Abstract:
A mold assembly device for use in sand casting of engine cylinder blocks is disclosed, the mold assembly device includes a magnet for securing a cast-in-place cylinder bore liner during assembly of a mold package, wherein the magnet militates against undesirable movement of the bore liner during assembly of the mold package.

Description:
FIELD OF THE INVENTION 
     The invention relates to a mold assembly device and more particularly to a mold assembly device for use in sand casting of engine cylinder blocks, the device including a magnet for securing a cast-in-place cylinder bore liner during assembly of a mold package. 
     BACKGROUND OF THE INVENTION 
     In a sand casting process for an aluminum internal combustion engine block, an expendable mold package is assembled from a plurality of resin-bonded sand cores that define the internal and external surfaces of the engine block. Typically, each of the sand cores is formed by blowing resin-coated foundry sand into a core box and curing it therein. Cast-in-place bore liners are often used in such castings. 
     Typically, in the manufacture of an aluminum engine block with cast-in-place bore liners, the mold assembly method involves positioning a base core on a suitable surface and building up or stacking separate mold elements to shape such casting features as the sides, ends, water jacket, cam openings, and crankcase. The bore liners are positioned on barrel core features such that the liners become embedded in the casting after the metal is poured into the mold. Additional cores may be present as well depending on the engine design. Various designs for the barrel cores are used in the industry. These include individual barrel cores, “V” pairs of barrel cores, barrel-slab cores, and integral barrel crankcase cores. The barrel-slab and integral barrel crankcase designs are often preferred because they provide more accurate positioning of the liners within the mold assembly. 
     The engine block casting must be machined in a manner to ensure, among other things, that the cylinder bores (formed from the bore liners positioned on the barrel features of the barrel cores) have uniform bore liner wall thickness, and that other critical block features are accurately machined. This requires the liners to be accurately positioned relative to one another within the casting. The ease and consistency with which the bore liners are brought into the desired final position during the mold assembly process is an important consideration. 
     In barrel slab cores, the bore liners are positioned on the barrel core features by slidingly placing the bore liners on the barrel core features. Alternatively, the liners may be placed into the core tooling and the core sand blown into the liners to form the barrel core feature. Prior to casting, the barrel-slab cores are inverted for assembly into the mold package. Undesirable movement of the bore liners relative to the slab core may occur while the assembly is inverted. 
     One attempt to resolve the issues described above is disclosed in U.S. Pat. No. 5,365,997. In the &#39;997 patent, an internal diameter chamfer is incorporated into the cylinder bore liner design to militate against undesirable displacement of the cylinder bore liner. Another attempt to resolve the issues described above is disclosed in U.S. Pat. No. 5,730,200. In the &#39;200 patent, an expanding mandrel is used inside of a hollow barrel core to secure the cylinder bore liner to the barrel core during assembly of the mold package. 
     It would be desirable to produce a mold assembly device which secures a cast-in-place cylinder bore liner for use in sand casting of engine cylinder blocks during assembly of a mold package, wherein the mold assembly device militates against undesirable movement of the bore liner during assembly of the mold package. 
     SUMMARY OF THE INVENTION 
     Consistent and consonant with the present invention, a mold assembly device which secures a cast-in-place cylinder bore liner for use in sand casting of engine cylinder blocks during assembly of a mold package, wherein the mold assembly device militates against undesirable movement of the bore liner during assembly of the mold package, has surprisingly been discovered. 
     In one embodiment, the mold assembly device comprises a handling fixture adapted to be releasably connected to a barrel slab core; and means for producing a magnetic field to attract a cylinder bore liner disposed on a barrel core feature of the barrel slab core toward an inner surface of the barrel slab core. 
     In another embodiment, the mold assembly device comprises a handling, fixture releasably connected to a barrel slab core, the barrel slab core having an inner surface, an outer surface, and a plurality of barrel core features extending outwardly from the inner surface, each of the barrel core features having a cylinder bore liner disposed thereon; and at least one magnet disposed between the handling fixture and the barrel slab core, the at least one magnet attracting the cylinder bore liner of each barrel core feature toward the inner surface of the barrel slab core. 
     The invention also provides methods of assembling a mold package. 
     In one embodiment, the method of assembling a mold package comprises the steps of providing a barrel slab core having an inner surface, an outer surface, and a plurality of barrel core features extending outwardly from the inner surface; positioning a cylinder bore liner on each of the barrel core features of the barrel slab core; providing a handling fixture adapted to be releasably connected to the barrel slab core; providing at least one magnet; and positioning the at least one magnet between the barrel slab core and the handling fixture, wherein a magnetic field produced by the magnet attracts the cylinder bore liner of each barrel core feature toward the inner surface of the barrel slab core to militate against movement of the cylinder bore liner during assembly of the barrel slab core in a mold package. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
         FIG. 1  is a perspective view of a barrel slab core including three barrel core features; 
         FIG. 2  is a perspective view of the barrel slab core of  FIG. 1  including a cylinder bore liner disposed on each of the barrel core features; 
         FIG. 3  is a sectional view of a single barrel core feature and a bore liner during installation of the barrel slab core in an engine block mold package according to an embodiment of the invention; 
         FIG. 4  is a partial sectional view of a cylinder block mold package for forming an engine block casting after installation of the barrel slab core; and 
         FIG. 5  is an enlarged partial sectional view of the cylinder bore liner and the barrel core feature of the cylinder block mold package illustrated in  FIG. 4 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and appended drawings describe and illustrate an exemplary embodiment of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. For purposes of illustration, and not limitation, a mold package for a six-cylinder V-type engine is shown. It is understood that the invention can be used with mold packages for engines having more or fewer cylinders and different cylinder configurations if desired. 
       FIG. 1  depicts a barrel slab core  10  adapted to be assembled with additional mold cores such as a base core and a crankcase core, for example, to form a cylinder block mold package  12  as shown in  FIG. 4 . A typical cylinder block mold package is shown and described in commonly owned U.S. Pat. No. 6,615,901 B2, hereby incorporated herein by reference. It should be noted that the mold package shown and described in the &#39;901 patent includes an integral barrel crankcase core (IBCC), whereas the embodiment of the invention shown and described herein includes a barrel slab core having barrel core features disposed thereon. 
     In the embodiment shown, the barrel slab core  10  is produced from resin bonded sand. The resin bonded sand cores can be made using conventional core-making processes such as a phenolic urethane cold box or Furan hot box where a mixture of foundry sand and resin binder is blown into a core box and the binder cured with either a catalyst gas or heat, respectively. The foundry sand can comprise silica, zircon, fused silica, and others. An inner surface  14  of the barrel slab core  10  defines a portion of an outer surface of an engine block (not shown) after casting. 
     Barrel core features  16  having an outer surface  18  extend outwardly from the inner surface  14  of the barrel slab core  10  and terminate at a free end. The barrel core features  16  are slightly tapered cylinders. The barrel core features  16  are disposed in a row with a common plane passing through a longitudinal axis L of each of the barrel cores  16  to form a linear array of barrel core features  16 . A core print  20  is formed in the free end of each of the barrel core features  16 . In the embodiment shown, the core prints  20  have a substantially circular cross section. However, it is understood that other cross sectional shapes could be used. The core prints  20  are adapted to mate with corresponding core prints  21 , illustrated in  FIG. 4 , formed upon a crankcase core  40  to promote proper assembly of the cylinder block mold package  12 . Other shapes and configurations of core prints can be used as desired. Additionally, although female core prints are shown, it is understood that male core prints can be used. 
       FIG. 2  shows the barrel slab core  10  illustrated in  FIG. 1  including a metal cylinder bore liner  22  disposed on each of the barrel core features  16 . The cylinder bore liners  22  have a hollow interior with a substantially uniform diameter adapted to receive the barrel core features  16  therein. The bore liners  22  form a cylinder wall for each cylinder of the cast engine block. The cylinder bore liners  22  can be produced by machining or casting a ferrous material. Typically, the cylinder bore liners  22  are used in an aluminum engine block and the cylinder bore liners  22  are formed of cast iron. However, it is understood that other magnetic materials can be used for the bore liners  22  and other materials can be used for the engine block as desired. 
     In  FIG. 3 , a single barrel core feature  16  and a cylinder bore liner  22  of the barrel slab core  10  are shown inverted from the position shown in  FIGS. 1 and 2 , and prior to assembly in the cylinder block mold package  12 . Note that it is not necessary to fully invert the barrel slab core  10  for assembly into the cylinder block mold package  12 . Apertures  24  are formed in the barrel slab core  10  on an outer surface  26  thereof adjacent an end of the cylinder bore liner  22 . A first end  28  of a u-shaped magnet  30  is disposed in the apertures  24 . Any conventional magnet can be used such as a rare earth permanent magnet or an electromagnet, for example. Additionally, although a single magnet  30  is shown, it is understood that a plurality of magnets can be used if desired. It is further understood that an intermediate article of suitable construction, shape, and material may be imposed between the magnet  30  and the barrel slab core  10 , extending into the apertures  24 , for the purpose of conducting the magnetic field. Any conventional magnet shape can be used. 
     A second end  32  of the magnet  30  is joined with a handling fixture  34 . As used herein, the handling fixture  34  means an assembly device, a robotic end-effector, and the like, which can be manual or automatic. The handling fixture  34  is used in the art to assist in assembly and positioning of the barrel slab core  10  in the cylinder block mold package  12 . The handling fixture  34  is releasably connected to the barrel slab core  10 . Any conventional means of releasable connection such as opposed articulating grip pads or expanding mandrels inserted into female features of the barrel slab core  10 , for example, can be used as desired. 
       FIG. 4  illustrates a partial view of the cylinder block mold package  12 . The cylinder block mold package  12  includes a crankcase core  40  having a side core  44  disposed adjacent thereto. A water jacket core  46  is disposed adjacent and between the barrel core features  16  of the barrel slab core  10 . A valley core  48  is disposed between corresponding barrel slab cores  10 . Additional cores may be included as desired such as a base core (not shown).  FIG. 5  shows an enlarged view of the cylinder bore liner  22  and the barrel core feature  16  of the cylinder block mold package  12  in  FIG. 4 . Note that the cylinder bore liner  22  is seated against the crankcase core  40 . It is also understood that the present invention can be used in configurations where the cylinder bore liner  22  is not seated against the crankcase core  40 . 
     Assembly of the barrel slab core  10  including the cylinder bore liners  22  with the cylinder block mold package  12  will now be described. The steps of the process are intended to be exemplary in nature, and thus, the order of the steps is not necessary or critical. The barrel slab core  10  is formed according to methods well known in the art. Once formed, the barrel slab core  10  is placed in the position shown in  FIG. 1 . One of the cylinder bore liners  22  is placed on each of the barrel core features  16  of the barrel slab core  10 . The barrel slab core  10  is then ready for assembly with the cylinder block mold package  12 . 
     In order to assemble the barrel slab core  10  in the cylinder block mold package  12 , the barrel slab core  10  must be inverted from the position shown in  FIGS. 1 and 2 . However, the cylinder bore liners  22  are susceptible to shifting or sliding off of the barrel core features  16  in the inverted position. In order to counteract this tendency, the magnet  30  is inserted into the apertures  24  formed in the barrel slab core  10 . This places the magnet  30  sufficiently close to the cylinder bore liner  22  for the cylinder bore liner  22  to be affected by the magnetic field produced by the magnet  30 . The magnetic field attracts the cylinder bore liner  22  toward the inner surface  14  of the barrel slab core  10 . This militates against movement of the cylinder bore liner  22  such as shifting or sliding off of the barrel core feature  16 . Additionally, the cylinder bore liner  22  is brought into contact with the inner surface  14  of the barrel slab core  10  resulting in the cylinder bore liner  22  being squared against the inner surface  14 . This encourages proper concentric positioning of the cylinder bore liner  22  for assembly into the cylinder block mold package  12 . 
     It is understood that the apertures  24  could be omitted if the magnetic field produced by the magnet  30  is sufficiently strong to affect the cylinder bore liner  22  while positioned adjacent the outer surface  26  of the barrel slab core  10 . Conversely, the apertures  24  may penetrate the entire thickness of barrel slab core  10  if desired. In the embodiment shown, the magnet  30  is held by the handling fixture  34 . When the handling fixture  34  is connected to the barrel slab core  10 , the magnet  30  is positioned adjacent the cylinder bore liner  22 . It is understood that the magnet  30  can be brought into position using other means without departing from the scope and spirit of the invention. 
     The joined barrel slab core  10 , magnet  30 , and handling fixture  34  are then inverted for assembly with the cylinder block mold package  12 . The barrel slab core  10  is then assembled with the cylinder block mold package  12 . Once the barrel slab core  10  is positioned as desired in the cylinder block mold package  12 , the handling fixture  34  is released from the barrel slab core  10  and initially withdrawn from the barrel slab core  10  in a direction parallel to the centerline of the cylinder bore liner  22 . Movement of the magnet  30  away from the cylinder bore liner  22  with the handling fixture  34  releases the cylinder bore liner  22  from the magnetic field produced by the magnet  30 . Further assembly of the cylinder block mold package  12  and casting of the engine block can now be accomplished. Alternatively, the magnet  30  can be withdrawn from the apertures  24  before the release of the handling fixture  34  from the barrel slab core  10 . 
     From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.