of the ring-rolled piece, does not appear to be cracked, and can also make the amount of rebound of the ring-rolled piece after each bulging smaller; and by rolling the ring piece during the bulging process Rotating 45° in the same direction twice can eliminate the trace formed by the gap between adjacent bulging blocks on the inner circumferential surface of the ring rolling piece when the bulging block expands and bulges in the radial direction, thereby facilitating the smooth progress of the bulging process and Obtaining the bulging ring rolling piece with higher dimensional accuracy; in the whole bulging process, the bulging block can measure the change of the inner diameter size of the ring rolling piece and the rebound amount of the inner diameter size after each bulging, and measure The data is transmitted to the display of the bulging machine in time, so that the bulging size of the ring rolling piece can be precisely controlled during bulging. In summary, the final product size with higher dimensional accuracy can be obtained by using a ring-shaped rolled piece that is bulged by the method of the present invention.

During the bulging process, the axial tensile force F applied by the bulging machine to the mandrel slider is determined by the bulging coefficient of the bulging machine ( ξ ), the yield strength of the material at the bulging temperature ( σ. ₂ ), and the ring. The longitudinal section area (S) of the rolled piece is determined. Therefore, the axial tensile force F can be determined for different bulging machines and ring-shaped pieces of different materials and sizes, so that the ring-shaped piece is stressed during the bulging process. Uniform and reasonable, able to ensure bulging The smooth progress of the process, to avoid excessive force caused by bursting or too little force caused by the phenomenon of swelling. The thermal bulging inner diameter dimension (D) of the bulging ring rolling piece is the inner product inner diameter dimension (D.) of the final product in the cold state after the bulging of the ring rolling piece, and the temperature compensation of the ring rolling piece at the bulging temperature The coefficient (p _t ) and the rebound amount (d) of the inner diameter of the ring-shaped rolled piece are calculated and determined, so that the hot-state size of the ring-rolled part can be precisely controlled during the bulging, and after the bulging ring-shaped part is cooled The cold size of the dimensional accuracy is obtained, that is, the final product size of the ring-shaped rolled piece after bulging.

The invention swells the stainless steel rectangular ring rolling piece which has just been rolled and formed from the ring rolling mill, and not only the heat of the heat can meet the bulging temperature requirement, but also can avoid the phenomenon that the stress of the ring rolling piece is further increased after cooling and shrinking. The hot bulging shape is beneficial to reduce the influence of stress on the dimensional accuracy of the ring rolling piece before the stress of the ring rolling piece increases. Thermal bulging also reduces the need for reheating, saving energy and increasing labor productivity. Moreover, preheating the bulging block can also prevent the temperature of the ring rolling piece from being too slow when bulging, and affecting the bulging temperature parameter.

Taking the stainless steel rectangular ring rolling piece of the grade lMnl8Crl8N as an example, the cold size of the stainless steel rectangular ring rolling piece after the bulging is detected, that is, the final product size, reaches 1% of the corresponding size. ~ 2%. After testing the internal structure of the ring rolling piece, no change occurred, and there were no defects such as deformation and warpage. DRAWINGS

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a longitudinal sectional view of a hot rolled rectangular ring rolling piece along its center line.

Figure 2 is a schematic view of the structure of the bulging machine.

Figure 3 is a schematic view of the installation of hot rolled rectangular ring rolling.

Fig. 4 is a schematic view showing the process of thermal expansion of a hot rolled rectangular ring rolling piece.

Fig. 5 is a schematic view of a rectangular ring rolling piece after the bulging block is separated from the bulging shape. detailed description

The method of thermal bulging of the stainless steel rectangular ring rolling piece according to the present invention needs to provide a device such as a bulging machine, a robot, and the like. The following is a detailed description of the specific implementation of the method by taking the stainless steel of China material grade lMnl8Crl8N as an example:

The main chemical element content (% by weight) of the stainless steel is: 0.1% C, including The amount of Si is 0.8%, the content of Mn is 17.5% to 20.0%, the content of P is 0.050%, the content of S is 0.015%, the content of Cr is 17.5% to 20.0%, the amount of N is >0.50%, the amount of A1 is 0.025%, and B is contained. The amount is 0.001%, and the amount of lanthanum is Fe.

FIG. 2 is a schematic structural view of a bulging machine for carrying out the thermal bulging method of the present invention. The bulging machine is mainly composed of a mandrel slider 1, a radial slider 2, a bulging block 3, and a table. 4 and the rail 5 is composed. The mandrel slider 1 is conical and fits within the radial slider 2 to cooperate with the tapered inner circumferential surface of the radial slider 2, and the mandrel slider 1 can be driven by the hydraulic cylinder of the bulging machine in the radial slider 2 The inner edge moves up and down in the axial direction and squeezes the radial slider 2; the radial slider 2 is mounted on the guide rail 5 of the bulging machine and can move back and forth along the guide rail 5, and the radial slider 2 looks from the top view of FIG. It is 12 separate fan-shaped block shapes, and the bulging blocks 3 are fixedly mounted on the outer circumferential surfaces of the respective fan-shaped blocks, and each of the fan-shaped blocks can form a circular ring shape together with the bulging block 3 when the fan-shaped blocks are closed; 1 When the radial sliding block 2 moves downward in the axial direction, the radial sliding blocks 2 can be synchronously moved and diffused in the radial direction to make the bulging block 3 reach the purpose of the bulging ring member, when the mandrel slider 1 is in the diameter When the slider 2 moves upward in the axial direction, the bulging machine can drive the radial sliders 2 to move synchronously in the radial direction to close the bulging block 3 away from the bulging ring member, and the bulging block 3 is in the process of bulging. a function of measuring the inner diameter of the ring in real time and transmitting the measurement data to the display of the bulging machine; in addition, in the bulging machine The table 4 also has a guide roller (not shown) that drives the ring member to rotate along the central axis on the table.

The process steps of the stainless steel from hot rolling after rolling into a rectangular ring rolling are as follows:

Step 1: Install the machine.

As shown in Figure 3, the bulging block 3 on the bulging machine is preheated to 255 ° C ~ 305 ° C, and then the 1Mnl8Crl8N stainless steel rectangular ring rolling piece shown in Figure 1 is rolled and formed from the ring rolling mill. 10 趁 heat set into the bulging machine, so that the inner ring surface is sleeved around the outer circumferential surface of the bulging block 3, and the bottom surface thereof is placed on the upper surface of the table 4, at this time, the radial slider 2 is in the closed state. Shipment of the workpiece at the time of installation is mainly done by robotic operation.

Step 2: The first bulging.

As shown in FIG. 4, the bulging machine is activated to move the mandrel slider 1 downward along its axial direction, and the mandrel slider 1 presses the radial slider 2 along the tapered surface thereof in the radial slider 2 so that Each of the radial sliders 2 is synchronously moved and diffused in the radial direction, and the outer circumferential surface of the bulging block 3 on the radial slider 2 is in contact with the inner circumferential surface of the ring rolling member 10, And pressing the ring rolling member 10 along the inner circumferential surface of the ring rolling member 10, so that the ring rolling member 10 receives a radial pressing force from the bulging block 3 from the inner circumferential surface to the outer circumferential surface, resulting in the inner portion of the ring rolling member 10. The circumferential surface is enlarged in the radial direction, and the ring rolling member 10 is expanded in inner and outer diameters, and the plastic deformation of the wall thickness is reduced. The ring rolling member 10 is firstly swollen by the bulging block 3, and the hydraulic pressure of the bulging machine during the bulging. The cylinder applies an axial pulling force F to the mandrel slider 1, the bulging temperature of the ring rolling member 10 is 890 ° C ~ 950 ° C, the bulging time is 15 s to 25 s, the dwell time is 7 s to 8 s, and the ring rolling 10 The amount of bulging deformation is 0.9% ~ 1.2%.

The bulging time is the time after the ring rolling member 10 is bulged from the beginning to the end of the bulging shape; the holding time is that the ring rolling member 10 is bulged to a deformation amount and no longer deforms and remains inflated until it is maintained. The time at which the shape ends.

Step 3: Rotate for the first time.

As shown in FIG. 5, the bulging machine drive mandrel slider 1 is moved upward in the axial direction in the radial slider 2, and the radial slider 2 is driven to move synchronously in the radial direction to close the bulging block 3 from the bulging shape. After the ring rolling member 10, the guide roller on the table 4 of the bulging machine is started to rotate the driving ring rolling member 10 on the table clockwise or counterclockwise along the central axis by 45°, thereby completing the ring rolling member 10 The first rotation.

Step 4: The second bulging.

Repeating the bulging process of step 1 causes the bulging block 3 to perform a second bulging of the ring rolling member 10, and the hydraulic cylinder of the bulging machine applies an axial pulling force F to the mandrel slider 1 during the bulging, the ring rolling member 10 The bulging temperature is 850 °C ~ 910 °C, the bulging time is 15s~25s, the dwell time is 9s~10s, and the bulging deformation of the ring rolling 10 is 0.7%~1%.

Step 5: Rotate a second time.

Step 3 is repeated to rotate the roller of the bulging machine to drive the ring rolling member 10 in the same direction as the first rotation direction by 45°, thereby completing the second rotation of the ring rolling member 10.

Step 6: The third bulging.

Repeating the bulging process of step 1 causes the bulging block 3 to perform a third bulging of the ring rolling member 10, and the hydraulic cylinder of the bulging machine applies an axial pulling force F to the mandrel slider 1 during the bulging, the ring rolling member 10 The bulging temperature is 800 °C ~ 870 °C, the bulging time is 25s~35s, the dwell time is 13s ~ 15s, and the bulging deformation of the ring rolling 10 is 0.5% ~ 0.8%.

After the three bulging ends, move the mandrel slider 1 upwards, close the radial slider 2 and make the bulging block 3 From the ring rolling member 10, the ring rolling member 10 is taken out by a robot to complete the bulging process.

During the bulging process of the ring rolling member 10, the axial tensile force F is calculated as follows:

F = ξ X σ ₀ . ₂ ^χ S

In the formula:

ξ 胀 bulging machine bulging coefficient, the invention takes 1. 26 ~ 1. 52 ;

σ ₀ . ₂ —— the yield strength (MPa) of the stainless steel material at the bulging temperature, the invention takes 180 MPa to 200 MPa;

S - the longitudinal cross-sectional area of the ring-rolled part 10 ( 匪² );

The calculation method of the bulging deformation amount of the ring rolling member 10 is as follows: bulging deformation amount = [(the median diameter of the bulging ring rolling member 10, the median diameter of the bulging front ring rolling member 10) / bulging shape The median diameter of the front ring rolling member 10 is χ ιοο%.

The median diameter of the ring rolling member 10 = (the inner diameter of the ring rolling member 10 + the outer diameter of the ring rolling member 10) ÷ 2

In order to ensure that the final size of the product can be obtained after the ring-shaped rolling element 10 is bulged, the bulging size of the ring-rolled part 10 in the hot state is calculated according to the following formula:

D = Do ( 1 + β ₍ ) +d

In the formula:

D——the inner diameter dimension (mm) of the ring-rolled piece 10 after being inflated in a hot state;

Do—the inner diameter of the final product (mm) in the cold state after the bulging of the ring-rolled part 10; β ₍ the temperature compensation coefficient (%) of the ring-rolled part 10 at the bulging temperature, for different materials at different temperatures The temperature compensation coefficient is different, and the invention takes 1.2% to 1.65%;

d——Resilience (mm) of the inner diameter dimension after the bulging of the ring-rolling member 10, the invention takes 2 匪 to 1⁄2 m.不锈钢The stainless steel rectangular ring rolling piece which is bulged by the above method has an inner diameter ranging from Φ 400 mm to Φ 4500 mm, a wall thickness of 10 mm to 200 mm, and a height of 40 mm to 750 mm. Industrial applicability

The invention directly bulges by rigid contact between the bulging block on the bulging machine and the stainless steel rectangular ring rolling piece, and can obtain the stainless steel rectangular ring rolling piece of the required bulging size, and the stainless steel rectangular ring rolling piece after the bulging is detected. The cold size is the final product size, reaching 1%o ~ 2% ₀ of the corresponding size; After testing the internal structure of the ring-rolled piece, no change occurred, and there were no defects such as deformation and warpage. The method is applicable to stainless steel rectangular ring parts for producing rotary parts such as simple shells used in aerospace and other fields.

Claims

Claim

A method for thermal expansion of a stainless steel rectangular ring rolling piece, comprising the steps of: setting a hot rolled stainless steel rectangular ring rolling piece into a bulging machine, and causing the inner ring surface to be preheated to

The outer circumferential surface of the bulging block of 255 ° C ~ 305 ° C, at this time, the radial slider is in a closed state; the starting bulging machine applies an axial pulling force F to the mandrel slider to move it downward in the axial direction And pressing the radial sliding block along the inner hole cone surface of the radial sliding block to make the radial sliding blocks synchronously move and diffuse in the radial direction, and the bulging block mounted on the outer circumferential surface of the radial sliding block from the ring rolling piece The inner circumferential surface presses the ring rolling piece in the radial direction, and the inner and outer diameters of the ring rolling piece are expanded and the wall thickness is thinned and plastically deformed to complete the first bulging shape; in the current bulging process, the ring is formed The bulging temperature of the rolled piece is 890 ° C ~ 950 ° C, the bulging time is 15 s ~ 25 s, the dwell time is 7 s ~ 8 s, and the bulging deformation is 0.9% ~ 1.2%;

The bulging machine drives the mandrel slider to move upward in the axial direction in the radial slider, and drives the radial slider to move synchronously in the radial direction to close the bulging block away from the bulging ring rolling piece, and start the bulging machine. The guide roller on the table drives the ring rolling member to rotate 45° along the central axis to complete the first rotation of the ring rolling member; according to the first bulging operation described above, the ring after the first bulging The rolling piece undergoes a second bulging. In this bulging process, the bulging temperature of the ring rolling piece is 850 ° C ~ 91 (TC, the bulging time is 15 s ~ 25 s, and the dwell time is 9 s ~ 10 s , the amount of bulging deformation is 0.7% ~ 1%;

According to the first bulging operation described above, the second bulging of the ring rolling piece after the second bulging is performed, and in the bulging process, the bulging temperature of the ring rolling piece is 800 ° C ~ 87{TC , bulging time % 25s ~ 35s, holding time is 13s ~ 15s, bulging deformation is 0.5% ~ 0.8%;

The method of thermal expansion of a rectangular ring-rolled product according to claim 1, wherein the stainless steel is lMnl8Crl8N.

3. The method of thermal bulging of a rectangular ring-rolled product according to claim 1 or 2, wherein: the axial pulling force F applied by the bulging machine to the mandrel slider is determined by the following formula: F = ξ x σ ₀ . ₂ ^x S

In the formula:

σ ₀ .2——the yield strength (MPa) of stainless steel material at bulging temperature, lMnl8Crl8N stainless steel takes 1 to make Pa ~ 200MPa;

S ——The longitudinal section area of the ring rolling

4. The method of thermal bulging of a rectangular ring-rolled product according to claim 1 or 2, characterized in that:

D = Do ( 1 + β ₍ ) +d

In the formula:

D——the inner diameter dimension (mm) of the ring-rolled piece after being bulged in a hot state;

β ₍ the temperature compensation coefficient of the ring-rolled part at the bulging temperature (%) lMnl8Crl8N stainless steel takes 1.2% ~ 1.65%;

d——The amount of rebound of the inner diameter after the bulging of the ring rolling piece (mm), lMnl8Crl8N stainless steel takes 2mm ~ 4mm.

The method for thermal bulging of a rectangular ring-shaped rolling stock according to claim 1 or 2, wherein: the bulging rectangular ring-shaped rolling piece has an inner diameter ranging from Φ400ηιηι~ Φ4500ηιηι, and a wall thickness of 10 mm to 200 mm. , height is 40mm ~ 750mm.