CN110548851A

CN110548851A - Radial vibration centrifugal casting method

Info

Publication number: CN110548851A
Application number: CN201910805988.1A
Authority: CN
Inventors: 毛凯田; 张新宇; 吴玉同; 李慧; 刘立国; 封艳
Original assignee: Shanghai Zhuoran Engineering Ltd By Share Ltd; ZHUORAN (JINGJIANG) EQUIPMENT MANUFACTURING Co Ltd
Current assignee: Shanghai Zhuoran Engineering Ltd By Share Ltd; ZHUORAN (JINGJIANG) EQUIPMENT MANUFACTURING Co Ltd
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2019-12-10
Anticipated expiration: 2039-08-29
Also published as: CN110548851B

Abstract

The invention discloses a radial vibration centrifugal casting method. The method comprises the following steps: 1) baking a pipe die, spraying a coating and installing baffles at two ends of the pipe die; 2) pouring molten metal from the pouring end of the pipe die, and starting a vibration power device when the molten metal is filled to the non-pouring end of the pipe die, so that the pipe die generates radial vibration; 3) after the molten metal is poured, spraying water to cool the pipe die, and closing the vibration device when the solidification thickness of the molten metal reaches half of the thickness of the centrifugal casting steel pipe; 4) and (4) completely solidifying the molten metal, and pushing or pulling the pipe to realize the separation of the cast steel pipe and the pipe die. For the austenite cast steel pipe, the cast dendrite is broken by the radial vibration of the pipe die, and the grain size of the cast structure is improved. For medium-low carbon cast steel pipes, the method has good inhibition effect on the carbon segregation of the cast steel pipes.

Description

Radial vibration centrifugal casting method

Technical Field

The invention is applied to the field of centrifugal casting, and particularly relates to a centrifugal casting method for radial vibration of a pipe die.

Background

The centrifugal casting technology belongs to a mature technology in China, and not only are more manufacturers used for centrifugally manufacturing ductile iron pipes, gray iron pipes and cast steel pipes, but also the yield is high. However, for austenitic stainless steel seamless pipes or nickel-based heat-resistant seamless pipes, a process route of casting, forging, hot extrusion, and cold rolling into pipes is often adopted, and centrifugally cast steel pipes are rarely used as raw material blanks. In practice, austenitic stainless steel seamless tubes or nickel-based heat-resistant seamless tubes can be produced by a process in which a centrifugally cast tube blank is hot extruded into an extruded tube and then cold rolled. The process route is short, and the manufacturing cost is saved. Therefore, the seamless tube rarely adopts a centrifugal blank as a raw material blank, so that the production rhythm of the centrifugal machine cannot meet the smelting production requirement, and the grain size of the centrifugal cast tube blank cannot meet the requirement. Because austenitic stainless steel and nickel-based heat-resistant steel are austenitic structures from high temperature to room temperature, the grain size of the structures cannot be changed through heat treatment, and the grain is refined only through deformation processing such as extrusion, forging, cold rolling and the like, so that the grain size is improved, and the performance of the steel is improved. In order to obtain satisfactory grain size, when cast steel pipes are used as raw material blanks, as the cast crystal grain size of centrifugal cast steel pipe blanks is larger, multiple or large-deformation processing is needed, if the cast crystal grain size of the raw material blanks of the cast steel pipes can be reduced, the grain size is improved, the pressure can be reduced for subsequent processing, and the production cost is saved.

The published patent materials CN109014110A and CN206839085U show vibration methods for vertical centrifugal casting, which are suitable for centrifugal production of small batches of pieces and are not suitable for horizontal centrifugal casting of centrifugal casting steel tubes with large weight of more than several hundred kilograms.

Disclosure of Invention

The technical problem solved by the invention is as follows: a radial vibration centrifugal casting method is provided, which can reduce the cast-state crystal grains and improve the grain size when the austenite material cast steel pipe is centrifugally cast.

The technical scheme adopted by the invention is as follows: the radial vibration centrifugal casting method comprises the steps that a centrifugal machine comprising a vibration riding wheel is used for centrifugal casting, the vibration riding wheel comprises a vibration driven wheel and a vibration device, the vibration device is connected with a motor power device through a clutch, and the vibration device comprises a rotating shaft and an eccentric assembly arranged on the rotating shaft; the vibration driven wheel comprises a bearing II and a vibration wheel which are arranged on the rotating shaft. The centrifugal casting method comprises the following steps: 1) baking a pipe die, spraying a coating and installing baffles at two ends of the pipe die; 2) pouring molten metal from the pouring end of the pipe die, starting a motor power device when the molten metal is filled to the non-pouring end of the pipe die, closing a clutch, rotating a rotating shaft, wherein the rotating direction and the rotating angular speed of the rotating shaft are consistent with those of a vibration wheel, a bearing II is relatively static, the rotating shaft drives an eccentric assembly to rotate, and the eccentric assembly drives the vibration wheel to generate radial vibration so that the pipe die generates radial vibration; 3) after the molten metal is poured, the pipe die is cooled by spraying water, when the solidification thickness of the molten metal reaches half of the thickness of the centrifugal casting steel pipe, the clutch is released, the motor power device is closed, the rotating shaft is static, the vibration wheel continues to rotate under the action of the bearing II, and the pipe die is kept to rotate; 4) and (4) completely solidifying the molten metal, and pushing or pulling the pipe to realize the separation of the cast steel pipe and the pipe die. If the bearing II is damaged by vibration or in other cases, the step 3) is not executed, namely the step 2) is consistently kept until the molten metal is solidified, and then the step 4) is executed.

The invention has the beneficial effects that: for the austenitic stainless steel or nickel-based heat-resistant steel centrifugal casting steel pipe, by adopting the casting method, the radial vibration of the pipe die can break cast dendrites, improve the grain size of cast structures and relieve the pressure for subsequent deformation processing. For medium-low carbon cast steel pipes, the method has good inhibition effect on the carbon segregation of the cast steel pipes.

drawings

FIG. 1 is a schematic view of a radial vibration centrifuge;

FIG. 2 is a schematic view of a vibrating riding wheel;

FIG. 3 is a schematic cross-sectional view A-A of FIG. 2;

FIG. 4 is an as-cast structure of a pipe die vibration-free nickel-based alloy cast steel pipe;

FIG. 5 is an as-cast structure of a nickel-based alloy cast steel pipe with a pipe die vibrating in the radial direction;

Wherein: the device comprises a 1-pipe die, a 2-driven wheel set, a 3-driving wheel set, a 4-riding wheel support, a 5-clutch, a 6-rotating shaft, a 7-bearing I, an 8-copper sleeve, a 9-bearing II, a 10-vibration wheel, an 11-bearing I end cover, a 12-eccentric component and a 13-supporting steel plate.

Detailed Description

Fig. 1 is a schematic structural diagram of a radial vibration centrifuge used in the present invention, the radial vibration centrifuge includes a driving wheel set 3 and a driven wheel set 2, the driving wheel set 3 includes a driving wheel driven by a motor to rotate and a driven wheel, the driven wheel set 2 includes two driven wheels, one of the driven wheels has a vibration device, which is a vibration riding wheel, and the vibration riding wheel can make a pipe die generate vibration in a radial direction. The rolling belt of the pipe die 1 is placed on the driving wheel set 3 and the driven wheel set 2, and the driving wheel set 3 can drive the pipe die to rotate at a high speed to complete centrifugal casting of the cast steel pipe.

FIG. 2 is a schematic structural diagram of a vibration riding wheel, the vibration riding wheel comprises a riding wheel support 4, a vibration driven wheel and a vibration device, the vibration driven wheel comprises a bearing II 9 and a vibration wheel 10, the bearing II 9 is installed in the vibration wheel 10 and sealed by an end cover II of the bearing, and the structure is consistent with other driven wheels. The vibrating device is connected with the motor power device through the clutch 5, and the clutch 5 and the motor power device are flexibly connected through a belt from the equipment safety perspective, so that the motor can be protected by slipping of the belt even when a pipe die stops rotating or an accident occurs. The vibrating device comprises a rotating shaft 6, a bearing I7, a copper sleeve 8 and eccentric assemblies 12, a clutch 5 is flexibly connected with the rotating shaft 6, the clutch 5 is connected to work, a motor power device can drive the rotating shaft 6 to rotate, two sets of eccentric assemblies 12 are fixedly connected to two ends of the rotating shaft 6, each set of eccentric assembly 12 is composed of two eccentric blocks, and eccentric vibrating force can be adjusted by adjusting the angle between one set of two eccentric blocks. The bearing I7 is arranged in the copper sleeve 8 and is sealed by an end cover 11 of the bearing I, and the inner hole of the bearing I is in interference connection with the rotating shaft 6. The copper bush 8 is arranged in the long circular holes of the supporting steel plates 13 on the two sides of the riding wheel support 4, as shown in the attached drawing 3, the center distance of two semicircles of the long circular holes is e, namely, an up-down moving allowance with the height of e is reserved for the copper bush 8, and the vibration amplitude of the copper bush 8 cannot exceed the height of e.

when radial vibrations centrifuge used, the motor power device who is connected with 5 belts of clutch was started, it is rotatory to drive pivot 6, the eccentric subassembly 12 in pivot 6 produces eccentric vibrations at rotatory in-process, drive copper sheathing 8 and the vibrations of bearing I7 in the slotted hole of supporting steel sheet 13, pivot 6 shakes from the driving wheel with vibrations simultaneously, vibrations are given pipe die 1 from the vibrations of driving wheel, make pipe die 1 produce the vibrations of radial direction.

because the bearing can be damaged by long-time vibration, the design and the use of the vibration riding wheel meet the following requirements: 1) adding a lubricant before the copper bush 8 and the bearing I7 are installed; 2) the rotating direction and the rotating angular speed of the rotating shaft 6 are consistent with those of the vibrating wheel 10; 3) the polarization force is adjustable, and the angle of the eccentric block can be adjusted in advance according to the weight of the pipe die and the cast steel pipe; 4) the clutch 5 is flexibly connected with a motor power device thereof, such as a belt, so that equipment accidents are prevented.

By adopting the radial vibration centrifugal machine, the radial vibration centrifugal casting method comprises the following steps: 1) baking a pipe die, spraying a coating and installing baffles at two ends of the pipe die; 2) pouring molten metal from one end (namely a pouring end) of the pipe die, starting a motor power device when the molten metal is filled to the other end (namely a non-pouring end) of the pipe die, closing the clutch 5, rotating the rotating shaft 6, wherein the rotating direction and the rotating angular speed of the rotating shaft are consistent with those of the vibrating wheel 10, the bearing II 9 is relatively static, the rotating shaft 6 drives the eccentric component 12 to rotate, and the eccentric component 12 drives the vibrating wheel 10 to generate radial vibration, so that the pipe die 1 generates radial vibration; 3) after the molten metal is poured, the pipe die is cooled by water spraying, when the solidification thickness of the molten metal reaches half of the thickness of the centrifugal casting steel pipe, the clutch 5 is released, the motor power device is closed, the rotating shaft 6 is static, and the vibrating wheel 10 continues to rotate under the support of the bearing II 9, so that the pipe die is kept to rotate. The vibration time can be determined by simulation, or by the temperature of the inner surface of the molten metal during centrifugation, or can be determined empirically. 4) And (4) completely solidifying the molten metal, and pushing or pulling the pipe to realize the separation of the cast steel pipe and the pipe die.

If the bearing II 9 is damaged by vibration during the rotation of the pipe die, the step 3) is not executed, namely the step 2) is consistently kept until the molten metal is solidified, and then the step 4) is executed. If bearing I7 is damaged by the vibrations, under the condition that bearing II 9 can normally work, can stop vibrating device. If the bearing I7 and the bearing II 9 are damaged by vibration at the same time, the rotation of the rotating shaft 6 is kept, the sliding friction generated between the bearing I7 and the copper sleeve 8 can continuously keep the pipe die to rotate, and the pouring of the cast steel pipe is completed. And after the pipe is pushed or pulled, the bearing is replaced. Therefore, the structure ensures that equipment accidents caused by the vibration damage of the bearing can be avoided when the centrifugal casting pipe vibrates in the radial direction.

in addition to the case that the bearing II 9 is damaged, the step 3) can be omitted in other normal or abnormal cases, namely, the step 4) is executed after the step 2) is executed.

For the centrifugal casting steel pipe of austenitic stainless steel or nickel-based heat-resistant steel, after the metal liquid is centrifugally poured, the radial vibration of the pipe die can break cast dendrites, improve the grain size of cast structures, and relieve the pressure for subsequent deformation processing. FIG. 4 shows the as-cast structure of a cast steel pipe of a certain nickel-based alloy when the pipe die does not vibrate, the thickness of the cast steel pipe is about 70mm, dendrites basically penetrate through the whole thickness of the cast steel pipe, FIG. 5 shows the as-cast structure of the cast steel pipe of the nickel-based alloy after the pipe die vibrates in the radial direction, the thickness of the cast steel pipe is about 72mm, the length of the dendrites is only about 10mm, and the rest of the dendrites are isometric crystals after 60mm, compared with FIG. 4, the length of the dendrites is greatly reduced, the isometric crystal proportion is basically not improved to 80%, distinct effects are generated, and the expectation is greatly exceeded.

The radial vibration centrifugal casting method can also be used for producing other cast steel pipes such as carbon steel or alloy steel, and the centrifugal machine also has the function of improving the grain size of the cast steel pipes with medium and low carbon content such as 16Mn or 40 Cr. In addition, the radial vibration centrifugal casting method is found to improve the carbon segregation of the cast steel pipe. For austenitic stainless steel or nickel-based heat-resistant steel, the carbon content is very low, and the carbon content is ultralow, so that the carbon segregation is not obvious. The following table shows carbon segregation data of 16Mn or 40Cr centrifugal casting steel pipes, numbers in a sampling position column in the table show that sampling is carried out layer by layer from the inner surface to the outer surface, the sampling is evenly divided into 10 layers according to the thickness, and carbon analysis is carried out after the sampling layer by layer, the result proves that the maximum value and the difference value of the carbon segregation are obviously reduced after radial vibration, particularly the difference value is reduced by 50 percent, and the radial vibration centrifugal casting method has a good effect of inhibiting the carbon segregation of the medium-low carbon casting steel pipes.

Claims

1. a centrifugal casting method with radial vibration is characterized in that a centrifugal machine comprising a vibration riding wheel is used for centrifugal casting, the vibration riding wheel comprises a vibration driven wheel and a vibration device, the vibration device is connected with a motor power device through a clutch (5), and the vibration device comprises a rotating shaft (6) and an eccentric assembly (12) arranged on the rotating shaft (6); the vibration driven wheel comprises a bearing II (9) and a vibration wheel (10) which are arranged on the rotating shaft (6); the radial vibration centrifugal casting method comprises the following steps:

1) Baking a pipe die, spraying a coating and installing baffles at two ends of the pipe die;

2) Pouring molten metal from the pouring end of the pipe die, starting a motor power device when the molten metal is filled to the non-pouring end of the pipe die, closing a clutch (5), rotating a rotating shaft (6), wherein the rotating direction and the rotating angular speed of the rotating shaft (6) are consistent with those of a vibration wheel (10), a bearing II (9) is relatively static, the rotating shaft (6) drives an eccentric component (12) to rotate, and the eccentric component (12) drives the vibration wheel (10) to generate radial vibration so that the pipe die generates radial vibration;

3) After the molten metal is poured, the pipe die is cooled by spraying water, when the solidification thickness of the molten metal reaches half of the thickness of the centrifugal cast steel pipe, the clutch (5) is released, the motor power device is closed, the rotating shaft (6) is static, the vibrating wheel (10) continues to rotate under the action of the bearing II (9), and the pipe die is kept to rotate;

4) And (4) completely solidifying the molten metal, and pushing or pulling the pipe to realize the separation of the cast steel pipe and the pipe die.

2. A radial vibratory centrifugal casting method as defined in claim 1, wherein: the step 3) is omitted.