Centrifugal casting method of high-chromium cast iron floating oil seal

Abstract

The invention provides a centrifugal casting method for a high-chromium cast iron floating oil seal, and solves the technical problems that in the prior art, the manufacturing process of the high-chromium cast iron floating oil seal manufactured through shell mold casting is complex, and the performance of the manufactured high-chromium cast iron floating oil seal is unstable. According to the centrifugal casting method for the high-chromium cast iron floating oil seal, the centrifugal casting process is adopted for casting high-chromium cast iron, a mold filling channel of a casting is short, the heat conduction speed of a mold material is higher than that of precoated sand, and it is found through HV hardness and metallographic inspection that the casting is good in structure uniformity, fine in grain crystal and free of segregation. In addition, a graphite mold or a metal mold is adopted as a mold for centrifugal casting, so that the high-temperature resistance is good, the mold can be reused, and the service life is long; the casting is high in dimensional precision and good in stability; the production process is short, the production efficiency is high, and the production cost is greatly reduced; the production process does not generate solid waste, is clean and environment-friendly, and has very high environment-friendly value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of casting, in particular to a centrifugal casting method of a high-chromium cast iron floating oil seal. BACKGROUND

[0002] The floating oil seal is a dynamic sealing device widely used in the fields of engineering machinery and mining machinery, which can achieve reliable sealing effect under harsh working conditions (such as environments with a lot of coal dust, silt, water vapor, etc.). The core function of the floating oil seal is to prevent lubricating oil leakage and to prevent external pollutants from entering the equipment interior, thereby ensuring the normal operation of mechanical parts. Generally, the floating oil seal is mainly used for chassis components of track-type engineering vehicles in agriculture, engineering, mining, etc., such as excavators or bulldozers.

[0003] Most of the existing high-chromium cast iron floating oil seals are manufactured by using shell mold casting process. However, the shell mold casting process generally needs to go through the following stages to produce the floating oil seal: molding stage, clamping stage, pouring stage, unclamping and sand cleaning stage, pouring and sprue polishing stage, rough machining and deburring stage, outer surface machining stage, heat treatment stage, process inspection stage, grinding and polishing stage, polishing stage, cleaning stage, and finished product inspection stage. Therefore, the manufacturing process is complicated.

[0004] This process generally uses coated sand shell molding. During pouring, the molten iron flows to fill the mold under gravity, which is slow and difficult to discharge gas. Meanwhile, the high-temperature molten iron can also cause the shell mold to collapse during pouring, resulting in surface sanding and sand holes. Therefore, the floating oil seal sealing surface has a high proportion of pores and sand hole defects.

[0005] The shell mold casting of high-chromium cast iron floating oil seals can produce surface sand sticking and size instability defects, and the outer surface generally needs to be machined by numerical control turning or grinding. For cases with heavy surface sand sticking and poor size accuracy of the castings, numerical control turning is needed to machine the outer surface. After the polishing stage of the pouring and sprue and the rough machining stage, an annealing heat treatment stage is added. After annealing, the outer surface is machined by numerical control turning, which needs to go through two high-temperature heat treatments, resulting in large heat treatment deformation and machining stress. SUMMARY

[0006] Therefore, the present application provides a centrifugal casting method of a high-chromium cast iron floating oil seal, which solves the technical problems of complicated manufacturing process of the high-chromium cast iron floating oil seal manufactured by using the shell mold casting in the prior art, and unstable performance of the manufactured high-chromium cast iron floating oil seal.

[0007] In order to achieve the above object, the application provides the following technical scheme: a centrifugal casting method of high chromium cast iron floating oil seal, comprising: preparing molten iron so that the composition of the molten iron is within the standard range of high chromium cast iron, wherein the high chromium cast iron comprises the following components by weight: C 3.8-4.2 Wt%; Si 0.5-2.5 Wt%; Mn 0.4-1.2 Wt%; Cr 15-19 Wt%; Mo 1.5-2.5 Wt%; Ni 0.5-1.5 Wt%; and the rest is Fe; heating the molten iron and controlling the temperature of the molten iron within a target temperature range; casting the molten iron by using a centrifugal process to obtain a high chromium cast iron floating oil seal blank; performing an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding on the high chromium cast iron floating oil seal blank to obtain a high chromium cast iron floating oil seal finished product.

[0008] In an embodiment of the application, the outer surface treatment process comprises: using a PA / F 60L bonded corundum grinding wheel to perform 60 seconds of grinding processing on the inner hole of the high chromium cast iron floating oil seal blank at a processing pressure of 0.25 MPa and a rotary speed of the bonded corundum grinding wheel of 300 rpm.

[0009] In an embodiment of the application, the heat treatment process comprises: quenching the high chromium cast iron floating oil seal blank by using a preset heating rate to heat the high chromium cast iron floating oil seal blank to 920-980℃, keeping the temperature for half an hour, and then taking out the high chromium cast iron floating oil seal blank and air cooling.

[0010] In an embodiment of the application, the preset heating rate is 30℃ / min.

[0011] In an embodiment of the application, the centrifugal process comprises: controlling the top die mechanism to fall back so that the mold falls and closes; starting the centrifugal device so that the centrifugal device rotates at a preset centrifugal speed; directly pouring a certain amount of molten iron into the rotating mold cavity to form a casting, and starting a timer to make the casting last for a preset time, and the molten iron rapidly fills the mold outward from the pouring point under the action of centrifugal force; stopping the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high chromium cast iron floating oil seal blank, and the high chromium cast iron floating oil seal blank is obtained.

[0012] In an embodiment of the application, the preset centrifugal speed is 600-1500 rpm.

[0013] In an embodiment of the present application, when the weight percentage of C is 4.1 Wt%, the preset centrifugal speed is a first preset centrifugal speed, and the preset centrifugal speed increases by 200 rpm for each 0.1 Wt% decrease in the weight percentage of C.

[0014] In an embodiment of the present application, the preset initial centrifugal speed of the centrifugal device is 600 rpm, and the initial rotary speed of the bonded corundum grinding wheel is an initial preset speed, which is 200 rpm. In an embodiment of the present application, the initial rotary speed of the bonded corundum grinding wheel increases by 15 rpm for each 200 rpm increase in the preset centrifugal speed of the centrifugal device.

[0015] In an embodiment of the present application, when the centrifugal device is started, the centrifugal device runs at a first preset centrifugal speed until the molten iron is poured. After the molten iron is poured, the centrifugal device is controlled to accelerate to a second preset centrifugal speed within a first preset time period, and runs at the second preset centrifugal speed for a second preset time period, wherein the first preset centrifugal speed is less than the second preset centrifugal speed.

[0016] In an embodiment of the present application, the target temperature range is 1520-1580℃.

[0017] The present application provides a centrifugal casting method of a high-chromium cast iron floating oil seal. The high-chromium cast iron is cast by using a centrifugal casting process. The casting filling channel is short, the heat conduction speed of the mold material is faster than that of the coated sand, and it is found through HV hardness and metallographic examination that the castings have good uniformity of microstructure, fine grain size, and no segregation phenomenon. In addition, the mold used in the centrifugal casting is a graphite mold or a metal mold, which has good high-temperature resistance, can be reused, has a long service life, high dimensional accuracy of the castings, and good stability. The production process is short, the production efficiency is high, and the production cost is greatly reduced. The production process does not produce solid waste, is clean and environmentally friendly, and has high environmental value. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description thereof provided in conjunction with the accompanying drawings. The drawings provided in the specification and the specifications constitute a part of the detailed description of the present application and serve to explain the present application together with the embodiments of the present application, but do not limit the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0019] Figure 1 Fig. 2 shows a metallographic structure diagram of a high-chromium cast iron floating oil seal provided by an embodiment of the present application, which is magnified 200 times.

[0020] Figure 2 Fig. 3 shows a metallographic structure diagram of a high-chromium cast iron floating oil seal provided by another embodiment of the present application, which is magnified 500 times. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0022] The present application provides a high chromium cast iron floating oil seal, which comprises the following components by weight: C 3.8-4.2 Wt%; Si 0.5-2.5 Wt%; Mn 0.4-1.2 Wt%; Cr 15-19 Wt%; Mo 1.5-2.5 Wt%; Ni 0.5-1.5 Wt%; and the rest is Fe.

[0023] The present application provides a centrifugal casting method of a high chromium cast iron floating oil seal, which specifically comprises the following steps: S101: preparing the iron liquid so that the composition of the iron liquid is within the standard range of high chromium cast iron, wherein the high chromium cast iron comprises the following components by weight: C 3.8-4.2 Wt%; Si 0.5-2.5 Wt%; Mn 0.4-1.2 Wt%; Cr 15-19 Wt%; Mo 1.5-2.5 Wt%; Ni 0.5-1.5 Wt%; and the rest is Fe.

[0024] Specifically, the preparation of the iron liquid can specifically comprise the following steps: according to the standard requirements of the high chromium cast iron, the alloy raw materials are put into the intermediate frequency furnace for smelting, and after smelting, the composition of the castings is detected by a spectrometer and adjusted to be within the standard range of high chromium cast iron; that is, the weight percentage content range of the main elements of the high chromium cast iron is C 3.8-4.2 Wt%; Si 0.5-2.5 Wt%; Mn 0.4-1.2 Wt%; Cr 15-19 Wt%; Mo 1.5-2.5 Wt%; Ni 0.5-1.5 Wt%, and the rest is the inevitable impurities generated during iron smelting.

[0025] S102: heating the iron liquid and controlling the temperature of the iron liquid to be within a target temperature range; Specifically, the target temperature range is 1520-1580℃.

[0026] That is, S102 is to purify the iron liquid according to the operation process, detect the temperature of the iron liquid by a contact type temperature gun, control the temperature of the iron liquid to be 1520-1580℃, and then pour out of the furnace for pouring.

[0027] S103: pouring the iron liquid by using a centrifugal process to obtain a high chromium cast iron floating oil seal blank; S104: performing an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding on the high chromium cast iron floating oil seal blank to obtain a high chromium cast iron floating oil seal finished product.

[0028] Optionally, the heat treatment process comprises: the high chromium cast iron floating oil seal blank is heated to 920-980℃ at a preset heating rate, and is kept for half an hour, and is quenched by the way of furnace out blast cooling, so as to obtain a microstructure of lath-shaped carbide uniformly distributed on a martensite matrix and a small amount of residual austenite, as shown in FIGS. 1 and 2. The Rockwell hardness thereof can reach HRc65 or above. Figure 1 and Figure 2

[0029] Optionally, the preset heating rate can be 30℃ / min.

[0030] Optionally, the outer surface treatment process comprises: the inner hole of the high chromium cast iron floating oil seal blank is ground for 60 seconds by using a PA / F 60L corundum grinding wheel at a processing pressure of 0.25MPa and a rotary speed of the corundum grinding wheel being a preset rotary speed, wherein the preset rotary speed is 200-300rpm, so as to eliminate slight concave and unevenness of the inner diameter caused by centrifugal force and casting cold shrinkage.

[0031] Optionally, the preset initial centrifugal speed of the centrifugal device is 600rpm, and the initial rotary speed of the corundum grinding wheel is an initial preset rotary speed, and the initial preset rotary speed is 200rpm; wherein, the preset centrifugal speed of the centrifugal device is increased by 200rpm, and the initial rotary speed of the corundum grinding wheel is increased by 15rpm. That is, when the preset centrifugal speed of the centrifugal device is increased by 200rpm on the basis of 600rpm, the initial rotary speed of the corundum grinding wheel is increased by 15rpm in the corresponding post-processing process, for example, when the preset centrifugal speed of the centrifugal device is 800rpm, the preset rotary speed of the corundum grinding wheel in the corresponding post-processing process is 215rpm. .

[0032] Optionally, the semi-finished product inspection can be performed by inspecting the appearance and roundness of the semi-finished product.

[0033] Optionally, the inner spherical surface grinding can be performed by controlling the granularity and grinding speed of the grinding abrasive to control the grinding surface roughness to be below Ra0.2, so as to obtain a lubrication and cooling channel of the floating oil seal grinding surface when sealing.

[0034] Optionally, the sealing surface grinding can be performed by controlling the flatness of the grinding disc to be less than 0.01mm and the grinding time to be greater than 30min, so as to make the flatness of the floating oil seal grinding surface be below 0.05mm, and to make the floating oil seal reach the best sealing performance state.

[0035] ​The high-chromium cast iron floating oil seal blank is post-processed to meet the corresponding size requirements and the surface roughness and flatness required by the sealing performance, so as to obtain the high-chromium cast iron floating oil seal semi-finished product; the high-chromium cast iron floating oil seal semi-finished product is cleaned and inspected, so as to obtain the high-chromium cast iron floating oil seal finished product. The centrifugal casting method for the high-chromium cast iron floating oil seal provided in the application adopts the centrifugal casting process to cast the high-chromium cast iron, the filling channel of the casting is short, the heat conduction speed of the mold material is faster than that of the coated sand, and it is found through the HV hardness and metallographic inspection that the casting has good uniformity of the organization, small grain size and no segregation phenomenon. In addition, the mold used in the centrifugal casting adopts a graphite mold or a metal mold, has good high-temperature resistance, can be reused, has a long service life, the casting has high size precision and good stability, the production process is short, the production efficiency is high, and the production cost is greatly reduced; the production process does not produce solid waste, is clean and environmentally friendly, and has high environmental protection value.

[0036] Optionally, the centrifugal process comprises: (1) cleaning impurities in the mold; Specifically, the physical method, ultrasonic cleaning method or chemical cleaning method can be used to clean the impurities in the mold. The specific cleaning method is not limited in the application as long as the impurities in the mold can be cleaned.

[0037] (2) controlling the top die mechanism to fall back so that the mold falls and closes; (3) starting the centrifugal device to rotate the mold at a preset centrifugal speed; Specifically, the preset centrifugal speed is 600-1500 rpm.

[0038] Optionally, when the weight percentage of C is 4.1 Wt%, the preset centrifugal speed is a first preset centrifugal speed, and when the weight percentage of C changes by 0.1 Wt%, the preset centrifugal speed changes by 200 rpm. For example, when the weight percentage of C is 4.2 Wt%, the preset centrifugal speed used is the first preset centrifugal speed, and the first preset centrifugal speed is 600 rpm, then for each decrease of 0.1 Wt%, the corresponding preset centrifugal speed used increases by 200 rpm, for example, when the weight percentage of C is 4.1 Wt%, the preset centrifugal speed used is 800 rpm, and when the weight percentage of C is 4.2 Wt%, the preset centrifugal speed used is 1000 rpm. The preset centrifugal speed changes with the change of the weight percentage of C, which avoids the situation that the components with large specific gravity are concentrated on the outside and the components with small specific gravity are concentrated on the inner diameter, and reduces the probability of segregation.

[0039] Specifically, the mold is a graphite mold or a metal mold.

[0040] When the centrifugal device is started, the centrifugal device rotates at a first preset centrifugal speed until the iron liquid is poured. Specifically, the first preset centrifugal speed can be 600 rpm.

[0041] (4) a quantitative iron liquid is directly poured into a rotating mold cavity to cast a mold, and a timer is started to cast the mold for a preset time, and the iron liquid is rapidly filled from the pouring point under the action of centrifugal force; When the iron liquid is poured, the centrifugal device is controlled to accelerate to a second preset centrifugal speed within a first preset time (for example, the first preset time is 10 seconds), and rotate at a second preset centrifugal speed for a second preset time (for example, the second preset time is 60 seconds), wherein the first preset centrifugal speed is less than the second preset centrifugal speed.

[0042] The second preset centrifugal speed can be the highest centrifugal speed, for example, the second preset centrifugal speed is 1500 rpm.

[0043] The preset time is the centrifugal time, which is the necessary process for the casting to achieve a specific controlled organization conversion and size stability during the casting process. Dividing the centrifugal time into a first preset time (speed acceleration time) and a second preset time (uniform speed centrifugal time) can reduce the generation of residual austenite undesirable organization, eliminate casting stress, and have high size stability.

[0044] In order to better understand the present application, the present application will be described in detail below with specific examples. Example 1

[0045] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S10: The ingredients are prepared according to the standard requirements of high-chromium cast iron, and the prepared alloy raw materials are put into a medium-frequency furnace for melting. After melting, the casting is detected by a spectrometer and the composition of the iron liquid is adjusted within the standard range of high-chromium cast iron. Among them, the high-chromium cast iron includes the following components by weight: C 3.8 Wt%; Si 0.5 Wt%; Mn 0.4 Wt%; Cr 15 Wt%; Mo 1.5 Wt%; Ni 0.5 Wt%; and the rest is Fe; S11: Purify the iron liquid according to the operation process, detect the temperature of the iron liquid with a contact type temperature measuring gun, control the temperature of the iron liquid to 1520℃, and then pour out and pour.

[0046] S12: clean the metal mold of impurities; control the top die mechanism to fall back so that the mold falls and closes; start the centrifugal device to make the mold rotate at a speed of 1500 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to form a casting, and start a timer to make the casting for a preset time, the molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 1500 rpm in 10 seconds, and rotates at 1500 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0047] S13: The high-chromium cast iron floating oil seal blank is subjected to an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding to obtain a high-chromium cast iron floating oil seal finished product.

[0048] The specific outer surface treatment process is that the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L bonded corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the bonded corundum grinding wheel is 200 rpm.

[0049] The heat treatment process is that the high-chromium cast iron floating oil seal blank is heated to 980℃ at a heating rate of 30℃ / min, and is kept for half an hour, and is quenched by air cooling. Example 2:

[0050] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S20: The alloy raw materials are put into the medium-frequency furnace according to the standard requirements of high-chromium cast iron, and the alloy raw materials are melted after the melting, and the composition of the castings is detected by a spectrometer and adjusted to be within the standard range of high-chromium cast iron. The high-chromium cast iron includes the following components by weight: C 4.2 Wt%; Si 2.5 Wt%; Mn 1.2 Wt%; Cr 19 Wt%; Mo 2.5 Wt%; Ni 1.5 Wt%; and the rest is Fe; S21: The molten iron is purified according to the operation process, the temperature of the molten iron is detected by a contact type temperature measuring gun, the temperature of the molten iron is controlled to 1580℃, and then the molten iron is poured out.

[0051] S22: clean the metal mold of impurities; control the top die mechanism to fall back so that the mold falls and closes; start the centrifugal device to make the mold rotate at a speed of 600 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to form a casting, and start a timer to make the casting for a preset time, the molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 600 rpm in 10 seconds, and rotates at 600 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0052] S23: The high-chromium cast iron floating oil seal blank is subjected to an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding to obtain a high-chromium cast iron floating oil seal finished product.

[0053] The specific outer surface treatment process is that the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the corundum grinding wheel is 230 rpm.

[0054] The heat treatment process is that the high-chromium cast iron floating oil seal blank is heated to 950℃ at a heating rate of 30℃ / min, and is quenched by air cooling after being kept for half an hour. Example 3:

[0055] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S30: The alloy raw materials are put into a medium-frequency furnace for smelting according to the standard requirements of high-chromium cast iron, and the composition of the castings is detected by a spectrometer after smelting and adjusted to be within the standard range of high-chromium cast iron. The high-chromium cast iron includes the following components by weight: C 4.0 Wt%; Si 1.5 Wt%; Mn 0.8 Wt%; Cr 17 Wt%; Mo 2.0 Wt%; Ni 1.0 Wt%; and the rest is Fe; S31: The molten iron is purified according to the operation process, and the temperature of the molten iron is detected by a contact type temperature measuring gun. After the temperature of the molten iron is controlled to 1560℃, the molten iron is poured out for casting.

[0056] S32: clean the metal mold of impurities; control the top die mechanism to fall back so that the mold falls and closes; start the centrifugal device to make the mold rotate at a speed of 800 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to cast, and start the timer to make the casting for a preset time, the molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 800 rpm within 10 seconds, and rotates at 800 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0057] S33: The high-chromium cast iron floating oil seal blank is subjected to an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding to obtain a high-chromium cast iron floating oil seal finished product.

[0058] The specific outer surface treatment process is that the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L bonded corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the bonded corundum grinding wheel is 215 rpm.

[0059] The heat treatment process is that the high-chromium cast iron floating oil seal blank is heated to 920℃ at a heating rate of 30℃ / min, and is kept for half an hour, and is quenched by air cooling. Example 4:

[0060] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S40: The alloy raw materials are put into the medium-frequency furnace for smelting according to the standard requirements of high-chromium cast iron, and the composition of the castings is detected by a spectrometer after smelting, and the composition of the molten iron is adjusted within the standard range of high-chromium cast iron. The high-chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 2.2 Wt%; Mn 1.0 Wt%; Cr 18 Wt%; Mo 2.2 Wt%; Ni 1.2 Wt%; and the rest is Fe; S41: Purify the molten iron according to the operation process, detect the temperature of the molten iron with a contact type temperature measuring gun, control the temperature of the molten iron to 1530℃, and then pour and cast.

[0061] S42: clean the metal mold of impurities; control the top die mechanism to fall back so that the mold falls and closes; start the centrifugal device to make the mold rotate at a speed of 1200 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to form a casting, and start a timer to make the casting for a preset time, the molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 1200 rpm in 10 seconds, and rotates at 1200 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0062] S43: The high-chromium cast iron floating oil seal blank is subjected to an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding to obtain a high-chromium cast iron floating oil seal finished product.

[0063] The specific outer surface treatment process is that the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L bonded corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the bonded corundum grinding wheel is 245 rpm.

[0064] The heat treatment process is that the high-chromium cast iron floating oil seal blank is heated to 940℃ at a heating rate of 30℃ / min, and is kept for half an hour, and is quenched by air cooling. Example 5:

[0065] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S50: The alloy raw materials are put into a medium-frequency furnace for smelting according to the standard requirements of high-chromium cast iron, and the composition of the castings is detected by a spectrometer after smelting, and the composition of the molten iron is adjusted within the standard range of high-chromium cast iron. The high-chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 2.2 Wt%; Mn 1.0 Wt%; Cr 18 Wt%; Mo 2.2 Wt%; Ni 1.2 Wt%; and the rest is Fe; S51: Purify the molten iron according to the operation process, detect the temperature of the molten iron with a contact type temperature measuring gun, control the temperature of the molten iron to 1530℃, and then pour out for casting.

[0066] S52: clean the metal mold of impurities; control the top die mechanism to fall back so that the mold falls and closes; start the centrifugal device to make the mold rotate at a speed of 1300 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to form a casting, and start a timer to make the casting for a preset time, the molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 1300 rpm in 10 seconds, and rotates at 1300 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the top die mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0067] S53: The high-chromium cast iron floating oil seal blank is subjected to an outer surface treatment process, a heat treatment process, a semi-finished product inspection, an inner spherical surface grinding, and a sealing surface grinding to obtain a high-chromium cast iron floating oil seal finished product.

[0068] The specific outer surface treatment process is that the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the corundum grinding wheel is 300 rpm.

[0069] The heat treatment process is that the high-chromium cast iron floating oil seal blank is heated to 940℃ at a heating rate of 30℃ / min, kept for half an hour, and then quenched by air cooling. Example 6:

[0070] A centrifugal casting method of a high-chromium cast iron floating oil seal, comprising: S60: The alloy raw materials are put into a medium-frequency furnace for smelting according to the standard requirements of high-chromium cast iron, and the composition of the castings is detected by a spectrometer after smelting to adjust the composition of the molten iron within the standard range of high-chromium cast iron. The high-chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 2.2 Wt%; Mn 1.0 Wt%; Cr 18 Wt%; Mo 2.2 Wt%; Ni 1.2 Wt%; and the rest is Fe; S61: Purify the molten iron according to the operation process, detect the temperature of the molten iron with a contact type temperature measuring gun, control the temperature of the molten iron to 1530℃, and then pour and cast.

[0071] S62: Clean impurities inside the metal mold; control the top mold mechanism to fall back so that the mold falls and closes; start the centrifugal device so that the mold rotates at a constant speed of 1200 rpm; pour a fixed amount of molten iron directly into the rotating mold cavity to cast the mold, and start the timer to allow the casting to proceed for the preset time. Under the action of centrifugal force, the molten iron quickly fills the mold from the pouring point. The centrifugal device accelerates to 1200 rpm within 10 seconds and runs at a constant speed of 1200 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device stops, the top mold mechanism lifts up, and the mold separates from the high-chromium cast iron floating oil seal blank to obtain the high-chromium cast iron floating oil seal blank.

[0072] S63: Perform external surface treatment, heat treatment, semi-finished product inspection, internal spherical grinding, and sealing surface grinding on the high-chromium cast iron floating oil seal blank to obtain the finished high-chromium cast iron floating oil seal.

[0073] The specific external surface treatment process is as follows: for the inner hole of the high chromium cast iron floating oil seal blank, a PA / F 60L corundum grinding wheel is used to perform grinding for 60 seconds with a processing pressure of 0.25MPa and a rotation speed of 300rpm.

[0074] The heat treatment process is as follows: the high-chromium cast iron floating oil seal blank is heated to 940℃ at a heating rate of 30℃ / min, held at that temperature for half an hour, and then quenched by air cooling after being taken out of the furnace. Example 7:

[0075] A centrifugal casting method for a high-chromium cast iron floating oil seal includes: S70: The alloy raw materials are prepared according to the standard requirements for high-chromium cast iron. The prepared alloy raw materials are then melted in an induction furnace. After melting, the castings are analyzed using a spectrometer, and the composition of the molten iron is adjusted to be within the standard range for high-chromium cast iron. The high-chromium cast iron comprises the following components by weight: C 3.9 wt%; Si 2.2 wt%; Mn 1.0 wt%; Cr 18 wt%; Mo 2.2 wt%; Ni 1.2 wt%; the remainder is Fe. S71: Purify the molten iron according to the work process, use a contact temperature gun to detect the temperature of the molten iron, control the temperature of the molten iron to 1530℃, and then pour it out of the furnace.

[0076] S72: clean the metal mold of impurities; control the ejection mechanism to fall back so that the mold falls and closes; start the centrifugal device to rotate the mold at a speed of 1000 rpm; pour a certain amount of molten iron directly into the rotating mold cavity to cast, and start the timer to cast for a preset time. The molten iron rapidly fills the mold under the action of centrifugal force from the pouring point, the centrifugal device accelerates to 1000 rpm in 10 seconds, and runs at a constant speed of 1000 rpm for 60 seconds; stop the centrifugal device, and when the centrifugal device is stable, the ejection mechanism is lifted, the mold is separated from the high-chromium cast iron floating oil seal blank, and the high-chromium cast iron floating oil seal blank is obtained.

[0077] S73: the high-chromium cast iron floating oil seal blank is subjected to outer surface treatment process, heat treatment process, semi-finished product inspection, inner spherical surface grinding, and sealing surface grinding to obtain a finished high-chromium cast iron floating oil seal.

[0078] The specific outer surface treatment process is: the inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L corundum grinding wheel at a processing pressure of 0.25 MPa, and the rotary speed of the corundum grinding wheel is 300 rpm.

[0079] The heat treatment process is: the high-chromium cast iron floating oil seal blank is heated to 940℃ at a heating rate of 30℃ / min, and is kept for half an hour, and is quenched by air cooling. Example 8:

[0080] Different from example 1 is that the high-chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 0.5 Wt%; Mn 0.4 Wt%; Cr 15 Wt%; Mo 1.5 Wt%; Ni 0.5 Wt%; and the rest is Fe.

[0081] The centrifugal uniform speed in S12 is 1300 rpm. The rest is the same as example 1. Example 9:

[0082] Different from example 8 is that the high-chromium cast iron includes the following components by weight: C 4.1 Wt%; Si 0.5 Wt%; Mn 0.4 Wt%; Cr 15 Wt%; Mo 1.5 Wt%; Ni 0.5 Wt%; and the rest is Fe.

[0083] The centrifugal uniform speed in S12 is 900 rpm. The rest is the same as example 8.

[0084] Example 10: Different from example 1 is that the high-chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 0.5 Wt%; Mn 0.4 Wt%; Cr 15 Wt%; Mo 1.5 Wt%; Ni 0.5 Wt%; and the rest is Fe.

[0085] The rest is the same as example 1.

[0086] The C in the high chromium cast iron in example 1, example 8 and example 9 is increased by 0.1wt%, and the uniform speed for centrifugal is reduced by 200rpm. Relative to example 1, although the C in the high chromium cast iron in example 10 is increased by 0.1wt%, the uniform speed for centrifugal is kept consistent.

[0087] Comparative example 1: A centrifugal casting method of a high chromium cast iron floating oil seal, comprising: S10: ingredients are prepared according to the standard requirements of high chromium cast iron, and the prepared alloy raw materials are put into a medium frequency furnace for smelting. After smelting, the castings are detected by a spectrometer, and the composition of the molten iron is adjusted within the standard range of high chromium cast iron. The high chromium cast iron includes the following components by weight: C 3.8wt%; Si 0.5wt%; Mn 0.4wt%; Cr 15wt%; Mo 1.5wt%; Ni 0.5wt%; and the rest is Fe; S11: the molten iron is cast by taking a coated sand shell mold to obtain a high chromium cast iron floating oil seal blank.

[0088] S12: the high chromium cast iron floating oil seal blank is subjected to turning processing of the outer surface, heat treatment and numerical control turning processing to obtain a high chromium cast iron floating oil seal.

[0089] Comparative example 2: A centrifugal casting method of a high chromium cast iron floating oil seal, comprising: S20: ingredients are prepared according to the standard requirements of high chromium cast iron, and the prepared alloy raw materials are put into a medium frequency furnace for smelting. After smelting, the castings are detected by a spectrometer, and the composition of the molten iron is adjusted within the standard range of high chromium cast iron. The high chromium cast iron includes the following components by weight: C 4.2wt%; Si 2.5wt%; Mn 1.2wt%; Cr 19wt%; Mo 2.5wt%; Ni 1.5wt%; and the rest is Fe; S21: the molten iron is cast by taking a coated sand shell mold to obtain a high chromium cast iron floating oil seal blank.

[0090] S22: the high chromium cast iron floating oil seal blank is subjected to turning processing of the outer surface, heat treatment and numerical control turning processing to obtain a high chromium cast iron floating oil seal.

[0091] Comparative example 3: A centrifugal casting method of a high chromium cast iron floating oil seal, comprising: S30: ingredients are prepared according to the standard requirements of high chromium cast iron, the prepared alloy raw materials are put into a medium frequency furnace for smelting, and after smelting, the castings are detected by a spectrometer and the composition of the molten iron is adjusted within the standard range of high chromium cast iron. The high chromium cast iron includes the following components by weight: C 4.0 Wt%; Si 1.5 Wt%; Mn 0.8 Wt%; Cr 17 Wt%; Mo 2.0 Wt%; Ni 1.0 Wt%; and the rest is Fe; S31: the molten iron is taken to a coated sand shell mold for casting to obtain a high chromium cast iron floating oil seal blank.

[0092] S32: the high chromium cast iron floating oil seal blank is subjected to turning processing of the outer surface, heat treatment, and numerical control turning processing to obtain a high chromium cast iron floating oil seal.

[0093] Comparative Example 4: The components and the weight parts of the high chromium cast iron floating oil seal in Comparative Example 4 and Example 4 are the same.

[0094] A centrifugal casting method of a high chromium cast iron floating oil seal, comprising: S40: ingredients are prepared according to the standard requirements of high chromium cast iron, the prepared alloy raw materials are put into a medium frequency furnace for smelting, and after smelting, the castings are detected by a spectrometer and the composition of the molten iron is adjusted within the standard range of high chromium cast iron. The high chromium cast iron includes the following components by weight: C 3.9 Wt%; Si 2.2 Wt%; Mn 1.0 Wt%; Cr 18 Wt%; Mo 2.2 Wt%; Ni 1.2 Wt%; and the rest is Fe; S41: the molten iron is taken to a coated sand shell mold for casting to obtain a high chromium cast iron floating oil seal blank.

[0095] S42: the high chromium cast iron floating oil seal blank is subjected to turning processing of the outer surface, heat treatment, and numerical control turning processing to obtain a high chromium cast iron floating oil seal.

[0096] The type of is selected for a running-in test of 100 h at a speed of 450 rpm, the weight difference before and after running-in is measured, the wear rate per unit time is calculated, and the test results are shown in the following table: Test group Load Kgf Linear velocity Rpm Running time h Wear rate ug / h Seal face condition Example 1 69.8 450 100 40.8 OK Example 2 70.5 450 100 39.8 OK Example 3 69.4 450 100 39.4 OK Example 4 71.3 450 100 40.6 OK Example 5 69.8 450 100 39.2 OK Example 6 70.5 450 100 40.1 OK Example 7 69.4 450 100 39.6 OK Example 8 69.5 450 100 40.4 OK Example 9 69.5 450 100 40.1 OK Example 10 69.7 450 100 40.7 OK Comparative Example 1 69.8 450 100 48.6 OK Comparative Example 2 70.5 450 100 49.8 OK Comparative Example 3 69.4 450 100 50.2 OK Comparative Example 4 71.3 450 100 51.3 OK From the test results, it is known that the C content in the high chromium cast iron in Examples 1, 8 and 9 is increased by 0.1 Wt%, and the uniform speed for centrifugation is reduced by 200 rpm. Relative to Example 1, the C content in the high chromium cast iron in Example 10 is increased by 0.1 Wt%, but the uniform speed for centrifugation remains the same. When the uniform speed for centrifugation is reduced as the weight content of C increases, the probability of segregation is reduced, and the wear rate is further reduced.

[0097] The above description of disclosed embodiments enables one skilled in the art to make or use the application. Numerous modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A centrifugal casting method for a high-chromium cast iron floating oil seal, characterized in that, include: Iron molten metal is prepared such that its composition is within the standard range for high-chromium cast iron, wherein the high-chromium cast iron comprises the following components by weight: C 3.8-4.2 wt%; Si 0.5-2.5 wt%; Mn 0.4-1.2 wt%; Cr 15-19 wt%; Mo 1.5-2.5 wt%; Ni 0.5-1.5 wt%; the remainder being Fe. The molten iron is heated and its temperature is controlled within the target temperature range. The molten iron was poured using a centrifugal process to obtain a high-chromium cast iron floating oil seal blank. The high-chromium cast iron floating oil seal blank is subjected to external surface treatment, heat treatment, semi-finished product inspection, internal spherical grinding, and sealing surface grinding to obtain the finished high-chromium cast iron floating oil seal.

2. The centrifugal casting method according to claim 1, characterized in that, The external surface treatment process includes: The inner hole of the high-chromium cast iron floating oil seal blank is ground for 60 seconds using a PA / F 60L corundum grinding wheel at a processing pressure of 0.25MPa and a preset rotation speed of 200-400rpm.

3. The centrifugal casting method according to claim 2, characterized in that, The heat treatment process includes: The high-chromium cast iron floating oil seal blank is heated to 920℃-980℃ at a preset heating rate, held at that temperature for half an hour, and then air-cooled after being taken out of the furnace for quenching heat treatment.

4. The centrifugal casting method according to claim 3, characterized in that, The preset heating rate is 30℃ / min.

5. The centrifugal casting method according to claim 2, characterized in that, The centrifugal process includes: controlling the top mold mechanism to fall back, so that the mold falls and closes; Start the centrifuge to make it rotate at the preset centrifugal speed; A fixed amount of molten iron is poured directly into the rotating mold cavity to form a mold. At the same time, a timer is started to allow the mold to be cast for a preset duration. Under the action of centrifugal force, the molten iron quickly fills the mold from the pouring point. Stop the centrifuge device, and after the centrifuge device has come to a stable stop, the top mold mechanism lifts up, and the mold separates from the high-chromium cast iron floating oil seal blank to obtain the high-chromium cast iron floating oil seal blank.

6. The centrifugal casting method according to claim 5, characterized in that, The preset centrifugal speed is 600-1500 rpm.

7. The centrifugal casting method according to claim 6, characterized in that, When the weight percentage of C is 4.1 wt%, the preset centrifugal speed is the first preset centrifugal speed. For every 0.1 wt% decrease in the weight percentage of C, the preset centrifugal speed increases by 200 rpm.

8. The centrifugal casting method according to claim 6, characterized in that, The preset initial centrifugal speed of the centrifugal device is 600 rpm, and the initial rotational speed of the corundum grinding wheel is the initial preset speed, which is 200 rpm. Wherein, for every 200 rpm increase in the preset centrifugal speed of the centrifugal device, the initial rotational speed of the corundum grinding wheel increases by 15 rpm.

9. The centrifugal casting method according to claim 6, characterized in that, When the centrifuge is started, the centrifuge operates at a constant speed of the first preset centrifugal speed until the molten iron is poured. After the molten iron is poured, the centrifugal device is controlled to accelerate to the second preset centrifugal speed within a first preset time period, and then runs at the second preset centrifugal speed at a constant speed for a second preset time period, wherein the first preset centrifugal speed is less than the second preset centrifugal speed.

10. The centrifugal casting method according to claim 1, characterized in that, The target temperature range is 1520-1580℃.

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