CN115430820A - Method for centrifugally casting cast iron roller sleeve - Google Patents
Method for centrifugally casting cast iron roller sleeve Download PDFInfo
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- CN115430820A CN115430820A CN202211193640.XA CN202211193640A CN115430820A CN 115430820 A CN115430820 A CN 115430820A CN 202211193640 A CN202211193640 A CN 202211193640A CN 115430820 A CN115430820 A CN 115430820A
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- molten iron
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- inoculant
- inner layer
- silicon content
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- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000005266 casting Methods 0.000 title claims abstract description 39
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 384
- 229910052742 iron Inorganic materials 0.000 claims abstract description 188
- 239000002054 inoculum Substances 0.000 claims abstract description 109
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 76
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 69
- 239000010703 silicon Substances 0.000 claims abstract description 69
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 32
- 229910045601 alloy Inorganic materials 0.000 claims description 26
- 239000000956 alloy Substances 0.000 claims description 26
- 229910052799 carbon Inorganic materials 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- 230000002035 prolonged effect Effects 0.000 abstract description 10
- 230000008569 process Effects 0.000 abstract description 9
- 230000000052 comparative effect Effects 0.000 description 27
- 239000002893 slag Substances 0.000 description 9
- 238000000137 annealing Methods 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 229910000640 Fe alloy Inorganic materials 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical group [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 230000001737 promoting effect Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 238000009750 centrifugal casting Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000227425 Pieris rapae crucivora Species 0.000 description 1
- 229910001037 White iron Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005338 heat storage Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
Classifications
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- 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
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
Abstract
The application provides a method for centrifugally casting a cast iron roller sleeve, which comprises the following steps: pouring molten iron into the cavity under a centrifugal condition until the pouring amount of the molten iron reaches a first pouring amount; and continuously pouring the molten iron into the cavity, and simultaneously pouring an inoculant into the cavity so as to melt the inoculant into the molten iron to form inner-layer molten iron, continuously pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring. The molten iron is continuously injected, so that the inner layer molten iron and the outer layer molten iron can be well compounded, the inoculant with more silicon content is added into the molten iron to form the inner layer molten iron, so that the silicon content of the inner layer is more, the hardness of the inner layer is reduced, the toughness is increased, the inner layer is not easy to crack in the using process, the service life of the cast iron roller sleeve is prolonged, and meanwhile, the components of the outer layer molten iron are not changed, so that the outer layer still has good wear resistance.
Description
Technical Field
The application relates to the technical field of manufacturing cast iron roller sleeves, in particular to a method for centrifugally casting a cast iron roller sleeve.
Background
With the continuous development of brick and tile and sand making industries, the service life of the roller sleeve for the roller crushing and fine breaking section becomes a main factor restricting the development of the whole industry, and the service life of the roller sleeve is limited by the toughness and the wear resistance of the roller sleeve. The wall thickness of the roller sleeve for the roller crushing and fine breaking section in the brick and tile industry is very thin and is basically within the range of 80-100 mm. The roller sleeve made of a single material has high hardness and large brittleness, so that the roller sleeve is good in wear resistance, but poor in toughness, so that cracks are easy to appear in the using process, and the service life is short.
In order to improve the toughness of the cast iron roller sleeve, a centrifugal casting method is explored in the industry for preparing the bimetal composite cast iron roller sleeve, namely the inner layer and the outer layer of the cast iron roller sleeve are respectively prepared by materials with different components, so that the inner layer of the cast iron roller sleeve has good toughness, cracks are not easy to appear in the using process, and meanwhile, the outer layer has good wear resistance, and the service life of the cast iron roller sleeve is further prolonged.
In the actual preparation process, in order to ensure the respective performances of the inner layer and the outer layer, the outer layer of molten iron needs to be poured first, and then the inner layer of molten iron needs to be poured at intervals. However, because the wall thickness of the roll sleeve is very thin, the amount of molten iron poured into the inner layer and the outer layer is relatively small, after the outer layer molten iron is poured first, the outer layer molten iron is rapidly cooled and solidified due to cold type heat storage, and after a period of time, the outer layer molten iron is completely solidified when the inner layer molten iron is poured into the roll sleeve, so that the inner layer molten iron and the outer layer molten iron cannot be well compounded, a slag inclusion layer can be formed, the casting of the double-layer roll sleeve cannot be realized, the toughness of the cast iron roll sleeve cannot be improved, and the service life of the cast iron roll sleeve cannot be prolonged.
Disclosure of Invention
In view of the above, the present application aims to propose a method for centrifugally casting a cast iron roll shell.
In view of the above, the present application provides a method of centrifugally casting a cast iron roll shell, comprising:
pouring molten iron into the cavity under a centrifugal condition until the pouring amount of the molten iron reaches a first pouring amount;
continuously pouring the molten iron into the cavity, and simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is larger than the first pouring amount, and the silicon content in the inoculant is larger than the silicon content in the molten iron.
Further, the silicon content in the inoculant is 50-80%.
Further, the silicon content in the inoculant is 70-75%.
Further, the inoculant is ferrosilicon alloy, and the grain size of the ferrosilicon alloy is 1-3 mm.
Further, the silicon content in the inner molten iron is 1.4-1.6%.
Further, the ratio of the casting speed of the inoculant to the casting speed of the molten iron is 1-1.4: 10.
further, the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 1.2:10.
further, before the inoculant is poured into the cavity, the inoculant is heated to 500-600 ℃.
Further, the preset pouring amount is twice the first pouring amount.
Further, the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
From the above, it can be seen that in the method for centrifugally casting the cast iron roller sleeve, the molten iron is continuously injected, so that the molten iron on the inner layer and the molten iron on the outer layer can be well compounded, the inoculant with more silicon content is added into the molten iron to form the molten iron on the inner layer, so that the silicon content of the inner layer is more, the hardness of the inner layer is reduced, the toughness is increased, the inner layer is not easy to crack in the using process, meanwhile, the components of the molten iron on the outer layer are not changed, the outer layer still has good wear resistance, and the service life of the cast iron roller sleeve is prolonged.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, the present disclosure is further described in detail below with reference to specific embodiments.
It is to be noted that, unless otherwise defined, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.
As described in the background art, in order to improve the toughness of the cast iron roller sleeve, the centrifugal casting method is explored in the industry to prepare the bimetal composite cast iron roller sleeve, namely, the inner layer and the outer layer of the cast iron roller sleeve are respectively prepared by using materials with different components, so that the inner layer of the cast iron roller sleeve has good toughness, cracks are not easy to appear in the using process, meanwhile, the outer layer has good wear resistance, and the service life of the cast iron roller sleeve is prolonged.
In the actual preparation process, in order to ensure the respective performances of the inner layer and the outer layer, the outer layer molten iron is poured first, and then the inner layer molten iron is poured at intervals. However, because the wall thickness of the roll sleeve is very thin, the amount of molten iron poured into the inner layer and the outer layer is relatively small, after the outer layer molten iron is poured first, the outer layer molten iron is rapidly cooled and solidified due to cold type heat accumulation, and after the inner layer molten iron is poured into the outer layer molten iron, the inner layer molten iron and the outer layer molten iron cannot be well compounded, a slag inclusion layer can be formed, so that the casting of the double-layer roll sleeve cannot be realized, the toughness of the cast iron roll sleeve cannot be improved, and the service life of the cast iron roll sleeve cannot be prolonged.
Based on the problems, the application provides a method for centrifugally casting a cast iron roller sleeve so as to solve the problem that a double-layer roller sleeve cannot be cast.
Specifically, the application provides a method for centrifugally casting a cast iron roller sleeve, which comprises the following steps:
(1) Pouring molten iron into the cavity under a centrifugal condition until the pouring amount of the molten iron reaches a first pouring amount;
(2) Continuously pouring the molten iron into the cavity, and simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is larger than the first pouring amount, and the silicon content in the inoculant is larger than the silicon content in the molten iron.
Specifically, molten iron is poured into the cavity until the pouring amount of the molten iron reaches a first pouring amount, and the outer layer of the cast iron roller sleeve can be formed after the molten iron is solidified. And continuously pouring the molten iron into the cavity, and simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, continuously pouring until the pouring amount of the molten iron reaches a preset pouring amount, and solidifying the inner-layer molten iron (namely a mixture of the molten iron and the inoculant) to form an inner layer of the cast iron roller sleeve. Because the molten iron is injected continuously, when the molten iron in the inner layer is injected, the outer layer can not be solidified completely, so that the outer layer and the inner layer can be compounded well, a slag inclusion layer can not be formed between the inner layer and the outer layer, and the double-layer roller sleeve can be cast successfully.
Meanwhile, the inoculant with more silicon content is added into the molten iron to form the inner layer molten iron, so that the silicon content of the inner layer is more, the hardness of the inner layer is reduced, the toughness is increased, the inner layer is not prone to cracking in the using process, meanwhile, the components of the outer layer molten iron are not changed, the outer layer still has good wear resistance, and the service life of the cast iron roller sleeve is prolonged.
The silicon content in the inoculant is 50-80%, and further the silicon content in the inoculant is 70-75%. Specifically, the silicon content in the inoculant can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc. When the silicon content in the inoculant is 50-80%, the silicon content in the inoculant is moderate, so that the silicon content in the molten iron of the inner layer formed after the inoculant is added is obviously improved, the toughness of the inner layer is obviously improved, the hardness of the inner layer is reduced, and meanwhile, the inner layer can be ensured to have certain wear resistance. When the silicon content in the inoculant is less than 50%, the silicon content in the inoculant is not high enough, so that the silicon content in the molten iron in the inner layer cannot be obviously improved, and the toughness of the inner layer cannot be obviously improved; when the silicon content in the inoculant is more than 80%, the silicon content in the inoculant is too high, so that the silicon content in the molten iron in the inner layer can be obviously improved, and the toughness of the inner layer is further obviously improved.
The inoculant is a ferrosilicon alloy, the grain size of the ferrosilicon alloy is 1-3 mm, and specifically, the grain size of the ferrosilicon alloy can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm and the like. When the particle size of ferrosilicon is 1 ~ 3mm, the particle size of ferrosilicon is moderate for ferrosilicon both can melt in the molten iron completely, can not have too big scaling loss in the molten iron again, can effectively promote the silicon content in the inlayer molten iron. When the grain size of the ferrosilicon alloy is smaller than 1mm, the grain size of the ferrosilicon alloy is too small, so that the ferrosilicon alloy is easily seriously burnt and damaged after entering high-temperature molten iron, and after the burnt ferrosilicon alloy absorbs oxygen in air, impurities such as silicon dioxide and the like are formed and dissociated in the molten iron in the inner layer, so that silicon in the ferrosilicon alloy cannot be effectively absorbed by the molten iron in the inner layer, the silicon content of the molten iron in the inner layer cannot be obviously improved, and some impurities also exist in the molten iron in the inner layer; when the grain size of the ferrosilicon is larger than 3mm, the grain size of the ferrosilicon is too large, so that the ferrosilicon cannot be completely melted by molten iron, and finally, dross is formed in the molten iron of the inner layer, and the toughness of the inner layer is damaged.
The ferrosilicon alloy comprises the following components: 70-75% of Si, 21-28% of Fe and 2-4% of C. The component content of the ferrosilicon alloy is adjusted, so that the ferrosilicon alloy can better play a role in improving the toughness of the inner layer.
The content of silicon in the molten iron of the inner layer is 1.4-1.6%, and specifically, the content of silicon in the molten iron of the inner layer can be 1.4%, 1.45%, 1.5%, 1.55%, 1.6%, and the like. When the silicon content in the inner molten iron is 1.4-1.6%, the silicon content in the inner molten iron is moderate, so that the formed inner layer has good toughness and proper wear resistance. When the silicon content in the molten iron of the inner layer is less than 1.4 percent, the silicon content in the molten iron of the inner layer is too low, so that the formed inner layer is too brittle and has insufficient toughness; when the silicon content of the inner molten iron is more than 1.6%, the silicon content of the inner molten iron is so high that the formed inner layer has good toughness but poor wear resistance.
The ratio of the casting speed of the inoculant to the casting speed of the molten iron is 1-1.4: 10, further, the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 1.2:10. specifically, the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron may be 1:10. 1.1: 10. 1.2:10. 1.3: 10. 1.4:10, etc. The pouring speed is the pouring amount in unit time. When the ratio of the casting speed of the inoculant to the casting speed of the molten iron is 1-1.4: and when 10 hours, the proportion of the inoculant and the molten iron added simultaneously is moderate, so that the inoculant can be completely melted in the molten iron, and the silicon content of the molten iron in the inner layer is moderate. When the ratio of the casting speed of the inoculant to the casting speed of the molten iron is less than 1: when 10 hours, the adding speed of the inoculant is too slow, and the adding amount of the inoculant in the same time is too small, so that the silicon content in the formed molten iron of the inner layer cannot be obviously improved, and the toughness of the inner layer cannot be obviously improved; when the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is more than 1.4: at 10 hours, the addition speed of the inoculant is too high, the addition amount of the inoculant in the same time is too much, so that the inoculant cannot be completely melted in molten iron, and the unmelted inoculant is remained in the molten iron at the inner layer as slag so as to influence the toughness of the inner layer.
Before the inoculant is poured into the cavity, the inoculant is heated to 500-600 ℃. Specifically, the inoculant may be first heated to 500 ℃, 520 ℃, 540 ℃, 560 ℃, 580 ℃, 600 ℃, or the like. The inoculant is heated to 500-600 ℃, so that the temperature of the molten iron is not reduced too severely after the inoculant is added, and the molten iron still has good fluidity. When the temperature of the inoculant is lower than 500 ℃, the temperature of the inoculant is too low, and the molten iron is cooled too fast after the inoculant is added, so that the liquidity of the molten iron is reduced, the liquidity of the molten iron is poor, and the molten iron in the cavity cannot be quickly and uniformly paved on the inner layer of the roller sleeve under the action of centrifugal force; when the temperature of the inoculant is higher than 600 ℃, the temperature of the inoculant is too high, so that the temperature of molten iron after the inoculant is added is too high, the subsequent casting heat preservation process is difficult, and the casting process is difficult to control.
The preset pouring amount is twice of the first pouring amount, so that the pouring amount of the inner layer is the same as that of the outer layer, and finally a uniform double-layer roller sleeve with the thickness ratio of the inner layer to the outer layer being 1 is formed.
The molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe. The component proportion of the molten iron is adjusted, so that the outer layer of the obtained roll sleeve has good wear resistance.
Example 1
A method for centrifugally casting a cast iron roll shell comprises the following steps:
(1) Pouring molten iron into the cavity under a centrifugal condition (the rotating speed of a centrifugal machine is 550-600 revolutions per minute) until the pouring amount of the molten iron reaches a first pouring amount; the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
(2) Continuously pouring the molten iron into the cavity, simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, continuously pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is twice of the first pouring amount, and the silicon content in the inoculant is greater than that in the molten iron.
The inoculant is a silicon-iron alloy, the silicon content in the inoculant is 50%, and the grain size of the silicon-iron alloy is 1mm. The ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 1:10. the inoculant was heated to 500 ℃ prior to the inoculant being poured into the mold cavity.
Wherein the silicon content in the molten iron of the inner layer is 1.4 percent.
(3) And after the pouring is finished, adding the covering slag into the inner hole for heat preservation, and promoting the molten iron to be sequentially solidified in the wall thickness direction of the roller sleeve. And (3) operating for 1.5-2 hours, stopping the centrifugal machine, opening the roller sleeve, demoulding, feeding into a kiln, heating to 550 ℃, preserving heat for 20-25 hours, performing stress relief annealing, and processing after annealing to obtain a finished product of the cast iron roller sleeve.
Example 2
A method of centrifugally casting cast iron roll shells comprising the steps of:
(1) Pouring molten iron into the cavity under a centrifugal condition (the rotating speed of a centrifugal machine is 550-600 revolutions per minute) until the pouring amount of the molten iron reaches a first pouring amount; the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
(2) Continuously pouring the molten iron into the cavity, simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, continuously pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is twice of the first pouring amount, and the silicon content in the inoculant is greater than that in the molten iron.
The inoculant is a ferrosilicon alloy, the silicon content in the inoculant is 80%, and the particle size of the ferrosilicon alloy is 3mm. The ratio of the casting speed of the inoculant to the casting speed of the molten iron is 1.4:10. the inoculant was heated to 600 ℃ prior to the introduction of the inoculant into the mold cavity.
Wherein the silicon content in the molten iron of the inner layer is 1.6 percent.
(3) And after the pouring is finished, adding the covering slag into the inner hole for heat preservation, and promoting the molten iron to be sequentially solidified in the wall thickness direction of the roller sleeve. And (3) operating for 1.5-2 hours, stopping the centrifugal machine, opening the roller sleeve, demoulding, feeding the roller sleeve into a kiln, heating to 550 ℃, preserving heat for 20-25 hours, performing stress relief annealing, and processing after annealing to obtain a finished product of the cast iron roller sleeve.
Example 3
A method for centrifugally casting a cast iron roll shell comprises the following steps:
(1) Pouring molten iron into the cavity under a centrifugal condition (the rotating speed of a centrifugal machine is 550-600 revolutions per minute) until the pouring amount of the molten iron reaches a first pouring amount; the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
(2) Continuously pouring the molten iron into the cavity, simultaneously pouring an inoculant into the cavity so as to melt the inoculant into the molten iron to form inner molten iron, continuously pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is twice of the first pouring amount, and the silicon content in the inoculant is greater than that in the molten iron.
The inoculant is a silicon-iron alloy, the silicon content in the inoculant is 70%, and the grain size of the silicon-iron alloy is 2mm. The ratio of the casting speed of the inoculant to the casting speed of the molten iron is 1.2:10. the inoculant was heated to 550 ℃ prior to the inoculant being poured into the mold cavity.
Wherein the silicon content in the inner molten iron is 1.5%.
(3) And after the pouring is finished, adding the covering slag into the inner hole for heat preservation, and promoting the molten iron to be sequentially solidified in the wall thickness direction of the roller sleeve. And (3) operating for 1.5-2 hours, stopping the centrifugal machine, opening the roller sleeve, demoulding, feeding the roller sleeve into a kiln, heating to 550 ℃, preserving heat for 20-25 hours, performing stress relief annealing, and processing after annealing to obtain a finished product of the cast iron roller sleeve.
Comparative example 1
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the silicon content in the inoculant was 30%.
Comparative example 2
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the silicon content in the inoculant is 90%.
Comparative example 3
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the grain diameter of the ferrosilicon alloy is 0.5mm.
Comparative example 4
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the grain diameter of the ferrosilicon alloy is 3.5mm.
Comparative example 5
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 0.8:10.
comparative example 6
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 1.6:10.
comparative example 7
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the silicon content in the molten iron of the inner layer is 1.3%.
Comparative example 8
A method of centrifugally casting a cast iron sleeve, which differs from example 3 in that: the silicon content in the molten iron of the inner layer is 1.7%.
Comparative example 9
A method for centrifugally casting a cast iron roll shell comprises the following steps:
(1) Pouring molten iron into the cavity under a centrifugal condition (the rotating speed of a centrifugal machine is 550-600 revolutions per minute) until the pouring amount of the molten iron reaches a preset pouring amount; the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
(2) And after pouring, adding covering slag into the inner hole for heat preservation, and promoting molten iron to solidify in sequence in the wall thickness direction of the roller sleeve. And (3) operating for 1.5-2 hours, stopping the centrifugal machine, opening the roller sleeve, demoulding, feeding the roller sleeve into a kiln, heating to 550 ℃, preserving heat for 20-25 hours, performing stress relief annealing, and processing after annealing to obtain a finished product of the cast iron roller sleeve.
The properties of the inner layer and the outer layer of the cast iron sleeve prepared in the above examples and comparative examples were measured, and the measurement results are detailed in table 1 below. Wherein, the inner layer performance and the outer layer performance both comprise Rockwell Hardness (HRC) and tensile strength, and the service life is the service life of the whole roller sleeve.
TABLE 1 Experimental data and test results tabulation of examples and comparative examples
As can be seen from table 1 above, overall, the cast iron roller shell prepared in the embodiment has the advantages that the hardness of the inner layer is low, the tensile strength is high, the toughness of the inner layer is good, the strength of the outer layer is high, the tensile strength is poor, the hardness of the outer layer is good, and the wear resistance is good, so that the service life of the whole roller shell reaches 9-10 months.
Comparative example 1, which has the outer layer of unchanged properties, the inner layer of higher hardness and lower tensile properties, compared to example 3, demonstrates that the toughness of the inner layer is not so good that cracks still occur during use, thereby resulting in a shorter service life. This is because the silicon content in the inoculant in comparative example 1 is too small to significantly increase the silicon content in the molten iron of the inner layer, and thus the toughness of the inner layer cannot be significantly increased, and the service life thereof cannot be significantly increased.
Comparative example 2, which has the same properties as example 3 in the outer layer, lower hardness and higher tensile properties in the inner layer, demonstrates good toughness in the inner layer, but still has a shorter service life than example 3. This is because the silicon content in the inoculant in the comparative example 2 is too high, and although the silicon content in the molten iron of the inner layer can be remarkably increased, and the toughness of the inner layer can be remarkably improved, the wear resistance of the inner layer is greatly reduced due to the too high silicon content in the inner layer, so that the service life of the inoculant is shortened.
Comparative example 3, in which the properties of the outer layer were not changed, the hardness of the inner layer was high and the tensile properties were low, demonstrated that the toughness of the inner layer was not so good that cracks still occurred during use, thereby resulting in a short service life. The reason is that the grain size of the ferrosilicon alloy in the comparative example 3 is too small, so that the ferrosilicon alloy is easily seriously burnt after entering the high-temperature molten iron, and impurities such as silicon dioxide and the like are formed after the burnt ferrosilicon alloy absorbs oxygen in air and are dissociated in the molten iron in the inner layer, so that silicon in the ferrosilicon alloy cannot be effectively absorbed by the molten iron in the inner layer, the silicon content of the molten iron in the inner layer cannot be obviously improved, and impurities also exist in the molten iron in the inner layer, so that the toughness of the ferrosilicon alloy is not obviously improved, and the service life of the ferrosilicon alloy cannot be obviously prolonged.
Comparative example 4, which has the same properties as example 3 in the outer layer, higher hardness and poorer tensile properties in the inner layer, demonstrates that the toughness of the inner layer is not so good and the service life thereof is still less than example 3 because the grain size of the ferrosilicon alloy in comparative example 4 is so large that the ferrosilicon alloy cannot be completely melted by molten iron, and finally dross is formed in the molten iron in the inner layer to deteriorate the toughness of the inner layer, which cannot be significantly increased.
Comparative example 5, in which the outer layer properties were unchanged, the inner layer hardness was higher and the tensile properties were lower, demonstrated that the toughness of the inner layer was not so good that cracks still occurred during use, thereby resulting in a shorter service life, as compared to example 3. This is because the pouring speed of the inoculant in the comparative example 5 is smaller than that of the molten iron, the adding speed of the inoculant is too slow, and the adding amount of the inoculant in the same time is too small, so that the silicon content in the molten iron of the inner layer cannot be obviously improved, the toughness of the inner layer cannot be obviously improved, and the service life of the molten iron cannot be obviously prolonged.
Comparative example 6, in comparison with example 3, in which the properties of the outer layer were not changed, the hardness of the inner layer was high and the tensile properties were low, demonstrated that the toughness of the inner layer was not so good that cracks still occurred during use, thereby resulting in a short service life. This is because the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron in comparative example 6 is too large, the addition speed of the inoculant is too high, the addition amount of the inoculant in the same time is too large, so that the inoculant cannot be completely melted in the molten iron, and the unmelted inoculant remains as slag in the molten iron in the inner layer, so that the toughness of the molten iron in the inner layer is affected, and the service life of the inoculant cannot be significantly increased.
Comparative example 7, which has the outer layer having the same properties as example 3, the inner layer having a higher hardness and a lower tensile strength, demonstrates that the toughness of the inner layer is not so good that cracks still occur during use, thereby resulting in a shorter service life. This is because the silicon content in the molten iron of the inner layer in comparative example 7 was reduced, so that the formed inner layer was too brittle and insufficient in toughness, and the service life thereof could not be significantly increased.
Comparative example 8, which has the same properties as example 3 in the outer layer, lower hardness and higher tensile properties in the inner layer, demonstrates good toughness in the inner layer, but still has a shorter service life than example 3. This is because the silicon content in the inner molten iron is so high that the toughness of the formed inner layer is good, but the wear resistance of the inner layer is greatly lowered due to the too high silicon content in the inner layer, so that the service life thereof is shortened.
Comparative example 9 is the manufacturing method of the existing cast iron roller shell, and the prepared cast iron roller shell is a single material, has no difference between an inner layer and an outer layer, has high hardness, large brittleness and no toughness, and is easy to crack in the using process, so the service life of the cast iron roller shell is very short.
From the above, it can be seen that in the method for centrifugally casting the cast iron roller shell, the molten iron is continuously injected, so that the molten iron on the inner layer and the molten iron on the outer layer can be well compounded, the inoculant with higher silicon content is added into the molten iron to form the molten iron on the inner layer, so that the silicon content of the inner layer is higher, the hardness of the inner layer is reduced, the toughness is increased, the inner layer is not easy to crack in the using process, meanwhile, the components of the molten iron on the outer layer are not changed, the outer layer still has good wear resistance, and finally the service life of the cast iron roller shell is prolonged.
The roller sleeve solves the problems that the common white cast iron roller sleeve cannot be used for a roller crushing section due to poor toughness and cracking, the cast iron roller sleeve made of a single material is high in brittleness and easy to crack, the thin-wall roller sleeve cannot realize centrifugal inner and outer layering, and the problem that inoculant is added along with molten iron to enable molten iron to be cooled quickly and cause poor flowability is solved.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the concept of the present disclosure, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of brevity.
The disclosed embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the embodiments of the disclosure are intended to be included within the scope of the disclosure.
Claims (10)
1. A method of centrifugally casting a cast iron sleeve, comprising:
pouring molten iron into the cavity under a centrifugal condition until the pouring amount of the molten iron reaches a first pouring amount;
continuously pouring the molten iron into the cavity, and simultaneously pouring an inoculant into the cavity so as to enable the inoculant to be melted in the molten iron to form inner-layer molten iron, pouring until the pouring amount of the molten iron reaches a preset pouring amount, and stopping pouring; wherein the preset pouring amount is larger than the first pouring amount, and the silicon content in the inoculant is larger than the silicon content in the molten iron.
2. The method of claim 1, wherein the silicon content in the inoculant is between 50% and 80%.
3. The method of claim 1, wherein the silicon content in the inoculant is between 70% and 75%.
4. The method of claim 3, wherein the inoculant is a ferrosilicon alloy having a grain size of 1 to 3mm.
5. The method according to claim 1, wherein the silicon content in the molten iron of the inner layer is 1.4-1.6%.
6. The method of claim 1, wherein the ratio of the pouring speed of the inoculant to the pouring speed of the molten iron is 1-1.4: 10.
7. the method of claim 1, wherein the ratio of the pouring rate of the inoculant to the pouring rate of the molten iron is 1.2:10.
8. the method of claim 1, wherein the inoculant is heated to a temperature of between 500 and 600 ℃ prior to the inoculant being poured into the mold cavity.
9. The method of claim 1, wherein the pre-set amount of pour is twice the first amount of pour.
10. The method according to claim 1, wherein the molten iron comprises the following components: 3.2 to 3.6 percent of C, 0.5 to 0.7 percent of Si, 0.4 to 0.6 percent of Mn, less than or equal to 0.1 percent of P, less than or equal to 0.06 percent of S, 0.2 to 0.6 percent of Cr, 0.2 to 0.6 percent of Mo, and the balance of Fe.
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