Nodular cast iron mold adjusting nut and production process thereof

Abstract

According to the spheroidal graphite cast iron mold adjusting nut and the production technology thereof, the hardness and tensile strength are enhanced by balancing the carbon-silicon proportion, inhibiting graphitization expansion and reducing shrinkage porosity and meanwhile adjusting the proportion of manganese and chromium, the spheroidization rate is increased through the magnesium element and rare earth, and the problem of uneven hardness is solved; then the proportion of elements such as sulfur, phosphorus, titanium, zinc, lead and vanadium is controlled, impurity harm is reduced, and the stability of tensile strength, yield strength and hardness of the mold adjusting nut is ensured, so that the casting defects of the mold adjusting nut can be effectively reduced by adjusting the component proportion of the nodular cast iron mold adjusting nut, and the mold adjusting nut quality is improved. Therefore, the tensile strength, the yield strength and the hardness of the mold adjusting nut are improved, and the hardness uniformity of the mold adjusting nut is improved.

Description

Technical Field

[0001] The present application relates to the technical field of casting technology, and in particular to a ductile iron mold adjusting nut and a production process thereof. Background Art

[0002] As an important transmission part of compression molding equipment (such as die-casting machines, injection molding machines, etc.), the die-adjusting nut has very high requirements for the die-adjusting nut casting. However, the current die-adjusting nut castings not only have casting defects such as slag inclusion, cold shut and shrinkage after fine processing, but also have problems such as insufficient hardness or uneven hardness of the casting body. Especially when the die-adjusting nut is heavy or has a thick wall, the problems caused by casting defects are more prominent, seriously affecting the qualified rate of the die-adjusting nut. Therefore, there is currently a lack of a solution that can reduce casting defects and improve the hardness of the die-adjusting nut, so improvement is needed. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a ductile iron die-adjusting nut and a production process thereof, which can effectively reduce casting defects of the die-adjusting nut and improve the hardness and hardness uniformity of the die-adjusting nut.

[0004] In a first aspect, an embodiment of the present application provides a ductile iron mold adjusting nut, which comprises the following components based on mass percentage statistics: 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%, and the rest is Fe.

[0005] The ductile iron mold adjusting nut provided in the embodiment of the present application comprises the following components based on mass percentage statistics: 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.

[0006] In a second aspect, an embodiment of the present application provides a production process for a ductile iron die-adjusting nut, comprising the following steps: Step 1, pouring molten iron into a casting mold of a ductile iron mold adjustment nut to form a nut blank; wherein the composition of the molten iron includes: 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; Step 2: Place the nut blank into a furnace and heat it to 920°C to 970°C, maintain the temperature for 4 hours, then remove it from the furnace and cool it to 370°C to 420°C; Step 3: Send the cooled nut blank into a furnace and heat it to 550°C to 600°C, maintain the temperature for 3 hours, then cool it to 150°C with the furnace, and process the nut blank after cooling out of the furnace to obtain a ductile iron mold adjustment nut.

[0007] In the production process provided in the embodiment of the present application, the composition of the molten iron in step 1 includes: 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.

[0008] In the production process provided in the embodiment of the present application, the step 2 also includes: sending the nut blank into the furnace and heating it to 920°C to 970°C at a temperature rise rate of 60 to 80°C / h, and maintaining the temperature for 4 hours, and then taking it out of the furnace and cooling it to 370°C to 420°C.

[0009] In the production process provided in the embodiment of the present application, the step three also includes: sending the cooled nut blank into the furnace and heating it to 550°C to 600°C at a temperature rise rate of 100°C / h, and maintaining the temperature for 3 hours, and then cooling it to 150°C with the furnace, and processing the nut blank after cooling out of the furnace to obtain a ductile iron mold adjustment nut.

[0010] In the production process provided in the embodiment of the present application, the casting mold includes: a mold body, the mold body includes a straight runner, an ingrown runner, a cross runner, and a cavity corresponding to the adjusting nut, the ingrown runner is connected to the bottom of the cavity, the straight runner is connected to the ingrown runner through the cross runner, wherein the straight runner and the cross runner are arranged perpendicular to each other.

[0011] In the production process provided in the embodiment of the present application, the cross-sectional area ratio of the sprue, the runner and the ingrown runner is 1:1.8~2.0:1.1~1.5.

[0012] In the production process provided in an embodiment of the present application, the casting mold further includes a filter, which is arranged below the runner, and the runner is connected to the ingrown runner through the filter.

[0013] In a third aspect, an embodiment of the present application provides a ductile iron mold adjusting nut, which is prepared using the production process of the ductile iron mold adjusting nut as described in the embodiment of the second aspect.

[0014] The ductile iron mold adjusting nut and its production process provided in the embodiments of the present application have at least the following beneficial effects: by balancing the carbon-silicon ratio, graphitization expansion is suppressed and shrinkage is reduced; at the same time, the ratio of manganese and chromium elements is adjusted to enhance hardness and tensile strength, and magnesium and rare earth elements are used to improve the spheroidization rate and reduce the problem of uneven hardness; in addition, the ratios of elements such as sulfur, phosphorus, titanium, zinc, lead and vanadium are controlled to reduce the hazards of impurities and ensure the stability of the tensile strength, yield strength and hardness of the mold adjusting nut; therefore, by adjusting the component ratio of the ductile iron mold adjusting nut, the casting defects of the mold adjusting nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the mold adjusting nut and improving the hardness uniformity of the mold adjusting nut.

[0015] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained through the structures particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present application is further described below with reference to the accompanying drawings and embodiments; Figure 1 Schematic diagram of the structure of the casting mold of the ductile iron mold adjusting nut provided in the embodiment of the present application; Figure 2 1. It is a bottom view of a casting mold for a ductile iron mold adjusting nut provided in an embodiment of the present application; Figure 3 Schematic diagram of the cross-section of the structure of the casting mold of the ductile iron mold adjusting nut provided in the embodiment of the present application; Figure 4 This is a metallographic diagram of the matrix structure of the ductile iron die adjustment nut after corrosion provided in an embodiment of the present application. DETAILED DESCRIPTION

[0017] This section will describe the specific embodiments of the present application in detail. The preferred embodiments of the present application are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present application, but it cannot be understood as a limitation on the scope of protection of the present application.

[0018] 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 it is not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features. "At least one" means one or more, and "more than one" means two or more. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items.

[0019] In addition, unless otherwise clearly specified and limited, the term "connection / connected" should be understood in a broad sense. For example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or able to communicate with each other; it can be a direct connection or an indirect connection through an intermediate medium.

[0020] In the description of the embodiments of the present application, the reference terms "one embodiment / implementation", "another embodiment / implementation" or "certain embodiments / implementations", "in the above-mentioned embodiments / implementations" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least two embodiments or implementations disclosed in the present application. In the disclosure of this application, the schematic representation of the above terms does not necessarily refer to the same exemplary embodiment or implementation. It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different from that in the flowchart.

[0021] As an important transmission part of compression molding equipment (such as die-casting machines, injection molding machines, etc.), the die-adjusting nut has very high requirements for the die-adjusting nut casting. However, the current die-adjusting nut castings not only have casting defects such as slag inclusion, cold shut and shrinkage after fine processing, but also have problems such as insufficient hardness or uneven hardness of the casting body. Especially when the die-adjusting nut is heavy or has a thick wall, the problems caused by casting defects are more prominent, seriously affecting the qualified rate of the die-adjusting nut. Therefore, there is currently a lack of a solution that can reduce casting defects and improve the hardness of the die-adjusting nut, so improvement is needed.

[0022] In order to at least solve the technical problems existing in the above-mentioned prior art, the present application proposes a ductile iron mold adjusting nut and a production process thereof. By adjusting the component ratio of the ductile iron mold adjusting nut, the casting defects of the mold adjusting nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the mold adjusting nut, and improving the hardness uniformity of the mold adjusting nut.

[0023] It should be noted that the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0025] In a first aspect, an embodiment of the present application provides a ductile iron mold adjusting nut, and the ductile iron mold adjusting nut is described below with reference to a specific embodiment.

[0026] Example 1 The various components of the ductile iron mold adjusting nut are counted according to mass percentage, specifically: the carbon content can be 3.60% to 3.90%, the silicon content can be 2.30% to 2.50%, the manganese content can be 0.35% to 0.55%, the chromium content can be 0.15% to 0.20%, the tin content can be 0.040% to 0.060%, the magnesium content can be 0.035% to 0.055%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.005% to 0.02%, the rare earth content can be 0.007% to 0.012%, and the total content of titanium, zinc, lead and vanadium can be less than or equal to 0.015%, and the rest is iron.

[0027] Among them, the mechanical properties of the ductile iron die-adjusting nut proposed in Example 1 can reach a tensile strength Rm: 615~705MPa, a yield strength R p0.2 : 420~487MPa, elongation after fracture A: 7~11%, hardness: 175~208HBW. Metallographic structure: spheroidization rate: 90~95%, pearlite content: 45~65%, ferrite content: 35~55%.

[0028] It is worth noting that in order to achieve the same mechanical properties and metallographic structure indicators as the ductile iron mold adjusting nut of the above-mentioned embodiment 1, the proportions of various components adopted in the relevant technology are: the carbon content can be 3.90% to 4.40%, the silicon content can be 2.80% to 4.00%, the manganese content can be 0.50% to 0.55%, the copper content can be 0.40% to 0.60%, the magnesium content can be 0.035% to 0.055%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.005% to 0.02%, the rare earth content can be 0.007% to 0.012%, and the rest is iron. The product qualification rate of the ductile iron mold adjusting nut using the various component proportions adopted in the relevant technology is 80%~90%. By comparison, it can be seen that in the various component ratios of the ductile iron die-adjusting nut proposed in Example 1, by adjusting the contents of carbon, silicon, chromium, and tin, a corresponding proportion is formed. By combining chromium with carbon to form fine dispersed carbides, the strength and wear resistance of the casting are improved, while grain growth is inhibited and the toughness of the casting material is improved. By limiting the content range of chromium and tin, the formation of excessive hard carbides in the casting can be avoided. Specifically, when the chromium content is between 0.15% and 0.20% and the tin content is between 0.040% and 0.060%, no carbides that seriously affect the mechanical properties appear in the matrix structure, thus avoiding embrittlement of the casting. In addition, the pearlite plate spacing can be further refined, and the strength can be improved, thereby achieving cast properties and metallographic structure that meet the casting requirements, and the product qualification rate can be increased to 99.5%. In other words, the solution provided in the embodiment of the present application can replace the high copper content solution used in the related art, thereby effectively reducing casting defects of the die-adjusting nut while reducing production costs.

[0029] Example 2 The various components of the ductile iron mold adjusting nut are counted according to mass percentage, specifically: the carbon content can be 3.70% to 3.75%, the silicon content can be 2.35% to 2.45%, the manganese content can be 0.45% to 0.50%, the chromium content can be 0.15% to 0.20%, the tin content can be 0.040% to 0.050%, the magnesium content can be 0.040% to 0.050%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.008% to 0.015%, the rare earth content can be 0.009% to 0.010%, and the total content of titanium, zinc, lead and vanadium can be less than or equal to 0.010%, and the rest is iron.

[0030] The mechanical properties of the ductile iron die-adjusting nut proposed in the second embodiment can reach a tensile strength Rm of 650-700 MPa and a yield strength R p0.2 : 440~480MPa, elongation after fracture A: 8~10%, hardness: 180~200HBW. Metallographic structure: spheroidization rate: 90~95%, pearlite content: 45~65%, ferrite content: 35~55% Compared to Example 1, Example 2 refines the composition range of the ductile iron die-adjusting nut, limits the ratio of carbon and silicon elements, reduces the risk of overburning, improves graphitization stability, optimizes the synergistic effect of silicon and carbon, improves the consistency of spheroidization, and thus reduces shrinkage. Simultaneously, by reducing the sulfur content, slag inclusion and uneven hardness are reduced, and further limiting the contents of rare earth, titanium, zinc, lead, and vanadium elements, it can improve spheroidization uniformity and reduce impurity hazards, thereby effectively improving the mechanical properties of the die-adjusting nut. Specifically, the lower limit of tensile strength is increased from 615 MPa to 650 MPa, while the upper limit of tensile strength is also increased by 5 MPa. The yield strength is also correspondingly improved. Although the upper limit of yield strength decreases slightly by 7 MPa, the lower limit increases by 20 MPa. The elongation and hardness are also more stable, and the overall stability of the tensile strength, yield strength, elongation, and hardness of the ductile iron die-adjusting nut is improved.

[0031] Similarly, the composition ratios of the ductile iron mold adjusting nut proposed in Example 2 can achieve as-cast properties and metallographic structures that meet casting requirements, and the product qualification rate can be increased from 80% using the composition ratio scheme in the relevant technology to 99.5%. Even when the chromium content is between 0.15% and 0.20%, no carbides that seriously affect the mechanical properties appear in the matrix structure. This can replace the high copper content scheme used in the relevant technology, thereby effectively reducing casting defects of the mold adjusting nut while reducing production costs.

[0032] Combining Example 1 and Example 2, it can be seen that by adjusting the ratio of carbon and silicon, graphitization expansion can be effectively suppressed and shrinkage can be reduced. At the same time, the ratio of manganese and chromium elements can be adjusted to enhance hardness and tensile strength, and magnesium and rare earth elements can be used to improve the spheroidization rate and reduce the problem of uneven hardness. In addition, the ratio of elements such as sulfur, phosphorus, titanium, zinc, lead and vanadium is controlled to reduce the harm of impurities and ensure the stability of the tensile strength, yield strength and hardness of the mold adjusting nut. Therefore, by adjusting the component ratio of the ductile iron mold adjusting nut, the use of copper and molybdenum elements for casting in related technologies is eliminated, and while ensuring the casting effect, the casting defects of the mold adjusting nut can be effectively reduced, thereby reducing costs, improving the tensile strength, yield strength and hardness of the mold adjusting nut, and improving the hardness uniformity of the mold adjusting nut.

[0033] In a second aspect, an embodiment of the present application provides a production process for a ductile iron mold adjusting nut. The production process for a ductile iron mold adjusting nut is described below with reference to a specific embodiment.

[0034] Example 3 The production process of ductile iron die adjustment nuts can include the following steps: Step 1: pouring molten iron into a casting mold of a ductile iron mold-adjusting nut to form a nut blank; Step 2: Heat the nut blanks in a furnace to 920°C to 970°C and maintain the temperature for 4 hours, then remove them from the furnace and cool them to 370°C to 420°C. Step 3: Send the cooled nut blank into the furnace and heat it to 550℃ to 600℃, maintain the temperature for 3 hours, then cool it to 150℃ with the furnace, and process the nut blank after cooling to obtain ductile iron mold adjustment nuts.

[0035] In step 1, the various components in the molten iron are counted according to mass percentage, specifically: the carbon content can be 3.60% to 3.90%, the silicon content can be 2.30% to 2.50%, the manganese content can be 0.35% to 0.55%, the chromium content can be 0.15% to 0.20%, the tin content can be 0.040% to 0.060%, the magnesium content can be 0.035% to 0.055%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.005% to 0.02%, the rare earth content can be 0.007% to 0.012%, and the total content of titanium, zinc, lead and vanadium can be less than or equal to 0.015%, and the rest is iron. Among them, the parameters achieved by the molten iron casting according to the above component ratios are: tensile strength Sm: 650~700MPa, yield strength R p0.2 : 440~480MPa, elongation after fracture A: 8%~10%, hardness: 180~200HBW, spheroidization rate: 90%~95%, pearlite quantity: 45%~65%, ferrite quantity: 35%~55%.

[0036] The molten iron is obtained by the following steps: placing casting pig iron (high-purity pig iron), high-purity scrap steel, recarburizer, ferrosilicon, ferromanganese, ferrochrome and tin particles into a medium-frequency melting furnace to melt and form liquid molten iron, so that the various components of the molten iron meet the required requirements; when the temperature of the molten iron reaches 1450°C to 1470°C, the molten iron can be subjected to spheroidization inoculation treatment, and 0.1% sulfur-oxygen inoculant is added during the process of pouring the molten iron into the casting mold for sulfur inoculation treatment; it should be noted that the total content of titanium, zinc, lead and vanadium in both high-purity pig iron and high-purity scrap steel is less than 0.015%.

[0037] Reference Figure 1 and Figure 2 , Figure 1 Schematic diagram of the structure of the casting mold of the ductile iron mold adjusting nut provided in the embodiment of the present application. Figure 2 It is an overhead view of the casting mold provided in an embodiment of the present application. The casting mold of the ductile iron mold adjustment nut includes a mold body 100, and the mold body 100 includes a straight runner 110, an ingrown runner 130, a cross runner 120, and a cavity 150 corresponding to the adjusting nut. The ingrown runner 130 is connected to the bottom of the cavity 150, and the straight runner 110 is connected to the ingrown runner 130 through the cross runner 120, wherein the straight runner 110 and the cross runner 120 are arranged perpendicular to each other.

[0038] Specifically, the ingrowth 130 is located at the bottom of the cavity 150, and the sprue 110 is connected to the ingrowth 130 through the cross runner 120. The molten iron is poured into the sprue 110 to form a bottom pouring process, which promotes balanced filling of the molten iron, reduces eddy currents and oxidation slag inclusions, thereby reducing the shrinkage and slag inclusion problems of the ductile iron mold adjustment nut and ensuring the density of the ductile iron mold adjustment nut.

[0039] Among them, such as Figure 1 and Figure 2 As shown, the casting mold of the ductile iron mold adjustment nut can be a one-mold two-piece mold, the sprue 110 is connected to the runner 120, and multiple ingrowns 130 can be provided, so that the sprue 110 can be connected to multiple ingrowns 130 through the runner 120, and each ingrown 130 is connected to the corresponding cavity 150, and then the molten iron can be injected into the multiple cavities 150 through the sprue 110. It is worth noting that the pouring temperature of the molten iron can be controlled at 1375℃ to 1390℃, and the pouring speed can be controlled at 42kg / s to 48kg / s, so as to ensure a good liquid-solid solidification phase in the subsequent process flow, and can also effectively reduce casting defects such as cold shut and slag inclusion.

[0040] The cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130 is 1:1.8-2.0:1.1-1.5. By limiting the cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130, the runner is ensured to remain full, preventing slag inclusions from entering the mold and ensuring a smooth filling process. This optimizes the molten iron flow rate and pressure distribution, reducing eddy currents and oxidized slag inclusions.

[0041] Reference Figure 3 , Figure 3It is a structural cross-sectional schematic diagram of the casting mold provided in an embodiment of the present application. It is worth noting that the casting mold also includes a filter 160. The filter 160 is arranged below the runner 120. The runner 120 is connected to the ingrowth 130 through the filter 160. There can be multiple filters 160, and each filter 160 is individually and evenly arranged below the runner 120. Therefore, when the molten iron passes through the runner 120 and enters the ingrowth 130, the filter 160 can filter out part of the slag in the molten iron, thereby reducing slag inclusion defects.

[0042] The number of the ingrows 130 and the number of the filters 160 are equal, that is, each ingrow 130 is connected to the runner 120 through a filter 160 .

[0043] It should be noted that the casting mold of the ductile iron mold adjustment nut can place a split conformable chill 140 in the mold cavity 150, wherein the material of the conformable chill 140 can be HT150, and the thickness of the conformable chill 140 can be 80% to 90% of the thickness of the ductile iron mold adjustment nut.

[0044] Therefore, the casting mold of the ductile iron mold-adjustable 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.

[0045] It is worth noting that in the normalizing high-temperature treatment of the related art, the heating temperature of the nut blank is 870°C to 940°C, and the holding time is 1 hour to 3 hours. In the normalizing high-temperature treatment of step 2 proposed in the embodiment of the present application, by increasing the heating temperature and extending the holding time, it is possible to ensure that the nut blank matrix is ​​completely converted into austenite, promoting the spheroidization of graphite. After being taken out of the furnace, the cooling rate and cooling temperature are controlled, and the nut blank is cooled to 370°C to 420°C. While ensuring the spheroidization rate, it can promote the uniform precipitation of pearlite, balance the strength and toughness, and thus reduce the problem of uneven hardness of ductile iron mold adjustment nuts.

[0046] In the tempering treatment of step three, the tempering temperature is controlled at 550℃ to 600℃ to eliminate residual stress and stabilize the microstructure. Then, by slowly cooling with the furnace, the microstructure is ensured to be uniform and embrittlement is avoided, thereby effectively improving the hardness, hardness uniformity and elongation of the blank.

[0047] Reference Figure 4 , Figure 4 Schematic diagram of the metallographic structure of the ductile iron die adjustment nut after corrosion provided in the embodiment of the present application. Figure 4 As shown in the figure, the parameters of the ductile iron die adjustment nut produced based on the production process of the ductile iron die adjustment nut are as follows: tensile strength Rm: 850~900MPa, yield strength R p0.2: 590-630 MPa, elongation after fracture A: 7-9%, hardness: 300-350 HBW. Spheroidization rate: 90-95%, pearlite content: 95%, ferrite content: 5%. Therefore, the production process of ductile iron die-adjustable nuts proposed in the embodiments of this application can effectively reduce casting defects in die-adjustable nuts, thereby increasing the tensile strength, yield strength, and hardness of the die-adjustable nuts and improving the hardness uniformity of the die-adjustable nuts.

[0048] Example 4 Step 1: pouring molten iron into a casting mold of a ductile iron mold-adjusting nut to form a nut blank; Step 2: Heat the nut blanks in a furnace to 920°C to 970°C and maintain the temperature for 4 hours, then remove them from the furnace and cool them to 370°C to 420°C. Step 3: Send the cooled nut blank into the furnace and heat it to 550℃ to 600℃, maintain the temperature for 3 hours, then cool it to 150℃ with the furnace, and process the nut blank after cooling to obtain ductile iron mold adjustment nuts.

[0049] In step 1, the various components in the molten iron are counted according to mass percentage, and are specifically adjusted as follows: the carbon content can be 3.70% to 3.75%, the silicon content can be 2.35% to 2.45%, the manganese content can be 0.45% to 0.50%, the chromium content can be 0.15% to 0.20%, the tin content can be 0.040% to 0.050%, the magnesium content can be 0.040% to 0.050%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.008% to 0.015%, the rare earth content can be 0.009% to 0.010%, and the total content of titanium, zinc, lead and vanadium can be less than or equal to 0.010%, with the remainder being iron.

[0050] Among them, the casting mold of the ductile iron mold adjustment nut includes a mold body 100, and the mold body 100 includes a straight runner 110, an ingrown runner 130, a cross runner 120, and a cavity 150 corresponding to the adjusting nut, the ingrown runner 130 is connected to the bottom of the cavity 150, and the straight runner 110 is connected to the ingrown runner 130 through the cross runner 120, wherein the straight runner 110 and the cross runner 120 are arranged perpendicular to each other.

[0051] Specifically, the ingrowth 130 is located at the bottom of the cavity 150, and the sprue 110 is connected to the ingrowth 130 through the cross runner 120. The molten iron is poured into the sprue 110 to form a bottom pouring process, which promotes balanced filling of the molten iron, reduces eddy currents and oxidation slag inclusions, thereby reducing the shrinkage and slag inclusion problems of the ductile iron mold adjustment nut and ensuring the density of the ductile iron mold adjustment nut.

[0052] Among them, such as Figure 1 and Figure 2 As shown, the casting mold of the ductile iron mold adjusting nut can be a two-piece mold, the straight runner 110 is connected to the cross runner 120, and multiple ingrowns 130 can be provided, so that the straight runner 110 can be connected to multiple ingrowns 130 through the cross runner 120, and each ingrown runner 130 is connected to the corresponding cavity 150, and then the molten iron can be injected into the multiple cavities 150 through the straight runner 110.

[0053] The cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130 is 1:1.8-2.0:1.1-1.5. By limiting the cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130, the runner is ensured to remain full, preventing slag inclusions from entering the mold and ensuring a smooth filling process. This optimizes the molten iron flow rate and pressure distribution, reducing eddy currents and oxidized slag inclusions.

[0054] It is worth noting that the casting mold also includes a filter 160, which is arranged below the runner 120. The runner 120 is connected to the ingrowth 130 through the filter 160. There can be multiple filters 160, and each filter 160 is individually and evenly arranged below the runner 120. Therefore, when the molten iron passes through the runner 120 and enters the ingrowth 130, the filter 160 can filter out part of the slag in the molten iron, thereby reducing slag inclusion defects.

[0055] The number of the ingrows 130 and the number of the filters 160 are equal, that is, each ingrow 130 is connected to the runner 120 through a filter 160 .

[0056] It should be noted that the casting mold of the ductile iron mold adjustment nut can place a split conformable chill 140 in the mold cavity 150, wherein the material of the conformable chill 140 can be HT150, and the thickness of the conformable chill 140 can be 80% to 90% of the thickness of the ductile iron mold adjustment nut.

[0057] Example 5 The production process of the ductile iron die adjusting nut may further comprise the following steps: Step 1: pouring molten iron into a casting mold of a ductile iron mold-adjusting nut to form a nut blank; Step 2: Place the nut blank into a furnace and heat it to 920°C to 970°C at a temperature rise rate of 60 to 80°C / h, maintain the temperature for 4 hours, then remove it from the furnace and cool it to 370°C to 420°C. Step 3: Send the cooled nut blank into the furnace and heat it to 550°C to 600°C at a temperature rise rate of 100°C / h, and maintain the temperature for 3 hours, then cool it to 150°C with the furnace, and process the nut blank after cooling out of the furnace to obtain ductile iron mold adjustment nuts.

[0058] In step 1, the various components in the molten iron are counted according to mass percentage, and are specifically adjusted as follows: the carbon content can be 3.70% to 3.75%, the silicon content can be 2.35% to 2.45%, the manganese content can be 0.45% to 0.50%, the chromium content can be 0.15% to 0.20%, the tin content can be 0.040% to 0.050%, the magnesium content can be 0.040% to 0.050%, the phosphorus content can be less than or equal to 0.015%, the sulfur content can be 0.008% to 0.015%, the rare earth content can be 0.009% to 0.010%, and the total content of titanium, zinc, lead and vanadium can be less than or equal to 0.010%, with the remainder being iron.

[0059] Among them, the casting mold of the ductile iron mold adjustment nut includes a mold body 100, and the mold body 100 includes a straight runner 110, an ingrown runner 130, a cross runner 120, and a cavity 150 corresponding to the adjusting nut, the ingrown runner 130 is connected to the bottom of the cavity 150, and the straight runner 110 is connected to the ingrown runner 130 through the cross runner 120, wherein the straight runner 110 and the cross runner 120 are arranged perpendicular to each other.

[0060] Specifically, the ingrowth 130 is located at the bottom of the cavity 150, and the sprue 110 is connected to the ingrowth 130 through the cross runner 120. The molten iron is poured into the sprue 110 to form a bottom pouring process, which promotes balanced filling of the molten iron, reduces eddy currents and oxidation slag inclusions, thereby reducing the shrinkage and slag inclusion problems of the ductile iron mold adjustment nut and ensuring the density of the ductile iron mold adjustment nut.

[0061] Among them, such as Figure 1 and Figure 2 As shown, the casting mold of the ductile iron mold adjusting nut can be a two-piece mold, the straight runner 110 is connected to the cross runner 120, and multiple ingrowns 130 can be provided, so that the straight runner 110 can be connected to multiple ingrowns 130 through the cross runner 120, and each ingrown runner 130 is connected to the corresponding cavity 150, and then the molten iron can be injected into the multiple cavities 150 through the straight runner 110.

[0062] The cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130 is 1:1.8-2.0:1.1-1.5. By limiting the cross-sectional area ratio of the sprue 110, runner 120, and ingredient 130, the runner is ensured to remain full, preventing slag inclusions from entering the mold and ensuring a smooth filling process. This optimizes the molten iron flow rate and pressure distribution, reducing eddy currents and oxidized slag inclusions.

[0063] It is worth noting that the casting mold also includes a filter 160, which is arranged below the runner 120. The runner 120 is connected to the ingrowth 130 through the filter 160. There can be multiple filters 160, and each filter 160 is individually and evenly arranged below the runner 120. Therefore, when the molten iron passes through the runner 120 and enters the ingrowth 130, the filter 160 can filter out part of the slag in the molten iron, thereby reducing slag inclusion defects.

[0064] The number of the ingrows 130 and the number of the filters 160 are equal, that is, each ingrow 130 is connected to the runner 120 through a filter 160 .

[0065] It should be noted that the casting mold of the ductile iron mold adjustment nut can place a split conformable chill 140 in the mold cavity 150, wherein the material of the conformable chill 140 can be HT150, and the thickness of the conformable chill 140 can be 80% to 90% of the thickness of the ductile iron mold adjustment nut.

[0066] In the high-temperature treatment of step 2, the temperature rise rate is controlled and the temperature is slowly increased to avoid the occurrence of cracks caused by thermal stress, ensuring uniform austenitization. In the tempering temperature of step 3, the temperature rise rate and the holding time are balanced by increasing the temperature rise rate and reducing the holding time to ensure uniform tempering effect, thereby effectively reducing internal structural defects and improving hardness consistency.

[0067] In a third aspect, the present application proposes a ductile iron die adjusting nut, which is prepared using the production process of the ductile iron die adjusting nut of the embodiment of the second aspect above.

[0068] The ductile iron mold adjusting nut and its production process provided in the embodiments of the present application have at least the following beneficial effects: by balancing the carbon-silicon ratio, graphitization expansion is suppressed and shrinkage is reduced; at the same time, the ratio of manganese and chromium elements is adjusted to enhance hardness and tensile strength, and magnesium and rare earth elements are used to improve the spheroidization rate and reduce the problem of uneven hardness; in addition, the ratios of elements such as sulfur, phosphorus, titanium, zinc, lead and vanadium are controlled to reduce the hazards of impurities and ensure the stability of the tensile strength, yield strength and hardness of the mold adjusting nut; therefore, by adjusting the component ratio of the ductile iron mold adjusting nut, the casting defects of the mold adjusting nut can be effectively reduced, thereby improving the tensile strength, yield strength and hardness of the mold adjusting nut and improving the hardness uniformity of the mold adjusting nut.

[0069] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. Ductile iron die adjusting nut, characterized in that: The ductile iron die adjusting nut comprises the following components based on mass percentage statistics: 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%, and the rest is Fe.

2. The ductile iron die adjusting nut according to claim 1, characterized in that: The ductile iron die adjusting nut comprises the following components based on mass percentage statistics: 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.

3. The production process of ductile iron die-adjusting nuts is characterized by: The following steps are involved: Step 1, pouring molten iron into a casting mold of a ductile iron mold adjustment nut to form a nut blank; wherein the composition of the molten iron includes: 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; Step 2: Place the nut blank into a furnace and heat it to 920°C to 970°C, maintain the temperature for 4 hours, then remove it from the furnace and cool it to 370°C to 420°C; Step 3: Send the cooled nut blank into a furnace and heat it to 550°C to 600°C, maintain the temperature for 3 hours, then cool it to 150°C with the furnace, and process the nut blank after cooling out of the furnace to obtain a ductile iron mold adjustment nut.

4. The production process according to claim 3, characterized in that: The composition of the molten iron in the step 1 includes: 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.

5. The production process according to claim 3, characterized in that: The step 2 also includes: sending the nut blank into the furnace and heating it to 920°C to 970°C at a temperature rise rate of 60 to 80°C / h, maintaining the temperature for 4 hours, and then taking it out of the furnace and cooling it to 370°C to 420°C.

6. The production process according to claim 3, characterized in that: The step three also includes: sending the cooled nut blank into the furnace and heating it to 550°C to 600°C at a temperature rise rate of 100°C / h, and maintaining the temperature for 3 hours, then cooling it to 150°C with the furnace, and processing the nut blank after cooling out of the furnace to obtain a ductile iron mold adjustment nut.

7. The production process according to claim 3, characterized in that: The casting mold includes: a mold body, the mold body includes a straight runner, an ingrown runner, a cross runner, and a cavity corresponding to the adjusting nut, the ingrown runner is connected to the bottom of the cavity, the straight runner is connected to the ingrown runner through the cross runner, wherein the straight runner and the cross runner are arranged perpendicular to each other.

8. The production process according to claim 7, characterized in that: The cross-sectional area ratio of the sprue, the runner and the ingrown is 1:1.8-2.0:1.1-1.

5.

9. The production process according to claim 7, characterized in that: The casting mold further includes a filter, which is arranged below the runner, and the runner is communicated with the ingrown runner through the filter.

10. Ductile iron die-adjusting nut, characterized in that: The ductile iron die adjusting nut is prepared by the production process of any one of claims 3 to 9.

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