US2831225A - Method of making cylinder blocks - Google Patents

Description

April 22, 1958 A. E. KOLBE ET AL 2,831,225

METHOD OF MAKING CYLINDER BLOCKS Filed. Oct. 4, 1954 4 Sheets-Sheet 2 4 ZL/Z/J INVENTOR /dziizzi 5 15/5 TTORNEY April 22, 1958 A. E. KOLBE ET AL METHOD OF MAKING CYLINDER BLOCKS Filed Oct. 4, 1954 Aprilf 22, 1958 A. E. KOLBE ET AL METHOD OF MAKING CYLINDER BLOCKS Filed Oct. 4, 1954 4 Sheets-Sheet 4 INVENTOR away/54%;;

ATTORNEY ilnited. States Patent METHGD 0F MAKENG CYLKNDER BLOCKS Adeibert E. Kellie, Detroit, and George J. Phillips, Saginaw, Mich, assignors to General Motors Corporation, Detroit, Mich a corporation of Delaware Application Gctoher 4, 1954, Serial No. 460,0li6

6 Ciaims. (Cl. 22--131) This invention relates to internal combustion engines and like devices, and more particularly to an improved method of casting cylinder blocks for V-type and other engines.

It was formerly the practice to cast cylinder blocks for engines by assembling relatively great numbers of individual cores to form the exterior, as well as the interior, surfaces of the cylinder blocks. The cylinder blocks were designed in a manner so that the core boxes had to be stripped from the cores in a direction which would be vertical with respect to the position of the cores within the cylinder block mold as the block is normally positioned in a complete engine. This coring method of course required the extra time and equipment needed for making the great number of individual cores and for pasting or otherwise securing these cores into core subassemblies which were then suitably located in the cope and drag molds.

U. S. application S. N. 339,098 filed September 26, 1952 in the name of Dolza et al., now Patent No. 2,783,- 510, pointed out the many disadvantages of this previous method of casting V-type cylinder blocks and proposed a new method of casting such blocks. The new method, as stated in the above identified patent, reduces the number of necessary cores from in the neighborhood of twenty to a minimum of five in a six-cylinder block, and six in an eight-cylinder block. This tremendous decrease in the number of cores required results in great savings in the cost of casting such blocks and is made possible by designing the surfaces of the block in a manner to eliminate the necessity of external cores to shape the exterior surfaces of the block and to permit the combining of the formerly separate bulkhead and barrel cores into a single core having a core box parting line extending through the axes of the cylinders. End cores were eliminated by providing fiat faces at the ends of the block, or at least faces which could be formed by green sand and without the use of external cores. A base slab core was eliminated by the use of a special fixture adapted to hold the otherwise loose complete core assembly together until the assembly could be lowered into the drag mold. Annular spacers were provided to retain the water jacket cores in proper position until the core assembly was placed in the drag mold, at which time these spacers were removed and the cope mold was then placed over the drag mold to complete the mold assembly. The removal of these spacers was possible at that time since prints were provided in the green sand of the cope and drag molds to support and anchor the ends of the water jacket cores.

However, despite the numerous advantages of using the method of casting cylinder blocks disclosed in the above identified patent, it has been found that improve ments may be made in the casting method therein disclosed, especially where relatively high production of such cylinder blocks is concerned. In the first place, the fixture proposed in the above patent for transporting the otherwise loose core assembly from the core room to the foundry, as is usually desirable in high production Opera'- ice tions where the core room is better kept separate from the foundry itself and where it is advantageous to have the drag and cope molds moving continuously on a conveyor line in the foundry to the pouring station, is quite complicated both as to structure and as to use. Where a continuous line of core assemblies must be maintained, a great many such fixtures would be required and this would represent a considerable item of cost. For these reasons, the fixture is not ideally adapted to high production situations. Secondly, the necessity of providing flat end walls on the cylinder block so that end cores -may be eliminated usually, if not necessarily, results in considerable metal at the ends of the block. This may not be desirable for various reasons, particularly because of the considerably greater weight of the final engine assembly. Further, the thicker end walls usually require considerable machining and additional timing gear and flywheel housing castings, for instance, may have to be separately made, machined and thereafter secured to the ends of the block. This would also add to the cost of the final engine assembly. Also, the elimination of end cores makes it necessary to support and in part anchor the water jacket cores on prints in the green sand in the cope and drag molds, which has been found to often resuit in sufficient damaging of the molds so that green sand may actually fall into the lower portions of the drag mold and become entrapped in the walls of the cast structure or so that misalignment of the various cores occurs to the extent that the block may have to be scrapped. The fixture holding the core assembly together may itself be a contributing factor in damage to the drag mold since the fixture must be removed from the otherwise loose core assembly before the cope mold may be applied. Further, it has been found that resting the combined barrel cores on green sand in the drag mold likewise results in the above mentioned damaging of the mold and the consequent misalignment of the cores.

In other words, while the casting method proposed in the above identified patent has contributed immensely to the improvement of the art of casting cylinder blocks for V-type engines, it is thought that the proposed method may be improved to make it more applicable to the case of high production of all types of engines.

Accordingly, it is proposed to provide a method of casting cylinder blocks for such engines which comprises a judicious selection between the fewer cores employed in the method proposed in the patent discussed above and the greater number of cores employed in the methods employed before that.

The proposed method, therefore, contemplates the use of the combined barrel and bulkhead and the water jacket main cores employed in the method disclosed by the above application to form the main internal surfaces of any block. Various other minor cores to be pasted or otherwise secured to these cores may be employed to form other interior surfaces peculiarly characteristic of any particular block. However, the proposed method further contemplates the use of front and rear end cor to reduce the overall weight of the block and'at the same time to reduce the number of extra castings necessary to complete the cylinder block assembly. These cores also reduce the ultimate machining required for the cylinder block assembly. A base slab core is employed to more positively locate the main cores than when they are located by prints in the green sand drag mold. Further, prints are provided in the water jacket core ends to re ceive supports on the end cores. This positively locates and anchors the Water jacket cores without the necessity of providing openings in the cylinder block through which the green sand cope mold may anchor the cores. In addition, all the cores are pasted or otherwise secured together in the core room so that the entire unitary core assem- 3. bly may then be easily transported from the core room by means of a simple air operated or other fixture and lowered into the drag molds in the foundry in one simple operation. This eliminates fixtures required to prevent individual cores from becoming misaligned or falling out of the core assembly. All of the gauging and checking, which is accomplished by the use of simple, reusable spacers, is done in the core room so that none need be done in the foundry. By thismethod, a perfect cylinder block casting may be made every time, at least insofar as the core and mold assembly affects the resulting casting.

In the drawings:

Figure 1 is a vertical longitudinal cross-sectional view through the center of a core and mold assembly embodying the invention. The spaces between the cores and the molds in Figure l and the succeeding figures are filled with metal so that they represent the walls of the cylinder block cast in such a core and mold assembly.

Figure 2 is a vertical transverse cross-sectional view of the core and mold assembly shown by Figure 1 and taken substantially in the plane of line 2'2 and looking in the direction of the arrows. The usual staggered relation of the banks of cylinders is readily apparent.

Figure 3 is a longitudinal cross-sectional view taken substantially in the plane of line 33 of Figure 2, and looking in the direction of the arrows.

Figure 4 is a fragmentary cross-sectional view taken substantially in the plane of line 4-4 of Figure 2, and

' looking in the direction of the arrows.

Referring to the drawings in greater detail, the proposed method of casting cylinder blocks for internal combustion engines and the like contemplates the use of a mold parting at 12, generally through the widest por tion of the block 14, with the green sand cope and drag halves 16 and 18 of the mold forming the longitudinal exterior surfaces of the block without the use of any external cores.

The interior surfaces of the cylinder block 14 are formed by a unitary core assembly 20 formed by pasting or otherwise securing together a judicious selection of individual cores, including the type of combined barrel and bulkhead cores and water jacket cores disclosed by Patent No. 2,783,510 already referred to above.

The structure and the advantages of the individual cores and the resulting unitary core assembly employed in the proposed method of casting can best be pointed out by explaining how the individual cores are assembled in the core room to form the unitary self-supporting core assembly.

First, the slab core 22 is placed upon a working surface so that the other cores may be applied to the slab core. It will be noted that the slab core 22 has a cylindrical ridge 24 extending the length of the slab, except at the very ends thereof where the prints 26 are formed in the slab. Between the end prints 26 are pairs of prints 28 spaced on opposite sides of the ridge 24. Next, the front, intermediate and rear combined barrel and bulkhead cores 30, 32' and 34, respectively, are placed so that the projections 36 at the bottoms thereof are received by the prints 26', with the projections 36 straddling the ridge 24 of the slab core 22. These combined cores are generally similar in that they each comprise a body portion 38 having a pair of barrels 40 extending obliquely therefrom, with a projection 42 forming a camshaft gallery extending between the barrels. It will be noted that the end faces 44 of the combined barrel and bulkhead cores 30, 32 and 34 abut one another so that these cores are simply and positively located on the base slab core 22.

The projections 36 and/or prints 28 and the end faces 44 may first be coated with a paste to secure the barrel and bulkhead cores to the slab core and together, and this is true in the case of joining portions of all the cores in the core assembly. Any minor cores that must be secured to any of the main cores discussed here may be so secured in a similar manner as a sub-assembly operation, and the sub-assemblies; and the entire assembly may be baked after pasting to better secure the same. Any other means may be used to secure all of the cores together. 7

Next, the water jacket cores 46, each of which comprises an elongated body having cylindrical openings 48 to spatially receive the barrels 40, are positioned by any suitable means, such as the cylindrical spacers disclosed by the earlier identified patent. These spacers are, of course, subsequently removed, preferably after the unitary core assembly is placed in the drag half of the mold but not necessarily so as will be seen later.

Now the front and rear end cores 5% and 52, respectively, may be applied to the base slab core 22 so that the projections fit into the slab end prints 26 and so that the inner surfaces 54 of the end cores abut the ends 56 of the ridge 24.- Again, portions of the end cores engaging other cores may be pasted thereto. Note also that the end cores 50 and 52 have at least one support 58 to be received by each of the prints 60 in the water jacket core ends 62. This scheme provides novel means for positioning and anchoring the water jacket cores 46 without the use of green sand-prints or the need of portions of the green sand kissing the cores to anchor them. Where two such prints 60 are provided in at least one end of each water jacket core the water jacket core cannot rotate and is still more positively anchored.

From the above, it can be seen that the individual cores fit together in jig-saw puzzle fashion, one always in contact with at least two others. In this way, very little care need be exercised to produce a dimensionally acceptable unitary core assembly 20 which can be transported in any manner, as by hooks on a conveyor inserted into the lifting holes 64 in the barrel ends and the end cores, from the core room to the foundry.

In the foundry, the unitary core assembly 20 may be lowered into the drag half 18 of the mold which has a bottom print 66 to receive the base slab core 22 and end prints 68 and 70 to receive the end cores 50 and 52. The individual cores are thus accurately and positively positioned on the base slab core, and the base slab core is accurately supported and positioned in the drag half due to the relatively large area of the base slab core. Thus, minimum opportunity is provided for damage to the green sand and consequent misalignment of the core assembly. Hooks on a conveyor fixture may be easily removed from the lifting holes 64 in the cores without damaging the drag mold, since these holes are all located well above the top of the drag half. After the conveyor fixture or other means for carrying the core assembly and lowering it into the drag half of the mold is removed, the cope half of the mold may be positioned over the drag half and the mold and core assembly may be moved to the pouring station where the cylinder blockis cast according to the usual practice.

The gates, risers and vents for the mold and core assembly, as well as any minor interior cores that may be desired, are not shown since they do not comprise part of the invention.

From the above specification and drawings it may be seen that the proposed method of casting a block comprises a judicious selection of a minimum number of certain cores required to reduce the amount of scrap castings due to misalignment of the cores and the core assembly and damage to the green sand molds. Also, the amount of metal at the ends of the cylinder block is reduced, which in turn reduces the ultimate weight of the block and the amount of machining required to finish the block. No expensive and complicated fixtures which may damage the green sand molds are required to hold the core assembly together, since the cores are all secured together by other means to form a unitary self-supporting structure. The use of the end cores provides front and rear housings for the block so that the number and size of ext-a housing castings for the block is reduced. The Water jacket cores are located and anchored by the end cores in a novel manner without the necessity of employing the more delicate green sand for this purpose. The entire core assembly may be assembled easily and quickly without the possibility of mistakes.

What is claimed is:

l. A method of casting a cylinder block, comprising forming front and rear end cores having faces adapted to shape the front and rear end faces of said block, forming combined barrel and bulkhead cores, forming water jacket cores adapted to provide continuous passages through said block, anchoringsaid water jacket cores to said front and rear end cores, securing all of said cores together to form a unitary self-supporting core assembly, positioning said unitary core assembly in a mold," and filling the spaces between said core assembly and said mold with material forming said block.

2. A method of making a core assembly for casting a cylinder block, comprising forming front and rear end cores having faces adapted to shape the front and rear faces of said block, forming barrel and bulkhead cores,

forming a base slab core having means to locate said front and rear end cores in fixed relation on said slab core, placing said front and rear end cores and said barrel and bulkhead cores on said base slab core, forming Water jacket cores adapted to provide continuous passages through said block, anchoring said water jacket cores to said front and rear end cores, and securing all of said cores together to form a unitary self-supporting core assembly.

3. A method of making a core assembly for casting a with the barrel portions of said combined cores disposed in spaced rows, forming water jacket cores adapted to provide continuous passages through said block, positioning said water jacket cores around said barrel portions of said combined barrel and bulkhead cores, anchoring said water jacket cores in spatial relation to said barrel portions on said front and rear end cores, and securing all of said cores together to form a unitary self-supporting core assembly.

4. A method of making a core assembly for casting a cylinder block, comprising forming a combined barrel and bulkhead core adapted to shape the individual crankthrow and associated cylinder cavity in said block, forming front and rear end cores adapted to shape the front and rear end faces of said cylinder block, forming a base slab core having means thereon to locate said combined barrel and bulkhead core and said front and rear end cores in fixed relation on said slab core, placing said cores on said slab core in abutting relation, forming a water jacket core adapted to provide a continuous passage through said block, positioning said Water jacket core around said barrel portion of said combined barrel and bulkhead core, anchoring said water jacket core in spatial relation to said barrel portion on said front and rear end cores, and securing all of said cores together to form a unitary self-supporting core assembly.

5. A mold and core assembly for casting a cylinder block, comprising a drag mold and a cope mold, said molds having depressions therein adapted to shape the entire longitudinal exterior surfaces of said block, and a core assembly including a base slab core, combined barrel and bulkhead cores, a front end core, a rear end core, and water jacket cores, said combined barrel and bulkhead cores and said end cores being located in abutting relation on said base slab core with the barrel portions of said combined cores being in spaced rows, said water jacket cores being located and anchored on said end cores, and all of said cores being secured together to form a unitary self-supporting core assembly.

6. A method of making a core assembly for casting a cylinder block, comprising forming a plurality of onepiece combined barrel and bulkhead cores each having a crankcase-defining body portion and integral outwardly extending and obliquely disposed engine cylinder-defining portions, forming front and rear end cores adapted to shape the front and rear end faces of said block, forming water jacket cores adapted to provide continuous passages through said block, positioning said water jacket cores in spaced relation around said cylinder-defining portions, anchoring said water jacket cores in said spaced relation on said front and rear end cores, and securing all of said cores together to form a unitary self-supporting structure. I

- References Cited in the file of this patent UNITED STATES PATENTS 1,075,290 Kerr Oct. 7, 1913 1,768,802 Stoney July 1, 1930 1,952,500 Huettemon Mar. 27, 1934 2,783,510 Dolza et al. Mar. 5, 1957 FOREIGN PATENTS 889,056 Germany Sept. 7, 1953

Images