FIELD OF INVENTION

The present invention comprises an improvement of the invention claimed in Indian Patent Application Numbered 648/CHE/2013. The present invention relates to a method of manufacturing hollow bodies by means of centrifugal casting technique using sand core of improved configuration. More specifically, the present invention relates to a method for manufacturing hollow bodies like cylinder liner by means of centrifugal casting technique using sand core without taper in its inner cylindrical wall. Further, the present invention relates to an apparatus for manufacturing improved cylinder liner with taper removed.

BACKGROUND ART

This patent of addition seeks to clarify certain improvements with regard to Patent Application No: 648/CHE/2013. It should be apparent that the primary aim of this patent of addition is for an improved liner body with taper removed. The object of the improved liner body with taper removed is to (a) reduce the weight of casting by 100 grams and (b) in core at casting collar to body joining taper in outer periphery was made plain [i.e. taper removed] and maintained as individual steps to avoid irregular flow of casting metal towards taper which thereby enhancing the casting quality.

The Indian Patent Application 648/CHE/2013 has been claimed for a method for production of hollow bodies by means of centrifugal casting technique using different grades of cast irons and an apparatus for manufacturing hollow bodies like cylinder liner. The method comprising inserting one or more cores within die sleeve of die assembly and locking the core; cleaning the die assembly with air when it is rotating; pouring centrifugally casting material through an orifice provided in front door of the die assembly and simultaneously cooling the casted material; and removing the casted liner and cleaning the die assembly for each cycle, wherein the die sleeve is coaxially fitted to die holder of the die assembly and is configured to hold the cores, wherein the core with a hole in its center is co-axially inserted within the die sleeve through its cylindrical outer portion forming external shape of the liner, wherein the die sleeve is provided with excess recess to accommodate another core forming internal shape of the liner resulting in profiled cylinder liner and thereby reducing weight of casting, and wherein the cores releasably holds the centrifugally casting material supplied to the inner surface thereof. Further, it has claimed for liner body with taper provided with two steps that is, the main core used in the claimed patent application comprises a first cylindrical straight portion, a second cylindrical straight portion and a tapered portion that connects the first and second cylindrical straight portions. The core draft is 0.3 degree and core draft alignment in relation to die assembly is 0.3 degree. Because of the taper provided hot metal gets separated during pouring in casting and thereby resulting in the formation of cold metal which thereby effects in casting quality. The invention disclosed in the present patent application provides solution to over come the above problem and claims improvement over the invention disclosed in the patent application 648/CHE/2013. Thus, the present patent application provides a method and apparatus for manufacturing hollow bodies by means of centrifugal casting with an aspect of improving quality and productivity that would be capable of eliminating the above discussed limitations of the state of the art. Also the present patent application would justify technical advancement over prior knowledge in the field by way of providing an improved sand core for centrifugal casting adapted to ensure cost-effectiveness, safe method of manufacturing, user friendly application in their production on one hand and enhancement in the quality of the casting produced on the other hand.

OBJECTS OF INVENTION

Accordingly, it is the primary object of the present invention to provide a method for manufacturing hollow bodies by means of centrifugal casting technique using sand core of improved configuration.
It is another object of the present invention to provide a method for manufacturing hollow bodies like cylinder liner (plain and profile) by means of centrifugal casting technique using sand core without taper in its inner cylindrical wall (inner surface).
It is another object of the present invention to provide an apparatus for manufacturing the improved cylinder liner (plain and profile) with taper removed.
It is another object of the present invention, wherein the improved sand core reduces the weight of casting by 100 grams and improves casting quality.
It is another object of the present invention, wherein the improved sand core helps eliminate the problem of cold metal formation.

SUMMARY OF INVENTION

Thus according to the basic aspect of the present invention, there is provided a method for manufacturing hollow bodies like cylinder liner by means of centrifugal casting technique, comprising:

inserting one or more cores within die sleeve of die assembly and locking the core; cleaning the die assembly with air when it is rotating; pouring centrifugally casting material through an orifice provided in front door of the die assembly and simultaneously cooling the casted material; and removing the casted liner and cleaning the die assembly for each cycle, wherein the die sleeve is coaxially fitted to die holder of the die assembly and is configured to hold the cores, wherein the core with a hole in its center is co-axially inserted within the die sleeve through its cylindrical outer portion forming external shape of the liner, wherein the die sleeve is provided with excess recess to accommodate the core forming nternal shape of the liner resulting in profiled cylinder liner and thereby reducing weight of casting, wherein the cores releasably holds the centrifugally casting material supplied to the inner surface thereof, and the improvement comprising the core constructed without taper in its inner cylindrical
wall. According to another aspect of the present invention, there is provided an apparatus for manufacturing hollow bodies like plain cylinder liner comprising: one or more die assemblies each comprising of: one or more bearings rotatably mounted in bearing blocks; shaft; die holder; die sleeve; and core, wherein the bearings are pre-fitted with the shaft before assembling into the bearing blocks, wherein the assembled shaft is fitted over base frame, wherein front end of the shaft is fitted with the die holder and rear end of the shaft is fitted with shaft pulley, wherein the die sleeve is coaxially fitted to the die holder and is configured to hold the core, wherein the core with a hole in its center is co-axially inserted within the die sleeve through its cylindrical outer portion, wherein the core releasably holds a centrifugally casting material supplied to the inner surface thereof, wherein the die assemblies are fitted adjacently and driven to a motor through a belt, the improvement comprises the core comprising a first cylindrical straight portion, a second cylindrical straight portion and a chamfered portion, and wherein the chamfered portion connects the first cylindrical straight portion and the second cylindrical portion thereby eliminating tapered portion in its inner cylindrical wall. According to yet another aspect of the present invention, there is provided an apparatus for manufacturing hollow bodies like profiled cylinder liner comprising: one or more die assemblies each comprising of: one or more bearings rotatably mounted in bearing blocks; shaft; die holder; die sleeve; and one or more cores, wherein the bearings are pre-fitted with the shaft before assembling into the bearing blocks, wherein the assembled shaft is fitted over base frame, wherein front end of the shaft is fitted with the die holder and rear end of the shaft is fitted with shaft pulley, wherein the die sleeve is coaxially fitted to the die holder and is configured to hold one or more core, wherein one of the cores with a hole in its center is co-axially inserted within the die sleeve through its cylindrical outer portion to form external shape of the liner,
wherein the another core is co-axially inserted within the die sleeve through excess recess provided in the die sleeve to form internal shape of the liner, wherein the cores releasably holds a centrifugally casting material supplied to the inner surface thereof, wherein the die assemblies are fitted adjacently and driven to a motor through a belt; the improvement comprises the core comprising a first cylindrical straight portion, a second cylindrical straight portion and a chamfered portion, and wherein the chamfered portion connects the first cylindrical straight portion and the second cylindrical portion thereby eliminating tapered portion in its inner cylindrical wall. It is another aspect of the present invention, wherein the elimination of taper in the core prevents irregular flow of molten metal thereby enhancing the casting quality. It is another aspect of the present invention, wherein the core reduces the weight of casting and improves casting quality. It is another aspect of the present invention, wherein the core reduces the weight of casting approximately by 100 grams.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGRURES

Figure 1: illustrates the die assembly for manufacturing of hollow plain bodies/liners by means
of centrifugal casting technique according to the invention disclosed in Patent Application
Numbered 648/CHE/2013.
Figure 2: illustrates the die assembly for manufacturing of hollow profiled bodies/liners by
means of centrifugal casting technique according to the invention disclosed in Patent Application Numbered 648/CHE/2013.
Figure 3: illustrates the cross sectional view of the main core according to the invention
disclosed In Patent Application Numbered 648/CHE/2013.
Figure 4: illustrates the cross sectional view of the main core according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES

The present invention provides a method for manufacturing hollow bodies by means of centrifugal casting technique using sand core of improved configuration. This is done by using sand core without the taper in its inner cylindrical wall (inner surface). Further, an apparatus for manufacturing the improved cylinder liner with taper removed is also disclosed in the present application. Reference is now invited to the accompanying Figure 1 that illustrates the die assembly for manufacturing of hollow plain bodies/liners by means of centrifugal casting technique disclosed in Patent Application Numbered 648/CHE/2013. The apparatus comprising of at least two die assemblies each comprising of at least two bearings rotatably mounted in bearing blocks (1, 2); shaft (3); die holder (9); die sleeve (10); and core (11). The bearings are pre-fitted with the shaft (3) before assembling into the bearing blocks. The bearing blocks are sealed by means of bearing covers (5, 6, 7, and 8) to protect from the foreign particles. The assembled shaft is fitted over base frame (18). The front end of the shaft (3) with flange (4) is fitted with the die holder (9) and rear end of the shaft is fitted with shaft pulley (17). The die sleeve (10) is coaxially fitted to the die holder (9) and is configured to hold the core (11). The design of the die sleeve (10) is based upon the size and shape of the casting (21) required. External size of die sleeve (10) is common for all models and internal shape is based upon the casting required. The core (11) with a hole in its center is co-axially inserted within the die sleeve (10) through its cylindrical outer portion. The core is made up of any type of sand, which will be inserted in to the permanent centrifugal die. The shape and size of the casting is determined by the core. After inserting core, it will be locked with face plate/front door (12), which is designed with a hole in its centre, thereby locking core movement. The core (11) releasably holds a centrifugally casting material supplied to the inner surface thereof. The die assemblies are fitted adjacently by a belt (13) and driven to a motor (14) through the motor pulley (15) and belt (16). The motor (14) is supported by a motor supporting channel (19).

Reference is now invited to the accompanying Figure 2, which illustrates the die assembly used for the manufacture of profiled bodies like cylinder liners disclosed in the Patent Application Numbered 648/CHE/2013, wherein additional core (23) is provided to obtain the internal shape of the hollow bodies like liner. While the core (11) is disposed to form the external shape, the additional core (23) is co-axially inserted within the die sleeve (10) through excess recess provided in the die sleeve to form internal shape of the liner, thereby reducing weight of casting. The core (11) is split type, which has to be assembled outside and inserted into the die sleeve (10). According to the shape of the casting it is necessary to use more than one additional core to obtain the different shapes of the casting.
A method for manufacturing hollow bodies like cylinder liner by means of centrifugal casting technique, comprising the steps of inserting one or more cores (11, 23) within die sleeve (10) of the die assembly and locking the core; switching on the die assembly, cleaning the die assembly with air when it is rotating; pouring centrifugally casting material/hot metal by spout (20) through an orifice provided in front door (12) of the die assembly and simultaneously cooling the casted material; switching off the die and removing the casted liner and cleaning the die assembly for each cycle. Simultaneous cooling of the casted material eliminates crack in the casted liner. The flow (22) of molten metal is shown in the Figures 1 and 2. The core (11) is co- axially inserted within the die sleeve (10) through its cylindrical outer portion forming external shape of the plain cylinder liner and the additional core (23) accommodates the die sleeve, which is provided with excess recess forming internal shape of the liner, resulting in profiled cylinder liners. The insertion of the core within the die sleeve eliminates direct contact of casting material with the die thereby eliminating the requirement of pre-heating of the die. Also, the insertion of sand core provides slow and uniform cooling rate thereby eliminating front and back parting off of the cylinder liner. Due to slow and uniform cooling rate, casting thickness is as per final requirement. Micro and hardness is achieved by cooling the outer surface of the cylinder liner and avoiding rapid cooling. Further, the method of the present invention eliminates the inner diameter (ID) and outer diameter (OD) roughing operation and thereby outer diameter finishing operation is directly performed on the cylinder liner. The cores (11, 23) are manufactured in any one of the known methods with necessary prints for keeping the core in position inside the die sleeve (10).

Reference is invited to the accompanying Figure 3 which illustrates the cross sectional view of the core according to the invention disclosed in the Patent Application Numbered 648/CHE/2013. The core (11) comprises a first cylindrical straight portion (11a), a second cylindrical straight portion (lie) and a tapered portion (lib) which connects the first cylindrical straight portion (11aand the second cylindrical straight portion (lie).

During pouring of hot metal in the core (11) rotatably held in the die assembly comprising the die holder (9) and the die sleeve (10), the hot metal gets separated due to the presence of the tapered portion (1 lb). This result in the formation of cold metal, which affects the quality of the casting produced.

In order to overcome the above problem, the core is constructed without the tapered portion as illustrated in Figure 4. The improvement comprises, the core (110) comprising a first cylindrical straight portion (110a), a second cylindrical straight portion (110b) and a chamfered portion (110c). The second cylindrical straight portion (110b) is merged with the first cylindrical straight portion (110a) with the help of the chamfered portion (110c) there by eliminating the tapered portion i.e. the core at casting collar to body joining taper in outer periphery was made plain and maintained as individual steps. This is to avoid metal irregular flow towards taper and after the changes are made, the metal is free from quality defects due to flow. The elimination of the tapered portion also results in reduction in the weight of rough casting produced. The core reduces the weight of casting approximately by 100 grams.

WE CLAIM:

1. A method for manufacturing hollow bodies like cylinder liner by means of centrifugal casting
technique, comprising: inserting one or more cores (110, 23) within die sleeve (10) of die assembly and locking the core; cleaning the die assembly with air when it is rotating; pouring centrifugally casting material through an orifice provided in front door (12) of the die assembly and simultaneously cooling the casted material; and removing the casted liner and cleaning the die assembly for each cycle, wherein the die sleeve (10) is coaxially fitted to die holder (9) of the die assembly and is configured to hold the cores (110,23), wherein the core (110) with a hole in its center is co-axially inserted within the die sleeve (10) through its cylindrical outer portion forming external shape of the liner, wherein the die sleeve is provided with excess recess to accommodate the core (23) forming internal shape of the liner resulting in profiled cylinder liner and thereby reducing weight of casting, wherein the cores (110, 23) releasably holds the centrifugally casting material supplied to the inner surface thereof, and the improvement comprising the core (110) constructed without taper in its inner cylindrical wall.

2. An apparatus for manufacturing hollow bodies like plain cylinder liner as claimed in claim 1
comprising: one or more die assemblies each comprising of: one or more bearings rotatably mounted in bearing blocks (1, 2); shaft (3); die holder (9); die sleeve (10); and core (110), wherein the bearings are pre-fitted with the shaft (3) before assembling into the bearing blocks, wherein the assembled shaft is fitted over base frame (18), wherein front end of the shaft (3) is fitted with the die holder (9) and rear end of the shaft is fitted with shaft pulley (17), wherein the die sleeve (10) is coaxially fitted to the die holder (9) and is configured to hold the core (110), wherein the core (110) with a hole in its center is co-axially inserted within the die sleeve (10) through its cylindrical outer portion, wherein the core (110) releasably holds a centrifugally casting material supplied to the inner surface thereof, wherein the die assemblies are fitted adjacently and driven to a motor (14) through a belt (16), the improvement comprises the core (110) comprising a first cylindrical straight portion (110a), a second cylindrical straight portion (110b) and a chamfered portion (110c), and wherein the chamfered portion (110c) connects the first cylindrical straight portion (110a) and the second cylindrical portion (110b) thereby eliminating tapered portion in its inner cylindrical wall.

3. An apparatus for manufacturing hollow bodies like profiled cylinder liner as claimed in claim 1 comprising: one or more die assemblies each comprising of: one or more bearings rotatably mounted in bearing blocks (1,2); shaft (3); die holder (9); die sleeve (10); and one or more cores (110, 23), wherein the bearings are pre-fitted with the shaft (3) before assembling into the bearing blocks, wherein the assembled shaft is fitted over base frame (18), wherein front end of the shaft (3) is fitted with the die holder (9) and rear end of the shaft is fitted with shaft pulley (17), wherein the die sleeve (10) is coaxially fitted to the die holder (9) and is configured to hold one or more core (110, 23), wherein one of the cores (110) with a hole in its center is co-axially inserted within the die sleeve (10) through its cylindrical outer portion to form external shape of the liner, wherein the another core (23) is co-axially inserted within the die sleeve (10) through excess recess provided in the die sleeve to form internal shape of the liner, wherein the cores (110, 23) releasably holds a centrifugally casting material supplied to the inner surface thereof, wherein the die assemblies are fitted adjacently and driven to a motor (14) through a belt (16); the improvement comprises the core (110) comprising a first cylindrical straight portion (110a), a second cylindrical straight portion (110b) and a chamfered portion (110c), and wherein the chamfered portion (110c) connects the first cylindrical straight portion (110a) and the second cylindrical portion (110b) thereby eliminating tapered portion in its inner cylindrical wall.

4. The apparatus as claimed in claims 2 and 3, wherein the elimination of taper in the core (110) prevents irregular flow of molten metal thereby enhancing the casting quality.

5. The apparatus as claimed in anyone of claims 2 to 4, wherein the core (110) reduces the weight of casting and improves casting quality.

6. The apparatus as claimed in claim 5, wherein the core (110) reduces the weight of casting approximately by 100 grams.