A casting molding method for a small shaft-hole propeller

Abstract

The present invention discloses a casting molding method for a small shaft-hole propeller, belonging to the technical field of propeller manufacturing. In the present invention, a seamless steel pipe filled with dry sand is used to replace the traditional sand molding at the position of the propeller shaft hole. This method is applied to small shaft-hole type propellers, which can effectively solve the problem of sand adhering to the shaft hole, shorten the production cycle, improve production efficiency, and reduce production costs.

Description

Technical Field

[0001] The invention relates to a propeller manufacturing technology, in particular to a casting modeling method for a propeller. Background Art

[0002] Fixed-pitch propellers are matched with propeller shafts by shaft-hole connection. In the sand casting process, the process is roughly as follows: making flowerpot core - propeller hub wooden mold - shaft hole modeling - blade modeling - box assembly - pouring - box punching. Among them, the propeller shaft hole is currently molded with carbon dioxide or ester-hardened water glass sand. This molding method works well for propellers with large shaft holes (propeller stern shaft hole size > 300mm), but for propellers with small shaft holes (propeller stern shaft hole size < 300mm), the smaller diameter of the sand mold will cause shaft The overall strength of the hole sand is relatively low. During the pouring and filling process, the shaft hole sand is easily broken due to the scouring and squeezing of the high-temperature copper liquid. The copper liquid enters the sand along the gap and mixes with the sand to form the shaft hole sand defect. After the copper liquid solidifies, the shaft hole defect is hard and difficult to clean. In the subsequent boxing process, it must be cleaned with carbon arc gouging, oxygen blowing rods and pneumatic picks. It takes multiple operators a long time to complete the shaft hole cleaning work, which not only greatly prolongs the casting process time, but also has certain safety risks during the operation. Especially when the shaft hole size is too small (the shaft hole size at the stern end of the propeller is less than 150mm) and the blade height is high, the operation space of the carbon arc gouging is limited, and it is very easy to damage the inner wall of the shaft hole, resulting in a "lack of meat" defect. If the defect cannot be repaired, the entire product will be scrapped. Summary of the invention

[0003] The purpose of the invention is to provide a casting method for a propeller with a small shaft hole, so as to solve the technical problem that sand sticking to the shaft hole is difficult to clean.

[0004] The present invention provides a method for casting a propeller with a small shaft hole, and the steps are as follows:

[0005] S1, molding material preparation, prepare a seamless steel pipe with an outer diameter the same as the diameter of the propeller shaft hole to be cast, and the wall thickness of the seamless steel pipe meets the requirements of the following formula:

[0006] D≥(R1-R2) / 20 (D≮10mm), where: D is the wall thickness of the seamless steel pipe; R1 is the radius of the large end of the propeller hub to be cast; R2 is the radius of the seamless steel pipe;

[0007] The length of seamless steel pipe meets the following formula requirements:

[0008] L≥H+350mm, where: L is the length of the seamless steel pipe (mm); H is the height of the propeller hub to be cast (mm);

[0009] Use a spirit level to inspect the straightness of the seamless steel pipe, and the straightness meets the requirements of GB / T 11336 - 2004.

[0010] S2, Molding. The molding steps are as follows:

[0011] (a) Ram the flower pot core. When making it, embed a cylindrical polystyrene board with a diameter 2 mm larger than the outer diameter of the seamless steel pipe at the center of the flower pot core. The height of the polystyrene board is greater than 100 mm. After the sand block of the flower pot core hardens, take out the polystyrene board to form a reserved central hole;

[0012] (b) Place the flower pot core on the molding bottom plate, place the propeller hub wooden mold at the center position of the flower pot core, and then mold the propeller blades according to the molding process;

[0013] (c) After the blade molding is completed, lift out the hub wooden mold, insert the seamless steel pipe into the reserved central hole of the flower pot core, and fill the gap between the seamless steel pipe and the central hole with a filler;

[0014] (d) Fill the seamless steel pipe with a filler. The height of each filling of the filler does not exceed 100 mm. After each filling of the filler, use a sand pestle to ram it until the height of the filler is more than 50 mm above the riser line;

[0015] (e) Close the mold. The lower blade box is fixed on the molding bottom plate by channel steel. The upper blade box is covered on the lower blade box. A casting pressure ring is welded at the top of the upper blade box. Several through bolts are arranged between the casting pressure ring and the molding bottom plate. The upper end of the through bolt is tightened with the casting pressure ring, and the lower end is tightened with the molding bottom plate to realize the fastening of the upper box and the lower box;

[0016] (f) Weld several steel bars circumferentially at the top of the seamless steel pipe. One end of the steel bar is welded to the seamless steel pipe, and the other end is welded to the casting pressure ring;

[0017] (g) Pour and shake out the mold according to the process. During the mold shaking out process, the dry sand in the seamless steel pipe can be automatically discharged under the action of gravity. Finally, cut off the exposed part of the seamless steel pipe above the riser.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) High molding dimensional accuracy. The shaft hole size is determined according to the outer diameter of the seamless steel pipe. During the filling process, the steel pipe has a small thermal expansion degree, which can improve the casting dimensional accuracy of the shaft hole and greatly reduce the casting allowance on the inner side of the shaft hole.

[0020] (2) Simple operation, saving the time for making shaft hole molding sand and painting coatings. The steel pipe can be directly positioned with the pre - set central hole of the flower pot core.

[0021] (3) The quality of the casting is good. Using seamless steel pipes can effectively avoid the situation where sand grains fall into the casting cavity during the operation of the shaft hole sand mold in the traditional molding method, ensuring the quality of the casting.

[0022] (4) The mold removal operation is simple. The dry sand inside the steel pipe automatically drains under the action of gravity during mold removal. Part of the dry sand adhering to the inner wall of the steel pipe can be removed by blowing air, eliminating the defect of sand sticking to the shaft hole caused by using the traditional method to manufacture small shaft hole type propellers.

[0023] (5) Cost savings and production efficiency improvement. Using this molding method can shorten the mold removal and cleaning time, save labor costs, avoid safety hazards during mold removal and the risk of casting quality defects, and improve production efficiency. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the molding structure of the present invention. Specific Embodiments

[0025] Next, the present invention will be described in detail with reference to the drawings

[0026] A casting molding method for a small shaft hole propeller, the steps are as follows:

[0027] S1, Preparation of molding materials. Prepare a seamless steel pipe with an outer diameter the same as the diameter of the shaft hole of the propeller to be cast. The wall thickness of the seamless steel pipe meets the following formula requirements:

[0028] D≥(R1 - R2) / 20 (D≮10mm), where: D is the wall thickness of the seamless steel pipe; R1 is the radius of the large end of the propeller hub to be cast; R2 is the radius of the seamless steel pipe;

[0029] The length of the seamless steel pipe meets the following formula requirements:

[0030] L≥H + 350mm, where: L is the length of the seamless steel pipe (mm); H is the height of the propeller hub to be cast (mm);

[0031] Use a level to inspect the straightness of the seamless steel pipe, and the straightness meets the requirements of GB / T11336 - 2004.

[0032] S2, Molding, as Figure 1 shown, the molding steps are as follows:

[0033] (a) Ram the flower pot core. When making it, embed a cylindrical polystyrene board with a diameter 2mm larger than the outer diameter of the seamless steel pipe at the center of the flower pot core. The height of the polystyrene board is greater than 100mm. After the sand block of the flower pot core hardens, take out the polystyrene board to form a reserved central hole;

[0034] (b)Place the flower pot core 5 on the molding base plate 6, place the propeller hub wooden mold at the center position of the flower pot core, and then mold the propeller blades according to the molding process;

[0035] (c)After the blade molding is completed, lift out the hub wooden mold, insert the seamless steel pipe 1 into the center hole reserved in the flower pot core, and fill the gap between the seamless steel pipe and the center hole with ester-cured sodium silicate sand;

[0036] (d)Fill dry sand 4 into the seamless steel pipe, and the height of each filling of dry sand does not exceed 100 mm. After each filling of dry sand, use a sand pestle to tamp it until the height of the dry sand is more than 50 mm above the riser line;

[0037] (e)Close the mold. The lower blade box 10 is fixed on the molding base plate 6 by 20# channel steel 8. The upper blade box 9 is placed on the lower blade box. A casting collar 3 is welded to the top end of the upper blade box. 4 - 6 through bolts 7 are arranged between the casting collar and the molding base plate. The upper end of the through bolt is tightened with the casting collar, and the lower end is tightened with the molding base plate to realize the fastening of the upper box and the lower box;

[0038] (f)Weld several Φ10 mm steel bars 2 circumferentially at 90° intervals at the top end of the seamless steel pipe. One end of the steel bar is welded to the seamless steel pipe, and the other end is welded to the casting collar;

[0039] (g)Pour and shake out the mold according to the process. During the mold shaking-out process, the dry sand in the seamless steel pipe can be automatically discharged under the action of gravity. Finally, cut off the part of the seamless steel pipe exposed above the riser.

Claims

1. A casting and molding method for a small shaft-hole propeller, characterized in that The steps are as follows: S1. Preparation of molding materials: Prepare a seamless steel pipe with an outer diameter equal to the diameter of the hole of the propeller shaft to be cast. The wall thickness of the seamless steel pipe shall meet the requirements of the following formula: D≥(R1 - R2) / 20 (D≮10mm), where: D is the wall thickness of the seamless steel pipe; R1 is the radius of the large end of the propeller hub to be cast; R2 is the radius of the seamless steel pipe; The length of the seamless steel pipe shall meet the requirements of the following formula: L≥H + 350mm, where: L is the length of the seamless steel pipe (mm); H is the height of the propeller hub to be cast (mm); Use a level to inspect the straightness of the seamless steel pipe, and the straightness shall meet the requirements of GB / T11336 - 2004; S2. Molding. The molding steps are as follows: (a) Ram the flowerpot core. When making it, embed a cylindrical polystyrene board with a diameter 2mm larger than the outer diameter of the seamless steel pipe at the center position of the flowerpot core. The height of the polystyrene board is greater than 100mm. After the sand block of the flowerpot core hardens, take out the polystyrene board to form a reserved center hole; (b) Place the flowerpot core on the molding bottom plate, place the propeller hub wooden mold at the center position of the flowerpot core, and then mold the propeller blades according to the molding process; (c) After the blade molding is completed, lift out the hub wooden mold, insert the seamless steel pipe into the reserved center hole of the flowerpot core, and fill the gap between the seamless steel pipe and the center hole with a filler; (d) Fill the seamless steel pipe with a filler. The height of each filling of the filler does not exceed 100mm. After each filling of the filler, use a sand pestle to ram it until the height of the filler is more than 50mm above the riser line; (e) Close the mold. The lower blade box is fixed on the molding bottom plate by channel steel. The upper blade box cover is placed on the lower blade box. A casting pressure ring is welded at the top of the upper blade box. Several through bolts are arranged between the casting pressure ring and the molding bottom plate. The upper end of the through bolt is tightened with the casting pressure ring, and the lower end is tightened with the molding bottom plate to realize the fastening of the upper box and the lower box; (f) Weld several steel bars circumferentially at the top of the seamless steel pipe. One end of the steel bar is welded to the seamless steel pipe, and the other end is welded to the casting pressure ring; (g) Pour and shake out the mold according to the process. During the mold shaking-out process, the dry sand in the seamless steel pipe is automatically discharged under the action of gravity, and finally cut off the part of the seamless steel pipe exposed above the riser.

2. The small shaft hole propeller casting and molding method according to claim 1, characterized in that, The filler for the gap between the seamless steel pipe and the center hole is ester-hardened sodium silicate sand.

3. The small-axis-hole propeller casting and molding method according to claim 1, characterized in that, The filler in the seamless steel pipe is dry sand.

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