CN108907132B - Production method of 304L/SA210 bimetal hot rolled tube blank - Google Patents
Production method of 304L/SA210 bimetal hot rolled tube blank Download PDFInfo
- Publication number
- CN108907132B CN108907132B CN201810684881.1A CN201810684881A CN108907132B CN 108907132 B CN108907132 B CN 108907132B CN 201810684881 A CN201810684881 A CN 201810684881A CN 108907132 B CN108907132 B CN 108907132B
- Authority
- CN
- China
- Prior art keywords
- molten metal
- pouring
- outer layer
- inner layer
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D13/00—Centrifugal casting; Casting by using centrifugal force
- B22D13/02—Centrifugal casting; Casting by using centrifugal force of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
Abstract
The invention discloses a production method for centrifugal casting of a 304L/SA210 bimetal thin-wall tube blank, which can be used for hot rolling a raw material tube blank. During centrifugal casting, the inner layer metal liquid and the outer layer metal liquid are respectively poured from two ends of the pipe die; the outer layer 304L molten metal is mixed and cast by adopting low-melting-point covering slag; before and during the pouring of the inner and outer layer molten metal, inert gas is fed into the inner and outer layer molten metal through a flow nozzle; the molten metal pouring time of the outer layer 304L is not more than 5 seconds, and the molten metal pouring time of the inner layer SA210 is not more than 8 seconds. In order to prevent the temperature from being reduced too fast, the steel ladle used for pouring the outer layer 304L molten metal is strictly baked and covered for heat preservation. The 304L/SA210 bimetallic pipe blank produced according to the technical scheme has the advantages that the inner layer components are well controlled, the content of each component of the SA210 is guaranteed, the interface of the inner layer and the outer layer is clean and has no slag inclusion, metallurgical bonding is generated, and the requirements of hot rolling deformation can be met.
Description
Technical Field
The invention is applied to the field of centrifugal casting, and provides a production method of a 304L/SA210 bimetal hot-rolled tube blank for producing a bimetal seamless steel tube by hot rolling.
Background
The 04L/SA210 bimetal seamless steel pipe is a boiler pipe for a black liquid boiler, the outer layer is 304L and is mainly used for preventing black liquid from being corroded, the inner layer SA210 is a common pipe of the boiler pipe, the heat conductivity coefficient of the 304L is small although the corrosion resistance is good, the heat transfer efficiency of the boiler pipe is not improved, and therefore the SA210 is adopted in the inner layer.
The current specification of the bimetallic tube is phi 63.5 multiplied by 6.53mm, the thickness of the outer layer is 1.65mm, and the bimetallic tube is produced by extrusion cold rolling. A method for producing extruded tube blanks is disclosed by CN10530897B and is manufactured by a centrifugal casting process. In order to guarantee the composition of the inner layer, the method needs to cast a transition layer to prevent the composition of the outer layer from influencing the composition of the inner layer. For the 304L/SA210 bimetal seamless steel pipe, the transition layer brings adverse effects on the final heat treatment and the performance of the finished pipe, and the finished pipe yield is greatly reduced due to the existence of hard and brittle phases. Later, an extruded bimetallic pipe blank is produced by adopting a mechanical bushing method disclosed in CN104266003B to eliminate a transition layer, but the yield of cold-rolled finished pipes is also low due to the problem of weak bonding force of an inner layer and an outer layer, so that the 304L/SA210 bimetallic pipe with phi 63.5 multiplied by 6.53 cannot be industrially produced.
Disclosure of Invention
The technical problem solved by the invention is as follows: the centrifugal casting process is adopted to produce the 304L/SA210 bimetal hot rolled tube blank without a transition layer and with good bonding force.
The technical scheme adopted by the invention is as follows:
a production method of a 304L/SA210 bimetal hot rolled pipe blank comprises the steps of respectively pouring an outer layer 304L molten metal and an inner layer SA210 molten metal from two ends of a pipe die; the outer layer 304L molten metal is poured by mixing low-melting-point covering slag, and the pouring time is not more than 5 seconds; the casting time of the molten metal of the inner layer SA210 is not more than 8 seconds; when the inner layer SA210 metal liquid is poured, the temperature of 304L is 1230-1300 ℃; before and during pouring of the inner layer SA210 molten metal, before and during pouring of the outer layer 304L molten metal and during cooling, the inert gas is fed into the inner layer SA210 molten metal through the flow nozzle; and the inert gas is fed into the pipe die from the outlet of the pipe die and is blown out from the outlets of the circumferentially distributed baffles to protect the pouring gate. The low-melting-point covering slag comprises 25-30 wt%, 20-25 wt%, 15-20 wt% and 35 wt% of lime, quartz, bauxite and fluorite, and the alkalinity is 1.1-1.3; the low-melting-point casting powder also comprises sodium metasilicate, the weight of the sodium metasilicate is 50-100% of the weight of the four materials, and the melting point of the low-melting-point casting powder is 1150-1200 ℃. The low-melting-point covering slag can also contain borax, and the weight of the borax is 5-10% of the total weight of the five materials.
Because the amount of the pouring molten steel is small, in order to achieve the purpose of pouring temperature, the steel ladle used for pouring the outer layer 304L molten metal is covered with heat-preservation cotton for heat preservation.
The pipe die is quick in die filling, the temperature drop of molten metal is reduced, the content of impurities is reduced, and the rotating speed of the pipe die is not lower than 100G.
The invention has the beneficial effects that: the 304L/SA210 bimetallic pipe blank produced according to the technical scheme has the advantages that the inner layer components are well controlled, the content of each component of the SA210 is guaranteed, meanwhile, the interface of the inner layer and the outer layer is free of a transition layer, the pipe blank is clean and free of slag inclusion, metallurgical bonding is generated, and the requirements of hot rolling deformation can be met.
Drawings
FIG. 1 is a schematic view of a bimetallic pipe billet casting scheme;
FIG. 2 is a schematic view of a spout;
wherein: 1-pipe die, 2-baffle, 3-spout, 4-pouring ladle, 5-inert gas cavity, 6-gas inlet pipe, 7-wedge, 8-pipe die outlet and 9-baffle outlet.
Detailed Description
Example 1.
The centrifugally cast 304L/SA210 bimetallic tube blank is a hot-rolled raw material tube blank and is used for producing 304L/SA210 bimetallic seamless steel tubes.
The size of the 304L/SA210 bimetal hot rolled pipe blank is phi 178 (outer diameter) x phi 158 (inner diameter) x 3000-.
The machining amount of the inner surface and the outer surface is increased to remove casting defects, the centrifugal casting bimetal blank is phi 186 multiplied by phi 150 multiplied by 3600, the outer layer thickness is 6.5mm, the outer layer casting weight is 103kg, the inner layer thickness is 11.5mm, and the inner layer casting weight is 165 kg. The composition requirements for the inner and outer layers are given in the following table.
| C | Si | Mn | P | S | Cr | Ni | |
| 304L | ≤0.03 | ≤0.75 | ≤2.0 | ≤0.040 | ≤0.030 | 18.0～20.0 | 8.0～13.0 |
| SA210 | 0.18～0.23 | 0.2～0.4 | 0.6～0.8 | ≤0.030 | ≤0.030 | ≤0.30 | ≤0.30 |
It can be seen that for the composition control of the inner layer, after the outer layer is fused, the control of Si, Mn, P and S is relatively difficult, the control of C is difficult, and the control of Cr and Ni is difficult, especially the Cr content of the outer layer is high, the weight of the fused outer layer 304L is not more than 1.5% of the total weight of the inner layer SA210, otherwise, the weight of the fused outer layer exceeds the requirement of being less than or equal to 0.30%, namely, the thickness of the fused outer layer of the inner layer is not more than 0.3 mm.
Analysis of the centrifugal casting process:
1. the melting point of 304L is about 1310-1360 ℃, and the pouring temperature of SA210 is about 1580-1620 ℃, in order to control the melting amount, the SA210 molten metal must be poured after the 304L is completely solidified. Therefore, 304L must adopt the way of casting the low-melting-point covering slag and steel slag in a mixed way to prevent the interface between the inner layer and the outer layer from slag inclusion. The low-melting-point covering slag means that the melting point of the covering slag is far lower than the melting point of metal, generally the melting point is not less than 100 ℃ lower than the melting point of the metal, and the melting point of the low-melting-point covering slag is not more than 1150-1200 ℃.
2. Because the centrifugal tube blank is longer, the thickness of the outer layer is very thin and is only about 6.5mm, and the temperature difference of metal liquid at two ends of the tube die is very large, a mode of pouring at two ends of the tube die is needed.
3. In order to obtain a good protection effect, the dosage of the low-melting-point mold flux is calculated according to the minimum thickness of 0.5mm, and 3-3.5kg is needed. This results in a large temperature drop due to the melting of mold flux for the outer layer molten metal of 103 kg. If the dosage of the covering slag is reduced, the inert gas protection is needed to be added.
From the above process analysis, it can be seen that the casting scheme of low melting point casting powder steel slag mixed casting, inner and outer layer molten metal two-end casting, casting process and cooling process whole course inert gas protection must be adopted, and fig. 1 is a schematic diagram of 304L/SA210 bimetal blank casting scheme. Baffle 2 is installed respectively at the both ends of pipe die 1, and pouring ladle 4's stem bar 3 passes through the baffle hole and inserts in the pipe die, and interior outer metal liquid pours into the pipe die through the pouring ladle at both ends and stem bar respectively. The concrete pouring steps and parameters are as follows:
1. after the molten components of the 304L molten metal are adjusted, the temperature is raised to 1550-. When tapping, a deoxidizer and low-melting-point covering slag are added into the ladle. The ladle is strictly executed according to the ladle drying process, the heat preservation is preferably carried out by adopting refractory asbestos, and the ladle opening is covered and insulated after tapping.
2. One end of the 304L pouring of the pipe die is a pouring end, and the other end of the pipe die is a non-pouring end, namely the pouring end of the inner layer molten metal SA 210. And the rotating speed of the pipe die is not less than 700 and 740rpm according to the calculation of G = 100. The coating is sprayed in the pipe die, in order to reduce the temperature drop in the process of filling the metal liquid in the pipe die, the thickness of the coating is not less than 2.0mm, and the coating is baked to the temperature of 240-300 ℃ for pouring.
3. Introducing inert protective gas from a pouring end, pouring 304L of molten metal and low-melting-point casting powder simultaneously, and quickly pouring into a high-speed rotating pipe die within 4 seconds, wherein the pouring temperature of the 304L of molten metal is not lower than 1460 ℃, and the using amount of the casting powder is 2-2.5 kg.
4. The temperature of 304L is measured by an infrared temperature measuring gun from the non-pouring end, after the temperature is set at 1230-. The melting point of the low-melting-point covering slag is 1150-1200 ℃, and the covering slag is in a liquid state and can float up to the inner surface of the blank under the action of centrifugal force when the inner layer SA210 molten metal is poured.
5. And after the SA210 molten metal is poured, closing the inert protective gas, opening cooling water and cooling the pipe die.
The technological key points of the centrifugal casting of the 304L/SA210 bimetallic tube blank are as follows:
1. low-melting-point mold flux
The low-melting-point covering slag plays a role in cleaning molten metal and protecting against oxidation. The low melting point covering slag is added into a ladle, is melted rapidly during tapping, is stirred with molten metal, can adsorb deoxidized inclusion in the molten metal, and floats to the surface of the molten metal in the static process. The low-melting-point covering slag comprises lime, quartz, bauxite and fluorite, so as to be beneficial to adsorbing impurities or slag inclusion in molten metal, wherein the weight percentages of the four materials are respectively 25-30%, 20-25%, 15-20% and 35-45%, and the alkalinity is 1.1-1.3; and sodium metasilicate, the weight of which is 50-100% of the weight of the four materials, so as to reduce the melting point of the covering slag. The protective slag can also contain borax, and the weight of the borax is 5-10% of the total weight of the five materials.
2. Pouring time of inner layer SA210 molten metal
If the molten metal of the inner layer SA210 is poured early, the fusion amount of the outer layer 304L is large, and the contents of Cr and Ni in the inner layer SA210 exceed the standard. If the casting is late, the inner layer cannot be fused with the outer layer, and the binding force of the inner layer and the outer layer cannot meet the requirement of subsequent hot working deformation. The optimal time is 304L at 1230-1300 ℃.
3. Inert gas
The low-melting-point covering slag and the inert gas play roles in isolating air and preventing oxidation pollution in the processes of 304L pouring and cooling, and lay a foundation for improving the purity and the binding force of the inner-layer and outer-layer bimetal joint surfaces. The inert gas shield employs a flow nozzle as shown in figure 2. The pouring ladle 4 and the spout 3 are fixedly connected by the inclined iron 7, so that the pouring ladle is convenient to replace. The flow nozzle is sealed by nesting two steel pipes, an inert gas cavity 5 is designed in the middle and is connected with an inert gas inlet pipe 6, and an inert gas pipe die outlet 8 and a baffle plate outlet 9 which are distributed circumferentially are respectively arranged on the flow nozzle. When the flow nozzle is inserted into the pipe die, the outlet 8 of the pipe die can send inert protective gas into the pipe die to exhaust the air in the pipe die. Meanwhile, inert gas is blown out from the baffle outlet 9, so that the pouring gate can be isolated from air, the air is prevented from entering the pipe die from the pouring gate, and the molten metal is completely protected by the inert gas after flowing into the pipe die from the pouring ladle.
4. Two-end two-liquid pouring
In the embodiment, because the walls of the centrifugal tube blank tubes are thin, the temperature difference between two ends of the tube die is large after molten metal is poured, and the best scheme is to pour the inner layer molten metal from the non-pouring end in order to obtain a well fused bimetallic tube blank.
5. Quick pouring forming
Because the walls of the centrifugal tube blank tubes are thin, the outer layer pouring time is not more than 4 seconds, and the inner layer pouring time is not more than 6 seconds in order to ensure the forming.
6. Steel ladle heat preservation
Because the pipe wall is thin, the metal liquid pouring amount is small, and the temperature of the metal liquid is greatly reduced, heat preservation measures must be taken, firstly, the ladle is roasted, and firstly, the surface of the metal liquid is covered with heat preservation cotton.
Example 2.
In this example, the 304L/SA210 centrifugally cast bimetallic pipe billet is also a hot rolled raw material pipe billet as in example 1, and is used for producing a 304L/SA210 bimetallic seamless steel pipe. The sizes are slightly different at different times, the size of the bimetal tube blank in the embodiment is phi 195 (outer diameter) x phi 175 (inner diameter) x 3000 and 4000 (length), and the middle diameter size phi 190 of the inner-layer and outer-layer joint surface also belongs to the thin-wall bimetal tube blank.
The composition control and process analysis of the inner and outer layers of this example are substantially the same as in example 1. The specific casting steps are also consistent, with only the specific process parameters differing due to dimensional changes.
Considering that the machining amount of the inner surface and the outer surface is increased except for casting defects, the size of a centrifugally cast bimetallic blank is phi 205 multiplied by phi 165 multiplied by 3600, the thickness of the outer layer is 7.5mm, the pouring weight of the outer layer is 124kg, the thickness of the inner layer is 12.5mm, and the pouring weight of the inner layer is 195 kg. The rotating speed of the pipe die is not less than 680rpm, the adding amount of the 304L low-melting-point covering slag ladle is 3-3.5kg, the pouring time is not more than 5 seconds, and the pouring time of the inner layer SA210 is not more than 8 seconds.
The pouring considerations and control points are essentially the same as in example 1.
The inner layer of the 304L/SA210 bimetallic pipe blank with two specifications poured according to the process method is well controlled, particularly the content of Cr is strictly controlled below 0.3%, the content of each component of the SA210 is ensured, meanwhile, the interface of the inner layer and the outer layer has no slag inclusion, the binding force is also ensured, metallurgical binding is generated, and the binding force exceeds 400MPa through experimental detection, so that the requirement of hot rolling deformation can be met.
Claims (3)
1. A production method of a 304L/SA210 bimetal hot rolled tube blank is characterized by comprising the following steps: respectively pouring the outer layer 304L molten metal and the inner layer SA210 molten metal from two ends of the pipe die; the outer layer 304L molten metal is poured by mixing low-melting-point covering slag, and the pouring time is not more than 5 seconds; the casting time of the molten metal of the inner layer SA210 is not more than 8 seconds; when the inner layer SA210 metal liquid is poured, the temperature of 304L is 1230-1300 ℃; before and during pouring of the inner layer SA210 molten metal, before and during pouring of the outer layer 304L molten metal and during cooling, the inert gas is fed into the inner layer SA210 molten metal through the flow nozzle; the inert gas is blown out from a pipe die outlet (8) of the flow nozzle and enters the pipe die, and is blown out from a baffle plate outlet (9) which is circumferentially distributed on the flow nozzle to isolate the air of the pouring gate; the low-melting-point covering slag comprises 25-30 wt%, 20-25 wt%, 15-20 wt% and 35 wt% of lime, quartz, bauxite and fluorite, and the alkalinity is 1.1-1.3; the weight of the sodium metasilicate is 50-100% of the weight of the four materials; the low-melting-point covering slag also contains borax, and the weight of the borax is 5-10% of the total weight of the five materials.
2. The production method of the 304L/SA210 bimetal hot rolled tube blank according to claim 1, characterized by comprising the following steps of: and the steel ladle for pouring the outer layer 304L of molten metal is covered with heat insulation cotton.
3. The production method of the 304L/SA210 bimetal hot rolled tube blank according to claim 1, characterized by comprising the following steps of: the rotating speed of the pipe die is not lower than 100G.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810684881.1A CN108907132B (en) | 2018-06-28 | 2018-06-28 | Production method of 304L/SA210 bimetal hot rolled tube blank |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810684881.1A CN108907132B (en) | 2018-06-28 | 2018-06-28 | Production method of 304L/SA210 bimetal hot rolled tube blank |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108907132A CN108907132A (en) | 2018-11-30 |
| CN108907132B true CN108907132B (en) | 2020-09-04 |
Family
ID=64421811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810684881.1A Active CN108907132B (en) | 2018-06-28 | 2018-06-28 | Production method of 304L/SA210 bimetal hot rolled tube blank |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108907132B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109482835B (en) * | 2018-12-27 | 2020-11-24 | 桂林理工大学 | Manufacturing method of annular casting blank with different thicknesses of outer alloy steel and inner aluminum alloy |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU409781A1 (en) * | 1971-02-18 | 1974-01-05 | ||
| JPS5465129A (en) * | 1977-11-04 | 1979-05-25 | Daido Steel Co Ltd | Production of composite metal material by centrifugal casting |
| JPS5550958A (en) * | 1978-10-05 | 1980-04-14 | Kubota Ltd | Method and apparatus for centrifugal casting |
| JPS5770069A (en) * | 1980-10-21 | 1982-04-30 | Kubota Ltd | Centrifugal casting method |
| JPS6072654A (en) * | 1983-09-30 | 1985-04-24 | Nippon Kokan Kk <Nkk> | Production of composite metallic pipe |
| CN1751826A (en) * | 2005-10-28 | 2006-03-29 | 新兴铸管股份有限公司 | Centrifugal casting method for mfg. double metal steel pipe or blank with fused layer |
| CN101530897B (en) * | 2008-07-24 | 2010-11-17 | 新兴铸管股份有限公司 | Bimetal clad pipe blank with transition layer and production method and production device thereof |
| CN101530898B (en) * | 2009-02-17 | 2010-10-13 | 新兴铸管股份有限公司 | Corrosion-resistant dual metal clad tube blank and manufacturing method thereof |
| CN101774010B (en) * | 2010-01-29 | 2011-08-31 | 新兴铸管股份有限公司 | Bimetallic metallurgical composite wear-resisting tube blank and manufacturing method thereof |
-
2018
- 2018-06-28 CN CN201810684881.1A patent/CN108907132B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN108907132A (en) | 2018-11-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105170947B (en) | A kind of preparation method of more than two layers metal composite pipe blank | |
| CN105537549B (en) | The production method of 100 DEG C of low temperature seamless steel pipe steel continuous cast round billets | |
| CA2560681A1 (en) | Method and installation for producing light gauge steel with a high manganese content | |
| CN108823492B (en) | Method for producing high-alloy high-strength peritectic steel by CSP (cast steel plate) thin plate continuous casting machine | |
| CN105018761A (en) | Continuous casting method for high-manganese and high-aluminum type austenite low-magnetic steel | |
| CN103252466A (en) | Continuous casting process for high-class high-quality chain steel | |
| CN102218514A (en) | Medium and low carbon steel continuous casting mold powder as well as preparation method thereof and continuous casting method | |
| CN103056624B (en) | Method for producing high-quality forged material by using large-scale vertical type continuous casting round billet, product and application thereof | |
| CN106513605A (en) | Method for improving low-carbon aluminum killed steel cold-rolled plate coil peeling | |
| CN107385282A (en) | A kind of heat-resisting alloy steel thin-wall pipe sand casting process | |
| CN108907132B (en) | Production method of 304L/SA210 bimetal hot rolled tube blank | |
| CN102717045B (en) | Double-phase stainless steel continuous casting method | |
| CN111761038B (en) | Process for producing peritectic steel by ultra-wide slab continuous casting machine | |
| CN108580829B (en) | A kind of bimetallic pipe billet centrifugation production method | |
| CN104278193B (en) | A kind of Glass Mould of Alloy Cast Iron mouth die material and preparation method thereof | |
| CN116422853B (en) | Die steel and continuous casting production method thereof | |
| CN108889918B (en) | Centrifugal production method of thin-wall bimetallic tube | |
| CN106270422A (en) | Improve high-carbon steel continuous casting and open the method watering effect | |
| CN116441501A (en) | Vacuum horizontal continuous casting and die casting device | |
| CN116372122A (en) | Method for reducing cracks at joint of ingot riser and ingot body | |
| CN102019389B (en) | P91 steel round billet continuous casting method | |
| CN107790654B (en) | A kind of control method of low-carbon Al killed cold heading steel continuous casting square billet pattern cracking | |
| CN107794340A (en) | A kind of method for controlling low-carbon Al killed cold heading steel Concasting Bloom crackle | |
| CN108927502A (en) | A kind of centrifugal casting low melting point covering slag | |
| CN103525977A (en) | Dehydrogenation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address | ||
| CP03 | Change of name, title or address |
Address after: West of Fuyang Road, Chengnan Park, Economic Development Zone, Jingjiang City, Taizhou City, Jiangsu Province 214500 Patentee after: SUPEZET (JINGJIANG) EQUIPMENT MANUFACTURING Co.,Ltd. Patentee after: Jiangsu Bosong Energy Technology Co.,Ltd. Address before: 214500 Fuyang Road West, Chengnan Park, Jingjiang City, Taizhou City, Jiangsu Province Patentee before: SUPEZET (JINGJIANG) EQUIPMENT MANUFACTURING Co.,Ltd. Patentee before: JIANGSU ZHUORAN INTELLIGENT HEAVY INDUSTRY Co.,Ltd. |