Casting process of casting strut made of long casting body cast iron

Abstract

The invention discloses a casting process of a long casting body cast iron pillar, which is characterized by comprising the following steps of: 1, flatly placing a model, and manufacturing a sand mold by adopting a sand box; 2, a split core box is adopted for manufacturing a sand core, a steel pipe is adopted as a core bar in the split core box, and a plurality of small air holes are formed in the steel pipe; thirdly, after the sand core in the second step is formed, the formed sand core is placed in a sand mold, the sand box is erected, the upper section, extending out of the sand box, of the sand core is in lap joint with the sand box through a steel bar, one end of the steel bar is fixed to a core bar, the other end of the steel bar is fixed to the sand box, and therefore the sand core can be effectively prevented from floating upwards in the casting process; and 4, during casting, the sand box, the sand mold and the sand core are vertically placed. Manufacturing of the hot blast stove stand column can be completed, and the yield reaches 95% or above.

Description

Technical Field

[0001] The invention relates to the technical field of casting of cast iron parts, in particular to a casting process of a long cast iron pillar. Background Art

[0002] The main component of the pillars used to support the hot blast furnace grate is QTRSi4Mo, which is a ductile iron casting. In the casting process of ductile iron castings, the casting process is a very critical link. Reasonable casting technology can save the manufacturing cost of the product, improve the product qualification rate, and bring practical benefits to the foundry.

[0003] The Chinese utility model patent authorization announcement number CN210359137U discloses a sand core for hot blast furnace pillar casting, which includes a core bone, a core body, and a core head. The core body and the core head are attached to the outer wall of the core bone, and the core head is arranged at both ends of the core body. The core body and the core head are made of self-hardening resin sand; the core bone is a metal straight cylindrical or solid cylindrical structure, the outer diameter of the core bone is Φ80mm~Φ150mm, the diameter of the core head is not less than the diameter of the core body, an annular groove is provided between the core body and the core head, and the sand intake at the sand core groove is ≥15mm.

[0004] China's utility model patent authorization announcement number CN202804093U discloses a casting sand core that ensures the wall thickness accuracy of the blast furnace hot blast stove pillar. The middle section of the sand core is provided with an anti-deformation arc segment. The maximum disturbance fc of the horizontal center of the arc segment is calculated as fc=5ql4 / 384EI=5(F floating-G weight)l3 / / 384EI. The core head is eccentrically arranged relative to the sand core, and the central axis of the core head is higher than the central axis of the sand core. The eccentricity b is 2mm-4mm, which offsets the deformation caused by the overall lifting of the sand core during pouring. It solves the problem of thinning of the wall thickness of the barrel part of the hot blast stove pillar product and out-of-tolerance of the size caused by the buoyancy of the molten iron.

[0005] At present, there are the following difficulties in the casting process of this type of long casting:

[0006] 1. It is difficult to ensure uniform wall thickness of the column during the casting process;

[0007] 2. During the molding process, the sand core of the column is too long, making it difficult to shape when making the sand core;

[0008] 3. During the casting process of the column, due to the high density of the molten iron itself, the sand core in the middle will tend to float up, causing the sand core to float up;

[0009] 4. During the casting process, the casting system may cause more slag inclusions on the casting surface due to slag rolling;

[0010] 5. During the casting process, void defects may occur on the surface of the casting due to shrinkage of molten iron. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a casting process for a casting pillar of a long casting to solve the difficulties in the long casting process.

[0012] The technical problem to be solved by the present invention can be achieved by the following technical solutions:

[0013] A casting process for a long cast iron pillar comprises the following steps:

[0014] Step 1: Lay the model flat and use a sand box to make a sand mold;

[0015] Step 2: Use a split core box to make a sand core. During the process of making the sand core, plugging plates are placed at both ends of the split core box to fix the core bone; a Φ80mm×6mm steel pipe is used as the core bone in the split core box. Straw is wrapped around the steel pipe and several small air holes are opened on the steel pipe to facilitate the discharge of gas generated by the sand core during the casting process; the bottom plate of the lower core box of the split core box is a fully enclosed structure, and a sand filling hole for sand filling is made at intervals on the top plate of the upper core box. In addition, after the sand core is formed, it is convenient to scrape out the excess sand in the water outlet of the upper half of the sand core through the sand filling hole;

[0016] Step 3: After the sand core of step 2 is formed, the formed sand core is placed in the sand mold and the sand box is erected. The upper section of the sand core extending out of the sand box is overlapped on the sand box through steel bars, wherein one end of the steel bar is fixed on the core bone and the other end is fixed on the sand box, which can effectively prevent the sand core from floating during the casting process;

[0017] Step 4: During casting, the sand box, sand mold and sand core are placed vertically, and an annular open riser is arranged on the upper part of the sand box, which is connected to the upper part of the casting space between the sand mold and the sand core; in addition, an annular cross runner and a plurality of ingates are arranged at the bottom of the sand box, and the annular cross runner is connected to the lower part of the casting space between the sand mold and the sand core through a plurality of ingates; a plurality of water inlets are arranged at intervals from top to bottom on the sides of the sand box and the sand mold, and the annular open riser is connected to the water inlet and the annular cross runner through an external runner; a slag collecting bag is arranged at the bottom of the ingates.

[0018] Step 5: Heat the molten iron to above 1380°C for spheroidization reaction. After the spheroidization reaction is completed, wait until the temperature reaches 1320-1340°C and 24 hours after casting, open the sand box and remove the sand mold and sand core to obtain the finished long cast iron pillar.

[0019] In a preferred embodiment of the present invention, a sand replenishing hole for replenishing sand is formed on the top plate of the upper core box at intervals of 400 mm.

[0020] In a preferred embodiment of the present invention, the annular cross runner and the plurality of inner runners constitute an annular bottom pouring runner.

[0021] In a preferred embodiment of the present invention, a plurality of ingates are evenly distributed circumferentially on the annular runner.

[0022] In a preferred embodiment of the present invention, the runner is a ceramic runner.

[0023] In a preferred embodiment of the present invention, in step 2, a sand scraper is used to scrape out excess sand in the upper water inlet of the sand core through the sand replenishing hole.

[0024] Due to the adoption of the above technical solution, the present invention has the following characteristics:

[0025] 1. The ingates are ceramic ingates, which effectively prevents the sand in the sand box from entering the molten iron when the molten iron is filled.

[0026] 2. Shape the model in a flat manner. After the modeling is completed, stand the sand mold upright for casting. The following operation method can effectively eliminate the problem of uneven wall thickness of cylindrical castings after casting.

[0027] 3. Unique and convenient tools and methods for making sand cores. The casting sand core is longer and heavier. The unique design makes it easier for molders to operate during production.

[0028] 4. The annular bottom pouring runner design is conducive to the filling of the casting, has a certain slag blocking effect and can effectively improve the surface quality of the casting.

[0029] 5. The nozzle design effectively alleviates the problem of uneven molten iron temperature during the casting process.

[0030] The invention can complete the production of hot blast furnace columns, and the yield rate reaches more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of a long cast iron pillar.

[0032] Figure 2 for Figure 1 Left view of .

[0033] Figure 3 Schematic diagram of using a sand box to make a sand mold in order to lay the model flat and then standing the sand box up for casting.

[0034] Figure 4 It is a structural schematic diagram of the split core box of the present invention.

[0035] Figure 5 It is a structural schematic diagram of the scraper plate.

[0036] Figure 6 This is a schematic diagram of the sand mold, sand core and sand box structure after molding.

[0037] Figure 7 It is a schematic diagram of casting a long cast iron pillar by the casting system of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0039] A casting process for a long cast iron pillar of the present invention comprises the following steps:

[0040] Step 1: See Figure 3 , placing the model flat in the sand box 10, and using the sand box 10 to make a sand mold 40;

[0041] Step 2: See Figure 4 and Figure 5 , a split core box 20 is used to make a sand core 30. During the process of making the sand core 30, plugging plates 21 and 22 are placed at both ends of the split core box 20 to fix the core bone; a Φ80mm×6mm steel pipe 31 is used as the core bone in the split core box 20 (see Figure 6 ), while wrapping straw around the steel pipe 31, several small air holes 31a are opened on the steel pipe 30 to facilitate the discharge of gas generated by the sand core 30 during the casting process; the bottom plate 21a of the lower core box 20a of the split core box 20 is a fully enclosed structure, and a sand replenishment hole 21ba for sand replenishment is made on the top plate 21b of the upper core box 20b at a distance of 400mm. In addition, after the sand core is formed, it is convenient to use a sand scraper 40 to scrape out the excess sand in the upper half of the sand core from the sand replenishment hole 21ba;

[0042] Step 3: See Figure 3 and Figure 6 After the sand core 30 of step 2 is formed, the formed sand core 30 is placed in the sand mold 40 and the sand box 20 is erected. The sand core 30 extends out of the upper section of the sand box 10 and is overlapped on the sand box 10 through the steel bar 50, wherein one end of the steel bar 50 is fixed on the core bone and the other end is fixed on the sand box 10, which can effectively solve the problem of preventing the sand core 30 from floating during the casting process; resulting in the defect of incorrect size of the long cast iron pillar;

[0043] Step 4: During casting, the sand box 10, the sand mold 40 and the sand core 30 are placed vertically, and an annular open riser 50 is arranged on the upper part of the sand box, which can effectively reduce the generation of concave defects during the casting process. The annular open riser 50 is connected to the upper part of the casting space 60 between the sand mold 40 and the sand core 30; in addition, an annular horizontal runner 70 and a plurality of inner runners 80 are arranged at the bottom of the sand box 10, and the plurality of inner runners 80 are evenly distributed on the annular horizontal runner 70 in the circumferential direction, forming an annular bottom pouring runner, which can effectively collect slag and make the molten iron liquid stable. The annular horizontal pouring 70 is connected to the lower part of the casting space 80 between the sand mold 40 and the sand core 30 through a plurality of inner runners 80; a plurality of water inlets 11, 41 are arranged at intervals from top to bottom on the sides of the sand box 10 and the sand mold 40; the annular open riser 50 is connected to the water inlets 11, 41 and the annular horizontal pouring 70 through a ceramic outer runner 90; a slag collecting bag 91 is arranged at the bottom of the ceramic outer runner 90. The plurality of water inlets 11, 41 form a stepped waterway, which can effectively replenish molten iron when the long cast iron pillar is cast to a certain height.

[0044] Step 5: Heat the molten iron to above 1380°C for spheroidization reaction. After the spheroidization reaction is completed and the temperature reaches 1320-1340°C, 24 hours after the casting is completed, open the sand box and remove the sand mold and sand core to obtain the finished long cast iron pillar.

Claims

1. A casting process for a long cast iron pillar, characterized in that: The steps include: Step 1: Lay the model flat and use a sand box to make a sand mold; Step 2: Use a split core box to make a sand core. During the process of making the sand core, plugging plates are placed at both ends of the split core box to fix the core bone; a Φ80mm×6mm steel pipe is used as the core bone in the split core box. Straw is wrapped around the steel pipe and several small air holes are opened on the steel pipe to facilitate the discharge of gas generated by the sand core during the casting process; the bottom plate of the lower core box of the split core box is a fully enclosed structure, and a sand filling hole for sand filling is made at intervals on the top plate of the upper core box. In addition, after the sand core is formed, it is convenient to scrape out the excess sand in the water outlet of the upper half of the sand core through the sand filling hole; Step 3: After the sand core of step 2 is formed, the formed sand core is placed in the sand mold and the sand box is erected. The upper section of the sand core extending out of the sand box is overlapped on the sand box through steel bars, wherein one end of the steel bar is fixed on the core bone and the other end is fixed on the sand box, which can effectively prevent the sand core from floating during the casting process; Step 4: During casting, the sand box, sand mold and sand core are placed vertically, and an annular open riser is arranged on the upper part of the sand box, which is connected to the upper part of the casting space between the sand mold and the sand core; in addition, an annular cross runner and a plurality of ingates are arranged at the bottom of the sand box, and the annular cross runner is connected to the lower part of the casting space between the sand mold and the sand core through a plurality of ingates; a plurality of water inlets are arranged at intervals from top to bottom on the sides of the sand box and the sand mold, and the annular open riser is connected to the water inlet and the annular cross runner through an external runner; a slag collecting bag is arranged at the bottom of the ingates. Step 5: Heat the molten iron to above 1380℃ for spheroidization reaction. After the spheroidization reaction is completed, wait until the temperature reaches 1320-1340℃ for casting. 24 hours after the casting is completed, open the sand box and remove the sand mold and sand core to obtain the finished long cast iron pillar.

2. The casting process of a long cast iron pillar according to claim 1, characterized in that: On the top plate of the upper core box, a sand replenishing hole is made every 400mm for replenishing sand.

3. The casting process of a long cast iron pillar according to claim 1, characterized in that: The annular cross runner and a plurality of inner runners form an annular bottom pouring runner.

4. The casting process of a long cast iron pillar according to claim 1, characterized in that: A plurality of inner runners are evenly distributed on the annular horizontal runner in the circumferential direction.

5. The casting process of a long cast iron pillar according to claim 1, characterized in that: The runner is a ceramic runner.

6. The casting process of a long cast iron pillar according to claim 1, characterized in that: In step 2, a scraper is used to scrape out the excess sand in the water inlet of the upper half of the sand core through the sand replenishing hole.

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