Preparation method of exothermic and insulated riser bush for casting

Abstract

The invention provides a preparation method of an exothermic and insulated riser bush for casting, which comprises the following steps: S1, manufacturing an inner layer of the riser bush, namely an exothermic material layer, the inner diameter of the opening part is phi a, the outer diameter of the opening part is phi b, the inner diameter of the blind end part is phi a ', the outer diameter of the blind end part is phi b', the inner height of the blind end part is m, the total height of the blind end part is n, 2-phi f exhaust holes are formed in the top of the blind end part, phi a and phi b are larger than phi a 'and phi b' respectively, and an inner layer mold of the riser sleeve is filled with mixed heating materials and binding materials. After the inner-layer heating material burns and emits heat, generated heat is reflected by the heat insulation and preservation layer when radiated outwards, the heat preservation effect of the riser is achieved, a continuous process is achieved, it is also guaranteed that heat in the riser sleeve is not largely and rapidly dissipated, and the heat preservation process is beneficial for molten steel in the riser to be kept in a high-temperature liquid state for a longer time; and the temperature gradient of the three phases of the riser, the riser sleeve and the casting mold is obviously higher than the temperature gradient of a single-component insulated riser sleeve.

Description

Technical Field

[0001] The present invention relates to the field of steel casting process in the machinery industry, and in particular to a method for preparing a heat-insulating riser sleeve for casting. Background Art

[0002] China has a long history of casting, and modern industrial casting technology has made great progress. However, there are still some technical challenges in the casting process. For cast steel, after pouring, the molten steel will undergo physical and chemical processes such as liquid shrinkage and solid shrinkage. Due to the structure of the casting, the two shrinkage processes in different parts have a certain overlap in time. The parts with thin structures and good heat dissipation environment solidify first, and the thick and large parts, namely the hot spots, solidify later. After the surface and surrounding areas of the thick and large parts solidify, the hot spots need to be supplemented with molten steel during the solidification process, that is, shrinkage feeding, otherwise shrinkage cavities will occur in the hot spots. The riser design in the casting process is to solve this shrinkage cavity that is easy to form inside the casting.

[0003] When designing risers in a casting process, the riser position is usually higher than the hot spot position and the bulk modulus is larger than the bulk modulus of the local area of ​​the casting that needs to be fed, so that the riser can play a feeding role. When a riser sleeve is used for a riser of equal volume, its effective modulus will be increased, and the feeding effect will be better.

[0004] There are many types of casting risers in casting process design, and they are classified according to whether or not a riser sleeve is used. One type does not use a riser sleeve, and the molten steel in the riser is in direct contact with the mold. The molten steel in the riser is affected by the characteristics of the mold and dissipates heat quickly, and the temperature drops quickly, so the shrinkage feeding effect of the riser is not obvious; the other type uses a riser sleeve. Riser sleeves are divided into ordinary insulation risers and heat-generating insulation risers based on the insulation effect.

[0005] Ordinary insulation riser sleeves are mainly used for insulation. Heat-generating insulation riser sleeves are based on ordinary insulation riser sleeves, and heat-generating materials are added to the riser material components. That is, after the riser is formed during pouring, the heat-generating materials of the riser sleeve undergo an exothermic chemical reaction at high temperature. The reaction residues and other materials also take into account the subsequent heat-insulating effect, so that the molten steel in the riser sleeve lags further behind the solidification of the casting than the ordinary insulation riser sleeve, achieving a better shrinkage compensation effect.

[0006] However, as a single-component insulation riser sleeve, the heat-generating insulation riser sleeve also has the following limitations:

[0007] 1. The heating material and the insulation material are mixed, and the bonding material of a certain strength is added after drying, which requires the riser sleeve to be formed. The heating effect and insulation effect are weakened;

[0008] 2. After pouring, the riser sleeve burns and generates heat, and the heat generated radiates to the surrounding area. Taking the middle interface of the riser sleeve as the benchmark, the heat generated on the outside radiates and transfers more to the outer mold, and the heat generated on the inside radiates and transfers mainly inward. In the first stage when the riser sleeve plays a role, since the mold temperature is the lowest and the molten steel temperature is relatively the highest, a temperature gradient from high to low is formed based on the riser center, that is, the riser center - insulation riser sleeve - riser sleeve outer mold; in the second stage, the heat-generating material of the riser sleeve generates a heat reaction, and the heat radiates and transfers inward and outward at the same time. Since the temperature of the molten steel after pouring is 1500℃, the heat generated by the heat generated by the riser sleeve is 1500℃. In the above, after the riser sleeve is heated, its own temperature is usually still lower than the temperature of the center of the riser, and the temperature gradient of the riser center - the insulation riser sleeve - the outer mold temperature of the riser sleeve is still maintained. In the third stage, the riser sleeve heating stage ends, the initial temperature of the mold is low, and heat is continuously transferred from the center of the riser to the mold through the riser sleeve. At this time, the speed of heat transfer depends on the insulation effect of the mixed material after the riser sleeve heating material is burned. The temperature of the center of the riser gradually approaches the melting point of the molten steel and solidifies. The riser loses its shrinkage feeding function. Its shrinkage feeding effect depends on whether the riser can continue to supply molten steel when the hot section of the casting to be fed finishes solidification.

[0009] 3. The exothermic and insulating riser sleeves currently used in the casting process are theoretically not designed to be too large due to factors such as the casting process yield. The molten steel they can provide to the hot zone of the casting during solidification is limited. However, the burning time and insulation time of the single material of the exothermic and insulating riser are short, which limits their effectiveness. Even if the riser volume is large enough, the shrinkage compensation effect is still poor, and shrinkage cavities may appear in the hot zone of the casting, resulting in the shrinkage compensation effect not meeting expectations. Summary of the Invention

[0010] (1) Technical problems solved

[0011] In response to the shortcomings of the existing technology, the present invention provides a method for preparing a heating and insulating riser sleeve for casting, which solves the problem in the existing technology that the heating material and the insulating material are mixed, and a certain strength of adhesive material is required to be formed into the riser sleeve after drying, which weakens the heating and insulating effects.

[0012] (2) Technical solution

[0013] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preparing a heat-insulating riser sleeve for casting, comprising the following steps:

[0014] S1. Make the inner layer of the riser sleeve, that is, the heating material layer, with an inner diameter of Φa and an outer diameter of Φb at the opening part, an inner diameter of Φa' and an outer diameter of Φb' at the blind end part, an inner height of m, and a total height of n. There are 2-Φf exhaust holes on the top, where Φa and Φb are larger than Φa' and Φb' respectively. The mixed heating material and adhesive material are filled into the inner layer mold of the riser sleeve, that is, between the inner outer frame and the inner liner and on the top of the inner outer frame. The center hole ΦS of the negative pressure plate is connected to the negative pressure pipe to extract part of the gas and the mixed liquid, so that the inner heating material is compacted and shaped. Then the inner outer frame is removed from the bottom to the top, leaving the inner layer of the riser sleeve attached to the inner liner, wherein the inner liner and the negative pressure plate are fastened together by connecting bolts, and the inner outer frame and the inner liner 4 are positioned and oriented by positioning pins, and positioned and abutted against each other;

[0015] S2. Use the outer filler of the riser sleeve, that is, the thermal insulation material layer, with the inner diameter of the opening part being Φb, the outer diameter being Φc, the inner diameter of the blind end being Φb' and the outer diameter being Φc', the inner height being n, the total height being q, and 2-Φf exhaust holes being provided on the top, with Φb and Φc being larger than Φb' and Φc', respectively. Align the outer frame with the positioning pins and insert it into the inner liner and the inner layer of the riser sleeve formed in step S1 to form an outer mold assembly. Fill the outer mold assembly of the riser sleeve with the mixed thermal insulation material and the bonding material, that is, fill the thermal insulation material between the inner heating material and the outer frame under negative pressure conditions;

[0016] S3, flip and remove the inner liner and the negative pressure plate, and after completing the outer layer filling, obtain the inner liner and the negative pressure plate, the inner layer, the outer layer, and the outer frame. Flip the combination 180 degrees to obtain a flipped combination, hold the inner liner and the negative pressure plate, and remove them upward to obtain the inner layer, the outer layer, and the outer frame.

[0017] S4, flip and remove the outer layer frame, flip the inner layer, outer layer, and outer layer frame assembly 180 degrees to obtain a flipped assembly, hold the outer layer frame, and remove it upward to obtain the inner layer and outer layer assembly, which is the binary combination heating and heat preservation riser sleeve of the inner layer heating material component and the outer layer heat insulation material component in this case.

[0018] Preferably, in S1, the inner diameter Φa of the opening of the inner layer of heating material is in the range of Φ25mm to Φ800mm, the outer diameter Φb is in the range of Φ30mm to Φ900mm, the inner height m is in the range of 50mm to 1200mm, and the total height n is in the range of 60mm to 1200mm. In S2, the inner diameter Φb of the opening of the outer layer of heat insulation material is in the range of Φ30mm to Φ900mm, the outer diameter Φc is in the range of Φ35mm to Φ1000mm, and the total height q is in the range of 60mm to 1200mm.

[0019] (3) Beneficial effects

[0020] The present invention provides a method for preparing a heat-insulating riser sleeve for casting, which has the following beneficial effects:

[0021] 1. The dual-component heat-insulating riser sleeve of the present invention has a continuous process in which the heat generated by the inner heat-generating material is reflected by the heat-insulating layer when radiating outward, thereby playing a role in heat insulation of the riser. This process also ensures that the heat in the riser sleeve will not be lost rapidly in large quantities. In addition, this heat-insulating process helps to keep the molten steel in the riser in a high-temperature liquid state for a longer period of time, maximizing the compensation for the heat node of the casting. The temperature gradient of the three phases of riser, riser sleeve and casting mold is significantly higher than that of a single-component heat-insulating riser sleeve.

[0022] 2. In the present invention, since the molten steel in the riser remains liquid for a long time, the hot spot of the casting is fully fed. After the hot spot of the casting is completely solidified, the casting becomes the main target of heat transfer from the riser. Then the riser is cooled and solidified slowly. In this process, the riser sleeve realizes a good temperature gradient among the riser, the hot spot of the casting, the non-hot spot of the casting and the mold, which will not cause any negative impact on the production rhythm of the casting, even for large castings.

[0023] 3. The adoption of this riser sleeve can reduce the volume of the riser and reduce the consumption of molten steel in production on the basis of a single-component insulation riser sleeve, so that a smaller riser can be used to compensate for a larger hot spot. At the same time, the subsequent cleaning of the riser cutting and riser root grinding can also reduce energy consumption, further promoting the realization of green casting;

[0024] 4. For special structures such as box-type castings, if a hidden riser is designed to feed shrinkage in the limited space within the casting box, the invention can show significant advantages, giving full play to the small size and strong feeding effect. The tooling for making the riser sleeve is easy to implement and apply in terms of design, manufacturing and maintenance. The process of making this riser sleeve is one more process than that of a single-component insulation riser sleeve, but compared with the amount of molten steel saved, the comprehensive benefits are still obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a conventional single-component heating and heat-insulating riser sleeve for existing steel castings.

[0026] Figure 2 The invention relates to a heat-generating and heat-insulating riser sleeve with a heat-generating inner layer and a heat-insulating outer layer.

[0027] Figure 3 It is a schematic diagram of the inner layer structure of the present invention.

[0028] Figure 4 It is a schematic diagram of the inner mold structure.

[0029] Figure 5 It is a schematic diagram of the inner and outer frame structure.

[0030] Figure 6It is a schematic diagram of the structure of the inner liner.

[0031] Figure 7 It is a schematic diagram of the negative pressure plate structure.

[0032] Figure 8 It is a schematic diagram of the outer layer structure of the present invention.

[0033] Figure 9 It is a schematic diagram of the outer mold structure.

[0034] Figure 10 It is a schematic diagram of the outer frame structure.

[0035] Figure 11 It is a schematic diagram of the combined structure of the inner liner and the negative pressure plate, the inner layer, the outer layer, and the outer frame.

[0036] Figure 12 It is a schematic diagram of the combined structure of the inner layer and the outer layer after the outer frame is removed.

[0037] Among them, the figure marks are: 1 is the inner layer, 2 is the outer layer, 3 is the inner layer outer frame, 4 is the inner layer liner, 5 is the negative pressure plate, 6 is the outer layer outer frame, 7 is the connecting pin, and 8 is the positioning pin. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative work shall fall within the scope of protection of the present invention.

[0039] Example:

[0040] An embodiment of the present invention provides a method for preparing a heat-insulating riser sleeve for casting, comprising the following steps:

[0041] S1, make the inner layer of the riser sleeve ( Figure 2 1. Figure 3 1), namely the heating material layer, has an opening with an inner diameter of Φa, an outer diameter of Φb, a blind end with an inner diameter of Φa' and an outer diameter of Φb', an inner height of m, and a total height of n. There are 2-Φf exhaust holes on the top, where Φa and Φb are larger than Φa' and Φb' respectively. The mixed heating material and adhesive material are filled into the inner layer mold of the riser sleeve ( Figure 4 ), that is, the inner outer frame ( Figure 5 、 Figure 4 3) and the inner liner and the top of the inner outer frame, accompanied by the negative pressure plate ( Figure 7 、 Figure 45) The center hole ΦS is connected to a negative pressure pipe to remove part of the gas and mixed liquid, so that the inner heating material is compacted and shaped, and then the inner outer frame is removed from bottom to top, leaving the inner layer of the riser sleeve attached to the inner liner, wherein the inner liner ( Figure 6 、 Figure 4 4) and negative pressure plate ( Figure 7 、 Figure 4 5) by connecting bolts ( Figure 6 7) fasten the connection, inner and outer frame ( Figure 5 、 Figure 4 3) and inner liner ( Figure 6 、 Figure 4 4) through the positioning pin ( Figure 4 8) Positioning, orientation, mutual positioning and abutment;

[0042] S2, use the outer layer of the riser sleeve ( Figure 8 2. Figure 3 1) Filler, that is, the thermal insulation material layer, the inner diameter of the opening part is Φb, the outer diameter is Φc, the inner diameter of the blind end part is Φb' and the outer diameter is Φc', the inner height is n, the total height is q, and there are 2-Φf exhaust holes on the top, Φb and Φc are larger than Φb' and Φc' respectively, the outer frame ( Figure 10 、 Figure 9 6) Align the positioning pin ( Figure 9 8) insert the inner layer liner and the inner layer of the riser sleeve formed in step S1 to form the outer layer mold ( Figure 9 ), the mixed heat insulation material and bonding material are filled into the outer mold of the riser sleeve ( Figure 9 ), that is, under negative pressure conditions, the inner heating material ( Figure 9 1) Fill the space between the outer frame and the heat insulation material;

[0043] S3, turn over and remove the inner liner and negative pressure plate, and after completing the outer layer of filling, obtain Figure 11 The inner liner and the negative pressure plate, the inner layer, the outer layer, and the outer frame are combined. The combination is turned 180 degrees to obtain a flipped combination. The inner liner and the negative pressure plate are held and removed upward to obtain Figure 12 Shows the inner layer, outer layer, and outer frame of the outer layer combined;

[0044] S4, turn over and remove the outer frame, Figure 12 The inner layer, outer layer and outer layer outer frame are flipped 180 degrees to obtain a flipped combination, and the outer layer outer frame is held and removed upward to obtain the inner layer and outer layer combination, which is a binary combination heating and heat preservation riser sleeve of the inner layer heating material component and the outer layer heat insulation material component in this case.

[0045] In S1, the inner diameter Φa of the opening part of the inner layer heating material is in the range of Φ25mm to Φ800mm, the outer diameter Φb is in the range of Φ30mm to Φ900mm, the inner height m is in the range of 50mm to 1200mm, and the total height n is in the range of 60mm to 1200mm. In step S2, the inner diameter Φb of the opening of the outer layer heat insulation material is in the range of Φ30mm to Φ900mm, the outer diameter Φc is in the range of Φ35mm to Φ1000mm, and the total height q is in the range of 60mm to 1200mm.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a heat-insulating riser sleeve for casting, characterized in that: The following steps are involved: S1. Make the inner layer of the riser sleeve, that is, the heating material layer, with an inner diameter of Φa and an outer diameter of Φb at the opening part, an inner diameter of Φa' and an outer diameter of Φb' at the blind end part, an inner height of m, and a total height of n. There are 2-Φf exhaust holes on the top, where Φa and Φb are larger than Φa' and Φb' respectively. The mixed heating material and adhesive material are filled into the inner layer mold of the riser sleeve, that is, between the inner outer frame and the inner liner and on the top of the inner outer frame. The center hole ΦS of the negative pressure plate is connected to the negative pressure pipe to extract part of the gas and the mixed liquid, so that the inner heating material is compacted and shaped. Then the inner outer frame is removed from the bottom to the top, leaving the inner layer of the riser sleeve attached to the inner liner, wherein the inner liner and the negative pressure plate are fastened together by connecting bolts, and the inner outer frame and the inner liner 4 are positioned and oriented by positioning pins, and positioned and abutted against each other; S2, the outer layer filler of the riser sleeve, that is, the thermal insulation material layer, the inner diameter of the opening part is Φb, the outer diameter is Φc, the inner diameter of the blind end part is Φb' and the outer diameter is Φc', the inner height is n, the total height is q, and there are 2-Φf exhaust holes on the top, Φb and Φc are respectively larger than Φb' and Φc', the outer layer outer frame is aligned with the positioning pin and inserted into the inner layer liner and the inner layer of the riser sleeve formed in step S1 to form an outer layer mold composition, and the mixed thermal insulation material and bonding material are filled into the outer layer mold composition of the riser sleeve, that is, the thermal insulation material is filled between the inner layer heating material and the outer layer outer frame under negative pressure conditions; S3, flip and remove the inner liner and the negative pressure plate, and after completing the outer layer filling, obtain the inner liner and the negative pressure plate, the inner layer, the outer layer, and the outer frame. Flip the combination 180 degrees to obtain a flipped combination, hold the inner liner and the negative pressure plate, and remove them upward to obtain the inner layer, the outer layer, and the outer frame. S4. Flip and remove the outer frame, flip the inner layer, outer layer and outer frame combination 180 degrees to obtain a flipped combination, hold the outer frame, remove it upwards, and obtain the inner layer and outer layer combination, which is the binary combination heating and heat preservation riser sleeve of the inner layer heating material component and the outer layer heat insulation material component in this case.

2. The method for preparing a heat-insulating riser sleeve for casting according to claim 1, characterized in that: In S1, the inner diameter Φa of the opening part of the inner layer heating material is in the range of Φ25mm to Φ800mm, the outer diameter Φb is in the range of Φ30mm to Φ900mm, the inner height m is in the range of 50mm to 1200mm, and the total height n is in the range of 60mm to 1200mm. In S2, the inner diameter Φb of the opening of the outer layer heat insulation material is in the range of Φ30mm to Φ900mm, the outer diameter Φc is in the range of Φ35mm to Φ1000mm, and the total height q is in the range of 60mm to 1200mm.

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