Middle opening casting iron mold

Abstract

The utility model provides a middle-opening casting iron mold. The middle-opening casting iron mold comprises a pouring cup, a transverse pouring gate, a vertical pouring gate, an inner pouring gate, an inner pouring gate, a mold cavity and a sand core, the sprue cup is arranged at the upper part of the cross gate, is fixedly connected with the cross gate and is used for receiving ladle molten iron; the transverse pouring gate is communicated with the multiple columns of vertical pouring gates, the multiple columns of mold cavities are arranged, and the vertical pouring gates are communicated with each column of mold cavities through the inner pouring gates and the inner pouring gates; the inner gate is arranged at a middle pipe orifice of the cavity, and molten iron flows in from the middle pipe orifice of the cavity during casting; the sand cores are contained in the cavities and connected to the cavities in the column in a penetrating mode, and the outer walls of the sand cores are matched with the inner walls of the cavities to form casting forming faces. The light-weight drift-diameter three-way pipe fitting has the advantages that the longitudinal arrangement distance of the cavities is further shortened, the proportion of an overall casting system is reduced, and the molten iron utilization rate of the light-weight drift-diameter three-way pipe fitting is increased; the slag blocking piece and the ingate jointly play roles of blocking live sand in the mold, ramming a piece, shunting molten iron to a cavity, feeding and the like.

Description

Technical Field

[0001] The utility model belongs to the field of cast iron molds, and particularly relates to a medium-port cast iron mold. Background Art

[0002] In the design of ductile iron (commonly known as "malleable iron") green sand casting molds, there are various design forms according to factors such as the quality of molten iron, the wall thickness and shape of the cast pipe fittings, etc.

[0003] In conventional ductile iron molds, the molten iron generally enters the ingate, riser, and sprue through the cross-riser or vertical-riser for diversion or splitting, and finally fills the cavity. Among them, except for the cavity part, the rest are gating and risering systems. The gating and risering system is the key to ensuring the formation of green blanks of pipe fittings in the cavity; the gating and risering system will be removed manually after the formation of malleable iron green blanks and recycled. The malleable iron green blanks are then threaded after multi-stage processing such as annealing, shot blasting, grinding the mouth, inspection, and galvanizing to obtain finished pipe fittings.

[0004] The position design of the riser, ingate, and runner in the gating and risering system is very crucial, which not only affects whether the pipe fittings can be cast and formed in the mold, but also affects the production rate of the pipe fittings; the ideal mold design is to reduce the proportion of the gating and risering system as much as possible on the basis of ensuring casting and forming, increase the proportion of the cavity volume in the mold, and facilitate the removal of the green blank pipe fittings from the gating and risering system, thereby reducing the labor cost during the recycling of the gating and risering system and the damage of the green blank pipe fittings caused by gravity knocking.

[0005] Patent application CN116037868A discloses a processing technology for increasing spherical graphite in ductile iron and cast iron parts, which mentions that adding an appropriate amount of rare earth magnesium silicon alloy to the molten iron can effectively prevent the shrinkage of the molten iron, increase the strength and toughness of the green blank, and prevent the green blank from cracking during ramming; the change of the molten iron enables the corresponding sand mold to also adopt a reduced design, reducing the proportion of the gating and risering system to increase the proportion of the cavity in the sand mold, thereby improving the utilization rate of molten iron and reducing the subsequent ramming difficulty.

[0006] However, due to the large variety of pipe fittings, for pipe fittings of different specifications or sizes, the reduced design of the molten iron mold applicable to this application is also different. Further improving the utilization rate of molten iron while ensuring casting and forming is a problem that needs to be solved.

[0007] The utility model patent CN219274390U provides a riserless short core head cast iron mold for this molten iron, which is applicable to a large number of pipe fitting types, cancels the riser design, shortens the length of the single-row sand core and the size of the ingate; greatly improves the utilization rate of molten iron (i.e., the proportion of the cavity volume in the mold).

[0008] This improvement method is relatively general. However, with the trend of lightweight manufacturing of malleable cast iron fittings in recent years to improve cost-effectiveness, the wall thickness of malleable cast iron fittings has also decreased accordingly. On the premise of meeting relevant standards, the wall thickness of lightweight malleable cast iron fittings will shrink by 10% - 20% depending on the specifications. For example, for a DN15 tee, the normal wall thickness is 2.5 mm, and the lightweight wall thickness is 2.3 mm; for a DN80 tee, the normal wall thickness is 4.5 mm, and the lightweight wall thickness is 3.8 mm. Correspondingly, the thickness of the pipe fitting mouth also shrinks by about 15%.

[0009] This also makes the amount of molten iron required in the inner cavity part of the mold decrease when manufacturing lightweight pipe fittings. However, the flow space of the molten iron in the cavity becomes smaller accordingly, and the inner gate also becomes thinner due to the influence of the pipe mouth thickness, resulting in worse overall molten iron fluidity. Therefore, the gating and risering system needs to be wider or thicker to better ensure the overall molten iron fluidity and ensure casting formation. Eventually, the molten iron utilization rate of lightweight pipe fittings is lower than that of conventional pipe fittings.

[0010] Therefore, designing a mold structure suitable for lightweight malleable cast iron fittings and further improving the molten iron utilization rate during the forming of lightweight malleable cast iron fittings is very economically beneficial on the premise of ensuring casting formation. Summary of the Utility Model

[0011] Aiming at the problems of low proportion of the inner cavity volume in the mold of lightweight malleable cast iron fittings and low molten iron utilization rate in the prior art, the present utility model provides a middle-gate cast iron mold.

[0012] To achieve the above object, the technical solutions provided by the present utility model are as follows:

[0013] A middle-gate cast iron mold includes a pouring cup, a horizontal runner, a vertical runner, an inner runner, an inner gate, a cavity, and a core. The pouring cup is arranged on the upper part of the horizontal runner and fixedly connected to the horizontal runner for receiving molten iron from the ladle. The horizontal runner is connected to multiple columns of vertical runners, multiple columns of cavities are provided, and the vertical runners are connected to each column of cavities through inner runners, inner gates. The inner gate is arranged at the middle pipe mouth position of the cavity, and the molten iron flows into the cavity from the middle pipe mouth during casting. The core is placed in the cavity and is connected through the cavity of the corresponding column. The outer wall of the core cooperates with the inner wall of the cavity to form a casting forming surface.

[0014] Further, the middle-gate cast iron mold adopts a vertical parting flaskless squeeze molding template, which is applicable to the casting of through-hole tees, medium-large tees, and some reducing tees. For the part of reducing tees, the outer diameter of the middle pipe mouth is less than 2 times the diameter of the upper pipe mouth, and the positions of the two straight pipe mouths are arranged in the template in such a way that the diameter of the lower pipe mouth is greater than that of the upper pipe mouth.

[0015] Further, the number of cavities in each column is set to 3 - 10 according to the size of the pipe fitting.

[0016] Preferably, the ingate is triangular, and the sprue is directly connected to the ingate, which is conducive to the direct diversion of molten iron into the cavity and increases the filling force of the molten iron.

[0017] Furthermore, the thickness of the inner gate is two-thirds of the thickness of the nozzle opening of the cavity, and the width of the ingate is the same as the width of the inner gate.

[0018] Furthermore, when the sprue is used to supply molten iron to two columns of cavities arranged symmetrically, the nozzle openings in the middle of the left and right adjacent two columns of cavities are arranged opposite to each other and share one ingate; the ingate is an equilateral triangle, the apex of the triangle is connected to the sprue, and the two base angles of the triangle are respectively connected to the middle nozzle openings of the symmetrically arranged cavities; the middle position of the bottom edge of the triangle is connected to the next section of the sprue.

[0019] Furthermore, when the sprue is used to supply molten iron to one column of cavities, the triangular ingate is a right triangle, the right angle of the right triangle is connected to the next section of the sprue, and one of the other two angles is connected to the previous section of the sprue, and the other is connected to the middle opening of the cavity.

[0020] Furthermore, core positioning blocks are provided at the ends of the core or at the gaps in the arrangement of the cavities. The core positioning blocks are engaged with the sand mold shell of the mold to achieve the positioning of the core in the cavity.

[0021] Furthermore, slag blocking sheets perpendicular to the direction of the sprue are provided on the sprue. The slag blocking sheets are in the shape of thin sheets, saving the longitudinal space of the sprue.

[0022] Furthermore, the slag blocking sheets are arranged above the ingate. The slag blocking sheets and the ingate act together to better play the role of blocking the loose sand and molten slag in the mold.

[0023] The advantages of the present utility model are as follows: compared with the filling form from the upper and lower double ports in CN219274390U, the number of inner gates and the total length of the sprue can be reduced, the longitudinal arrangement spacing of the cavities is further shortened, the proportion of the overall gating and risering system is reduced, the filling force of the molten iron is strong, and the utilization rate of the molten iron for the lightweight through-hole three-way pipe fittings is improved; the slag blocking sheets and the ingate act together to intercept the loose sand in the mold, facilitate ramming, facilitate the diversion of the molten iron into the cavity, feeding, etc. Without the need to additionally set risers, water replenishing blocks, and widened runners, the casting forming of the lightweight through-hole three-way pipe fittings is ensured. Description of the Drawings

[0024] Figure 1 It is the front view of the mold for casting the middle opening of the through-hole three-way;

[0025] Figure 2 It is the front view of the mold for casting the middle opening of the large through-hole three-way;

[0026] Figure 3It is a schematic diagram of the position of the slag blocking piece inside the middle-gate casting mold. Specific embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0028] The middle-gate cast iron mold provided by the present utility model is applicable to the casting of full-diameter tees, medium-large tees, and some reducing tees. The cavities corresponding to the tee pipe fittings are vertically arranged along the straight pipe direction of the tee pipe fittings in the mold. The outer diameters of the three pipe orifices of the full-diameter tee pipe fittings are the same. The outer diameter of the middle pipe orifice of the medium-large tee pipe fittings is greater than the outer diameter of the straight pipe orifices, and the outer diameters of the two straight pipe orifices are the same. Some reducing tee pipe fittings satisfy that the outer diameter of the middle pipe orifice is less than twice the diameter of the upper pipe orifice, and the positions of the two straight pipe orifices are arranged such that the diameter of the lower pipe orifice is greater than the diameter of the upper pipe orifice.

[0029] As Figure 1 shown, the middle-gate cast iron mold adopts a vertically split flaskless squeeze molding template, including a pouring cup 1, a horizontal runner 2, a vertical runner 3, an ingate 4, an inner gate 5, a cavity 6, and a core 7. The inner gate 5 is arranged at the middle pipe orifice position of the cavity 6. During casting, the molten iron flows into the cavity 6 from the middle pipe orifice, so it is named middle-gate casting.

[0030] The pouring cup 1 is arranged on the upper part of the horizontal runner 2 and is fixedly connected to the horizontal runner 2 for receiving the molten iron from the ladle. The horizontal runner 2 is connected to multiple groups of vertical runners 3.

[0031] The molten iron composition adopted by the present utility model is: iron 92 - 95%, carbon 2.8 - 3.8%, silicon 1.8 - 3.8%, manganese < 0.6%, sulfur < 0.2%, phosphorus < 0.1%, magnesium < 0.055%, chromium < 0.1%. This molten iron is obtained by adding a rare earth ferrosilicon magnesium alloy modifier to the original molten iron. Such a composition can increase the strength and toughness of the green compact, prevent the green compact from cracking during ramming, and has good fluidity of the molten iron, which can ensure that the molten iron in the mold is not prone to shrinkage.

[0032] Preferably, the ingate 4 is triangular. When a column of vertical runners 3 is used to supply molten iron to two symmetrically arranged columns of cavities 6, the middle pipe orifices of the two adjacent columns of cavities 6 on the left and right are arranged opposite to each other and share one ingate 4. At this time, the ingate 4 is an equilateral triangle. The apex of the triangle is connected to the vertical runner 3, and the two base angles of the triangle are respectively connected to the middle gates of the symmetrically arranged cavities 6. The middle position of the base of the triangle is connected to the next section of the vertical runner 3.

[0033] When a vertical runner 3 is only used to supply molten iron to a column of cavities 6, the triangular ingate 4 is a right triangle. The right angle of the right triangle thin plate is connected to the next section of the vertical runner 3, and the other two angles are respectively connected to the previous section of the vertical runner 3 and the middle opening of the cavity 6.

[0034] The ingate 3 is arranged in a triangular shape. Firstly, it is beneficial to intercept live sand, slag, etc. in the mold. Secondly, the triangle is also beneficial to increasing the force-bearing area during ramming, facilitating the ramming down of the green blank of the pipe fitting from the position of the ingate 4. Thirdly, the triangular ingate 4 is more conducive to the direct diversion of molten iron along both sides of the triangle into the cavity 6, without the need to additionally widen or thicken the runner to ensure the fluidity of molten iron. When the molten iron flows down from the vertical runner, it changes to a 45° oblique flow by means of the triangular ingate, reducing the loss of kinetic energy of the molten iron compared to the traditional way where the molten iron directly changes to a 90° flow direction. Therefore, the molten iron can maintain a stronger impact force and is more likely to fill the inside of the cavity of the thin-walled tee pipe fitting. Fourthly, a part of the molten iron can be temporarily stored in the ingate 4 to play a role in feeding the cavity 6.

[0035] The ingate 5 is arranged at the pipe orifice of the cavity 6 to make the molten iron enter the water inlet of the cavity 6. The ingate 4 is connected to the nearest ingate 5, and the molten iron flows into the cavity through the ingate 5. The thickness of the ingate 5 is about 2 / 3 of the thickness of the pipe orifice of the cavity 6, facilitating the filling of molten iron; the width of the ingate 4 is the same as the width of the ingate 5.

[0036] The cavities 6 are arranged in multiple columns in the mold, and each column is provided with 3 - 10 cavities according to different pipe fitting sizes; each cavity 6 is provided with only one ingate 5 at the middle pipe orifice; the core 7 is placed in the cavity 6, and the outer wall of the core 7 cooperates with the inner wall of the cavity 6 to form the casting molding surface. The core 7 is connected through and to the cavities 6 in its column.

[0037] Since the riser is not provided, the ingate 5 and the ingate 4 are arranged at the position of the middle pipe orifice. Compared with the traditional arrangement of the ingate and the ingate at the upper or lower end of the cavity 6, the longitudinal arrangement space is effectively saved. The longitudinal arrangement spacing of the cavities is further shortened compared with CN219274390U, and the overall length of the corresponding core 7 is also further shortened, reducing the flow length of the molten iron, facilitating rapid filling, reducing the solidification time difference of the molten iron at different positions of the cavities in the mold, and ensuring the quality of the green blank; or after the core is shortened, 1 - 3 groups of cavities of the same type or other types of malleable cast iron can be additionally arranged in the remaining positions in the template. Without increasing the overall length of the core, the arrangement density of the cavities in the mold is increased, the production rate of the mold is increased, and the utilization rate of the molten iron is improved.

[0038] A core positioning block 8 can be timely arranged at the end of the core 7 or at the gap between the arrangements of the cavities 6 to be clamped with the sand mold shell of the mold, realizing the positioning of the core 7 in the cavity 6.

[0039] As shown Figures 1-3 in the figure, when the specification of the three-way is relatively large, the inner diameter of the corresponding gating system is also relatively large. In order to further block the loose sand, slag, etc. in the mold, a slag baffle 9 perpendicular to the vertical sprue direction can be arranged on the vertical sprue. The slag baffle 9 is in the shape of a thin sheet, but is different from the conventional slag baffle blocks arranged parallel to the vertical sprue, and is more like being "inserted" on the vertical sprue. This setting method does not occupy the length space of the vertical sprue and is more suitable for the form of middle-gate pouring with a relatively short longitudinal arrangement pitch of the cavities. The slag baffle 9 is located above the inner gate 3, and the slag baffle 9 and the triangular inner gate 3 work together to better play the role of blocking impurities such as loose sand and slag in the mold.

[0040] It should be noted that the middle-gate casting method adopted by the present utility model is only applicable to the casting of full-diameter three-ways, medium-large three-ways and some reducing three-way pipe fittings mentioned above. When the molten iron is poured into the middle port of the three-way, according to the flow direction of the molten iron in the vertical parting template, it is easy to first fill the middle pipe orifice part and the lower pipe orifice position of the three-way cavity, but for the upper pipe orifice position, the molten iron is filled last. The filling process of the upper pipe orifice depends more on the upward inertia during the filling process of the molten iron. Therefore, the relative diameter of the upper pipe orifice (corresponding to the size of the upper pipe orifice space in the cavity) should not be too large, otherwise it is easy to have defects at the upper pipe orifice position of the finished product. Therefore, in the present utility model, the three-way types are limited to full-diameter three-ways, medium-large three-ways and some reducing three-way pipe fittings; the diameter relationships between the upper pipe orifice and the middle pipe orifice of these three-way types can ensure the completion of the filling of the molten iron; and the forms of these three-way pipe fittings are relatively common and belong to the three-way categories with a large demand in the market, which can meet the casting of most three-way pipe fittings under the lightweight trend. Compared with the form of filling from the upper and lower double ports in CN219274390U, the longitudinal space where the cavity is located is further increased, the proportion of the overall gating system is reduced, and the utilization rate of the molten iron for the three-way pipe fitting is improved. The inner gate 4 combines its triangular thin sheet shape to play multiple roles such as intercepting the loose sand in the mold, facilitating the ramming of the workpiece, facilitating the diversion of the molten iron to the two-side cavities 6, and feeding the cavities 6, ensuring the casting and forming of the lightweight full-diameter three-way pipe fitting without the need to additionally set risers, water compensation blocks, and widened runners.

[0041] During casting, the molten iron enters from the pouring cup 1, flows to the cross sprue 2, is divided into multiple vertical sprues 3 through the cross sprue 2, and then passes through the inner gate 4. After filtering slag and blocking loose sand therein, it enters the corresponding cavity 6 along the inner gate opening 5.

[0042] The above is only a preferred embodiment of the present utility model, and does not impose any form of limitation on the present utility model. Any simple modification and equivalent change made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A middle-port cast iron mold, characterized in that: It includes a pouring cup, a runner, a downsprue, an ingate, an inner gate, a cavity, and a core; the pouring cup is arranged above the runner and fixedly connected to the runner for receiving the molten iron from the ladle; the runner is connected to multiple rows of downsprues, the cavity is provided with multiple rows, and the downsprue is connected to each row of the cavity through the ingate, the inner gate; the inner gate is arranged at the middle pipe orifice position of the cavity, and the molten iron flows into the cavity from the middle pipe orifice during casting; the core is accommodated in the cavity, is connected through the cavity of the row where it is located, and the outer wall of the core cooperates with the inner wall of the cavity to form the casting forming surface.

2. The medium-gate cast iron mold according to claim 1, characterized in that: The middle-gated cast iron mold adopts a vertically split flaskless squeeze molding template, which is applicable to the casting of through-diameter tees, medium-large tees, and some reducing tees; in the part of the reducing tees, the outer diameter of the middle pipe orifice is less than twice the diameter of the upper pipe orifice, and the positions of the two straight pipe orifices are arranged in the template in such a way that the diameter of the lower pipe orifice is larger than that of the upper pipe orifice.

3. The medium-port pouring cast iron mold according to claim 1 or 2, characterized in that: The number of cavities in each row is set to 3 - 10 according to the size of the pipe fitting.

4. The medium-gate cast iron mold according to claim 1 or 2, characterized in that: The ingate is triangular, and the downsprue is directly connected to the ingate, which is conducive to the direct diversion of the molten iron into the cavity and increases the filling force of the molten iron.

5. The middle gate cast iron mold according to claim 1 or 2, characterized in that: The thickness of the inner gate is two-thirds of the thickness of the pipe orifice of the cavity, and the width of the ingate is the same as that of the inner gate.

6. The medium-gate cast iron mold according to claim 1 or 2, characterized in that: When the downsprue is used to supply molten iron to two symmetrically arranged rows of cavities, the middle pipe orifices of the two adjacent rows of cavities on the left and right are arranged opposite to each other and share one ingate; the ingate is an equilateral triangle, the apex of the triangle is connected to the downsprue, and the two base angles of the triangle are respectively connected to the middle pipe orifices of the symmetrically arranged cavities; the middle position of the base of the triangle is connected to the next section of the downsprue.

7. The middle gating cast iron mold according to claim 1 or 2, characterized in that: When the downsprue is used to supply molten iron to one row of cavities, the triangular ingate is a right triangle, the right angle of the right triangle is connected to the next section of the downsprue, one of the other two angles is connected to the previous section of the downsprue, and the other is connected to the middle orifice of the cavity.

8. The middle gating cast iron mold according to claim 1 or 2, characterized in that: Sand core positioning blocks are arranged at the ends of the core or at the gaps in the arrangement of the cavities. The sand core positioning blocks are clamped with the sand mold shell of the mold to realize the positioning of the core in the cavity.

9. The middle gating cast iron mold according to claim 1 or 2, characterized in that: A slag damper perpendicular to the direction of the downsprue is arranged on the downsprue. The slag damper is in the shape of a thin sheet, saving the longitudinal space of the downsprue.

10. The middle gating cast iron mold according to claim 9, characterized in that: The slag damper is arranged above the ingate. The slag damper and the ingate work together to better play the role of blocking the live sand and molten slag in the mold.

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