Casting method of bearing groove

Abstract

The invention relates to the field of sand mold casting, in particular to a casting method of a bearing groove. The problems that in the prior art, the bearing groove part is still sintered and burnt-on sand is serious, burnt-on sand can only be cleaned through burning and cutting of an oxygen dissolving rod, a large amount of manpower and material resources need to be consumed in the finishing process, a body is prone to being seriously damaged during cleaning, the molded line and quality of the bearing groove are affected, and casting scrapping is even caused by serious burnt-on sand are solved. According to the casting method of the bearing groove, the sand burning problem of the thick and large-section bearing groove and the airway surface is solved, and the appearance quality of similar castings is effectively improved. The special core bar and the chromium ore sand core are matched with the special graphite chilling block to form a whole, and the sand burning-on resistance of the graphite chilling block is utilized, so that the sand burning-on problem of the bearing groove is effectively solved. Meanwhile, the size of the special core bar and the graphite chilling block are flexible and adjustable according to the sand core structure, and the universality is high.

Description

Technical Field

[0001] The invention relates to the field of sand casting, and in particular to a casting method for a bearing groove. Background Art

[0002] The intermediate pressure outer cylinder of the steam turbine is the outer shell of the steam turbine. Its core function is to isolate the flow part of the steam turbine from the outside atmosphere, thus constructing a closed steam chamber. The nozzle chamber, partition, partition sleeve, bearing and other key components are precisely installed inside. In particular, the quality requirements of the bearing groove are very high, requiring it to be smooth and have good original contours. Therefore, the requirements for casting quality are also increased accordingly. Due to the special structure of the bearing groove position, the thickness of the entire bearing seat reaches 500mm, and the width of the bearing groove is only 25mm, which makes the casting difficulty exponentially higher.

[0003] The problem that has been growing and plaguing the casting process and has not been solved for a long time is the problem of sand sticking to the bearing groove. Figure 1 Shown is a schematic diagram of the bearing groove structure of the medium-pressure outer cylinder.

[0004] In the past, the problem of sand sticking in the bearing groove was analyzed, and research and improvement were carried out from the aspects of casting process, sand core structure, core making material, application method, coating, etc. However, the ideal effect was not achieved. The bearing groove was still severely sintered and sand stuck. It could only be cleaned by burning with oxygen dissolving rods. The finishing process required a lot of manpower and material resources, and it was easy to cause serious damage to the body during cleaning, affecting the bearing groove line and quality. Severe sand sticking may even cause the casting to be scrapped. Summary of the Invention

[0005] The present invention overcomes the problems in the prior art where the bearing groove is still severely sintered and sand-adhered, and can only be cleaned by burning and cutting with an oxygen-dissolving rod. The finishing process requires a lot of manpower and material resources, and the cleaning process is likely to cause serious damage to the body, affecting the bearing groove line and quality. Severe sand adhesion may even lead to the scrapping of the casting. A casting method for a bearing groove is provided. The purpose of the present invention is achieved in this way. A casting method for a bearing groove comprises the following steps:

[0006] S1: Designing a core bone, wherein the core bone structure matches the airway core structure;

[0007] S2: Fixing a chill on the core bar and placing a core iron inside the chill;

[0008] S3: placing the core bone into a core box to produce an airway core;

[0009] S4: placing the airway core into a bearing core box, and making the bearing core by flowing sand layer by layer;

[0010] S5: Assembling the box and pouring.

[0011] In one embodiment, two semicircular core bones are provided on the inner side of the core bone, and the two semicircular core bones are connected by tie bars.

[0012] In one embodiment, the core bone and the semicircular core bone are fixedly connected via end core bones.

[0013] In one embodiment, the surface of the end core bone is flat.

[0014] In one embodiment, the chiller is fixed between the semicircular core bar and the outer edge of the core bar.

[0015] In one embodiment, a hole with a diameter of 6 mm is provided on both sides of the inner and outer diameters of the chill, and four holes with a diameter of 10 mm are provided in the thickness direction of the chill.

[0016] In one embodiment, the core iron is disposed in the hole.

[0017] In one embodiment, zircon powder coating is applied on the surfaces of the air channel core and the bearing core.

[0018] In one embodiment, the zircon powder paint is applied at least three times.

[0019] In one embodiment, the core bone can be recovered after boxing.

[0020] The special core bone, chromium ore core, and special graphite chiller of the present invention form an integral whole, which has the following beneficial effects in solving the problem of sand sticking to thick and large-section bearing grooves and airway surfaces:

[0021] 1. After the casting is boxed, the special core bone will separate naturally and can be recycled for repair;

[0022] 2. The special graphite chiller has a simple structure and is easy to manufacture and promote;

[0023] 3. The cost of graphite chilled iron is much lower than the cost of cleaning the sand sticking on the casting, while ensuring the surface quality of the casting;

[0024] 4. Special core bones, chrome ore sand cores and special graphite chillers are used together to form an integral sand core, effectively improving the sand core strength and size control level. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the bearing groove structure;

[0026] Figure 2 Schematic diagram of the bearing core structure;

[0027] Figure 3 Schematic diagram of the core bone structure;

[0028] Figure 4This is a schematic diagram of the chill and core bone combined structure;

[0029] Figure 5 This is a schematic diagram of the airway core production process;

[0030] Figure 6 Schematic diagram of coating the airway core;

[0031] 100-bearing, 110-bearing groove, 200-bearing core, 300-core bone, 310-chill iron, 320-fixed step, 400-airway core. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] A method for casting a bearing groove, comprising the following steps:

[0035] S1: Design a core bone structure that matches the airway core structure. Two semicircular core bones are positioned inside the core bone, connected by several tie bars. The core bone and the semicircular core bones are fixedly connected by end core bones, and the end core bones have a flat surface.

[0036] S2: A chill is fixed to the core bar. The chill is located in the thick section of the casting, and the core bar is positioned within the chill. The chill is fixed between the semicircular core bar and its outer edge. A 6mm diameter hole is provided on both the inner and outer diameter sides of the chill 310, and four 10mm diameter holes are provided through the thickness of the chill. The core bar is positioned in these holes to control the solidification rate, prevent shrinkage cavities and porosity, and improve the surface hardness and wear resistance of the casting.

[0037] S3: placing the core bone into a core box to produce an airway core. According to the bearing structure, two airway cores need to be produced for casting the bearing groove.

[0038] S4: placing the airway core into a bearing core box, and making a bearing core by layering flowing sand; and applying zircon powder paint on the A / B surfaces of the airway core and the bearing core.

[0039] S5: Combining the box and pouring. The core bone can be recovered after boxing.

[0040] To better illustrate the present invention, let's take the bearing core of a medium-pressure outer cylinder as an example. Based on the sand core structure and dimensions, a core bar 300 needs to be designed and placed within the airway core 400. A graphite chill 310 is secured to the core bar 300. The airway core 400 is pre-produced, and the graphite chill 310 forms part of the airway core structure. After the core is disassembled, it is pre-embedded within the bearing core 200 to form a single piece. The entire sand core production process primarily includes the following steps:

[0041] According to the structural design of the airway core 400, a special core bone 300 is added. Two semicircular core bones are added to the inner side of the special core bone 300, and four tie bars are added between the two semicircular core bones to enhance the structural strength and rigidity, and at the same time enhance the structural strength and rigidity of the casting. By setting tie bars on the core bone, deformation and cracks caused by shrinkage during the solidification and cooling process of the casting can be effectively prevented, stress distribution can be optimized, and the quality of the casting can be improved. The special core bone and the semicircular core bone are fixedly connected by the end core bone, and are processed and welded according to the dimensions of the drawing: the special core bone and the two semicircular core bones are welded with ordinary threaded steel, and the end connection core bones need to be cut to ensure flatness to prevent affecting the casting quality of the airway core, such as Figure 3 shown.

[0042] The special graphite chill 310 is formed into a bearing groove structure, and a fixed step 320 is added on the outside to further increase the sand intake of the airway core and improve the quality of the casting. At the same time, two φ6mm holes are drilled on both sides of the inner and outer radius of the graphite chill 310, and four φ10mm holes are drilled in the thickness direction according to the drawing size. The core iron is passed through the graphite chill 310, and the graphite chill 310 is fixed to the special core bone 300 with iron wire. The two ends of the core iron passing through the graphite chill 310 are welded to the core bones on both sides. Figure 4 shown.

[0043] Place the special core bone 300 and the fixed graphite chill 310 into the core box, return the lower side live material to its place, and completely fix the graphite chill 310; start to produce the airway core 400 according to the chromium ore sand with good proportion, and compact it through the sand flow at both ends and the sand filling port. Then stand up the core box, return the upper side live material to its place, and use special tools to pound it along the arc side to complete the production of the airway core 400. It will harden naturally. Figure 5 shown.

[0044] According to the bearing groove structure, produce the airway core again according to the above method. After removing the core, apply three coats of zircon powder paint on the A / B surface. Figure 6 As shown;

[0045] Place the airway core into the bearing core box, tie the air rope and lead it to the positioning hole of the horizontal material, and compact the sand layer by layer to complete the core making operation. Figure 2 As shown, after removing the core, the entire bearing core and airway core are painted with zircon powder paint three times.

[0046] Normal box assembly and pouring.

[0047] After the casting is boxed, the special core bone is recovered, inspected and repaired before being reused to confirm the appearance quality of the bearing groove.

[0048] The special core bar, chromium ore sand core, and special graphite chiller described in this invention form a single unit, effectively solving the problem of sand sticking to thick, heavy-section bearing slots and airway surfaces. The special core bar naturally separates after casting boxing and can be recycled and used for repair. The special graphite chiller has a simple structure, making it easy to manufacture and market. The cost of the graphite chiller is far less than the cost of cleaning sand sticking to the casting, while ensuring the surface quality of the casting. The special core bar, chromium ore sand core, and special graphite chiller work together to form a single sand core, effectively improving the core's strength and dimensional control. This solves the problem of sand sticking to thick, heavy-section bearing slots and airway surfaces, effectively improving the appearance quality of similar castings. The special core bar, chromium ore sand core, and special graphite chiller form a single unit, leveraging the graphite chiller's anti-sand sticking ability to effectively solve the problem of sand sticking to the bearing slot. Furthermore, the size of the special core bar and graphite chiller can be flexibly adjusted according to the sand core structure, ensuring high versatility.

[0049] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for casting a bearing groove, characterized in that: The casting method comprises the following steps: S1: Designing a core bone, wherein the core bone structure matches the airway core structure; S2: Fixing a chill on the core bar and placing a core iron inside the chill; S3: placing the core bone into a core box to produce an airway core; S4: placing the airway core into a bearing core box, and making the bearing core by flowing sand layer by layer; S5: Assembling the box and pouring.

2. The method for casting a bearing groove according to claim 1, characterized in that: Two semicircular core bones are arranged on the inner side of the core bone, and the two semicircular core bones are connected by tension bars.

3. The method for casting a bearing groove according to claim 2, characterized in that: The core bone and the semicircular core bone are fixedly connected via the end core bone.

4. The casting method of the bearing groove according to claim 3 is characterized in that the surface of the end core bone is flat.

5. The method for casting a bearing groove according to claim 2, characterized in that: The cold iron is fixed between the semicircular core bar and the outer edge of the core bar.

6. The method for casting a bearing groove according to claim 1, characterized in that: A hole with a diameter of 6 mm is provided on both sides of the inner and outer diameters of the chill, and four holes with a diameter of 10 mm are provided in the thickness direction of the chill.

7. The method for casting a bearing groove according to claim 6, characterized in that: The core irons are respectively arranged in holes with different apertures.

8. The method for casting a bearing groove according to claim 1, characterized in that: Zircon powder coating is applied on the surfaces of the airway core and the bearing core.

9. The method for casting a bearing groove according to claim 8, characterized in that: The zircon powder paint is applied at least three times.

10. The method for casting a bearing groove according to claim 1, characterized in that: The core bone can be recovered after boxing.

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