A gating system without riser for the upper flange of a compressor and a production process for the upper flange

Abstract

The present invention belongs to the field of casting processing, and discloses a riserless gating system for the upper flange of a compressor, including a sand mold. A plurality of cavities matching the shape of the upper flange are arranged in the sand mold. A sprue cup, a horizontal runner, a vertical runner, and an ingate are sequentially connected in the sand mold, and the ingate is communicated with the cavity. The ingate is of a wedge-shaped thin sheet structure. An exhaust strip is connected to the cavity. A pressure relief groove is arranged on the vertical runner, and a plurality of spoke grooves corresponding to the spokes of the upper flange are arranged in the cavity. At least one spoke groove is directly opposite to the ingate. The pressure relief groove is located between two rows of cavities arranged vertically. This system can control the position of the hot spot circle, make the molten iron filling stable, and avoid turbulence. At the same time, a production process is also provided, and through improving the formula, the comprehensive improvement of product quality is realized.

Description

Technical Field

[0001] The present invention relates to the field of casting processing, and specifically to a riserless gating system for the upper flange of a compressor and a production process for the upper flange. Background Art

[0002] With the continuous progress of science and technology, people's living standards have been increasing day by day. People's awareness of environmental protection has also been enhanced, and there are higher requirements for the quality of life. Correspondingly, higher requirements have also been put forward for household electrical appliances products that are closely related to each family. Taking air conditioners as an example, people now pay more attention to the energy conservation, environmental protection, quietness and comfort of air conditioners. Therefore, higher requirements have also been put forward for air conditioner manufacturers. As a result, higher requirements have been placed on the performance of the compressor, which is the core component of the air conditioner. As one of the excellent suppliers of core components for air conditioner compressors with the widest product coverage, the most complete product specifications and models, and the most prominent equipment capabilities in the industry, our company has correspondingly increased the research and development efforts of compressor castings and improved product quality to meet the higher quality requirements of customers for products.

[0003] With the continuous increase of current labor costs and the increasingly high environmental protection requirements in the industry, the salary and welfare of employees and environmental protection investment are also increasing. The production cost is getting higher and higher, and the profit is getting lower and lower. Coupled with the entry of some new manufacturers, the market competition has become increasingly fierce. Only by continuously reducing costs and increasing efficiency, developing and innovating, improving product quality, and increasing market share can the company survive in the current harsh market environment.

[0004] The bearing is the core component of the compressor. During the high-speed operation of the compressor, due to the combined action of the magnetic attraction generated between the motor stator and rotor and the eccentric force generated by the eccentric part of the crankshaft, on the one hand, it causes radial deformation of the crankshaft and the bearing shank, increasing the vibration and noise of the compressor; on the other hand, it makes the upper and lower bearing shanks closely fit with the outer circumference of the crankshaft to form a friction pair. This friction pair is a local surface contact with extremely high surface pressure, and the contact surface is prone to significant wear and even sintering, affecting the reliability of the long-term operation of the compressor. Therefore, it is required that the bearing has high mechanical properties. The central shank part of the bearing is the thickest and largest part of the casting, which is the hot spot of the casting. The traditional production process uses a riser feeding production process, with a low process yield. Moreover, due to the relatively thin wall thickness at the position of the bearing spoke, the feeding channel is not smooth, and the feeding effect is not ideal. Coupled with the interaction of the temperature field, the hot spot of the casting moves outward, resulting in a slight non-dense phenomenon after the inner hole of some castings is machined, which cannot meet the high-performance requirements of the existing compressor for bearings.

[0005] The applicant, Zhaoqing Jingtong Machinery Co., Ltd., filed a patent for invention ZL201510406233.6 in 2015, which discloses a ductile iron bearing for a compressor. Its structure includes a flange and a shank located in the middle of the flange. At the lower end of the shank, a semi-open hole is designed with the bearing central axis as the center and upward from the end face of the flange. The height of the semi-open hole is greater than 1.5 times the height of the flange and less than the total height of the ductile iron bearing for the compressor. The aperture size of the hole is 20% - 90% of the diameter of the shank. The design principle of the ductile iron bearing for the compressor in this invention is that by designing the semi-open hole structure, the hot spot circle diameter of the flange near the end face of the ductile iron bearing casting for the compressor is smaller than the hot spot circle diameter of the central part of the shank, making the hot spot circle at the central part of the shank the last solidification position of the ductile iron bearing casting for the compressor. Therefore, shrinkage cavity and porosity defects are controlled to the position of the hot spot circle at the central part of the shank, and the distribution is concentrated. The subsequent shrinkage cavity and porosity positions are removed by drilling.

[0006] This solution makes the hot spot circle move to the central part of the shank by setting a semi-open hole on the flange.

[0007] This solution is an effective solution; however, the product produced in this application is a flange with multiple thinner spokes. Using the traditional riser feeding casting process, there is a problem that the feeding channel is too long and the feeding effect is not ideal. Coupled with the interaction of the temperature field, the hot spots of the casting move outward, resulting in a slight non-dense phenomenon after the inner holes of some castings are machined, which cannot meet the requirements of customers for high-quality and high-performance products; the corresponding technical problems cannot be solved by the above means.

[0008] At the same time, the upper flange of gray iron needs to be prepared in this application, while the flange of ductile iron is prepared in ZL201510406233.6, which makes it impossible to use the above solution means for preparation in terms of the formula.

[0009] Therefore, the technical problem to be solved by this solution is: how to control the position of the hot spot circle to reach the central position of the shank to improve the product quality. Summary of the Invention

[0010] The purpose of the present invention is to provide a riserless gating system for the upper flange of a compressor, which can control the position of the hot spot circle, make the molten iron filling stable and avoid turbulence. At the same time, a production process is also provided, and through the improvement of the formula, the comprehensive improvement of the product quality is realized.

[0011] To achieve the above object, the present invention provides the following technical solutions: A riserless gating system for the upper flange of a compressor, including a sand mold. Multiple cavities matching the shape of the upper flange are provided in the sand mold. A sprue cup, a runner, a downsprue, and an ingate are sequentially connected in the sand mold, and the ingate communicates with the cavity; the ingate is a wedge-shaped thin plate structure; an exhaust strip is connected to the cavity; a pressure relief groove is provided on the downsprue, and multiple spoke grooves corresponding to the spokes of the upper flange are provided in the cavity; at least one spoke groove is aligned with the ingate; the pressure relief groove is located between two rows of cavities arranged vertically.

[0012] In the above riserless gating system for the upper flange of a compressor, the tail end of the runner is a wedge-shaped structure.

[0013] In the above riserless gating system for the upper flange of a compressor, the runner and the downsprue are connected through a dovetail joint.

[0014] In the above riserless gating system for the upper flange of a compressor, the ratio of the cross-sectional area of the runner, the cross-sectional area of the dovetail joint, the cross-sectional area of the downsprue, and the maximum cross-sectional area of the ingate is 1:0.8:1:1.05.

[0015] In the above riserless gating system for the upper flange of a compressor, the ratio of the cross-sectional area of the runner, the cross-sectional area of the dovetail joint, the cross-sectional area of the downsprue, and the maximum cross-sectional area of the ingate is 1:0.8:1:1.05.

[0016] Meanwhile, the present invention also discloses a production process for the upper flange of a compressor, which is cast using any one of the above gating systems; the composition of the molten iron for casting is:

[0017] C: 3.35 - 3.45%, Si: 2.30 - 2.40%, Mn: 0.65 - 0.80%, P < 0.06%, S: 0.06 - 0.10%, trace amounts of Sb or Sn, and the balance is iron.

[0018] In the above production process for the upper flange of a compressor, the melting temperature of the molten iron for casting is 1480 - 1520 °C; the molten iron is allowed to stand for 5 - 10 minutes after melting; the temperature of the molten iron during casting is 1400 - 1420 °C.

[0019] In the above production process for the upper flange of a compressor, the temperature of the molten iron during casting is 1400 - 1420 °C; the amount of molten iron tapped per ladle is controlled at 670 ± 10 kg, and the casting time per ladle is ≤ 8 minutes.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The inner gate is a wedge-shaped thin plate structure, which enables the molten iron to flow steadily into the casting cavity and has the function of blocking slag (sand). Combined with the decompression groove and the spoke groove, the decompression groove can reduce the injection speed of the molten iron and improve the stability of the molten iron flow. The spoke groove is aligned with the inner gate, which can improve the filling stability.

[0022] 2. The inner gate is a wedge-shaped thin plate structure. During the solidification stage, the inner gate solidifies first, which can avoid the mutual influence between the vertical runner and the cavity.

[0023] 3. The casting process of traditional riser feeding is cancelled, and the feeding effect is improved through the comprehensive improvement of the gating system.

[0024] Combining the above 1-3, the hot spots of the casting can reach the upper-middle position of the handle and can be removed after opening the hole, improving the product qualification rate.

[0025] At the same time, the tail end of the horizontal runner is a wedge-shaped structure, which can improve the filling stability and prevent the molten iron from flowing back.

[0026] The dovetail lap joint has the function of blocking slag (sand).

[0027] In addition, through the change of the formula in the process of the present invention, the CE value is increased to reduce the liquidus temperature, and the expansion effect generated by the precipitation of graphite during the solidification of the casting is enhanced, so that its shrinkage and expansion offset each other, and finally high-quality castings with a dense center handle can be produced without using risers.

[0028] In addition, 0.02-0.035% of Sb or Sn is added to the composition to refine graphite, increase the pearlite content, and improve the strength and hardness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the structural diagram of Embodiment 1 of the present invention;

[0030] Figure 2 It is the vertical sectional view of the partial C of Embodiment 1 of the present invention;

[0031] Figure 3 It is the top view of the upper flange of Embodiments 1 and 2 of the present invention;

[0032] Figure 4 It is the sectional view of the upper flange of Embodiments 1 and 2 of the present invention;

[0033] Figure 5 It is the sectional view of the inner gate of Embodiment 1 of the present invention;

[0034] Figure 6 It is the sectional view of the upper flange of Comparative Example 1 of the present invention;

[0035] Figure 7Schematic structural diagram of the gating system of Comparative Example 1 of the present invention. Detailed implementation manners

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment 1

[0038] Please refer to Figures 1 to 5 , a riserless gating system for an upper flange of a compressor, including a sand mold 1. A plurality of cavities 2 matching the shape of the upper flange A are provided in the sand mold 1. A sprue cup 3, a runner 4, a downsprue 5, and an ingate 6 are sequentially connected in the sand mold 1, and the ingate 6 communicates with the cavity 2; the ingate 6 is a wedge-shaped thin plate structure, and specifically, reference can be made to Figure 5 , Figure 5 , which is a cross-section along the liquid flow direction; an exhaust strip 7 is connected to the cavity 2; a pressure relief groove 8 is provided on the downsprue 5, and a plurality of spoke grooves corresponding to the spokes A3 of the upper flange A are provided in the cavity 2; at least one spoke groove is aligned with the ingate 6; the pressure relief groove 8 is located between two rows of cavities 2 arranged vertically.

[0039] In this embodiment, 1. The ingate 6 is a wedge-shaped thin plate structure, which enables the molten iron to flow smoothly into the casting cavity 2 and has the function of blocking slag (sand). Combining the pressure relief groove 8 and the spoke groove, the pressure relief groove 8 can reduce the injection speed of the molten iron and improve the stability of the molten iron flow. The alignment of the spoke groove and the ingate 6 can improve the filling stability. 2. The ingate 6 is a wedge-shaped thin plate structure. In the solidification stage, the ingate 6 solidifies first, which can avoid the mutual influence between the downsprue 5 and the cavity 2 and ensure effective feeding in the cavity 2. 3. The riserless gating process of the traditional riser is cancelled, and the feeding effect is improved through the comprehensive improvement of the gating system. Combining the above 1-3, the hot spot of the casting can reach the upper middle position of the handle A4 and can be removed after opening the hole. The product qualification rate is improved.

[0040] Of course, the cancellation of the riser is not only related to the structural modification of the gating system, but also related to the molten iron composition. However, the above system can effectively improve the stability of the molten iron flow and lay a foundation for the cancellation of the riser.

[0041] Preferably, the tail end 41 of the runner 4 is a wedge-shaped structure, which can improve the filling stability and avoid the backflow of the molten iron. The runner 4 and the downsprue 5 are connected by a dovetail joint 9, and the dovetail joint 9 has the function of blocking slag (sand).

[0042] In this embodiment, the cross-sectional areas of the runner 4, the sprue 5, the dovetail joint 9, and the ingate 6 are related to the stable flow rate of the molten iron. Specifically, the ratio of the cross-sectional areas of the runner 4, the sprue 5, the dovetail joint 9, and the maximum cross-sectional area of the ingate 6 is F_horizontal:F_dovetail (lap):F_vertical:F_in (total) = 1:1:0.8:1.05. The cross-sectional area of the dovetail joint 9 is 264 mm 2

[0043] Preferably, the ratio of the cross-sectional area of the pressure relief groove 8 to the cross-sectional area of the sprue 5 is F_relief:F_vertical = 0.45:1.

[0044] The upper flange A involved in this embodiment is prepared by the following process:

[0045] Reference Figure 3 and 4 , the upper flange A includes a flange plate A1 and a shank A4. There are several waist-shaped holes A2 on the flange surface, and the height of the waist-shaped holes A2 is 14 mm; the height of the flange plate A1 is 23 mm; the thickness of the spoke A3 is 12.4 mm; the diameter of the flange plate A1 is 126 mm; the height of the shank A4 is 47 mm.

[0046] The composition of the poured molten iron is:

[0047] C: 3.39 ± 0.03%, Si: 2.35%, Mn: 0.8%, P < 0.06%, S: 0.06 - 0.09%, Sb: 0.025%, with the balance being iron;

[0048] The specific process is as follows:

[0049] Step 1: Melting, melting according to the formula, with a melting temperature of 1480 - 1520 °C; after melting, the molten iron is allowed to stand for 5 - 10 minutes;

[0050] Step 2: Pouring, when pouring, the temperature of the molten iron is 1400 - 1420 °C; the amount of molten iron poured per ladle is controlled at 670 ± 10 kg, and the pouring time per ladle ≤ 8 minutes.

[0051] Step 3: Post-treatment, the cleaning process is as follows: 1 separating the gating system and the casting; 2 shot blasting (removing the residual sand, scale, and flash burrs on the casting surface); 3 grinding (removing the residual sprue, and cleaning with a grinding wheel).

[0052] Through the above treatment, its thermal node moves to the upper middle position of the shank A4, referring to Figure 4 the position shown by the circle E in, which is located at the position where the flange plate and the shank are joined.

[0053] The advantages of this embodiment are:

[0054] 1. The product qualification rate is high. Compared with the traditional process (refer to Comparative Example 1), the product yield is increased from 55 - 60% to about 70%, and the electric furnace can reduce the molten iron by 119 tons.

[0055] 2. The residue at the nozzle is less, reducing the grinding and cleaning cost in the subsequent process by 20,000 yuan per month.

[0056] 3. The product quality is good and stable.

[0057] Comparative Example 1

[0058] Same as Example 1, but it adopts a different gating system, which can be referred to Figure 7 ; Figure 7 It includes a pouring basin B1, a horizontal runner B2, a vertical runner B3, and an ingate B4. A riser B6 is arranged on the vertical runner B3, and the ingate B4 is connected to the cavity B5. The cross-sectional area ratio of the horizontal runner B2, the vertical runner B3, and the ingate B4 is B2:B3:B4 = 1:3.8:1.05.

[0059] The formula and process are the same as those in Example 1.

[0060] Its qualification rate is 55 - 60%. The hot spots are as shown by the circles D in Figure 6 and are located on the flange.

[0061] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A riserless gating system for the upper flange of a compressor, comprising a sand mold. Multiple cavities matching the shape of the upper flange are provided inside the sand mold. A sprue cup, a runner, a downsprue, and an ingate are sequentially connected inside the sand mold, and the ingate is communicated with the cavity. Characterized in that, The ingate is a wedge-shaped thin plate structure; an exhaust strip is connected to the cavity; a pressure relief groove is provided on the downsprue; multiple spoke grooves corresponding to the spokes of the upper flange are provided in the cavity; at least one spoke groove is aligned with the ingate; the pressure relief groove is located between two rows of cavities arranged vertically. The runner and the downsprue are connected through a dovetail joint. The ratio of the cross-sectional area of the runner, the cross-sectional area of the dovetail joint, the cross-sectional area of the downsprue, and the maximum cross-sectional area of the ingate is 1:0.8:1:1.

05. The tail end of the runner is a wedge-shaped structure.

2. The riserless gating system for the upper flange of a compressor according to claim 1, Characterized in that, The ratio of the cross-sectional area of the pressure relief groove to the cross-sectional area of the downsprue is 0.45:

1.

3. A production process for the upper flange of a compressor, Characterized in that, Casting is carried out using the gating system according to any one of claims 1-2; the composition of the molten iron for casting is: C: 3.35-3.45%, Si: 2.30-2.40%, Mn: 0.65-0.80%, P < 0.06%, S: 0.06-0.10%, trace amounts of Sb or Sn, and the balance is iron.

4. The production process for the upper flange of a compressor according to claim 3, Characterized in that, The melting temperature of the molten iron for casting is 1480-1520°C; the molten iron is allowed to stand for 5-10 minutes after melting; the temperature of the molten iron during casting is 1400-1420°C.

5. The production process for the upper flange of a compressor according to claim 3, Characterized in that, The temperature of the molten iron during casting is 1400-1420°C; the amount of molten iron tapped per ladle is controlled at 670±10 kg, and the casting time per ladle is ≤ 8 minutes.

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