KR101361436B1 - Feeder element for metal casting - Google Patents

Abstract

In a metal casting process molten metal feeds to the casting form via a feed-charge funnel (52) whose first end (42) is attached to the form, and whose second end (43) receives the molten metal discharge spout. The first end and the second end are linked by a drill hole through the stepped funnel wall. In use the funnel is compressible, thereby reducing the distance between the first and second ends.

Description

Feeder element for metal casting {FEEDER ELEMENT FOR METAL CASTING}

The present invention relates in particular to an improved feeder element for use in metal casting operations using casting molds not limited to medium pressure sand mold systems.

In a conventional casting process, the melt is injected into a preformed mold cavity that defines the shape of the casting. However, as the metal solidifies, it contracts to form shrinkage pores, which in turn lead to unacceptable defects in the final casting. This is a well known problem in the casting industry and is addressed by the use of feeder sleeves or risers incorporated in the mold during the mold manufacturing process. Each feeder sleeve provides an additional (generally closed) volume or cavity in communication with the mold cavity such that the melt enters into the feeder sleeve as well. During solidification, the melt inside the feeder sleeve flows back into the mold cavity to cancel the shrinkage of the casting. It is important that the metal inside the feeder sleeve cavity remains molten for longer than the metal inside the mold cavity, so that the feeder sleeve is highly insulating or more generally to generate additional heat upon contact with the melt to delay solidification. It is manufactured to be exothermic.

After solidification and removal of the casting material, unnecessary residual metal from inside the feeder sleeve cavity remains attached to the casting, which must be removed. To facilitate removal of residual metal, the feeder sleeve cavity is tapered toward its base (ie, the end of the feeder sleeve closest to the mold cavity) in a design generally referred to as a neck down sleeve. Can be. When an impact is applied to the residual metal, the residual metal separates at the weakest point adjacent to the mold (a process commonly known as "knock off"). In addition, a small footprint on the casting is desirable to enable positioning of the feeder sleeves within the casting area where access may be restricted by adjacent elements.

Feeder sleeves may be applied directly onto the surface of the mold cavity but are mainly used with a breaker core. The breaker core is just a disc-shaped fireproof material (typically a resin bonded sand core or a core of a ceramic core or feeder sleeve) which has a hole in its center and sits between the mold cavity and the feeder sleeve. The diameter of the hole through the breaker core is designed (not necessarily tapered) to be smaller than the diameter of the inner cavity of the feeder sleeve so that knockoff occurs in the breaker core adjacent to the mold.

The breaker core may be made in metal. DE 196 42 838 A1 discloses an improved feeding system that replaces a conventional ceramic breaker core with a rigid flat annulus and DE 201 12 425 U1 utilizes a rigid "hat-shaped" annulus. An improved feeding system is disclosed.

Casting molds are generally formed using mold models that define mold cavities. On the model plate, pins are provided at preset positions as mounting points for the feeder sleeves. Once the required sleeves are mounted on the model plate, the mold is formed by pouring molding sand onto and around the feeder sleeves until the feeder sleeves are covered and the mold box is filled. The mold must have sufficient strength to withstand erosion during injection of the melt, to support the ferrostatic pressure acting on the mold when the melt is filled and to withstand expansion / contraction when the metal solidifies.

Foundry sands can be classified into two main categories: chemical conjugated and clay conjugated (based on whether they are organic or inorganic binders). Chemically bonded molding binders are typically self-hardening systems in which the binder and chemical hardener are mixed with the foundry sand and the binder and hardener react immediately while the foundry sand is shaped around the model plate for removal and casting. Reaction is slow enough to cure sufficiently.

Clay-bonded moldings use clay and water as binders and can be used "green" or undried and are generally referred to as greensand. The green sand mixture does not easily flow or move easily under compressive forces, thus squeezing, vibrating, squeezing and ramming, in order to squeeze green sand around the model to provide the mold with sufficient strength properties as described above. A variety of combinations of) are applied to produce molds of uniform strength with high productivity. Foundry sand is typically compressed (compacted) to high pressure, typically using hydraulic rams (this process is called "ramming up.") As mold complexity and productivity requirements increase, molds with higher dimensional stability This is required and tends to increase the ramming pressure, which can lead to breakage of the feeder sleeve and / or breaker core present, especially if the breaker core or feeder sleeve is in direct contact with the model plate before ramming up. .

The above problem is partially alleviated by the use of spring pins. The feeder sleeve and optional positioning cores (composition and overall dimensions similar to breaker cores) are initially spaced from the model plate but move towards the model plate when ramming up. The spring pin and feeder sleeve can be designed so that the final position of the sleeve after ramming can be located typically 5 to 25 mm away from the model surface without direct contact with the model plate. The knock-off point is often unpredictable because it depends on the dimensions and profile of the base of the spring pin, thus requiring additional cleaning costs. The solution provided in EP-A-1184104 is a two-part feeder sleeve. When pressed during mold formation, one mold (sleeve) portion is stretched and stretched into another mold portion. One of the mold parts always contacts the model plate and does not require a spring pin. However, there is a problem with the telescoping arrangement of EP-A-1184104. For example, due to the stretching action, the volume of the feeder sleeve after molding is variable and depends on a range of factors including molding mechanical pressure, casting geometry and sand properties. Such unpredictability can have a fatal effect on supply performance. In addition, this arrangement is not ideally suited for applications where exothermic sleeves are desired. When exothermic sleeves are used, direct contact of the casting surface with the heating material is undesirable and can result in poor surface finish, local contamination of the casting surface and even gas defects under the surface.

Another disadvantage of the stretch arrangement of EP-A-1184104 is due to the tabs or flanges required to maintain the initial spacing of the two mold (sleeve) sections. During molding, these small tabs are broken (this allows for stretching action to occur) and fall directly into the foundry sand. Over time, these pieces will accumulate in the foundry sand. This problem is particularly acute when these pieces are made of heating material. Moisture from the foundry sand can potentially react with heating elements (eg metal aluminum) to form small explosive defects.

DE 201 12 425 publication (U1) mitigates the effect of sleeve breakage by providing a pair of spaced ribs on the mounting surface that supports the weight of the sleeve, thereby allowing the spaced ribs to form a channel or groove in which the sleeve will seat with the mounting surface. An attempt was made. The inner lip prevents the broken piece of the sleeve from falling into the mold and the outer lip prevents the broken piece from falling into the molding sand.

WO 2005/051568 (which is hereby incorporated in its entirety) discloses a feeder element (collapsed breaker core) which is particularly useful for high pressure sand forming systems. The feeder element has a first end for mounting on the mold model, an opposite second end for receiving the feeder sleeve, and a bore between the first and second ends defined by the stepped sidewall. The stepped sidewall is designed to be irreversibly deformed when subjected to a predetermined load (corresponding to the compressive strength). The feeder element offers a number of advantages over conventional breaker cores:

(Iii) smaller feeder element contact areas (openings to the casting);

(Ii) small footprint on the casting surface (external profile contact)

(Iii) the possibility of breaking the feeder sleeve under high pressure during mold formation;

(Iii) Constant rust-off, significantly reducing cleaning requirements

The feeder element of WO 2005/051568 is illustrated by a high pressure sand forming system. The accompanying high ramming pressures require the use of high strength (and expensive) feeder sleeves. This high strength is achieved by a combination of the design of the feeder sleeve (ie, shape, thickness, etc.) and the material (ie, refractory, binder type and addition, manufacturing process, etc.). The examples illustrate the use of a feeder element with a FEEDEX HD-VS159 feeder sleeve that has pressure resistance (ie high strength) and is designed for spot feeding (high density, high heat resistance, thick wall, not high volume supply requirements). The feeder sleeve bears the weight of the feeder sleeve and is secured to the feeder element via a mounting surface perpendicular to the bore axis. In the case of medium pressure molding, there is a potential opportunity to use lower strength sleeves, ie different designs (ie, shape and wall thickness, etc.) and / or different compositions (ie, lower strength). Regardless of sleeve design and composition, there is still a need for rust-off from castings (variability and size of footprint on castings) and the need for good sand compaction under the feeder element. When the feeder element of WO 2005/051568 is applied to an intermediate pressure molding line, it is necessary to design the feeder element so that it collapses sufficiently to a low molding pressure (relative to the high molding pressure), ie to have a lower initial compressive strength. Will be needed. It may also be very advantageous to use lower strength feeder sleeves (typically low density sleeves), which feeder sleeves with a wider range of sleeve designs and compositions, and correspondingly less expensive feeder sleeves. Will be used successfully and optimally for However, the inventors have found that when this is attempted, the feeder sleeve is surprisingly damaged and broken during molding, creating a defective casting when used for casting.

The object of the invention in the first embodiment is to provide an improved feeder element that can be used in casting molding operations. In particular, the object of the invention in the first embodiment is to extend the use of the collapsible feeder element to a medium pressure molding system while allowing the use of relatively weak feeder sleeves without introducing casting defects.

According to a first embodiment of the invention there is provided a feeder element for use in metal casting, the feeder element comprising (i) a first end for mounting on a mold mockup, and (ii) for receiving a feeder sleeve A bore between the opposite second end and (i) the first and second ends defined by the stepped sidewall; The feeder element is compressible to reduce the distance between the first and second ends in use, wherein the stepped sidewall defines an mounting surface for the second end of the feeder element and the feeder sleeve in use, but at an angle of less than 90 ° toward the bore axis. And a second sidewall region in contact with the first sidewall region, the second sidewall region inclined at an angle different from the first sidewall region toward or parallel to the bore axis so as to define a staircase on the sidewall.

The feeder element may include additional sidewall areas such that a plurality of steps are defined on the sidewalls, where at least one of the additional sidewall areas is preferably inclined at an angle greater than the first sidewall area toward the bore axis.

In WO 2005/051568, although the direction of the sidewall area defining the mounting surface for the feeder sleeve and supporting the weight of the feeder sleeve is not particularly limited, it is preferably perpendicular to the bore axis as shown in all embodiments. Must see The only significance given to the direction of this mounting surface is the most convenient for mounting the feeder sleeve.

The first sidewall area is angled between 5 ° and 85 °, preferably between 15 ° and 80 °, more preferably between 25 ° and 75 °, and most preferably between 30 ° and 70 ° toward the bore axis. It is preferable to incline at an angle between degrees. For example, the first sidewall region can be inclined at an angle of 60 degrees towards the bore axis.

It will be appreciated that the amount of compression and the force required for compression will be affected by many factors, including the material of the feeder element and the shape and thickness of the sidewalls. It will likewise be understood that the individual feeder elements can be designed according to the desired use, the expected pressures involved and the feeder size requirements.

The initial compressive strength (ie, the force required to initiate compression to irreversibly deform the feeder element beyond the inherent flexibility it has in the unused and non-compressed state) is 5000 N or less, more preferably 3000 N or less. desirable. If the initial compressive strength is too high, the feeder sleeve may be damaged before compression starts due to molding pressure. The initial compressive strength is preferably at least 250N. If the compressive strength is too low, compression of the feeder element may suddenly begin, for example, when a plurality of elements are stacked for storage or during transportation.

The feeder element of the present invention may be considered a collapsible breaker core, as this term properly describes some function of the element in use. Traditionally, the breaker core comprises resin bonded sand or is a ceramic material or a core of feeder sleeve material. However, the feeder element of the present invention may be made from a variety of other suitable materials, including metals. In certain configurations, it will be more appropriate to regard the feeder element as a feeder neck.

In this application, the term "compressible" is used in a broad sense and is only intended to indicate that the length between the first and second ends of the feeder element is shorter after compression than before compression. Preferably, the compression is irreversible, ie the feeder element does not return to its original shape after removing the compression induction force.

In a particularly preferred embodiment, the stepped sidewalls of the feeder element are formed integrally interconnected with the sidewall regions of the second row (the second row having at least one member) (where the first row has more than one member) ) Sidewall regions of the first row (the first row having at least one member) of a ring shape (not necessarily need to be flat) of increasing diameter. The side wall regions have a substantially uniform thickness, so that the diameter of the bore of the feeder element is increased from the first end to the second end of the feeder element. Conveniently, the sidewall regions of the second row are cylindrical (ie, parallel to the bore axis), but may be truncated cones (ie, inclined to the bore axis). Both rows of sidewall regions may be non-circular (eg, oval, square, rectangular or star shaped). The second side wall area constitutes a side row area of the second row that is closest to the second end of the feeder element.

The compression behavior of the feeder element can be changed by adjusting the dimensions of each sidewall region. In one embodiment, all of the sidewall areas of the first row have the same length and all of the sidewall areas of the second row have the same length (which may be the same or different than the sidewall areas of the first row and may be the same or different from the first sidewall area). Has However, in a preferred embodiment, the length of the sidewall regions in the first row and / or the sidewall regions in the second row gradually increases toward the end of the feeder element.

The feeder element may be defined by the first sidewall area and the sidewall areas of one first and second row, respectively. However, the feeder element may have as many as six or more first and second rows of sidewall regions, respectively. In a particularly preferred embodiment, four first rows and five second rows of sidewall regions are provided.

The thickness of the sidewall regions is about 4 to 24%, preferably about 6 to 20%, more preferably about about the distance between the inner and outer diameters of the first sidewall regions (ie, the annular thickness in the case of flat rings (annulars)). It is preferable that it is 8 to 16%.

The distance between the inner diameter and the outer diameter of the side wall regions of the first row is preferably 4 to 10 mm, more preferably 5 to 7.5 mm. The thickness of the side wall area is preferably 0.2 to 1.5 mm, most preferably 0.3 to 1.2 mm. The ideal thickness of the sidewall area can vary depending on the element and can be influenced by the size, shape and material of the feeder element and the process used for manufacturing.

In a convenient embodiment, only edge contacts are formed between the feeder element and the casting, the first end (base) of the feeder element being defined by the sidewall areas of the first or second row that are not perpendicular to the bore axis. As can be seen from the discussion above, this arrangement is advantageous for minimizing the footprint and contact area of the feeder element. In such an embodiment, the sidewall area defining the first end of the feeder element may have a different length and / or direction than the other sidewall areas in the row. For example, the sidewall area defining the base may be inclined toward the bore axis at an angle of 5 to 30 degrees, preferably 5 to 15 degrees. The free edge of the sidewall area defining the first end of the feeder element preferably has an inwardly annular flange or bead.

As can be seen from the discussion above, the feeder element is for use with a feeder sleeve. The present invention thus provides, as a second embodiment, a feeder system for metal casting comprising a feeder element according to the first embodiment and a feeder sleeve fixed thereto.

The standard feeder sleeve has an annular base for mounting on the breaker core (collapsed or otherwise). In the feeder system of the second embodiment, the base of the feeder sleeve is profiled at the same angle as the first sidewall area of the feeder element.

The properties of the feeder sleeve are not particularly limited and can be, for example, insulating or pyrogenic or a combination of both. The production method is not particularly limited, but may be manufactured using, for example, a slurry or a core shot method. Typically, the feeder sleeve is made of a mixture of refractory fillers (eg fibers, hollow microspheres and / or particulates) and binder. The pyrogenic sleeve requires additional fuel (generally aluminum or aluminum alloy) and generally initiators / sensitisers. Suitable feeder sleeves are, for example, those sold under the trade names KALMIN, KALMINEX or FEEDEX from Foseco. Feeder sleeves are available in many shapes including closed or open cylinders, ovals, neckdowns, domes. The feeder element is used with all conventional insert sleeve designs or all other insert sleeve designs consisting of closed (cap) sleeves which may be flat, domed or flat domed. It is preferable. The feeder sleeve may conveniently be secured to the feeder element by an adhesive but may be press fit or mount the sleeve around a portion of the feeder element. The feeder sleeve is preferably attached to the feeder element.

The present invention augments the use of low strength sleeves that are used as low as 3.5 kN. Preferably, the sleeve strength is at least 5 kN. Preferably, the sleeve strength is less than 20 kN. For comparison convenience, the strength of the feeder sleeve is defined as the compressive strength of a 50 x 50 mm cylindrical specimen made of feeder sleeve material. A 201/70 EM compression tester (Form & Test Seidner, Germany) was used and operated according to the manufacturer's instructions. The specimen was placed in the center of the lower steel plate and the load was applied until it broke while moving the lower plate toward the upper plate at a rate of 20 mm / min. The effective strength of the feeder sleeve depends not only on the exact composition, the binder used and the manufacturing method, but also on the size and design of the sleeve, in which the strength of the specimen is more general than that measured for standard flat 6 / 9K sleeves. This is explained by the fact that it is high. The potential usefulness of the larger range of sleeve compositions and designs that can be used with the present invention allows the most suitable sleeve (technically and economically) to be specified for each individual casting, which is not possible in the prior art.

1 is a cross-sectional view of a specimen having features of the feeder element according to the present invention.

2A and 2B are cross sectional and top views, respectively, of known feeder elements.

3A is a known VSK feeder sleeve design.

3B is a known 6 / 9K feeder sleeve design.

3C is a flat domed feeder sleeve design.

4 is a cross-sectional view of another known feeder element.

5A-5C are computer simulations of the known feeder element of FIG. 4 in use.

6 is a cross-sectional view of the feeder element according to the invention.

7A and 7B are computer simulations of the feeder element of FIG. 6 in use.

8 is a cross-sectional view of another feeder element according to the present invention.

9 is a flat domed feeder sleeve with an improved base with a feeder element according to the invention.

10A is a graph showing the relationship of force applied to displacement in a KALMINEX 2000ZP 6 / 9K feeder sleeve under compression.

10B-10I are graphs illustrating the relationship of force applied to displacement in the specimen of FIG. 1 used with a KALMINEX 2000ZP 6 / 9K feeder sleeve when changing the angle α.

Drawing translation

In FIGS. 10A-10I

Force-N: Force-N

Displacement-mm: Displacement-mm

Feeder sleeve only-no feeder element: Feeder sleeve only-no feeder element

Deg: Degree

Hereinafter, various exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Methodology

In the following examples, standard feeder systems were tested that included a standard feeder element with a standard feeder sleeve as well as a feeder system according to the present invention. Both the standard type and the feeder element of the present invention are manufactured by pressing a steel sheet. Profiling of the base of the feeder sleeve of the present invention has been accomplished by making a sleeve (flat domed sleeve) with an existing profile or by using abrasive paper on a standard sleeve (6 / 9K type sleeve). When commercially manufacturing profiled 6 / 9K type feeder sleeves, it may be more practical to manufacture feeder sleeves with existing profiles.

Molding Test

Tests were performed in a commercial Herman molding machine using a clay-bonded green-liner system. The wooden model plate was bolted to the steel plate. The four feeder elements and corresponding feeder sleeves were then mounted to the model plate using a positioning pin spaced 150 mm and 114 mm from the centerline of the model plate. The mold was placed on the model plate to provide a mold having dimensions of approximately 576 mm x 432 mm x 192 mm (length x width x height). Sand was added to the mold so that its level was approximately 50 mm above the mold height. The sand weighed approximately 112 kg. 3 to 6 by placing a 576 mm x 432 mm ramplate 144 mm above the mold frame height (approximately 94 mm above the surface of the uncompressed sand) and compressing the mold to the desired pressure by moving the ramplate down. The sand was squeezed to the level of the mold for seconds. Thereafter, the mold was discharged to observe the conditions of the feeder element and the feeder sleeve.

Compression Test

Feeder element specimens and feeder sleeves were tested by seating between two parallel plates of a Hounsfield compressive strength tester.

The graph of the force applied against the displacement of the plate was shown by fixing the bottom plate and moving the top plate down by a mechanical thread mechanism at a constant speed of 30 mm per minute.

The feeder element specimens tested for compression had the basic configuration shown in FIG. 1. In brief, the feeder element specimen 10 consists of a circular base 12 (diameter D) in which the cylindrical sidewall region 14 (height h) extends upward. An outwardly tapered sidewall region 16 (maximum diameter d) inclined by an angle α with respect to the cylindrical sidewall region 14 abuts the cylindrical sidewall region 14. The tapered sidewall area 16 acts as a mounting surface for the feeder sleeve in use. These specimens used in the compression test will not be used for casting, so there are no openings in the base.

Various feeder elements with α of 90 ° (standard), 80 °, 70 °, 60 °, 50 °, 40 °, 30 ° or 20 ° were prepared. Specimens were made from mild steel with a thickness of 0.5 mm. For a standard feeder element specimen (α = 90 °), D was 53.5 mm, h was 7.5 mm and d was 80.0 mm. The specimens have a constant height (h) of the cylindrical sidewall region (14), maximum diameter (d) of the outwardly tapered sidewall region (16), and an area of the mounting surface provided by the first sidewall region (16) even if α is changed. It is designed to remain (ie, increase in diameter D of circular base 12 as α decreases). Feeder elements were tested using a KALMINEX 2000ZP 6 / 9K exothermic feeder sleeve provided by Foseco with a density of 0.55 to 0.65 g / cm 2 and a compressive strength of about 4 kN.

Comparative Example 1-Molding Test

The feeder element (metal collapsed breaker core sold under the name MH / 33 as described in WO2005 / 051568 and shown in FIGS. 2A and 2B) was tested in combination with the following feeder sleeves listed in Table 1.

Table 1

FEEDEX HD KALMINEX 95 KALMINEX 2000XP KALMINEX 2000XP shape VSK (back wall small sleeve as shown in FIG. 3A) 6 / 9K (parallel conical cap insert sleeve with Williams wedge as shown in FIG. 3B) 6 / 9K (parallel conical cap insert sleeve with Williams wedge as shown in FIG. 3B) Flat dome type (flat closed domed sleeve with variable wall portion as shown in FIG. 3C) Manufacture process Core shot Slurry formation Core shot Core shot Density (g / cm3) 1.35 to 1.45 0.85-0.95 0.55-0.65 0.55-0.65 Strength (kN) ^a High (> 25) (10-11) Medium (11-12) Medium (11-12) Strength (kN) ^b n / a (8-9) Medium (9-10) n / a

a) strength of standard cylindrical specimens b) strength of actual 6 / 9k sleeve

Sleeve compositions vary depending on the desired product properties, but all have a typical composition of 20% to 25% aluminum fuel, 10% to 20% oxidizer and photosensitizer, 5% to 10% organic binder, and 35% to 55% Has a refractory filler. The type of refractory filler used has the most direct effect on both the density and strength of the sleeve.

2A and 2B, the feeder element 20 has a first end (base) 22 for mounting on the mold model and an opposing second end (top) 24 for receiving the feeder sleeve. And a bore 26 defined between the first and second ends 22, 24 by the stepped sidewall 28. The second end 24 of the feeder element 20 is defined by a first sidewall region 25, which is perpendicular to the bore axis A. The second sidewall region 30 abuts the first sidewall region 25 and is parallel to the bore axis A. Stepped sidewall 28 further includes alternating first and second row sidewall regions 28a and 28b having approximately the same height. The second sidewall region 30 constitutes a first sidewall region of the second row 28b closest to the second end 24 of the feeder element 20. The sidewall area 28a of the first row is composed of three sidewall areas perpendicular to the bore axis A. The side wall area 28b of the second row is composed of four side wall areas. The three first sidewall regions of the second row 28b are parallel to the bore axis A. FIG. The fourth sidewall region 32 has an annular flange inclined at an angle of 15 degrees towards the bore axis A and inwardly to minimize its footprint to improve knock-off. In addition, the fourth sidewall region 32 is approximately twice the length of the other sidewalls of the second row 28b.

The feeder elements and feeder sleeves are molded as described above using a molding pressure of 380 PSI (2620 kN). The feeder elements collapsed as desired and there was no visible damage to the FEEDEX HD VSK feeder sleeves, but there were cracks and some breakages as well as some depressions (compression of the sleeves) in the base of the KALMINEX 95 6 / 9K sleeves and the KALMINEX 2000XP domed sleeves. . The KALMINEX 2000XP 6 / 9K sleeve was severely damaged and the sleeve base was broken into pieces. The KALMINEX 2000ZP feeder sleeve was not tested with the feeder element 20 because it is weaker than the damaged KALMINEX XP and KALMINEX 95 feeder sleeves at 380 PSI (2620 kN).

The series of tests was then repeated at higher molding pressures of 620 PSI (4275 kN). Again, all the feeder elements collapsed, but this time all the sleeves were visually damaged. There were several small internal cracks at the base of the FEEDEX HD VSK sleeve and in one case flawed adjacent to the feeder element. In the case of the KALMINEX 95 6 / 9K sleeves, there were more extensive cracks at the base of the sleeves and the sleeves were somewhat curved and recessed (the sleeve height was reduced by up to 10 mm after molding). The KALMINEX 2000XP flat domed sleeve showed severe damage and the sleeve base was broken into pieces. KALMINEX 2000XP 6 / 9K sleeves were not tested.

In all cases, the first sidewall region of the collapsed feeder element after molding was bent downward at an angle greater than 90 ° past the horizontal, ie with respect to the bore axis.

Comparative Example 2-Computer Simulation

Computer simulations (ABAQUS, manufactured by Abaquos) were used to evaluate the added stress for the feeder system comprising a standard feeder sleeve with dimensions similar to the FEEDEX HD VSK sleeve and the feeder element 40 of FIG. Performed. Advanced finite element analysis software includes static and dynamic stress-strain resolvers used in the simulation. The simulation was performed by fixing the feeder element to the z-axis and then placing the model under strain so that the feeder element was compressed to the z-axis by a distance within a predetermined time. This places various parts of the model under various stresses. The model was programmed using the mechanical properties of the sleeve and the feeder element to simulate the stress in the feeder sleeve and to compress the metal feeder element.

Referring to FIG. 4, the feeder element 40 includes a first end (base) 42 for mounting on the mold model, an opposing second end (top) 43 for receiving the feeder sleeve, and a stepped arrangement. A bore 44 is defined between the first and second ends 42, 43 by the side wall 45. The second end 43 is defined by the first sidewall region 46, which is perpendicular to the bore axis A. As shown in FIG. The second sidewall region 47 abuts the first sidewall region 46 and is parallel to the bore axis A. Stepped sidewall 45 further includes alternating first and second rows of sidewall regions 45a and 45b having approximately the same height. The second sidewall area 47 constitutes a first sidewall area of the second row 45b. The side wall area 45a of the first row is composed of two side wall areas perpendicular to the bore axis A. The sidewall region 45b of the second row consists of three sidewall regions parallel to the bore axis A.

FIG. 5A shows a portion of the feeder sleeve 50 mounted on the feeder element 40 of FIG. 4 before shaping. 5B is an enlarged view of the base of the feeder sleeve 50 mounted on the feeder element 40. 5C is an enlarged view of the same feeder sleeve 50 and feeder element 40 during molding. The feeder sleeve cavity is indicated by arrow A. The shade as shown in the key indicates the magnitude of the force applied to the feeder sleeve 50. Referring to FIG. 5C, it can be seen that the feeder element 40 is deformed by pressing as desired. Surprisingly, the mounting surface 46 is incrementally compressed downward in its peripheral edge. This results in a nonuniform distribution of the force concentrated on the inner wall (point load) of the feeder sleeve 50 as indicated by arrow B.

Example 1-Computer Simulation

The computer simulation of Comparative Example 2 suggests that the cracks observed in Comparative Example 1 may be caused by point loads on the inner wall of the feeder sleeve. The inventors have attempted to mitigate this by changing the shape of the feeder element. The simulation was again performed using the feeder element 52 of FIG. 6 instead of the feeder element 40 of FIG. 4. The feeder element 52 of the present invention is identical to the feeder element shown in FIG. 4 in all respects except that the mounting surface 54 of the feeder element is inclined at an angle of 60 ° toward the bore axis A. FIG. . The base of the feeder sleeve 56 (FIG. 7A) was profiled at the same angle.

7A and 7B show the base of the feeder element 52 and the corresponding feeder sleeve 56 before and during molding, respectively. 7B shows that during molding the force is no longer concentrated on the inner wall of the feeder sleeve 56. The force is more evenly distributed along the base of the feeder sleeve 56 so that no part of the base undergoes excessive force. The area of maximum force (arrow B) is the area of the sleeve away from the feeder sleeve cavity (arrow A). Fracture in this area will not cause debris in the feeder sleeve material to enter the casting and cause defects.

Example 1 Molding Test

The feeder element 60 as shown in FIG. 8 was tested in combination with the flat domed feeder sleeves (as shown in FIG. 9) described in Table 2 below.

Table 2

KALMINEX 2000ZP KALMINEX 95 KALMINEX 2000XP Manufacture process Slurry formation Slurry formation Core shot Density (g / cm3) 0.55-0.65 0.85-0.95 0.55-0.65 Strength (kN) ^a Low (4 ~ 5) (10-11) Medium (1-12)

a) strength of standard cylindrical specimens

Sleeve compositions vary depending on the desired product properties, but all have a typical composition of 20% to 25% aluminum fuel, 10% to 20% oxidizer and photosensitizer, 5% to 10% organic binder, and 35% to 55% Has a refractory filler. The type of refractory filler used has the most direct effect on both the density and strength of the sleeve.

Referring to FIG. 8, the feeder element 60 is identical to the feeder element 20 shown in FIGS. 2A and 2B except that the first sidewall area 62 is inclined at 60 ° toward the bore axis. The feeder element is made of soft iron and has a thickness of 0.5 mm. The maximum diameter is 92.9 mm and the height h is 35.4 mm. The diameter of the bore 26 is 22.9 mm at the base of the feeder element.

The feeder element 60 and feeder sleeve combination was molded as described above at various pressures between 420 PSI (2896 kPa) and 700 PSI (4826 kPa). Table 3 below summarizes the results.

TABLE 3

pressure KALMINEX 2000ZP KALMINEX 2000XP KALMINEX 95 420 PSI (2896 kPa) Sleeve Buckled No damage No damage 460 PSI (3172 kPa) Sleeve Buckled No damage No damage 520 PSI (3585 kPa) Sleeve Buckled No damage No damage 580 PSI (3999 kPa) Sleeve Buckled No damage No damage 600 PSI (4137 kPa) Sleeve Buckled No damage No damage 700 PSI (4826 kPa) Sleeve Buckled Crack in the dome No damage 700 PSI (4826 kPa)
Repeat test Collapsed Crack in the dome Buckled from one side of the sleeve

Feeder Element (60) and KALMINEX 2000ZP Feeder Sleeve

This combination was the most vulnerable tested and showed signs of damage at low molding pressure (420 PSI; 2896 kPa). The feeder element was not sufficiently compressed and the feeder sleeve was bent. Despite this, there was no sign of cracking or breaking at the base of the feeder sleeve adjacent to the feeder element.

Feeder Element (60) and KALMINEX 2000XP Feeder Sleeve

This combination was successful up to moderately high pressures (700 PSI; 4826 kPa). The feeder sleeve resulted in horizontal cracks along the dome of the sleeve. This was due to the influence of sleeve composition (binder) and sleeve shape and manufacturing method (core-shot). The damage was not immediately apparent, only when the sleeve was ejected from the sand mold after ram-up. As expected, the compression level of the feeder element increased with increasing molding pressure until the feeder element was almost completely compressed. No sleeve debris was found inside the feeder sleeve, so damage to this form would not necessarily result in debris falling and castings into the casting.

The flat upper hemispherical KALMINEX 2000XP feeder sleeve was used with the conventional feeder element 20 of Comparative Example 1 damaged at much lower pressure. The feeder sleeve was only recessed at 380 PSI (2620 kPa) and cracked along its base and severe damage occurred at 620 PSI (4275 kPa).

Feeder Element (60) and KALMINEX 95 Feeder Sleeve

This combination was also very successful. The feeder element 60 was compressed and the first damage of the feeder sleeve occurred only at a moderately high pressure (700 PSI; 4826 kPa). No feeder sleeve fragments were found inside the feeder sleeve after the feeder sleeve was bent, so that even if the mold was injected, the damage would not necessarily result in a casting bond.

The KALMINEX 95 6 / 9K feeder sleeve was used with the conventional feeder element 20 of Comparative Example 1 but the results were very different. The feeder sleeve cracked along its base at only 380 PSI (2620 kPa). The feeder sleeve had more extensive cracks along its base at 620 PSI (4275 kPa) and was heavily recessed. Cracks along the base are particularly problematic because pieces of the feeder sleeve can enter the casting.

The feeder element 60 of the present invention provides an effect superior to conventional feeder elements such as the feeder element 20 shown in Comparative Example 1. When used with the feeder element 52, the medium strength feeder sleeves KALMINEX 2000XP and KALMINEX 95 are successful up to much higher pressures. In addition, even if the feeder sleeves are eventually damaged, the damage mode is not easy to lead to casting defects.

Example 2 Compression Test

Referring to FIG. 10A, the force versus plate displacement is plotted for a KALMINEX 2000ZP 6 / 9K feeder sleeve (as shown in FIG. 3B) without a feeder element specimen. As the force increases in the present application, the feeder sleeve is compressed in conjunction with the inherent flexibility (compressibility) of the feeder sleeve, until a critical force, referred to as sleeve compressive strength (approximately 4.5 kN), is applied (point Z). Compression of the sleeve then proceeds steadily under lower load.

Referring to FIG. 10C, the force versus plate displacement is plotted in a feeder element specimen 10 having α at 80 ° and a KALMINEX 2000ZP 6 / 9K feeder sleeve whose base is profiled at an angle of 80 °. As the force increases until a critical force, referred to herein as initial feeder element compressive strength, is applied (point A), the feeder element and sleeve are compressed to a minimum and compression after the critical point proceeds rapidly under lower load, where Point B marks the minimum force measurement after the initial feeder element specimen compressive strength has occurred. Additional compression takes place and the force increases to the maximum value (maximum feeder element crimp strength, point C). When the feeder element specimen reaches or adjoins its maximum displacement (point D), the force increases rapidly until the sleeve body begins to break. According to the visual observation of the sleeve, at point A there is some breakage in the bottom corners (inner base and wall) of the feeder sleeve.

FIG. 10B is a plot of force versus plate displacement for a feeder element specimen 10 with α at 90 ° and a KALMINEX 2000ZP 6 / 9K feeder sleeve with a flat base. This is similar to the curve in FIG. 10C (α = 80 °) but shows a more gentle curve and the initial displacement occurs at a lower applied force and continues for a long time. This is due to the lower initial feeder element specimen compressive strength, but also to the larger feeder sleeve due to the force applied from the feeder element specimen to destroy (damage) the feeder sleeve so that the feeder element is pushed up into the feeder sleeve to produce a measured displacement. It is due to damage at the base.

10D and 10E show the plate on the feeder element specimen 10 having α of 70 ° and 60 °, respectively, when its base is tested with a KALMINEX 2000ZP 6 / 9K feeder sleeve profiled at an angle of 70 ° and 60 °, respectively. This is a plot of force versus displacement. Comparing these plots with FIG. 10C (α = 80 °), it can be seen that the initial feeder element specimen compressive strength (A) increases as α decreases. In addition, the amount of visible damage occurring at the base of the sleeve was greatly reduced and the minimum when α was 70 ° showed no breakage of the sleeve.

10F and 10G show the displacement of plate for feeder element specimens with α of 50 and 40 degrees, respectively, when the base is tested with a KALMINEX 2000ZP 6 / 9K feeder sleeve profiled at an angle of 50 and 40 degrees, respectively. It is a chart of power. For all of these, the initial feeder element specimen compressive strength (point A) is similar to the pre-measured feeder sleeve compressive strength (Z, approximately 4.5 kN). However, in both cases, due to the collapse of the feeder element, there is a greater displacement at point A compared to the normal sleeve compression point (Z point). No damage to the base of the feeder sleeve due to the feeder element specimens was observed.

10H and 10I show the plate on the feeder element specimen 10 having α of 30 ° and 20 °, respectively, when its base is tested with a KALMINEX 2000ZP 6 / 9K feeder sleeve profiled at an angle of 30 ° and 20 °, respectively. This is a plot of force versus displacement. Comparing these plots with FIG. 10G (α = 40 °), it can be seen that the initial feeder element compressive strength A now decreases as α decreases and the amount of displacement before the initial feeder element compressive strength increases. This is partly due to the distance traveled during the compaction of the feeder element specimens, and in part due to the small amount of compression of the feeder sleeve running from the base of the feeder sleeve into the feeder element specimen itself.

The ideal initial compressive strength of the feeder element will depend on the molding pressure used and the feeder sleeve (compressive strength). The initial feeder element compression strength should be clearly lower than the sleeve compression (compression) strength and ideally the initial compression strength should be lower than 3000 N. If the initial compressive strength is too high, the shaping pressure may cause damage to the feeder sleeve before the feeder element has a chance to compress. The ideal maximum compressive strength is much more dependent on the intended use of the feeder element core, namely the molding pressure and sleeve composition (strength) used. If the maximum compressive strength is too high for the molding pressure used, the feeder element will collapse insufficiently and subsequently the sand compaction will also be insufficient. In addition, too high maximum compressive strength limits the type (strength) of the sleeve that can be used successfully.

Claims (23)

A feeder element for use in metal casting, the feeder element being: (Iii) a first end for mounting on the mold mockup, (Ii) an opposite second end for receiving a feeder sleeve; (Iii) a bore between the first and second ends defined by the stepped sidewalls, The feeder element is compressible to reduce the distance between the first and second ends in use, The stepped sidewall defines a second end of the feeder element and a mounting surface for the feeder sleeve in use, the first sidewall area being inclined at an angle α less than 90 ° toward the bore axis, and in contact with the first sidewall area, And a second sidewall area parallel to the bore axis or inclined at an angle different from the first sidewall area toward the bore axis to define a step. The method according to claim 1, A feeder element comprising an additional sidewall area such that a plurality of steps are defined on the sidewall. The method of claim 2, At least one of the additional sidewall regions is inclined at an angle greater than the first sidewall region towards the bore axis. The method according to claim 1, The first sidewall region is inclined at an angle α between 5 ° and 85 ° toward the bore axis. The method according to claim 1, The first sidewall region is inclined at an angle α between 30 and 70 degrees towards the bore axis. The method according to claim 1, A feeder element, characterized in that the initial compressive strength is 5000 N or less. The method according to claim 1, A feeder element, characterized in that the initial compressive strength is at least 250 N. The method according to claim 1, And wherein the compression is irreversible when in use. The method according to claim 1, The stepped sidewall of the feeder element comprises ring-shaped first row sidewall areas interconnected integrally with the sidewall areas of the second row. The method of claim 9, A feeder element, characterized by a first sidewall region and a sidewall region of one first and second rows, respectively. The method of claim 9, A feeder element, characterized in that the thickness of the stepped sidewalls is between 0.2 and 1.5 mm. The method of claim 9, And the rings are circular. The method of claim 9, And the rings are flat. The method of claim 9, The stepped sidewalls have a substantially uniform thickness such that the diameter of the bore of the feeder element increases from the first end to the second end of the feeder element. The method of claim 9, The sidewall areas of the second row are annular. The method of claim 9, A feeder element, characterized in that the first end of the feeder element is defined by the side wall area having a length greater than the other side wall areas of the corresponding row. The method of claim 9, The sidewall region defining the first end of the feeder element is inclined at an angle of 5 to 30 degrees towards the bore axis. The method of claim 9, The thickness of the stepped sidewalls is 4 to 24% of the distance between the inner and outer diameters of the first sidewall region (s). 19. The method of claim 18, The free edge of the sidewall area defining the first end of the feeder element has an inwardly facing annular flange or bead. 20. A feeder system for metal casting, comprising a feeder element according to any one of claims 1 to 19 and a feeder sleeve fixed thereto. The method of claim 20, The feeder system is fixed to the feeder element by an adhesive or by press fit with the feeder element or by mounting the feeder sleeve around a portion of the feeder element. The method of claim 20, The base of the feeder sleeve is profiled at the same angle as the first sidewall area of the feeder element. The method of claim 20, A feeder system for metal casting, characterized in that the sleeve strength is at least 5 kN and less than 20 kN.

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