Spheroidal graphite cast iron adjusting die nut and its production process

Abstract

The application discloses nodular cast iron adjusting mode nuts and a production process thereof, which balances the carbon-silicon ratio, restrains graphitization expansion, reduces shrinkage, adjusts the ratio of manganese and chromium to enhance hardness and tensile strength, uses magnesium and rare earth to improve spheroidizing rate and reduce hardness unevenness, and controls the ratio of sulfur, phosphorus, titanium, zinc, lead and vanadium to reduce impurity hazards and ensure the stability of tensile strength, yield strength and hardness of the adjusting mode nuts. Therefore, the application can effectively reduce the casting defects of the adjusting mode nuts by adjusting the component ratio of the nodular cast iron adjusting mode nuts, thereby improving the tensile strength, yield strength and hardness of the adjusting mode nuts and improving the hardness uniformity of the adjusting mode nuts.

Description

Technical Field

[0001] This application relates to the field of casting technology, and in particular to a ductile iron mold adjusting nut and its manufacturing process. Background Technology

[0002] As an important transmission component in molding equipment (such as die casting machines and injection molding machines), the requirements for mold adjusting nuts are very high. However, current mold adjusting nut castings, after finishing, not only have casting defects such as slag inclusions, cold shuts, and shrinkage porosity, but also problems such as insufficient or uneven hardness of the casting body. Especially when the mold adjusting nut is heavy or has a large wall thickness, the problems caused by casting defects are more prominent, which seriously affects the yield rate of mold adjusting nuts. Therefore, there is currently a lack of a solution that can reduce casting defects and improve the hardness of mold adjusting nuts, so improvement is needed. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a ductile iron adjusting nut and its manufacturing process, which can effectively reduce casting defects in the adjusting nut and improve its hardness and hardness uniformity.

[0004] In a first aspect, embodiments of this application provide a ductile iron adjusting nut, which, based on a mass percentage statistical analysis, comprises the following components:

[0005] C: 3.60%–3.90%, Si: 2.30%–2.50%, Mn: 0.35%–0.55%, Cr: 0.15%–0.20%, Sn: 0.040%–0.060%, Mg: 0.035%–0.055%, P≤0.015%, S: 0.005%–0.02%, Rare Earth: 0.007%–0.012%, Ti+Zn+Pb+V≤0.015%, the remainder being Fe.

[0006] The ductile iron adjusting nut provided in this application embodiment comprises the following components based on a mass percentage statistical analysis:

[0007] C: 3.70%~3.75%, Si: 2.35%~2.45%, Mn: 0.45%~0.55%, Cr: 0.15%~0.20%, Sn: 0.040%~0.050%, Mg: 0.040%~0.050%, P≤0.015%, S: 0.008%~0.015%, Rare Earth: 0.009%~0.010%, Ti+Zn+Pb+V≤0.010%, the remainder is Fe.

[0008] In a second aspect, the embodiments of the present application provide a production process of nodular cast iron adjusting die nut, comprising the following steps:

[0009] Step one, pouring the molten iron into the casting mold of the nodular cast iron adjusting die nut to form a nut blank; wherein the composition of the molten iron comprises: C: 3.60% to 3.90%, Si: 2.30% to 2.50%, Mn: 0.35% to 0.55%, Cr: 0.15% to 0.20%, Sn: 0.040% to 0.060%, Mg: 0.035% to 0.055%, P≤0.015%, S: 0.005% to 0.02%, rare earth: 0.007% to 0.012%, Ti+Zn+Pb+V≤0.015%, and the rest is Fe;

[0010] Step two, sending the nut blank into the furnace to heat to 920℃ to 970℃, and maintaining the temperature for 4 hours, and then furnace cooling to 370℃ to 420℃;

[0011] Step three, sending the cooled nut blank into the furnace to heat to 550℃ to 600℃, and maintaining the temperature for 3 hours, and then furnace cooling to 150℃, and processing the nut blank after furnace cooling to obtain the nodular cast iron adjusting die nut.

[0012] In the production process provided by the embodiments of the present application, the composition of the molten iron in the step one comprises:

[0013] C: 3.70% to 3.75%, Si: 2.35% to 2.45%, Mn: 0.45% to 0.55%, Cr: 0.15% to 0.20%, Sn: 0.040% to 0.050%, Mg: 0.040% to 0.050%, P≤0.015%, S: 0.008% to 0.015%, rare earth: 0.009% to 0.010%, Ti+Zn+Pb+V≤0.010%, and the rest is Fe.

[0014] In the production process provided by the embodiments of the present application, the step two further comprises: sending the nut blank into the furnace to heat to 920℃ to 970℃ at a temperature rising rate of 60 to 80℃ / h, and maintaining the temperature for 4 hours, and then furnace cooling to 370℃ to 420℃.

[0015] In the production process provided by the embodiments of the present application, the step three further comprises: sending the cooled nut blank into the furnace to heat to 550℃ to 600℃ at a temperature rising rate of 100℃ / h, and maintaining the temperature for 3 hours, and then furnace cooling to 150℃, and processing the nut blank after furnace cooling to obtain the nodular cast iron adjusting die nut.

[0016] In the production process provided by the embodiment of the present application, the casting mold comprises a mold body, the mold body comprises a sprue, a runner, a cross runner, and a cavity corresponding to the adjusting nut, the runner is communicated to the bottom of the cavity, and the sprue is communicated to the runner through the cross runner, wherein the sprue and the cross runner are arranged vertically to each other.

[0017] In the production process provided by the embodiment of the present application, the cross-sectional area ratio of the sprue, the cross runner and the runner is 1:1.8-2.0:1.1-1.5.

[0018] In the production process provided by the embodiment of the present application, the casting mold further comprises a filter, the filter is arranged below the cross runner, and the cross runner is communicated to the runner through the filter.

[0019] In a third aspect, the embodiment of the present application provides a nodular cast iron adjusting nut, which is prepared by using the production process of the nodular cast iron adjusting nut according to the second aspect.

[0020] According to the nodular cast iron adjusting nut and the production process thereof provided by the embodiment of the present application, at least the following beneficial effects are achieved: by balancing the carbon-silicon ratio, inhibiting graphitization expansion, reducing shrinkage, adjusting the ratio of manganese and chromium to enhance hardness and tensile strength, using magnesium and rare earth to improve spheroidization rate and reduce hardness unevenness, and controlling the ratio of sulfur, phosphorus, titanium, zinc, lead and vanadium to reduce impurity hazards and ensure the stability of the tensile strength, yield strength and hardness of the adjusting nut, therefore, by adjusting the component ratio of the nodular cast iron adjusting nut, the casting defects of the adjusting nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the adjusting nut and improving the hardness uniformity of the adjusting nut.

[0021] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the description and the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The present application will be further described below in conjunction with the drawings and embodiments;

[0023] Figure 1 FIG. 1 is a structural schematic diagram of a casting mold of a nodular cast iron adjusting nut provided by the embodiment of the present application;

[0024] Figure 2 FIG. 2 is a bottom view of the casting mold of the nodular cast iron adjusting nut provided by the embodiment of the present application;

[0025] Figure 3is a structure section schematic view of a casting mold of a nodular cast iron adjusting die nut provided by an embodiment of the present application;

[0026] Figure 4 is a base body metallographic schematic view of the nodular cast iron adjusting die nut after corrosion provided by an embodiment of the present application. DETAILED DESCRIPTION

[0027] This part will describe the specific embodiments of the present application in detail, and the preferred embodiments of the present application are shown in the accompanying drawings, and the role of the drawings is to supplement the description of the text part with graphics, so that people can intuitively and visually understand each technical feature and the overall technical solution of the present application, but it cannot be understood as a limitation on the protection scope of the present application.

[0028] It should be understood that in the description of the embodiments of the present application, if there is a description of "first", "second", etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features. "At least one" means one or more, and "multiple" means two or more. "At least one of the following" and the like means any combination of these items, including any combination of single or multiple items.

[0029] In addition, unless otherwise explicitly specified and limited, the term "connection / connected" should be understood broadly, for example, it can be fixed connection or movable connection, or detachable connection or non-detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium.

[0030] In the description of the embodiments of the present application, the description of the reference terms "one embodiment / implementation", "another embodiment / implementation" or "some embodiments / implementation", "in the above embodiment / implementation" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are contained in at least two embodiments or implementations disclosed in the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same example or implementation. It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in an order different from that in the flowchart.

[0031] As an important transmission part of die forming equipment (such as die casting machine, injection molding machine, etc.), the die nut has very high requirements. However, after the die nut casting is finished, there are not only casting defects such as slag inclusion, cold shut and shrinkage, but also problems such as insufficient hardness or uneven hardness of the casting body. Especially when the weight of the die nut is high or the wall thickness is large, the problems caused by casting defects are more prominent, which seriously affects the qualified rate of the die nut. Therefore, there is currently a lack of a solution that can reduce casting defects and improve the hardness of the die nut, so improvement is needed.

[0032] To at least solve the above-mentioned technical problems in the prior art, the present application provides a nodular cast iron die nut and a production process thereof. By adjusting the component ratio of the nodular cast iron die nut, the casting defects of the die nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the die nut, and improving the hardness uniformity of the die nut.

[0033] It should be noted that the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0034] The embodiments of the present application will be further described below with reference to the accompanying drawings.

[0035] In a first aspect, the embodiments of the present application provide a nodular cast iron die nut, which will be described below with specific embodiments.

[0036] Embodiment one

[0037] The components of the nodular cast iron die nut are counted according to mass percentage, specifically: the content of carbon element can be 3.60% to 3.90%, the content of silicon element can be 2.30% to 2.50%, the content of manganese element can be 0.35% to 0.55%, the content of chromium element can be 0.15% to 0.20%, the content of tin element can be 0.040% to 0.060%, the content of magnesium element can be 0.035% to 0.055%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.005% to 0.02%, the content of rare earth can be 0.007% to 0.012%, and the total content of titanium element, zinc element, lead element and vanadium element can be less than or equal to 0.015%, and the rest is iron element.

[0038] Among them, the mechanical properties of the nodular cast iron die nut according to embodiment one can reach tensile strength Rm: 615~705MPa, yield strength R p0.2:420~487MPa, elongation A: 7~11%, hardness: 175~208HBW. Metallographic structure: spheroidization rate: 90~95%, pearlite amount: 45~65%, ferrite amount: 35~55%.

[0039] It is worth noting that, to achieve the same mechanical properties and metallographic structure indexes of the spheroidal graphite cast iron adjusting mode nut of the above-mentioned embodiment one, the component proportions adopted in the related art are that the content of carbon element can be 3.90% to 4.40%, the content of silicon element can be 2.80% to 4.00%, the content of manganese element can be 0.50% to 0.55%, the content of copper element can be 0.40% to 0.60%, the content of magnesium element can be 0.035% to 0.055%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.005% to 0.02%, the content of rare earth can be 0.007% to 0.012%, and the rest is iron element. The product qualified rate of the spheroidal graphite cast iron adjusting mode nut using the component proportions adopted in the related art is 80% to 90%. It can be seen through comparison that, in the component proportions of the spheroidal graphite cast iron adjusting mode nut proposed in embodiment one, by adjusting the contents of carbon element, silicon element, chromium element and tin element, the corresponding proportional collocation is formed, the fine dispersed carbide is formed by combining chromium element and carbon element, the strength and wear resistance of the casting are improved, the grain growth is inhibited, the toughness of the casting material is improved, by limiting the content range of chromium element and tin element, the formation of too much hard carbide in the casting can be avoided, specifically, when the content of chromium element is 0.15% to 0.20% and the content of tin element is 0.040% to 0.060%, no carbide that seriously affects the mechanical properties appears in the matrix structure, the casting embrittlement is avoided, and the pearlite interlamellar spacing can be further refined to improve the strength, so that the as-cast properties and metallographic structure meeting the casting requirements can be obtained, and the product qualified rate can be improved to 99.5%. That is to say, the scheme provided in the embodiment of the application can replace the scheme of using high copper element content in the related art, so as to effectively reduce the casting defects of the adjusting mode nut and reduce the production cost.

[0040] Embodiment two

[0041] The components of the spheroidal graphite cast iron die nut are counted according to mass percentage, specifically, the content of carbon element can be 3.70% to 3.75%, the content of silicon element can be 2.35% to 2.45%, the content of manganese element can be 0.45% to 0.50%, the content of chromium element can be 0.15% to 0.20%, the content of tin element can be 0.040% to 0.050%, the content of magnesium element can be 0.040% to 0.050%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.008% to 0.015%, the content of rare earth can be 0.009% to 0.010%, and the total content of titanium element, zinc element, lead element and vanadium element can be less than or equal to 0.010%, and the rest is iron element.

[0042] The mechanical properties of the spheroidal graphite cast iron die nut according to the second embodiment can reach tensile strength Rm: 650~700MPa, yield strength Rp0.2: 440~480MPa, elongation A: 8~10%, hardness: 180~200HBW, and the metallographic structure is: spheroidization rate: 90~95%, pearlite amount: 45~65%, and ferrite amount: 35~55%. p0.2

[0043] Compared with the first embodiment, the second embodiment refines the component interval of the spheroidal graphite cast iron die nut, limits the content ratio of carbon element and silicon element, reduces the risk of overburning, improves the stability of graphitization, optimizes the synergistic effect of silicon element and carbon element, improves the consistency of spheroidization rate, and thus reduces the problem of shrinkage. At the same time, by reducing the content of sulfur element, reducing the problem of slag inclusion and hardness unevenness, and further limiting the content of rare earth, titanium element, zinc element, lead element and vanadium element, the spheroidization uniformity is improved, the impurity harm is reduced, and thus the mechanical properties of the die nut are effectively improved. Specifically, the lower limit value of tensile strength is increased from 615MPa to 650Mpa, and the upper limit value of tensile strength is also increased by 5MPa. The yield strength is also improved accordingly. The upper limit value of yield strength decreases by 7MPa, but the lower limit value increases by 20MPa. The elongation and hardness are also more stable, and the stability of the spheroidal graphite cast iron die nut in tensile strength, yield strength, elongation and hardness is improved as a whole.

[0044] Similarly, the component ratio of the spheroidal graphite cast iron die nut according to the second embodiment can achieve the as-cast properties and metallographic structure that meet the casting requirements, and the product qualified rate can be increased from 80% of the component ratio scheme in the related technology to 99.5%. Even when the content of chromium element is 0.15% to 0.20%, no carbide that seriously affects the mechanical properties appears in the matrix structure, which can replace the high copper element content scheme in the related technology, thereby effectively reducing the casting defects of the die nut and reducing the production cost.​

[0045] In combination of Embodiment One and Embodiment Two, it can be seen that by adjusting the ratio of carbon element and silicon element, the graphitization expansion is effectively inhibited and the shrinkage is reduced, at the same time, the ratio of manganese and chromium elements is adjusted to enhance the hardness and tensile strength, and the magnesium element and rare earth are used to improve the spheroidization rate and reduce the hardness unevenness problem, in addition, the ratio of sulfur, phosphorus, titanium, zinc, lead and vanadium elements is controlled to reduce the impurity harm and ensure the stability of the tensile strength, yield strength and hardness of the adjusting die nut, therefore, by adjusting the component ratio of the nodular cast iron adjusting die nut, the related technology of using copper element and molybdenum element for casting is avoided, the casting effect is ensured and the casting defects of the adjusting die nut are effectively reduced, so as to reduce the cost, improve the tensile strength, yield strength and hardness of the adjusting die nut, and improve the hardness uniformity of the adjusting die nut.

[0046] In a second aspect, the embodiment of the present application provides a production process of the nodular cast iron adjusting die nut, and the production process of the nodular cast iron adjusting die nut is described below with specific embodiments.

[0047] Embodiment Three

[0048] The production process of the nodular cast iron adjusting die nut can include the following steps:

[0049] Step One, pouring the molten iron into the casting mold of the nodular cast iron adjusting die nut for pouring to form a nut blank;

[0050] Step Two, sending the nut blank into the furnace to heat to 920-970℃ and maintain the temperature for 4 hours, and then take out the furnace and cool to 370-420℃;

[0051] Step Three, sending the cooled nut blank into the furnace to heat to 550-600℃ and maintain the temperature for 3 hours, and then cool to 150℃ with the furnace, processing the nut blank after the furnace cooling to obtain the nodular cast iron adjusting die nut.

[0052] In step one, the ingredients in the molten iron are counted according to the mass percentage, specifically: the content of carbon element can be 3.60% to 3.90%, the content of silicon element can be 2.30% to 2.50%, the content of manganese element can be 0.35% to 0.55%, the content of chromium element can be 0.15% to 0.20%, the content of tin element can be 0.040% to 0.060%, the content of magnesium element can be 0.035% to 0.055%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.005% to 0.02%, the content of rare earth can be 0.007% to 0.012%, and the total content of titanium element, zinc element, lead element and vanadium element can be less than or equal to 0.015%, and the rest is iron element. Among them, the parameter results of the as-cast iron with the above ingredient proportion are: tensile strength Rm: 650~700MPa, yield strength R p0.2 : 440~480MPa, elongation A: 8%~10%, hardness: 180~200HBW, spheroidizing rate: 90%~95%, pearlite amount: 45%~65%, and ferrite amount: 35%~55%.

[0053] Among them, the molten iron is obtained by the following steps: putting cast pig iron (high-purity pig iron), high-purity scrap steel, carbon additive, silicon iron, manganese iron, chromium iron and tin particles into a medium-frequency melting furnace to melt and form liquid molten iron, so that the ingredients of the molten iron meet the requirements, when the temperature of the molten iron reaches 1450℃ to 1470℃, the molten iron can be subjected to spheroidizing inoculation treatment, and 0.1% sulfur oxygen inoculant is added during the pouring of the molten iron into the casting mold for sulfur inoculation treatment; it should be noted that the total content of titanium element, zinc element, lead element and vanadium element in high-purity pig iron and high-purity scrap steel is less than 0.015%.

[0054] Referring to Figure 1 and Figure 2 , Figure 1 is a structural schematic diagram of a casting mold of a nodular cast iron mold adjusting nut provided by the embodiment of the present application, Figure 2 is a bottom view of the casting mold, the casting mold of the nodular cast iron mold adjusting nut comprises a mold body 100, and the mold body 100 comprises a straight sprue 110, an inner sprue 130, a cross sprue 120, and a cavity 150 corresponding to the adjusting nut, the inner sprue 130 is communicated to the bottom of the cavity 150, and the straight sprue 110 is communicated to the inner sprue 130 through the cross sprue 120, wherein the straight sprue 110 and the cross sprue 120 are arranged vertically to each other.

[0055] Specifically, the inner runner 130 is located at the bottom of the cavity 150, the straight runner 110 is communicated with the inner runner 130 through the cross runner 120, and the molten iron is poured through the straight runner 110 to form a bottom pouring process, promote the iron level balance filling, reduce the eddy current and oxidized slag, thereby being able to reduce the spheroidal graphite cast iron adjusting mode nut shrinkage and slag inclusion problem, and ensure the compactness of the spheroidal graphite cast iron adjusting mode nut.

[0056] As shown in Figure 1 and Figure 2 , the casting mold of the spheroidal graphite cast iron adjusting mode nut can be one mold two pieces, the straight runner 110 is communicated with the cross runner 120, and the inner runner 130 can be provided with multiple, so that the straight runner 110 can be communicated with multiple inner runners 130 through the cross runner 120, and each inner runner 130 is communicated to the corresponding cavity 150, and then the molten iron can be poured into multiple cavities 150 through the straight runner 110. It is worth noting that the pouring temperature of the molten iron can be controlled at 1375℃ to 1390℃, and the pouring speed is controlled at 42kg / s to 48kg / s, so that a good liquid-solid solidification phase can be ensured in the subsequent process flow, and casting defects such as cold shut, slag inclusion and the like can be effectively reduced.

[0057] The cross-sectional area ratio of the straight runner 110, the cross runner 120 and the inner runner 130 is 1:1.8~2.0:1.1~1.5. By limiting the cross-sectional area ratio of the straight runner 110, the cross runner 120 and the inner runner 130, it is ensured that the cross runner always maintains a full state, avoids the slag in the molten iron from entering the mold, and ensures the smoothness of the molten iron filling process, so as to achieve the effect of optimizing the molten iron flow rate and pressure distribution, and reduce the eddy current and oxidized slag problem.

[0058] Referring to Figure 3 , Figure 3 is a structure cross-sectional view of the casting mold provided by the embodiment of the application, and it is worth noting that the casting mold further comprises a filter 160, the filter 160 is arranged below the cross runner 120, the cross runner 120 is communicated with the inner runner 130 through the filter 160, and the filter 160 can be provided with multiple, each filter 160 is arranged separately and uniformly below the cross runner 120, so that when the molten iron enters the inner runner 130 through the cross runner 120, the filter 160 can filter part of the slag in the molten iron, and reduce the slag inclusion defect.

[0059] The number of the inner runner 130 is equal to that of the filter 160, that is, each inner runner 130 is communicated with the cross runner 120 through a filter 160.

[0060] It should be noted that the casting mold of the spheroidal graphite cast iron adjusting mode nut can be placed with split conformal chill 140 in the cavity 150, wherein the material of the conformal chill 140 can be selected from HT150, and the thickness of the conformal chill 140 can be 80% to 90% of the thickness of the spheroidal graphite cast iron adjusting mode nut.

[0061] Therefore, the casting mold of the spheroidal graphite cast iron adjusting mode nut can effectively improve the purity of the nut blank and reduce the problem of local hardness unevenness or strength reduction caused by slag inclusion.

[0062] It is worth noting that in the relevant technology, the heating temperature of the nut blank in the normalizing high-temperature treatment is 870℃ to 940℃, and the holding time is 1 hour to 3 hours. In the normalizing high-temperature treatment of step two proposed in the present application, by increasing the heating temperature and prolonging the holding time, the nut blank matrix can be completely converted into austenite, and graphite spheroidization can be promoted. After the furnace is discharged, the cooling rate and cooling temperature are controlled to cool the nut blank to 370℃ to 420℃, which can promote the uniform precipitation of pearlite, balance the strength and toughness, thereby reducing the problem of uneven hardness of the spheroidal graphite cast iron adjusting mode nut.

[0063] In the tempering treatment of step three, the tempering temperature is controlled at 550℃ to 600℃, so as to eliminate residual stress and stabilize the organizational structure. Then, through slow cooling with the furnace, the uniformity of the organization is ensured, and embrittlement is avoided, thereby effectively improving the blank hardness, hardness uniformity, and elongation after fracture.

[0064] Referring to Figure 4 , Figure 4 is the base body metallographic structure schematic diagram of the spheroidal graphite cast iron adjusting mode nut provided by the present application, as Figure 4 shown, the parameter results of the spheroidal graphite cast iron adjusting mode nut produced based on the production process of the spheroidal graphite cast iron adjusting mode nut described above are: tensile strength Rm: 850~900MPa, yield strength R p0.2 : 590~630MPa, elongation after fracture A: 7~9%, hardness: 300~350HBW. Spheroidization rate: 90~95%, number of pearlite: 95%, number of ferrite: 5%. Therefore, the production process of the spheroidal graphite cast iron adjusting mode nut proposed in the present application can effectively reduce the casting defects of the adjusting mode nut, thereby improving the tensile strength, yield strength and hardness of the adjusting mode nut, and improving the hardness uniformity of the adjusting mode nut.

[0065] Example Four

[0066] Step one, pouring molten iron into the casting mold of the spheroidal graphite cast iron adjusting mode nut to form a nut blank;

[0067] Step two, the nut blank is sent into the furnace to heat to 920℃ to 970℃, and the temperature is maintained for 4 hours, and then the furnace is cooled to 370℃ to 420℃;

[0068] Step three, the cooled nut blank is sent into the furnace to heat to 550℃ to 600℃, and the temperature is maintained for 3 hours, and then the furnace is cooled to 150℃, and the nut blank after the furnace cooling is processed to obtain the nodular cast iron adjusting nut.

[0069] In step one, the components in the molten iron are counted according to the mass percentage, and the specific adjustment is as follows: the content of carbon element can be 3.70% to 3.75%, the content of silicon element can be 2.35% to 2.45%, the content of manganese element can be 0.45% to 0.50%, the content of chromium element can be 0.15% to 0.20%, the content of tin element can be 0.040% to 0.050%, the content of magnesium element can be 0.040% to 0.050%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.008% to 0.015%, the content of rare earth can be 0.009% to 0.010%, and the total content of titanium element, zinc element, lead element and vanadium element can be less than or equal to 0.010%, and the rest is iron element.

[0070] The casting mold of the nodular cast iron adjusting nut includes a mold body 100, and the mold body 100 includes a straight gate 110, an inner gate 130, a cross gate 120, and a cavity 150 corresponding to the adjusting nut, the inner gate 130 is communicated to the bottom of the cavity 150, and the straight gate 110 is communicated to the inner gate 130 through the cross gate 120, wherein the straight gate 110 and the cross gate 120 are arranged perpendicular to each other.

[0071] Specifically, the inner gate 130 is located at the bottom of the cavity 150, the straight gate 110 is communicated to the inner gate 130 through the cross gate 120, and the molten iron is poured into through the straight gate 110 to form a bottom pouring process, promote the balance of iron filling, and reduce the vortex and oxidized slag, thereby reducing the nodular cast iron adjusting nut shrinkage and slag inclusion problem, and ensuring the compactness of the nodular cast iron adjusting nut.

[0072] As shown in Figure 1 and Figure 2 The casting mold of the nodular cast iron adjusting nut can be one mold with two pieces, the straight gate 110 is communicated to the cross gate 120, and the inner gate 130 can be provided with multiple, so that the straight gate 110 can be communicated to multiple inner gates 130 through the cross gate 120, and each inner gate 130 is communicated to the corresponding cavity 150, and then the molten iron can be poured into multiple cavities 150 through the straight gate 110.

[0073] The cross-sectional area ratio of the sprue 110, the runner 120 and the ingate 130 is 1:1.8-2.0:1.1-1.5. By limiting the cross-sectional area ratio of the sprue 110, the runner 120 and the ingate 130, it is ensured that the runner is always kept in a full state, the slag in the molten iron is prevented from entering the mold, and the molten iron filling process is stable, the effects of optimizing the flow rate and pressure distribution of the molten iron are achieved, and the problems of vortex and oxidation slag are reduced.

[0074] It is worth noting that the casting mold further comprises a filter 160, the filter 160 is arranged below the runner 120, the runner 120 is communicated with the ingate 130 through the filter 160, and the filter 160 can be provided in plurality, each filter 160 is arranged separately and uniformly below the runner 120, so that when the molten iron passes through the runner 120 and enters the ingate 130, the filter 160 can filter part of the slag in the molten iron, thereby reducing the slag defect.

[0075] It is worth noting that the casting mold further comprises a filter 160, the filter 160 is arranged below the runner 120, the runner 120 is communicated with the ingate 130 through the filter 160, and the filter 160 can be provided in plurality, each filter 160 is arranged separately and uniformly below the runner 120, so that when the molten iron passes through the runner 120 and enters the ingate 130, the filter 160 can filter part of the slag in the molten iron, thereby reducing the slag defect.

[0076] It is worth noting that the casting mold further comprises a filter 160, the filter 160 is arranged below the runner 120, the runner 120 is communicated with the ingate 130 through the filter 160, and the filter 160 can be provided in plurality, each filter 160 is arranged separately and uniformly below the runner 120, so that when the molten iron passes through the runner 120 and enters the ingate 130, the filter 160 can filter part of the slag in the molten iron, thereby reducing the slag defect.

[0077] Example five

[0078] The production process of the nodular cast iron adjusting die nut can further comprise the following steps:

[0079] Step one, pouring the molten iron into the casting mold of the nodular cast iron adjusting die nut for casting to form a nut blank;

[0080] Step two, sending the nut blank into the furnace and heating at a temperature rising rate of 60-80℃ / h to 920-970℃, and maintaining the temperature for 4 hours, and then taking out of the furnace and cooling to 370-420℃;

[0081] Step three, sending the cooled nut blank into the furnace and heating at a temperature rising rate of 100℃ / h to 550-600℃, and maintaining the temperature for 3 hours, and then cooling to 150℃ with the furnace, and processing the nut blank taken out of the furnace to obtain the nodular cast iron adjusting die nut.

[0082] In step one, the ingredients in the molten iron are counted according to the mass percentage, and the specific adjustment is as follows: the content of carbon element can be 3.70% to 3.75%, the content of silicon element can be 2.35% to 2.45%, the content of manganese element can be 0.45% to 0.50%, the content of chromium element can be 0.15% to 0.20%, the content of tin element can be 0.040% to 0.050%, the content of magnesium element can be 0.040% to 0.050%, the content of phosphorus element can be less than or equal to 0.015%, the content of sulfur element can be 0.008% to 0.015%, the content of rare earth can be 0.009% to 0.010%, and the total content of titanium element, zinc element, lead element and vanadium element can be less than or equal to 0.010%, and the rest is iron element.

[0083] The casting mold of the nodular cast iron adjusting nut comprises a mold body 100, and the mold body 100 comprises a straight sprue 110, an inner sprue 130, a cross sprue 120, and a cavity 150 corresponding to the adjusting nut, the inner sprue 130 is communicated to the bottom of the cavity 150, and the straight sprue 110 is communicated to the inner sprue 130 through the cross sprue 120, wherein the straight sprue 110 and the cross sprue 120 are arranged vertically.

[0084] Specifically, the inner sprue 130 is located at the bottom of the cavity 150, the straight sprue 110 is communicated to the inner sprue 130 through the cross sprue 120, and the molten iron is poured into through the straight sprue 110 to form a bottom pouring process, promote the balance of iron filling, and reduce the vortex and oxidized slag, thereby reducing the problems of nodular cast iron adjusting nut shrinkage and slag inclusion, and ensuring the compactness of the nodular cast iron adjusting nut.

[0085] As shown in Figure 1 and Figure 2 The casting mold of the nodular cast iron adjusting nut can be one mold with two pieces, the straight sprue 110 is communicated to the cross sprue 120, and the inner sprue 130 can be provided with multiple, so that the straight sprue 110 can be communicated to multiple inner sprues 130 through the cross sprue 120, and each inner sprue 130 is communicated to the corresponding cavity 150, and then the molten iron can be poured into multiple cavities 150 through the straight sprue 110.

[0086] The cross section area ratio of the straight sprue 110, the cross sprue 120 and the inner sprue 130 is 1:1.8~2.0:1.1~1.5. By limiting the cross section area ratio of the straight sprue 110, the cross sprue 120 and the inner sprue 130, it is ensured that the cross sprue always maintains a full state, avoids the inclusion of molten iron into the mold, and ensures the smoothness of the molten iron filling process, so as to achieve the effect of optimizing the flow rate and pressure distribution of the molten iron, and reduce the problems of vortex and oxidized slag inclusion.

[0087] It is worth noting that the casting mold further comprises filters 160 arranged below the sprue 120, the sprue 120 is communicated with the ingates 130 through the filters 160, the filters 160 can be arranged in plurality, each filter 160 is arranged below the sprue 120 individually and uniformly, so that when the molten iron passes through the sprue 120 into the ingates 130, the filters 160 can filter the slag in part of the molten iron, and reduce the slag inclusion defects.

[0088] In the embodiment, the number of the filters 160 is equal to that of the ingates 130, that is, each ingate 130 is communicated with the sprue 120 through one filter 160.

[0089] It is to be noted that the casting mold of the nodular cast iron adjusting die nut can be placed with split conformal chills 140 in the cavity 150, wherein the material of the conformal chills 140 can be selected from HT150, and the thickness of the conformal chills 140 can be 80% to 90% of the thickness of the nodular cast iron adjusting die nut.

[0090] In the high-temperature treatment of step two, the heat stress leading to cracks is avoided by controlling the temperature rising rate and slowly rising the temperature, and the austenitizing is uniform, and in the tempering temperature of step three, the temperature rising rate and the holding time are balanced by increasing the temperature rising rate and reducing the holding time, so as to ensure the uniformity of the tempering effect, thereby effectively reducing the internal organizational defects and improving the hardness consistency.

[0091] In a third aspect, the application provides a nodular cast iron adjusting die nut prepared by the production process of the nodular cast iron adjusting die nut of the second aspect.

[0092] According to the nodular cast iron adjusting die nut and the production process thereof, the following beneficial effects can be achieved: by balancing the carbon-silicon ratio, inhibiting the graphitization expansion, reducing the shrinkage, adjusting the manganese and chromium element ratio to enhance the hardness and tensile strength, using magnesium and rare earth to improve the spheroidization rate and reduce the hardness unevenness, and controlling the proportion of sulfur, phosphorus, titanium, zinc, lead and vanadium elements to reduce impurity hazards and ensure the stability of the tensile strength, yield strength and hardness of the adjusting die nut, therefore, by adjusting the component ratio of the nodular cast iron adjusting die nut, the casting defects of the adjusting die nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the adjusting die nut, and improving the hardness uniformity of the adjusting die nut.

[0093] The above embodiments of the application are described in detail in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application.

Claims

1. A spheroidal graphite cast iron modulating nut, characterized by, The nodular cast iron adjusting die nut is based on the following components in percentage of mass: C: 3.70%-3.75%, Si: 2.35%-2.45%, Mn: 0.45%-0.55%, Cr: 0.15%-0.20%, Sn: 0.040%-0.050%, Mg: 0.040%-0.050%, P≤0.015%, S: 0.008%-0.015%, rare earth: 0.009%-0.010%, Ti+Zn+Pb+V≤0.010%, and the rest is Fe.

2. The process for producing a spheroidal graphite cast iron modulating nut, characterized by, The method comprises the following steps: Step one, pouring the molten iron into the casting mold of the nodular cast iron adjusting die nut to form a nut blank, wherein the composition of the molten iron comprises: C: 3.70%-3.75%, Si: 2.35%-2.45%, Mn: 0.45%-0.55%, Cr: 0.15%-0.20%, Sn: 0.040%-0.050%, Mg: 0.040%-0.050%, P≤0.015%, S: 0.008%-0.015%, rare earth: 0.009%-0.010%, Ti+Zn+Pb+V≤0.010%, and the rest is Fe; Step two, heating the nut blank to 920-970°C in a furnace and maintaining the temperature for 4 hours, and then cooling to 370-420°C out of the furnace; Step three, heating the cooled nut blank to 550-600°C in a furnace and maintaining the temperature for 3 hours, and then cooling to 150°C out of the furnace, and processing the nut blank to obtain the nodular cast iron adjusting die nut; The casting mold comprises a mold body, the mold body comprises a sprue, a runner, a cross gate, a filter, and a cavity corresponding to the nodular cast iron adjusting die nut, the runner is communicated to the bottom of the cavity, the sprue is communicated to the runner through the cross gate, the sprue and the cross gate are arranged perpendicularly to each other, the filter is arranged below the cross gate, the cross gate is communicated to the runner through the filter, and the cross sectional area ratio of the sprue, the cross gate and the runner is 1:1.8-2.0:1.1-1.

5.

3. The production process according to claim 2, characterized in that, The step two further comprises: heating the nut blank to 920-970°C in a furnace at a temperature rising rate of 60-80°C / h, and maintaining the temperature for 4 hours, and then cooling to 370-420°C out of the furnace.

4. The production process according to claim 2, characterized in that, The step three further comprises: heating the cooled nut blank to 550-600°C in a furnace at a temperature rising rate of 100°C / h, and maintaining the temperature for 3 hours, and then cooling to 150°C out of the furnace, and processing the nut blank to obtain the nodular cast iron adjusting die nut.

5. A spheroidal graphite cast iron modulating nut, characterized by The nodular cast iron adjusting die nut is prepared by the production process of any one of claims 2-4.

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