US2433109A

US2433109A - Chill mould for casting cylinder heads of air-cooled engines

Info

Publication number: US2433109A
Application number: US195909A
Authority: US
Inventors: Fouron Pierre
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-03-16
Filing date: 1938-03-14
Publication date: 1947-12-23
Anticipated expiration: 1964-12-23

Description

P. FOURON Dec. 23, 1947.

CHILL MOULD FOR CASTING CYLINDER HEADS OF AIR-COOLED ENGINES Filed March 14, 1958 4 Sheets-Sheet l Eve/afar P663178 P. FOURON 2,433,109

Filed March 14, 1938 4 Sheets-Sheet 2 ill Dec. 23, 1947.

' CHILL MOULD FOR CASTING CYLINDER HEADS OF AIR-COOLED ENGINES Ila, A!

P. FOURON- Dec. 23, 1947.-

GHILLMOULD FOR CASTING CYLINDER HEADS OF AIR-COOLED ENGINES Filed March 14, 1958 4 Sheets-Sheet 3 crezz Z707 r Dec. 23, 1947.

CHILL MOULD P. FOKIJRON ,433,109

FOR CASTING CYLINDER HEADS OF AIR COOLED ENGINES Filed March 14, 1938 4 Sheets-Sheet 4 Patented Dec. 23, 1947 CHILL MOULD FOR CASTING CYLINDER HEADS OF AIR-COOLED ENGINES Pierre Fouron, Paris, France Application March 14, 1938, Serial No. 195,909 In France March 16, 1937 Section 3, Public Law 690, August 8, 1946 Patent expires March 16, 1957 Claims.

The present invention has for its object a metal mould for casting cylinder heads of air-cooled engines.

Such cylinder heads have hitherto generally been manufactured by sand-moulding. This method has the drawback of being relatively slow, of necessitating a considerable amount of work for trimming the castings and of being delicate to use when it is desired to cast fins on the cylinder head which are long and close together, as is the case with numerous modern engines used in aviation. Cylinder heads having fins which are long and close together are frequently out from the solid by stamping and machining, which leads to a high cost of manufacture and entails a considerable loss of material.

One of the objects of the present invention consists in providing a chill-mould which enables cylinder heads of air-cooled engines of the above referred to type to be manufactured at a high output rate and with the minimum scrapped castings and Waste.

Another object of the present invention consists in the construction of such a chill-mould. which enables the castings to be readily and quickly stripped.

According to the invention, said chill-mould is characterized by the fact that it comprises, in a manner known per se, elements made of materials of dififerent thermal conductivities which come into contact with the casting, the arrangement being effected in such a manner that the elements of the lower part of the mould, which come into contact with the casings of the rockers, are made of a material of relatively high thermal conductivity (bronze, for example), whereas the elements of the adjacent part of the mould, which come into contact with the induction and exhaust pipes, are constructed of materials of poorer thermal conductivity, the upper stage of the mould being formed by a core of still poorer thermal conductivity, the runners being provided in said core.

This arrangement enables the speed of cooling of the various zones of the casting to be varied. Differences of molecular structure are thus avoid-- ed and, in particular, segregations or cracks due to defective cooling conditions.

Other advantages and peculiarities of the invention will become apparent from the ensuing description.

In the accompanying drawing, which is given solely by way of example:

Fig, 1 shows an elevation, with parts broken away, of an embodiment of the mechanical apparatus enabling the method to be .carried out.

Fig. 2 is a vertical section along the line IIII of Fig. 1.

Fig. 3 is a part plan View.

Fig. 4 shows a removable plate constructed the same shape as the fins.

' Fig. 5 is a side elevation of a rough cast cylinder head obtained with the chill-mould according to the invention.

Fig. 6 is a detail section.

The ensuing description refers to the manufacture of a cylinder head of an air-cooled engine in a metal mould according to the invention. The cylinder head (Fig. 5) generally has the shape of a spherical cap l9 provided with cooling fins 20. Said cap serves on the one hand as a support for the induction and exhaust pipes 2i and for the casings intended to hold and protect the rocker of the valves and the actuating members. The pouring gate is located at the upper part of the mould, that is to say on the circular section of the member forming the part of the cylinder head which is usually screwed on the cylinder. In order to obtain a progressive cooling of the casting, the latter will be decomposed into three different zones, starting from the lower part of the mould. (See Figs. 2 and 5.)

Zone Arocker casings 22.-Generally, such casings are of fairly considerabl mass: quick chilling caused by the fairly high thermal conductivity of the material which composes this part of the mould (bronze for example).

Zone B.-Induction and exhaust pipes 2| of fairly small thickness: cooling slower than for A, the inner part of the pipes being formed by a material of low thermal conductivity (sand) the cooling of the spherical cap i 9 is still slower, there being a considerable mass of metal and the inner part of the cap being formed of the same material of low thermal conductivity (sand). In the whole of the zone B, the outside of the mould is formed of removable steel parts.

Zone C.The risers and runners l5 which are to serve as feed reservoirs during the solidification of the casting are entirely contained in a sheath is of still lower thermal conductivity: asbestos, graphite, etc.

As the heat exchange between the metal, during the time required for the casting operation, and the material used for making the circulating channels is, owing to this fact, relatively small, the metal can more easily fill the recesses of the mould which have the print of the fins 20; the filling of said prints is, on the other hand, en-

hanced independently or the cooling zones b the fact that an adjustable partial vacuum is formed in said prints which is more or less deep according to their length, their location or their crosssection.

By way of example, if the depth of the fins is 20 mm., the depression may vary according to the position of said fins relatively to the runner and should be between 30 mm. and 100 mm. of mercury.

In the case of fins 40 mm. deep, the depres-- sion will be between '70 mm. and 200 m of mercury.

The above explanation will enable the process of solidification of the metal to be fully realized,

starting from the zone which is farthest away from the runner and finally reaching the latter. The molecular equilibrium of the casting is thus obtained and provides a metal having a. homogive ahollow print of the fins 20'; the plates l are guided and held in position by the grooves 3 provided in the base 2.

Said plates 4, in which. the shape of the fins 20--has previously been hollow' cut, carry on one of their faces parallel channels 1 which are open at their outer part.- Thetotal cross-sectionzof said channels is determined by the size of the.

passage which has been made at the end 6 of theprint inorder to make the depression eifec tive which is to be created in this zone throughou-t the casting operation.

In order to ensure the stability of the size of the: plates t and prevent deformations which mightoccur during their use, said plates are subjected to aheat treatment which consists in alternatel-y heating and cooling same a. number of times. Such treatment eliminates the hysteresis effects of expansion and enables an even opera tion of the mould to be obtained.

lntorde'r to prevent the plates 4 from moving back int-their recess under the pressure of the liquid metal, outer hoods Ii, which also serve another purpose, are fixed on each face of the apparatus beforezcasting they support and guide cams or eccentrics l2 which are operated from outside and which lock the plates 4- in position. Said hoods H, which are mounted on the mould without the interposition of a fluid-tight joint, are connected: to-the means for producing a partial vacuum. They may be divided into compartments so as to obtain a different depression in the various chambers thus created.

The depression ducts 9 may be formed directly in the based, one of their ends opening into a chamber of the hood, the other end. being connected by a flexible metal pipe 59 to themeans for producing a partial vacuum.

The top of the mould is formed by a support is supporting the mass of sand I 1 which forms the com c)? the casting and in which the down runner and the risers :5 have beeniformed.

Themanipulation of :the core i i and the fixingv of:'same;. andalsotheremoval of thecastin'gfromthe mould-,1 are .effectedby'means of an opening collar:l6uwhich'iis previously closed around the core and is secured to the support by cams or looking wedges l1.

Casting is effected in the manner which is customary for chill moulds, by gravity, using a ladle containing the 'molten metal. and pouring the latter into the opening provided in. the sand core l4. Shortly before the casting operation, the chambers or hoods II, which are fixed on the mould, are connected to the depression reservoirs and automatically controlled valves are kept open during the whole period of casting. The depression, which must be constant throughout the casting operation and is adjusted beforehand, is slight, of'the order of 50 to 200 millimetres of mercury. When the solidifying period has elapsed, the hoods II are removed, the movable parts 4* of the apparatus are moved back, as shown on the right in Fig. 2, and the casting is removed'from the mould.

It will be observed that none of the movable parts of the apparatus need be removed from the corresponding recess provided in the base inorder to enable the casting to be removed, but merely: requires to be moved back, thereby reducing/the wear and the deformations to'which said parts might be subjected.

Constructionalmodifications may be made in the means described herein without exceeding the scope of the invention.

I claim:

1.: A' chill mold for casting cylinder heads of air-cooled engines having parallel fins which are thin and close together, comprising a hollow block formed with guides, superimposed adjacent plates arranged in said guides to be slidable independently atone-another, the inner ends of the plates being shaped to form the part of the mold for casting the fins ofthecylinder head, vacuum hoods mounted on said block, and vacuum producing means connected to the said hoods, said plates being formed on their faces with channels connecting the interior of the mold to the vacuum hoods.

2. Achill mold'as defined in claim 1, including members mounted in the said hoods and coopcrating: with the slidable: plates to place the said plates in operative positions.

3'. A chill mold as defined in claim 1, including a support mounted on the block and forming the upper-part of the mold', a mass of sand held in thesupport, the mass of sand forming the core of the casting and being formed with a runner and risers, the said support holding and guiding the mass of sand during the period for which the mold is closed and. holding the casting during stripping, an opening collar surrounding the upper part of the core for manipulating and fixing the core, and locking means for locking the opening collar on said support.

4. A chill mold for casting cylinder heads of air-cooled engines having parallel fins which are thin and close together, comprising a hollow body" formed with guides, superimposed adjacent plates arranged in the guides to be slidable independently of one another, the inner ends of the plates being shaped to form apart of the mold for casting the fins of the cylinder head, vacuum hoods mounted on the body, and means for pro-- ducing a constant partial vacuum connected to the hoods, said plates being formed on their faces with channels connecting the interior of the mold to the vacuum hoods.

5." A chill mold as definedin claim 1, including at least one partition dividing the hood into compartments, and-meansfor producing different partial vacua connected to the said compart- Number ments. 1,693,222 PIERRE FOURON. 1,769,456 1 2,018,222 REFERENCES CITED 5 2, 3 ,6 9 The following references are of record in the file of this patent:

Number UNITED STATES PATENTS 423,905 Number Name Date 10 1,296,598 Jeffries Mar. 4, 1919 1,495,478 Gibson May 27, 1924 Name Date Croft et a1 Nov. 27, 1928 Pickering July 1, 1930 Norton Oct. 22, 1935 Speirs Oct. 11, 1938 FOREIGN PATENTS Country Date Great Britain Feb. 11, 1935