Machining process of centrifugal impeller

Abstract

The invention discloses a machining process of a centrifugal impeller in the technical field of pouring processes, and the machining process comprises the following steps: preparing a sand core: preparing an impeller mold, filling a sand core material into the mold, compacting, and taking down the mold after the sand core material is hardened and formed, so as to obtain the sand core; sand mold manufacturing, specifically, the upper swage mold and the lower swage mold are sleeved with a rectangular frame-shaped mold box, the mold box is filled with a sand core material and compacted, and an upper sand mold and a lower sand mold are obtained after hardening; when the lower sand mold is manufactured, a U-shaped ceramic tube is placed, and one end of the ceramic tube is communicated with the bottom of a cavity of the lower sand mold; mold closing is conducted, specifically, the sand core is placed in a cavity of the lower sand mold, and the upper sand mold and the lower sand mold are assembled; casting: injecting molten steel into the sprue, filling the cavity with the molten steel through the ceramic tube, and cooling to obtain the impeller; and sand mold removal: after the impeller is cooled, removing the residual sand core material on the surface of the impeller by using a tool. According to the scheme, the problems of wrinkling and low cold shut defects of the impeller caused by an existing impeller pouring process are solved.

Description

Technical Field

[0001] The invention relates to the technical field of casting technology, and in particular to a processing technology for a centrifugal impeller. Background Art

[0002] A centrifugal impeller is a core component used in centrifugal pumps, centrifugal fans, turbochargers and other equipment. It generates centrifugal force through high-speed rotation, thereby accelerating and discharging fluid or gas. When the impeller rotates at high speed inside the pump or fan, the fluid or gas entering the center of the impeller is pushed by the blades and moves outward. In this process, the fluid or gas gains speed and flows outward along the curved blades of the impeller. When the fluid or gas reaches the outer edge of the impeller, due to the action of centrifugal force, its speed reaches the maximum value and is discharged with higher kinetic energy.

[0003] Then, in the processing and production of centrifugal impellers (hereinafter referred to as impellers), casting is mainly used. However, this kind of casting system has a complex casting mold structure when producing impellers, which increases the difficulty of the molding process. When pouring molten steel into the mold, the molten steel is prone to form turbulence in the cavity, which in turn causes wrinkles and cold shut-like defects on the impeller blades and cover plates, resulting in the impellers not meeting the requirements. Therefore, a new casting process for centrifugal impellers is urgently needed to avoid the above problems that result in the impellers not meeting the requirements. Summary of the invention

[0004] The present invention aims to provide a processing technology for a centrifugal impeller to solve the problem that the existing impeller casting process may cause wrinkles and low cold insulation defects on the impeller.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A processing technology for a centrifugal impeller comprises the following steps: Step 1, sand core preparation: prepare a mold for preparing the sand core of the impeller, then add the sand core material for preparing the sand core into the mold and compact the sand core material in the mold, and after the sand core material is hardened and formed, remove the mold to obtain the sand core for casting the impeller; Step 2, making a sand mold: determine the mold for casting the outer shape of the impeller, the mold includes an upper mold and a lower mold, place the upper mold and the lower mold with the cavity surface facing upwards and then cover them with rectangular frame-shaped mold boxes respectively, then fill the sand core material into the mold box and compact it, after the sand core material hardens and forms, lift the two mold boxes, at this time, the sand core material is lifted together with the mold box and separated from the upper mold and the lower mold, to obtain an upper sand mold and a lower sand mold; when making the lower sand mold, a "U"-shaped ceramic tube is placed in the sand core material, one end of the ceramic tube extends upward from the top of the lower sand mold and is connected to the bottom of the cavity of the lower sand mold, and the other end of the ceramic tube extends upward to the upper surface of the lower sand mold; a gate is reserved on the upper sand mold; Step 3, mold closing: put the sand core prepared in step 1 into the cavity of the lower sand mold, and then assemble the upper sand mold and the lower sand mold so that the gate is connected to the ceramic tube; Step 4, casting: inject molten steel for forming the impeller into the gate, the molten steel enters the ceramic tube through the gate, and then flows along the U-shaped ceramic tube to the bottom of the lower sand mold cavity, and then under the action of atmospheric pressure, the molten steel flows upward from the bottom of the cavity into the cavity until the molten steel fills the cavity, and then cools to obtain the impeller; Step 5, sand mold removal: After the impeller in step 4 has cooled down, use a tool to knock or vibrate the sand mold to separate it from the impeller, and then use a brush or compressed air to remove the sand core material remaining on the impeller surface.

[0006] Furthermore, the mold in step one includes a base plate and a mold cover, and a plurality of blades distributed in a spiral shape are detachably connected to the base plate, and the blades are used to form blades of an impeller after the sand core is manufactured and cast, and the plurality of blades are composed of a first blade and a second blade, and the first blade and the second blade are both inserted into the base plate, and the first blade and the second blade are inserted with fixing blocks for fixing the first blade and the second blade.

[0007] Furthermore, the upper sand mold is provided with a plurality of exhaust holes distributed in a circular array, and the exhaust holes are all communicated with the mold cavity of the upper sand mold.

[0008] Furthermore, a plurality of risers distributed in a circular array are left on the upper sand mold.

[0009] Furthermore, after the upper sand mold and the lower sand mold are made in step 2, zircon powder coating is applied to the surface of the cavity of the upper sand mold and the lower sand mold, and after the coating is completed, the coating is ignited to accelerate its drying speed.

[0010] Beneficial effects of the present invention: 1. This scheme is used to cast the impeller. The cast molten steel flows from the gate to the bottom of the U-shaped ceramic tube, and then flows upward into the cavity through the discharge end of the ceramic tube under the pressure of atmospheric pressure, and gradually spreads upward from the bottom of the cavity, filling the entire cavity from bottom to top. Compared with the existing method of directly casting from the top gate of the cavity to the cavity, the existing impeller casting method, after casting from the top of the cavity, the molten steel directly flows into the cavity from a high place. Since the molten steel has a certain quality, it will cause an impact on the cavity and the sand core when it flows into the cavity from a high place, which may cause the sand core or the formation to deform. At the same time, due to the impact of the molten steel, turbulence is formed in the cavity, which causes the impeller to deform after cooling and forming, which does not meet the production requirements. However, this method introduces the molten steel into the bottom of the cavity through a U-shaped ceramic tube, and then gradually spreads upward from the bottom of the cavity to fill the cavity. In this way, the molten steel will not cause an impact on the inside of the cavity and the sand core, and will not cause the sand core and the cavity to deform due to the impact force. At the same time, it ensures that during the impeller production process, the molten steel will not have turbulence in the cavity due to impact, so that the impeller will not have defects such as wrinkles and cold shut.

[0011] 2. During casting, the chemical adhesive in the sand core material will decompose at high temperature and release gas. This solution uses bottom casting to continuously inject molten steel from the bottom of the cavity. The gas generated by the sand core material due to high temperature will only be above the liquid surface of the molten steel. Because of its light weight, it cannot flow down into the molten steel. As the molten steel continues to be poured, the gas in the cavity is squeezed out of the cavity from bottom to top by the molten steel and discharged through the exhaust hole. This effectively avoids the existing casting method, in which pouring molten steel from the top affects gas emission, resulting in the gas generated during the casting process not being able to overflow in time and being trapped in the sand core, resulting in the formation of pores in the impeller.

[0012] 3. Through this solution, when the molten steel fills the cavity from the bottom of the cavity upward, it helps to form a more uniform solidification process, which is beneficial to reduce the thermal stress in the casting and reduce the risk of cracks in the impeller.

[0013] 4. Due to the high density of molten steel, when molten steel is poured into the cavity from the bottom of the cavity, debris or other impurities will float on the surface of the molten steel. Therefore, as the molten steel gradually fills the cavity, the molten steel will push the debris or other impurities in the cavity to the riser at the top, reducing the distribution of debris or other impurities in the impeller and improving the purity of the impeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of a mold prepared by a sand core in an embodiment of the present invention; Figure 2 1 is a state diagram of the cavity after mold closing in step three of an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The following is further described in detail through specific implementation methods: The reference numerals in the drawings of the specification include: a mold cover 1 , a bottom plate 2 , a first blade 3 , a fixing block 4 , and a second blade 5 .

[0016] A processing technology for a centrifugal impeller comprises the following steps: Step 1, sand core preparation: prepare a mold for preparing the sand core of the impeller, then add the sand core material for preparing the sand core into the mold and compact the sand core material in the mold, and after the sand core material is hardened and formed, remove the mold to obtain the sand core for casting the impeller; Step 2, making sand mold: determine the mold for casting the outer shape of the impeller, the mold includes an upper mold and a lower mold, place the upper mold and the lower mold with the cavity surface facing upwards and then put on a rectangular frame-shaped mold box respectively, then fill the sand core material into the mold box and compact it, after the sand core material hardens and forms, lift the two mold boxes, at this time the sand core material is lifted together with the mold box and separated from the upper mold and the lower mold to obtain an upper sand mold and a lower sand mold; when making the lower sand mold, a "U"-shaped ceramic tube is placed in the sand core material, one end of the ceramic tube extends upward from the top of the lower sand mold and is connected to the bottom of the cavity of the lower sand mold, and the other end of the ceramic tube extends upward to the upper surface of the lower sand mold; a gate is reserved on the upper sand mold, and a plurality of exhaust holes distributed in a circular array are reserved on the upper sand mold, and the exhaust holes are all connected to the cavity in the upper sand mold; a plurality of risers distributed in a circular array are also reserved on the upper sand mold. After the upper sand mold and the lower sand mold are made, zircon powder paint is applied to the surface of the cavity of the upper sand mold and the lower sand mold. After the application is completed, the paint is ignited to accelerate its drying speed.

[0017] Step 3: mold closing: put the sand core prepared in step 1 into the cavity of the lower sand mold, and then assemble the upper sand mold and the lower sand mold so that the gate is connected to the ceramic tube, as shown in the attached figure. Figure 2 As shown; Step 4, casting: inject molten steel for forming the impeller into the gate, the molten steel enters the ceramic tube through the gate, and then flows along the U-shaped ceramic tube to the bottom of the lower sand mold cavity, and then under the action of atmospheric pressure, the molten steel flows upward from the bottom of the cavity into the cavity until the molten steel fills the cavity, and then cools to obtain the impeller; Step 5, sand mold removal: After the impeller in step 4 has cooled down, use a tool to knock or vibrate the sand mold to separate it from the impeller, and then use a brush or compressed air to remove the sand core material remaining on the impeller surface.

[0018] The mold in the embodiment is basically as shown in the attached Figure 1 As shown: The mold in step one includes a base plate 2 and a mold cover 1, a feed port is provided at the center of the mold cover 1, the mold cover 1 is buckled on the base plate 2 to form a complete mold, a plurality of spirally distributed blades are inserted on the base plate 2, the blades are used to form blades of the impeller after the sand core is made and cast, the plurality of blades are composed of a first blade 3 and a second blade 5 spliced ​​together, the first blade 3 and the second blade 5 are both plugged into the base plate 2, a fixing block 4 is provided at the connection between the first blade 3 and the second blade 5, a slot is provided on the top of the fixing block 4, the slot is used for inserting and fixing the first blade 3 and the second blade 5, and the bottom of the fixing block 4 contacts the inner surface of the mold cover 1 when the mold cover 1 is buckled.

[0019] When the mold is in use, the sand core material for preparing the sand core is added to the feed port of the mold cover 1 and the sand core material in the mold is compacted. After the sand core material is hardened and formed, the mold cover 1 is placed downward and the bottom plate 2 is placed upward, and then the bottom plate 2 is lifted vertically. When the bottom plate 2 is lifted, the bottom plate 2 is separated from the multiple blades, and then the first blade 3, the second blade 5 and the fixed block 4 are removed vertically upward, and then the space at the fixed block 4 is repaired with the sand core material, and after it hardens, a sand core for casting an impeller is obtained.

Claims

1. A processing technology for a centrifugal impeller, characterized in that: The following steps are involved: Step 1, sand core preparation: prepare a mold for preparing the sand core of the impeller, then add the sand core material for preparing the sand core into the mold and compact the sand core material in the mold, and after the sand core material is hardened and formed, remove the mold to obtain the sand core for casting the impeller; Step 2, making a sand mold: determine the mold for casting the outer shape of the impeller, the mold includes an upper mold and a lower mold, place the upper mold and the lower mold with the cavity surface facing upwards and then cover them with rectangular frame-shaped mold boxes respectively, then fill the sand core material into the mold box and compact it, after the sand core material hardens and forms, lift the two mold boxes, at this time, the sand core material is lifted together with the mold box and separated from the upper mold and the lower mold, to obtain an upper sand mold and a lower sand mold; when making the lower sand mold, a "U"-shaped ceramic tube is placed in the sand core material, one end of the ceramic tube extends upward from the top of the lower sand mold and is connected to the bottom of the cavity of the lower sand mold, and the other end of the ceramic tube extends upward to the upper surface of the lower sand mold; a gate is reserved on the upper sand mold; Step 3, mold closing: put the sand core prepared in step 1 into the cavity of the lower sand mold, and then assemble the upper sand mold and the lower sand mold so that the gate is connected to the ceramic tube; Step 4, casting: inject molten steel for forming the impeller into the gate, the molten steel enters the ceramic tube through the gate, and then flows along the U-shaped ceramic tube to the bottom of the lower sand mold cavity, and then under the action of atmospheric pressure, the molten steel flows upward from the bottom of the cavity into the cavity until the molten steel fills the cavity, and then cools to obtain the impeller; Step 5, sand mold removal: After the impeller in step 4 has cooled down, use a tool to knock or vibrate the sand mold to separate it from the impeller, and then use a brush or compressed air to remove the sand core material remaining on the impeller surface.

2. The processing technology of a centrifugal impeller according to claim 1, characterized in that: The mold in step one includes a base plate and a mold cover, and a plurality of blades distributed in a spiral shape are detachably connected to the base plate, and the blades are used to form blades of an impeller after the sand core is made and cast, and the plurality of blades are composed of a first blade and a second blade, and the first blade and the second blade are both inserted into the base plate, and the first blade and the second blade are inserted with fixing blocks for fixing the first blade and the second blade.

3. The processing technology of a centrifugal impeller according to claim 2, characterized in that: The upper sand mold is provided with a plurality of exhaust holes distributed in a circular array, and the exhaust holes are all communicated with the mold cavity of the upper sand mold.

4. The processing technology of a centrifugal impeller according to claim 3 is characterized in that: A plurality of risers distributed in a circular array are left on the upper sand mold.

5. The processing technology of a centrifugal impeller according to claim 4, characterized in that: After the upper sand mold and the lower sand mold are made in step 2, zircon powder paint is applied to the surface of the cavity of the upper sand mold and the lower sand mold. After the application is completed, the paint is ignited to accelerate its drying speed.

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