CN117483693A - Method for strengthening casting performance of spherical iron core centrifugal roller neck - Google Patents
Method for strengthening casting performance of spherical iron core centrifugal roller neck Download PDFInfo
- Publication number
- CN117483693A CN117483693A CN202311496081.4A CN202311496081A CN117483693A CN 117483693 A CN117483693 A CN 117483693A CN 202311496081 A CN202311496081 A CN 202311496081A CN 117483693 A CN117483693 A CN 117483693A
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- Prior art keywords
- mass fraction
- roll neck
- neck
- roll
- strengthening
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000005728 strengthening Methods 0.000 title claims abstract description 26
- 238000005266 casting Methods 0.000 title claims abstract description 24
- 229910052742 iron Inorganic materials 0.000 claims abstract description 18
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 5
- 229910000604 Ferrochrome Inorganic materials 0.000 claims description 28
- 239000000843 powder Substances 0.000 claims description 22
- 244000035744 Hura crepitans Species 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 11
- 238000000576 coating method Methods 0.000 claims description 11
- 238000000465 moulding Methods 0.000 claims description 8
- 239000012744 reinforcing agent Substances 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 238000003754 machining Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 239000003110 molding sand Substances 0.000 claims description 3
- 230000002708 enhancing effect Effects 0.000 claims 4
- 238000007493 shaping process Methods 0.000 abstract description 3
- 239000011247 coating layer Substances 0.000 abstract 1
- 239000011651 chromium Substances 0.000 description 36
- 239000010410 layer Substances 0.000 description 28
- 239000000306 component Substances 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 11
- 239000000956 alloy Substances 0.000 description 11
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 5
- 238000011049 filling Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- 239000008358 core component Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
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
- B22C—FOUNDRY MOULDING
- B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
Abstract
The invention discloses a method for strengthening casting performance of a roll neck of a spherical iron core centrifugal roll, which belongs to the field of roll casting. According to the invention, the reinforcing elements are added into the coating layer contacted with molten iron in the shaping process of the roll neck part, so that the precise control and reinforcing effects of the surface components of the core-filled cap neck are realized.
Description
Technical Field
The invention relates to the field of roller casting, in particular to a method for reinforcing the casting performance of a roller neck of a roller.
Background
The roll neck of the centrifugal roll is subjected to bending or torsion force in the using process, and good strength and toughness are required to be ensured; meanwhile, the roll neck is assembled in the bearing box, and rotates relative to the cylinder body in the use process, friction contact risks exist when lubrication is poor, and the main journal part needs to have certain surface hardness.
The centrifugal roller core and the roller neck are made of ductile iron, the core filling casting is in a vertical state, the core part melts the outer layer and mixes the outer layer alloy elements to play a role in strengthening, but the mixed alloy elements are deposited downwards by gravity before solidification after forming carbide particles, so that the pouring neck (the upper roller neck in the casting process) is difficult to receive the strengthening effect of the molten outer layer alloy, and a high alloy riser is required to be additionally cast, or the surface treatment is required to be carried out in a near-finished product stage. The former adds extra smelting and pouring processes and cost, and meanwhile, the toughness of the neck is affected to a certain extent, while the latter reduces the efficiency of the processing process, and the surface quality problem is easy to cause because the reinforced layer is shallow and needs to be close to the finished product.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for strengthening the casting performance of a spherical iron core centrifugal roller neck, wherein strengthening elements are added into a coating contacted with molten iron in the shaping process of the roller neck part, so that the precise control and strengthening effects of the surface components of the neck after filling are realized.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for reinforcing casting performance of spherical iron core centrifugal roller neck includes such steps as determining Cr mass fraction target according to hardness requirement of hardened layer of roller neck, controlling moulding size, and mixing ferrochrome powder as reinforcing agent with the paint on surface of sand box.
The technical scheme of the invention is further improved as follows: the mass fraction target of the surface Cr is 0.2% -0.4% when the roll neck is in the range of 30-35 HS; the mass fraction target of the surface Cr is 0.4-0.5% when the roll neck is in the range of 35-40 HS; the mass fraction of Cr on the surface of the roll neck is 0.5-0.6% when the roll neck is in the range of 40-45 HS.
The technical scheme of the invention is further improved as follows: the depth of the hardened layer after roll casting is 20-25mm, and the machining allowance of the part needing strengthening is at least 2-3mm smaller than the depth of the hardened layer.
The technical scheme of the invention is further improved as follows: the ferrochrome powder used as the reinforcing agent is ferrochrome with the brand of FeCr55C600 or FeCr55C1000, wherein the mass fraction of C and Cr is 6-10%, the mass fraction of Cr is 52-60%, the residual materials after the ferrochrome is crushed are screened, the mesh number is consistent with that of the surface coating of the molding sand box, the mesh number is 100-800, the ferrochrome powder is mixed into the surface coating of the sand box, and the contact surface between the sand box and the roller surface is brushed after molding before use.
The technical scheme of the invention is further improved as follows: the adding amount of the ferrochrome powder is calculated according to the mass fraction of Cr to be added and the weight of molten iron of the hardening layer: (1) the mass fraction of Cr to be added=the mass fraction of Cr target-core Cr mass fraction, (2) the weight of molten iron of the hardening layer=the surface area of the strengthening part of the roll neck=the strengthening depth=the density of molten iron; (3) the Cr yield of ferrochrome powder is generally 45% -55%; (4) ferrochrome powder addition amount= (mass fraction of Cr to be added x weight of molten iron of hardened layer)/(mass fraction of Cr of ferrochrome powder x Cr yield).
By adopting the technical scheme, the invention has the following technical progress:
the invention aims at a method for strengthening the performance of a roll neck in the casting process of a centrifugal roll, which is used for precisely controlling the content of alloy layer elements on the surface of the roll neck and the diffusion depth of the alloy layer elements, and realizing the aim of precisely controlling the depth of a hardening layer and the hardening effect. Compared with other strengthening modes, the method is easy to operate, reduces cost and improves efficiency. The method is suitable for alloy strengthening of the surface layer of the roll neck of the centrifugal roll. Through the design of strengthening components, strengthening elements are added into a coating contacted with molten iron in the shaping process of the roll neck part, and after core filling casting, alloy elements are melted and spread to the surface of the roll neck, so that a hardening effect is provided.
The centrifugal roller cast by the method can reach the expected surface strengthening depth and hardness of the roller neck, does not damage the toughness of the center, can solve the problem that the casting hardness of the counterfeit neck is insufficient and needs to be specially strengthened in the later processing stage in the traditional casting method, and simultaneously reduces the operation difficulty, saves the total alloy addition amount of the core part and maintains the toughness of the center compared with the method that the counterfeit neck is additionally cast with molten iron for one time.
Detailed Description
The invention is further illustrated by the following examples:
the method for strengthening casting performance of spherical iron core centrifugal roller neck includes determining Cr mass fraction target according to hardness requirement of hardened layer of roller neck, controlling molding size and maintaining hardened layer after machining to obtain finished product, mixing ferrochrome powder as strengthening agent into sand box surface paint, and includes the following steps:
and designing target components according to the hardness requirement of the roll neck hardening layer. The mass fraction of Cr on the surface is 0.2% -0.4% when the roll neck is in the range of 30-35HS (the core component can directly reach the level without additional strengthening); the mass fraction target of the surface Cr is 0.4-0.5% when the roll neck is in the range of 35-40 HS; the mass fraction of Cr on the surface of the roll neck is 0.5-0.6% when the roll neck is in the range of 40-45 HS.
The hardened layer can be still remained after the processing to the finished product through the control of the modeling size. The depth of the hardened layer after roll casting is 20-25mm by the method, so that the machining allowance of the part needing strengthening is at least 2-3mm smaller than the depth of the hardened layer, and the hardening is ensured to be uniform.
The ferrochrome powder used as the reinforcing agent is ferrochrome with the brand of FeCr55C600 or FeCr55C1000, wherein the mass fraction of C and Cr is 6% -10%, the mass fraction of Cr is 52% -60%, the mass fraction of P is less than or equal to 0.06%, the mass fraction of S is less than or equal to 0.06%, the other components are Fe or impurities, the rest materials are screened after the ferrochrome is crushed, the mesh number is consistent with that of the surface coating of the molding sand box, the ferrochrome powder is 100-800 meshes, the ferrochrome powder is mixed into the surface coating of the sand box, and the contact surface between the sand box and the roller surface is brushed before use after molding.
The adding amount of ferrochrome powder is calculated according to the mass fraction of Cr to be added and the weight of molten iron of a hardening layer: (1) the mass fraction of Cr to be added=the mass fraction of Cr of the target-core part Cr, the mass fraction of the core component Cr is designed according to the requirement of a bottom neck (lower roll neck), the lower roll neck can generally obtain a certain alloy after melting the outer layer, if the target component is A, the stokehole component is B, and the melting outer layer is estimated to obtain an alloy increment C, then B=A-C; c=weight of the etched outer layer/total weight after etching. (2) Molten iron weight of hardened layer = roll neck strengthening site surface area strengthening depth × molten iron density; (3) the Cr yield of ferrochrome powder is generally 45-55%, and can be properly adjusted according to actual production conditions; (4) ferrochrome powder addition amount= (mass fraction of Cr to be added x weight of molten iron of hardened layer)/(mass fraction of Cr of ferrochrome powder x Cr yield).
In the actual production process, because the core pouring temperature and the solidification time are slightly different, the roller with higher pouring temperature, larger specification and longer solidification time has higher yield of Cr iron powder and deeper hardening layer, and needs to be properly adjusted according to the production detection condition of the first-branch roller.
Example 1:
a centrifugal working roller for hot continuous rolling finish rolling is provided, wherein the diameter of a main shaft of a roller neck is 700mm, the length of the roller neck is 950mm, and the hardness of the main shaft of the roller neck is required to be 35-40HSD. The inner wall of the neck molding part is selected to have the diameter of 730mm and the length of 980mm according to the size. According to the outer layer component and the back erosion amount, the Cr% of the front component of the core molten iron is designed to be 0.2-0.25%, the Cr% of the reinforced surface is designed to be 0.4-0.5%, and 1.76Kg of chromium powder (52% of Cr) is calculated to be added into the reinforced cap neck. The chromium powder conforming to the components is screened for 1.76Kg and then mixed with the cavity coating in the same proportion, uniformly brushed on the inner surface of the neck-raising cavity, and dried for 24 hours for later use. The production process of the centrifugal core filling is unchanged, and after demoulding, the blank is detected to reach the expected 0.44 percent of the surface layer Cr0-950 mm of the cap neck; when the final finished product of the spindle is processed to the diameter of 700mm, the hardness is detected to be 36-38HS, so that the expected hardness is achieved.
Example 2:
a centrifugal working roller for hot continuous rolling finish rolling is provided, wherein the diameter of a main shaft of a roller neck is 420mm, the length of the roller neck is 1000mm, and the hardness of the main shaft of the roller neck is required to be 40-45HSD. The inner wall of the neck molding part is selected to have the diameter of 450mm and the length of 1030mm according to the size. According to the outer layer component and the back erosion amount, the Cr percent of the front component of the core molten iron is designed to be 0.3-0.35 percent, the Cr percent of the reinforced rear surface is designed to be 0.5-0.6 percent, and 1.13Kg of chromium powder (52 percent of Cr) is calculated to be added into the reinforced neck. Screening 1.13Kg of chromium powder conforming to the components, mixing the chromium powder with the cavity coating in the same proportion, uniformly brushing the mixture on the inner surface of the neck-raising cavity, airing the mixture for 24 hours, and drying the mixture for later use. The production process of centrifugation and core filling is unchanged, and after demolding, the blank is detected to reach the expected Cr0.53 percent of the 1000mm surface layer of the neck cap; and when the final finished product of the spindle is processed to be 420mm in diameter, detecting the hardness to be 41-44HS, and reaching the expected hardness.
The above examples are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the scope of protection defined by the claims of the present invention without departing from the spirit of the design of the present invention.
Claims (5)
1. A method for reinforcing casting performance of a roll neck of a spherical iron core centrifugal roll is characterized in that firstly, a mass fraction target of Cr is determined according to the hardness requirement of a hardening layer of the roll neck, then, the hardening layer can be still reserved after the casting is processed to a finished product through molding size control, and ferrochrome powder is mixed into a sand box surface coating to serve as a reinforcing agent.
2. The method for enhancing casting performance of the spherical iron core centrifugal roll neck according to claim 1, wherein the method comprises the following steps: the mass fraction target of the surface Cr is 0.2% -0.4% when the roll neck is in the range of 30-35 HS; the mass fraction target of the surface Cr is 0.4-0.5% when the roll neck is in the range of 35-40 HS; the mass fraction of Cr on the surface of the roll neck is 0.5-0.6% when the roll neck is in the range of 40-45 HS.
3. The method for enhancing casting performance of the spherical iron core centrifugal roll neck according to claim 1, wherein the method comprises the following steps: the depth of the hardened layer after roll casting is 20-25mm, and the machining allowance of the part needing strengthening is at least 2-3mm smaller than the depth of the hardened layer.
4. The method for enhancing casting performance of the spherical iron core centrifugal roll neck according to claim 2, wherein the method comprises the following steps: the ferrochrome powder used as the reinforcing agent is ferrochrome with the brand of FeCr55C600 or FeCr55C1000, wherein the mass fraction of C and Cr is 6-10%, the mass fraction of Cr is 52-60%, the residual materials after the ferrochrome is crushed are screened, the mesh number is consistent with that of the surface coating of the molding sand box, the mesh number is 100-800, the ferrochrome powder is mixed into the surface coating of the sand box, and the contact surface between the sand box and the roller surface is brushed after molding before use.
5. The method for enhancing the casting performance of the roll neck of the spherical iron core centrifugal roll according to claim 4, wherein the method comprises the following steps of: the adding amount of the ferrochrome powder is calculated according to the mass fraction of Cr to be added and the weight of molten iron of the hardening layer: (1) cr mass fraction to be added = Cr mass fraction target-core Cr mass fraction; (2) molten iron weight of hardened layer = roll neck strengthening site surface area strengthening depth × molten iron density; (3) the Cr yield of ferrochrome powder is generally 45% -55%; (4) ferrochrome powder addition amount= (mass fraction of Cr to be added x weight of molten iron of hardened layer)/(mass fraction of Cr of ferrochrome powder x Cr yield).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311496081.4A CN117483693A (en) | 2023-11-10 | 2023-11-10 | Method for strengthening casting performance of spherical iron core centrifugal roller neck |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311496081.4A CN117483693A (en) | 2023-11-10 | 2023-11-10 | Method for strengthening casting performance of spherical iron core centrifugal roller neck |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117483693A true CN117483693A (en) | 2024-02-02 |
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|---|---|---|---|
| CN202311496081.4A Pending CN117483693A (en) | 2023-11-10 | 2023-11-10 | Method for strengthening casting performance of spherical iron core centrifugal roller neck |
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| Country | Link |
|---|---|
| CN (1) | CN117483693A (en) |
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2023
- 2023-11-10 CN CN202311496081.4A patent/CN117483693A/en active Pending
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