RU139474U1 - CAST Billets FOR PIPELINE FITTINGS - Google Patents

Abstract

1. A cast billet of the body part of the pipe fittings, which is a steel hollow, profitable casting with at least two cylindrical or cylindrical and conical surfaces interconnected at an angle, obtained by gravity casting in wet molds, or in cold sand hardening mixtures, or in a chill mold, or in shell molds, or by investment casting method, characterized in that in the cavity of the casting adjacent to its inner surface there are tides communicated with spruce and arranged to partially or completely overlap the mating zones of the surfaces forming the casting, the ratio of the inner diameter of the cylinder in which the tides are located to the distance between them in the horizontal axial section of the cylinder is from 1.06 to 5.2. A cast billet according to claim 1, characterized in that the tides are made closed in a sub-profitable casting zone. 3. Cast billet according to claim 1, characterized in that the tides have a thickness that is variable over the entire height, and the expansion of the tides to profit is from 3 to 15 °. 4. A cast billet according to claim 1, characterized in that the ratio of the length of the cylinder in which the tide is located to the width of the tide in the horizontal axial section of the cylinder is from 3 to 10.5. A cast billet according to claim 1, characterized in that the body part of the pipe fittings is a valve body, in which the main passage and the connecting upper and lower cylinders are formed by interconnected cylindrical surfaces, while the tides in the casting of the valve body are oriented towards the main passage.

Description

The inventive utility model relates to the field of foundry and can be used in the manufacture of blanks for body parts of pipeline valves, namely, valve bodies and wedge gate valves, tees, etc.

One of the problems of foundry today is the presence of shrinkage defects in castings, such as shrinkage, shrinkage loosening, porosity, as well as defects in the form of non-metallic inclusions. The secrecy of the course of the solidification process of the metal in the form makes it difficult to eliminate the shrinkage defects of the castings that arise at the same time. In the case of complex casting, the volume of which is formed by the mutual intersection of several forming surfaces, in the zones of intersection of these surfaces, otherwise, thermal nodes, the main shrinkage defects appear that require further elimination, for example, mechanical cutting and brewing. One of the main tools practiced to produce castings without shrinkage shells is the use of profits. However, it is not always possible to provide casting with the necessary number of profits, especially for supplying thermal units.

From the description of the invention to A.S. USSR No. 1444058 known cast billet reinforcement parts having several thermal units (central and peripheral), while above the central thermal unit there is profit as a supply element, and technological tides connect the central thermal unit with peripheral thermal units.

In the manufacture of this design of the casting, proper nutrition of all thermal units is not provided, since the available technological tides do not completely cover the area of the thermal unit, but only ensure their connection.

The prior art also known casting containing a joint of volumetric elements with the formation of a thermal node of variable cross-section and profit placed on the side opposite to the maximum narrowing of a thermal node of variable cross-section (AS USSR No. 1082556).

As a result of the manufacture of this casting design, the task of eliminating shrinkage defects in the thermal units is not solved, since the joint zones of the volume elements are not covered by profit areas, and additional feeding elements, for example, in the form of tides, are not provided for by the casting design.

Closest to the technical nature of the claimed invention is a cast billet obtained by casting on a lost wax model (LVM) at the Voronezh Mechanical Plant (CADmaster Magazine, No. 4, 2004 "Lost wax casting: an inside view", Savelyev Yu., Turishchev V. ) The well-known cast billet is presented in the form of two interpenetrating cylindrical bodies with extended thin walls and massive flanges. The workpiece is characterized by the presence of thermal centers (thermal units) at the points of transition from thin to thick elements. Upon receipt of the casting, the problem of finding optimal crystallization conditions and reducing the number of shrinkage defects is solved by using five massive profits, one of which is installed in the center of the casting, three on the flanges, and one more on the conical part of the casting.

However, it follows from the indicated source of information that the authors could not avoid the presence of defects such as “shrinkage porosity” in the “blind pocket” zone and in the lower part of the horizontally oriented part of the casting.

The objective of the proposed technical solution is to improve the quality of castings intended for the manufacture of parts of pipe fittings, in particular, gate valves, by reducing the possibility of shrinkage defects and defects in the form of non-metallic inclusions in the area of the casting heat nodes as a result of supplying heat nodes with power.

The technical result achieved by using the claimed utility model is to provide directional crystallization and removal of non-metallic inclusions and gases from the casting to profit.

The problem is solved by the fact that the claimed cast billet of the casing part of the pipe fittings, which is a steel hollow casting with a profit. The casting is made in the form of at least two mutually conjugated at an angle of cylindrical or cylindrical and conical surfaces. The casting can be obtained by gravity casting in raw molds, cold sand hardening mixtures, in chill molds, shell molds, or by casting according to investment casting. According to the claimed technical solution, in the cavity of the casting adjacent to its inner surface there are tides arranged to partially or completely overlap the mating zones of the surfaces forming the workpiece, while the tides are made communicating through the surface of the casting with a profit, and the ratio of the inner diameter (A) of the cylinder in which the tides are located to the distance between them (D) in the horizontal axial section of the cylinder is from 1.06 to 5. The size of the tides and their location relative to each other Avis diameters of the mating surfaces and sizes lucrative part cast billet. Tides can be made by closing in a sub-profitable casting zone. In addition to the indicated geometric parameters, tides can satisfy the following relationships: the ratio of the length of the cylinder (L) in which the tide is located to the width of the tide (B) in the horizontal axial section of the cylinder is from 3 to 10. The tide can have a thickness that is variable throughout the height, expanding to the profit zone, while the expansion of the tide to the profit zone is from 3 ° to 15 °. From the cast billet according to the claimed utility model, body parts of pipe fittings are made, in particular, slide valve bodies or wedge gate valves. So, for example, the cast billet case body of the gate valve is an interconnected main passage and the connecting upper and lower cylinders as interlocking cylindrical surfaces, while the tides in the casting of the valve body are located in the casting cavity and oriented towards the main passage.

The inventive utility model is illustrated by the following schematic images:

Figure 1 presents a section of a cast billet (top view) indicating the possible location of defects in thermal nodes;

Figure 2 presents a side view of the workpiece without tides;

Figure 3 presents a section of the cast billet (top view), equipped with tides made in the zones of mutual intersection of the forming surfaces to prevent the occurrence of the defects shown in figure 1;

Figure 4 presents a side view of the workpiece with tides made in accordance with the claimed invention;

Figure 5 presents a section of the workpiece blank body parts of the valve with shrinkage defects in the thermal nodes;

Figure 6 shows the zone of the location of the tides according to the claimed utility model, respectively, to the places of formation of shrinkage defects;

Figure 7 presents the preparation of the valve body with tides and profits;

On Fig and 9 presents views of the body of the valve gate valve with and without defects, with tides.

Figure 10 presents a side view of the body part of the wedge gate valve with tides.

11-13 presents embodiments of the tides in the casting in accordance with the claimed utility model, differing in the level of closure of these tides, which is determined by their thickness and shape.

On Fig presents a schematic representation of the inventive workpiece made in the form of interconnected cylindrical and conical surfaces.

The positions in the drawings indicate:

1 cylindrical surface

2 tide

3 surface mating zone (thermal unit),

4 main passage,

5 connecting cylinder

6 slide groove,

7 profit

8 defects

9 point of closure of tides,

10 conical surface.

A detailed description of the design of the claimed technical solution and the method of its manufacture and use are shown on the example of a cast billet of the gate valve body, however, the invention is also possible for other volume cast billets of the body parts, for example, wedge gate valves, shut-off and control valves, tees, bends, etc. .d. In each case, the size and shape of the tides located in the mating zones forming the workpiece surfaces are calculated individually.

The valve body blank is made in the form of a cylindrical trunk passage 4 with a diameter of 100 to 2000 mm with connecting cylinders (pipes) 5 oriented perpendicular to it from two sides opposite its cylindrical surface (upper and lower). The cast blank of the valve body is a casting made, for example, by gravity casting into cold cold-hardening sand mixtures. Casting can also be carried out in raw molds, in chill molds, shell molds or in investment casting. Most casting defects are formed during the solidification of the casting after full filling. The shrinkage of the liquid and crystallizing alloy causes the formation in the castings of unfilled metal cavities (shrink shells and pores), which negatively affects the further operational characteristics of such castings (Figs. 1, 5, 8). The described castings are used as blanks for cases of pipe fittings used in the transportation of oil and gas. In the case of shrinkage defects in the casting, the risk of partial destruction of the metal and leakage of the transported medium into the environment increases significantly, which negatively affects the external environmental situation and poses a threat to the safety of the facility in operation. So, shrinkage shells are often formed in isolated nodes with the highest concentration of metal; in corners, in places of metal supply or in places with difficult heat removal. When casting blanks of simple shape, the task of reducing the number of shrinkage defects is achieved by setting profits over areas with a tendency to shrinkage defects. When casting blanks with complex configurations, at the intersection of the surfaces forming the blank, thermal units are formed, the supply of which is only profitable enough to prevent the occurrence of shrinkage defects. In addition, the supply of these arrays with profits causes high metal costs and unproductive additional costs for machining. In some cases, it is not possible to provide the casting with so many profits as to eliminate possible shrinkage. In the claimed utility model, the local problem of supplying metal with the heat nodes 3 of the casting formed at the intersection (conjugation) of the workpiece surfaces is solved. Figure 5, 6 schematically shows a cross-section of the workpiece of the gate valve body formed by interconnected cylindrical main passage 4 (generally 1) and the upper and lower connecting cylinders 5. From figure 5 it is seen that shrinkage defects 8 are formed in the mating zones of the forming surfaces so-called thermal nodes 3. Casting of the valve body has four thermal nodes, in the zone of which four tides 2 are identical in shape and size, closing in a sub-profit zone in the main passage. The shape of the tides is shown in figure 4, and is determined by the orientation in space of the line of intersection of the surfaces forming the workpiece. In general, tides have a thickness that is variable over the entire height and is made with increasing thickness to profit. The tides are made closed in the upper part of the main passage 4 of the blank of the valve body. The dimensions of the tides are not absolute values, but are determined by the geometric parameters of the cast billet.

So, for casting the gate valve body with a diameter of DN = 1200 mm, the following declared ratios of the geometric parameters of the casting are true: A / D = 2.35; A / G = 1.14; L / B = 5.56; and the expansion of the tide to profit (tidal angle) is 9 °.

The A / D ratio characterizes the dependence of the distance between two opposite tides in the horizontal section of the workpiece along the axis of the main steamboat on the diameter of the main passage, which is a characteristic of the height of the tides in the sub-profit zone.

The A / G ratio characterizes the dependence of the closure height of two adjacent tides in the main passage on the diameter of the main passage.

The ratio L / B characterizes the dependence of the magnitude of the tide on the length of the workpiece.

The indicated ratios for a body part with a diameter of DN = 1200 mm characterize the geometrical parameters of the tides, which provide an almost complete absence of shrinkage defects in thermal units and optimally contribute to the removal of non-metallic inclusions in profit. In the general case, all geometric relationships are interconnected, and their observance ensures the optimal configuration of tides.

11-13 show that the connection (closure) is formed in the sub-profit zone, that is, directly under the profit of the casting. It was previously noted that the ratio of the inner diameter of the cylinder (the inner diameter of the main passage for the case of cast billets of the valve body) to the distance between the tides, measured in the horizontal axial section of the cylinder (main passage), characterizes the height of the closing (connection) of the tides (see additional figures 11-13 ) So, figure 11 schematically shows an image of a part of a cast billet, the inner diameter of the cylinder of which is 500 mm, and the distance between the tides, measured by the horizontal axial section of the cylinder, is 251 mm, respectively, their ratio is 1.99. 12 schematically shows the situation when the tides are made thicker, as a result, the distance between them in the horizontal axial section of the cylinder is minimal, and is 100 mm with the same inner diameter of the cylinder. Thus, the ratio of the above values is 5, which is the boundary value from the claimed range. On Fig presents the opposite situation, when the thickness of the tides is minimal, they are made small, as a result of which the distance between them in the horizontal axial plane of 471 mm is almost equal to the inner diameter of the cylinder. Thus, for this case, the above ratio is 1.06. After cooling the metal of the casting, during its mechanical processing in the manufacturing process of the body part, the tides are removed.

Since the tides represent an additional volume of the injection mold, part of the gases and non-metallic inclusions along the shortest path to profit go through them. Tides on the casting provide the workpiece with a full metal feed, and contribute to the directional crystallization of the casting. With directional solidification, the casting is most dense, without concentrated shells, which are brought into profit by means of tides that communicate with profit through the surface of the casting. The result is a cast billet in which there is no need to brew shrink shells or other work to reduce the number of defects.

On Fig presents a variant of the cast billet formed by the mutual intersection of the conical 10 and cylindrical 1 surfaces. This design of the workpiece can be used in the manufacture of, for example, bodies of slide gate valves. The tides are located in the cylindrical part of the workpiece, and the conical part performs the function of a conical connecting pipe.

The choice of a specific value from the declared ranges of geometric ratios depends on many factors, including the requirements for the quality of the cast billet, namely, the requirements for the possible number or volume of various kinds of defects. So, the general requirements of Transneft for castings differ from the requirements of GOST 977-88. In accordance with GOST 977-88, on the untreated surfaces of castings, sinks and other defects are allowed without correction, except for cracks, the type, dimensions, quantity and location of which are indicated in the design documentation and specific technical requirements for casting. The requirements of Transneft contain a clear indication of the mandatory absence of various kinds of sinks and other defects. Thus, the allowable number of defects is determined by the input requirements of the host organization. Depending on this, the size of the tides also changes - for example, when requirements are tightened - up to the need for a complete absence of defects, tides are more massive, with a minimum distance between them.

Claims (5)

1. A cast billet of the body part of the pipe fittings, which is a steel hollow, profitable casting with at least two cylindrical or cylindrical and conical surfaces interconnected at an angle, obtained by gravity casting in wet molds, or in cold sand hardening mixtures, or in a chill mold, or in shell molds, or by investment casting method, characterized in that in the cavity of the casting adjacent to its inner surface there are tides communicated with spruce and arranged to provide partial or complete overlap of the mating zones of the surfaces forming the casting, while the ratio of the inner diameter of the cylinder in which the tides are located to the distance between them in the horizontal axial section of the cylinder is from 1.06 to 5. 2. A cast billet according to claim 1, characterized in that the tides are made closed in a sub-profitable casting zone. 3. Cast billet according to claim 1, characterized in that the tides have a thickness that is variable over the entire height, and the expansion of the tides to profit is from 3 to 15 °. 4. Cast billet under item 1, characterized in that the ratio of the length of the cylinder in which the tide is located to the width of the tide in the horizontal axial section of the cylinder is from 3 to 10. 5. The cast billet according to claim 1, characterized in that the body part of the pipe fittings is a valve body, in which the main passage and the connecting upper and lower cylinders are formed by interconnected cylindrical surfaces, while the tides in the casting of the valve body are oriented towards the main passage.

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