GB1596442A - Casting of long hollow objects - Google Patents

Description

(54) CASTING OF LONG HOLLOW OBJECTS (71) We, LYDMET LIMITED, a British Company, of Tutnalls, Lydney, Gloucestershire, formerly Brico Metals Limited, a British Company, of Tutnalls, Lydney, Gloucestershire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the casting of long hollow objects.

According to this invention a method of casting a long hollow object of cast iron includes the step of locating an extruded carbon rod in a sand mould to form a core, the core and the sand mould defining a cavity surrounding the core and within the mould, then pouring molten iron into said cavity, and allowing it to cool to form an iron casting.

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawing, which shows a camshaft produced in accordance with the present invention.

Referring to the drawing, in the production of an article approximately 500 mm long and 40 mm diameter, such as a camshaft 10, a pair of sand moulds are prepared using a pattern in the normal way to define the external form of the finished casting. The sand moulds will contain any necessary runners. risers or chills as required Betore the two halves of the mould are joined to form the mould cavity, a core is inserted in the form of a hollow carbon rod.

For a casting of the dimensions described, the carbon rod may be cylindrical and have an outside diameter of 7 mm from end to end. The carbon may be of the type used for carbon arc lamps and sold under the name Morganite CY9 extruded carbon (Morganite is a Trade mark). The two ends of the core are located in suitable parts of the mould.

Molten iron is then poured into the mould cavity flows round the core, and solidifies.

It has been found that in the manufacture of a long hollow casting as above described, cores made of ceramic material are apt to distort. This distortion is avoided by using a core in the form of a carbon rod. Although a hollow rod has been described, it is possible to use a solid rod.

The carbon rod is removed from the interior of the casting, after the latter has cooled, either by a vibratory impact method or by a rotary grinder, so as to produce a hole 11 from end to end of the camshaft, which is truly cylindrical.

WHAT WE CLAIM IS: 1. A method of casting a long hollow object of cast iron including the step of locating an extruded carbon rod in a sand mould to form a core, the core and the sand mould defining a cavity surrounding the core and within the mould, then pouring molten iron into said cavity, and allowing it to cool to form an iron casting.

2. A method of casting as claimed in claim 1 wherein the carbon rod is removed from the interior of the casting after the latter has cooled.

3. A method as claimed in claims 1 or 2 in which the carbon rod is cylindrical.

4. A method of casting a long hollow object substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. (54) CASTING OF LONG HOLLOW OBJECTS (71) We, LYDMET LIMITED, a British Company, of Tutnalls, Lydney, Gloucestershire, formerly Brico Metals Limited, a British Company, of Tutnalls, Lydney, Gloucestershire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the casting of long hollow objects. According to this invention a method of casting a long hollow object of cast iron includes the step of locating an extruded carbon rod in a sand mould to form a core, the core and the sand mould defining a cavity surrounding the core and within the mould, then pouring molten iron into said cavity, and allowing it to cool to form an iron casting. One embodiment of the invention will now be described by way of example, with reference to the accompanying drawing, which shows a camshaft produced in accordance with the present invention. Referring to the drawing, in the production of an article approximately 500 mm long and 40 mm diameter, such as a camshaft 10, a pair of sand moulds are prepared using a pattern in the normal way to define the external form of the finished casting. The sand moulds will contain any necessary runners. risers or chills as required Betore the two halves of the mould are joined to form the mould cavity, a core is inserted in the form of a hollow carbon rod. For a casting of the dimensions described, the carbon rod may be cylindrical and have an outside diameter of 7 mm from end to end. The carbon may be of the type used for carbon arc lamps and sold under the name Morganite CY9 extruded carbon (Morganite is a Trade mark). The two ends of the core are located in suitable parts of the mould. Molten iron is then poured into the mould cavity flows round the core, and solidifies. It has been found that in the manufacture of a long hollow casting as above described, cores made of ceramic material are apt to distort. This distortion is avoided by using a core in the form of a carbon rod. Although a hollow rod has been described, it is possible to use a solid rod. The carbon rod is removed from the interior of the casting, after the latter has cooled, either by a vibratory impact method or by a rotary grinder, so as to produce a hole 11 from end to end of the camshaft, which is truly cylindrical. WHAT WE CLAIM IS:

1. A method of casting a long hollow object of cast iron including the step of locating an extruded carbon rod in a sand mould to form a core, the core and the sand mould defining a cavity surrounding the core and within the mould, then pouring molten iron into said cavity, and allowing it to cool to form an iron casting.

2. A method of casting as claimed in claim 1 wherein the carbon rod is removed from the interior of the casting after the latter has cooled.

3. A method as claimed in claims 1 or 2 in which the carbon rod is cylindrical.

4. A method of casting a long hollow object substantially as hereinbefore described.