RU2844595C1 - Moulding core - Google Patents

Abstract

FIELD: foundry production.

SUBSTANCE: proposed casting core comprises head and tail parts with sign sections and end face. Tail part comprises constant-height rectangular cross-section section with transverse process ribs (11) made thereat perpendicular to casting core axis with equal spacing of 50-60 mm. In the head part, there is a hollow with an inward slope, which in cross-section is a set of conjugate tangential arcs of different radii, made convex and concave, and cylindrical opening (8) with a V-shaped protrusion. Edges of holes have slope of up to 5° relative to its axis perpendicular to axis of moulding core. Part corresponding to automatic coupler engagement outline accommodates insert made from sand-chromite mix. Between the head and tail parts there is a transition zone, in the corners of connection of vertical and horizontal walls of which there are anti-shrinkage ribs with pitch of 15-25 mm.

EFFECT: decreased amount of rejects in the production of castings.

4 cl, 4 dwg

Description

The claimed invention relates to the field of metallurgy (foundry production), in particular to the design of technological elements of a casting mold used in the manufacture of cast parts of the “Automatic coupling body”.

The problem, which the claimed invention is aimed at solving, is that when manufacturing the part "Automatic coupling housing", the commonly used casting molds with casting cores forming the internal cavity of the casting do not exclude the formation of casting defects, such as distortion of the geometry of the internal cavities of the part, flooding, since they are not firmly and securely fastened in the casting mold, as a result, the cores shift from their place during the pouring process, while the size of one wall of the part decreases, and the other increases, in addition, the formation of hot cracks in the casting, shrinkage cavities is not excluded due to an insufficient number of elements in the design of the casting cores that prevent the occurrence of these defects.

The task, which the claimed invention is aimed at solving, is to improve the filling of the casting mold with liquid melt; increase the accuracy of casting, and reduce the labor intensity of auxiliary operations associated with the preparation of the casting mold for pouring.

The technical result achieved from the declared technical solution is a reduction in the level of defects in the production of castings.

The prior art discloses a design of a casting mold for an automatic coupling housing (website https://studbooks.net/2555636/tovarovedenie/izgotovlenie_detaley_avtostsepnogo ustroystva), containing a rod consisting of several half-rods forming a head part including a recess forming a tenon for a lock holder, a sign part of the rod of the upper half-mold for fixing and positioning the rod when covering the upper half-mold, containing a projection to ensure the operation of the riser, a sign part of the rod of the lower half-mold for positioning the rod when installing it in the mold and keeping it from falling to the sides during transportation of the mold, and a tail part having a rectangular cross-section of constant height, containing an end element made in the form of an elliptical cylinder.

Also known from the prior art is a design of a casting mold for manufacturing automatic coupling housings (patent RU 187005, B22C 9/00, published 13.02.2019, Bulletin No. 9), consisting of a head and a tail with a jumper at the end, containing lower and upper half-molds made of hardened molding material, made with cavities that form casting cavities when the said half-molds are closed, forming the outer contours of the automatic coupling housings, rods forming the inner contours of the automatic coupling housings, and a gating-feed system including a riser, gating passages and direct feed risers located above the head sections of the automatic coupling housings, characterized in that the lower and upper half-molds are made by vacuum-film molding and contain hardened bulk molding material enclosed in upper and lower flasks and sealed with synthetic films, the upper and lower flasks are equipped with vacuum tubes, located evenly along the length of the said flasks and parallel to each other, while above the sections of the head and the web of the tail of the automatic coupler housings, shells are installed for forming direct feed risers, and above the shells of the direct feed risers, models of thrusts are installed.

In this case, the casting mold for manufacturing the automatic coupling housings shown in Fig. 1 ÷ Fig. 4 includes rods that form the internal contours of the automatic coupling housings, made in one piece and consisting of a head part, a sign part of the rod of the upper half-mold for fixing and positioning the rod when covering the upper half-mold, a sign part of the rod of the lower half-mold for positioning the rod when installing it in the mold and holding it from falling to the sides during transportation of the mold, and a tail part having a rectangular cross-section of constant height, containing transverse technological ribs located perpendicular to the axis of the rod, having an equal pitch over the entire surface of the tail part.

The design of this casting core was adopted by the authors of the claimed invention as a prototype.

Disadvantages of the analogue and prototype:

- casting molds with casting cores that form the internal cavity of the automatic coupling body do not exclude distortion of the geometry of the internal cavities of the part, since they are not firmly and securely fastened in the casting mold, as well as the formation of casting defects, such as floods, hot cracks, shrinkage cavities due to an insufficient number of elements in the casting core design that prevent the occurrence of these defects.

The stated problem is solved, and the specified technical result is achieved, in that a casting core for casting an automatic coupling body, comprising a head and a tail part with sign sections, wherein the tail part comprises a section of rectangular cross-section of constant height, on which transverse technological ribs are made with an equal pitch, located perpendicular to the axis of the casting core and an end, characterized in that a recess is made on the head part, ensuring the formation in the cast body of the automatic coupling of a tenon for the lock holder, grooves forming lugs in the cast body for the automatic coupling lifter, and a recess forming in the cast body of the automatic coupling a shelf for the automatic coupling safety catch, wherein in the head part there is an emptying with an inward slope, which is in cross-section a set of conjugate tangentially arcs of different radii, made convex and concave, and a cylindrical opening with a V-shaped a projection, the edges of which have an inclination of up to 5º relative to the axis of the hole, which is located perpendicular to the axis of the casting core, wherein in the part corresponding to the contour of the engagement of the cast body of the automatic coupling, an insert made of sand-chromite mixture (not shown) is installed, between the head and tail parts a transition zone is made in which at the corners of the mating of the vertical and horizontal walls of the core anti-shrinkage ribs are made with a pitch of 15-25 mm, wherein the anti-shrinkage ribs are made transitioning from the horizontal part of the casting core to its vertical part, cavities are made along the tail part, and transverse technological ribs are made with an equal pitch of 50-60 mm, wherein the thickness of the transverse technological and anti-shrinkage ribs is 4-6 mm, and their depth is 10-15 mm, the end is made in the form of an elliptical cylinder, and on its sign part for the upper half of the mold a step is made.

In a particular version of the casting core, the transverse technological and anti-shrinkage ribs are made 6 mm thick and 15 mm deep.

In a particular version of the casting core, the transverse technological ribs are made with an equal pitch of 55 mm.

In a particular version of the casting core, the anti-shrinkage ribs are made with a pitch of 20 mm.

The essence of the claimed invention is explained by graphic materials:

Fig. 1 – casting core (front view);

Fig. 2 – casting core (rear view);

Fig. 3 – casting core (location of transverse technological ribs relative to the axis of the casting core);

Fig. 4 – casting core (location of the cylindrical hole relative to the axis of the casting core).

A casting core comprising a head portion (1) with key sections and a tail portion (2) with key sections, which also has a section in the form of a rectangular cross-section of constant height, cavities (3) forming stiffening ribs which are located along the tail portion, a recess (4) forming a tenon for the lock holder, grooves (5) forming lugs for the lifter, a notch (6) creating a shelf for the safety catch, an emptying (7) which is in cross-section a set of conjugate tangential arcs of different radii, made both convex and concave, wherein this emptying is made by drawing with a slope inward of the cross-section, a cylindrical opening (8) with a V-shaped protrusion to prevent the core from rotating along the axis, intended for installing a sand core forming an opening into which the lifter roller is installed, wherein the axis of the cylindrical opening is perpendicular to the axis of the casting core, and the faces have slope of up to 5º relative to the axis of the cylindrical hole, an insert made of sand-chromite mixture (not shown) is installed on the inner radius of the engagement contour (13), the end is made in the form of an elliptical cylinder (9) and has a step (10) to ensure the operation of the riser, made on the sign part for the upper half of the mold, in the transition zone between the head and tail parts in the corners of the mating of the vertical and horizontal walls there are anti-shrinkage ribs (12), made with a reduced pitch in the range from 25 mm to 15 mm and passing from the horizontal part of the rod radius to the vertical part along the radius, wherein the transverse technological ribs (11) and anti-shrinkage ribs (12) are made with a thickness of 4 to 6 mm and a depth of 10 to 15 mm, and the transverse technological ribs (11) are made with an equal pitch in the range from 50 to 60 mm.

The casting core works as follows.

Before installing the casting core in the casting mold, a non-stick coating is applied to the recess (4) of the groove (5), the notch (6), the end (9) and to the inner radius of the engagement contour (13).

Then, a rod (not shown) is installed in the cylindrical hole (8) with a V-shaped protrusion, making a hole for the lift roller in the casting of the "automatic coupling body". When this rod is installed in the cylindrical hole (8) with a V-shaped protrusion, its reliable installation and fixation horizontally and vertically is ensured.

The casting core is installed in the lower half-mold, covered with the upper half-mold in such a way that the marked sections located on the head part (1) and tail part (2) of the casting core coincide with the corresponding recesses on the casting mold. After assembling the casting mold, it is filled with liquid metal (liquid steel) through the gating system and the feeder into the gap formed between the casting mold and the casting core in such a way that the head and tail parts of the casting core come into contact with the liquid metal on all sides except for the marked sections of the core. During the crystallization process of the liquid metal, the thin walls and protruding elements of the casting are the first to crystallize, including those formed by transverse technological ribs (11), anti-shrinkage ribs (12), cavities (3) forming stiffening ribs, which are located along the tail part of the casting core. Due to the fact that these elements of the casting crystallized earlier than the main part of the casting, this prevents the appearance of hot cracks on the inner surface of the casting at the junction corners of the vertical and horizontal walls, as well as transverse cracks on the inner horizontal surface of the tail part of the casting.

On the inner radius of the engagement contour (13) using an insert made of a sand-chromite mixture, the crystallization process is also accelerated along the entire plane of contact with this insert, due to the higher thermal conductivity of chromium sand in comparison with quartz sand, which ensures the absence of shrinkage cavities in this section of the casting.

During the further process of crystallization of the casting, the metal begins to shrink (linear shrinkage of steel is 2%) and, due to the presence of emptying (7), acceptable ductility of the massive head part (1) of the casting core is ensured, and the formation of stresses and cracks in the casting is also excluded.

The presence of a step (10) in the design of the casting core ensures the fixation of the core in the upper half-mold, and also provides the possibility of high-quality impregnation of the tail part of the casting without obstructing the operation of the riser.

Example: The production of the casting "automatic coupling body" from 20GL steel is carried out as follows.

Before installing the casting core in the casting mold, a non-stick coating is applied to the recess (4) of the groove (5), the notch (6) of the end (9) and to the inner radius of the engagement contour (13). Then, a core (not shown) is installed in the cylindrical opening (8) with a V-shaped protrusion, making an opening for the lift roller in the casting of the "automatic coupling body". The casting core is installed in the lower half-mold, covered with the upper half-mold in such a way that the symbolic sections located on the head part (1) and tail part (2) of the casting core coincide with the corresponding recesses on the casting mold. After the casting mold is assembled, it is poured with 20GL steel by gravity through the gating system and the feeder into the gap formed between the casting mold and the casting core in such a way that the head and tail parts of the casting core are in contact with the liquid metal on all sides except for the key sections of the core. During the crystallization process of the liquid metal, the thin walls and protruding elements of the casting crystallize first, including those formed by the transverse technological ribs (11) made with an equal pitch of 55 mm, the anti-shrinkage ribs (12) made with a reduced pitch of 20 mm and the cavities (3). In this case, the transverse technological ribs (11) and the anti-shrinkage ribs (12) are made 6 mm thick and 15 mm deep. Due to the fact that these elements of the casting crystallize before the main part of the casting, this prevents the appearance of hot cracks when moving from the vertical part of the casting to the horizontal part.

On the inner radius of the engagement contour (13), due to the use of an insert made of sand-chromite mixture, the absence of shrinkage cavities in this section of the casting is ensured.

The presence of an emptying section (7) in the design of the casting core ensures acceptable flexibility of the massive head part (1) of the casting core and also eliminates the formation of stresses and cracks in the casting.

The presence of a step (10) in the design of the casting core ensures the fixation of the core in the upper half-mold, and also provides the possibility of high-quality impregnation of the tail part of the casting without obstructing the operation of the riser.

Due to the fact that the casting core is made of a single-piece design, the casting core is securely fastened in the casting mold, the casting mold assembly is performed without violations, the casting core does not move from its place during the metal pouring process, and the dimensional part of the casting is without deviations. Accordingly, the use of this casting core helps to reduce the level of defects in the manufacture of castings.

Thus, the probability of casting defects is significantly reduced: when producing the annual volume of “automatic coupling housing” parts (20,000 pieces), casting defects decreased by 2% to 3% compared to previously used casting rods.

The claimed invention is used in the foundries of the enterprise JSC Scientific and Production Corporation Uralvagonzavod and has confirmed its technical and economic efficiency.

Claims (9)

1. A casting core for casting an automatic coupling body, comprising a head and a tail section with sign sections, wherein the tail section comprises a section of rectangular cross-section of constant height, on which transverse technological ribs are made with equal pitch, located perpendicular to the axis of the casting core, and an end, characterized in that a recess is made on the head section, ensuring the formation of a tenon for a lock holder in the cast body of the automatic coupling, grooves forming bosses for the automatic coupling lifter in the cast body, and a recess forming a shelf for the automatic coupling safety catch in the cast body of the automatic coupling, wherein in the head part there is a hollow with an inward slope, which in cross-section is a set of conjugate tangential arcs of different radii, made convex and concave, and a cylindrical opening with a V-shaped protrusion, the edges of which have an inclination of up to 5° relative to the axis of the opening, which is located perpendicular to the axis of the casting rod, while in the part corresponding to the contour of the engagement of the cast body of the automatic coupling, an insert made of a sand-chromite mixture is installed, between the head and tail parts there is a transition zone in which anti-shrinkage ribs are made in the corners of the junction of the vertical and horizontal walls of the core with a pitch of 15-25 mm, and the anti-shrinkage ribs are made to transition from the horizontal part of the casting core to its vertical part, cavities are made along the tail section, and transverse technological ribs are made with an equal pitch of 50-60 mm, where the thickness of the transverse technological and anti-shrinkage ribs is 4-6 mm, and their depth is 10-15 mm, The end face is made in the form of an elliptical cylinder, and on its symbolic part for the upper half-form a step is made. 2. A rod according to item 1, characterized in that the transverse technological and anti-shrinkage ribs are made 6 mm thick and 15 mm deep. 3. The rod according to item 1, characterized in that the transverse technological ribs are made with an equal pitch of 55 mm. 4. The rod according to item 1, characterized in that the anti-shrinkage ribs are made with a pitch of 20 mm.