Title of Invention

A NOVEL MACHINE FOR DECORATIVE STITCHING USEFUL IN THE MANUFACTURE OF CRICKET BALLS

Abstract

The present invention relates to a novel machine for decorative stitching useful in the manufacture of cricket balls. The novel machine of the present invention will be useful for decorative stitching of the two hemispherical cups which when put together and stitched provides the finished cricket ball. The machine of the present invention will be particularly useful to provide the step of decorative stitching prior to the manufacture of finished cricket ball. This will enhance the productivity level. The machine of the present invention is new as there is no such machine existing which is useful for providing decorative stitching on hemispherical leather cup of a cricket ball. Therefore, the machine of the present invention is itself novel and it is constructed to provide the desired output of decorative stitching which is an essential part during the process of manufacture of cricket balls by providing a unique dual needle looper assembly wherein the needles are placed parallel to other but in an offset manner.

Full Text

The present invention relates to a novel machine for decorative stitching useful in the manufacture of cricket balls. The novel machine of the present invention will be useful for decorative stitching of the two hemispherical cups which when put together and stitched provides the finished cricket ball. The machine of the present invention will be particularly useful to provide the step of decorative stitching prior to the manufacture of finished cricket ball. This will enhance the productivity level. The prior art search covering literature, patents and industrial survey reveals the following technologies for manufacture of cricket balls, specifically the step of decorative stitching. In fig. 1 of the drawing accompanying this specification, a schematic drawing of a cricket ball is given showing the decorative stitching. In the drawings (A) denotes decorative stitching and (B) seam stitching. The cricket balls are generally manufactured by completely manual process. For providing decorative stitching the two hemispherical cups are prepunched circumferentially in two rows and they are stitched with curved needle which passes at about an angle of 15° through prepunched holes. This manual operation usually takes stitching time of around 1 hr for one hemispherical cup. As the quality of stitching mainly depends upon the skill of the operator, it is very difficult to get consistent quality stitching and it varies from individual to individual. It may be noted there are international standards which specify the spacing of the rows of stitches and also total number of stitches on the circumference for each row. It is, however, not possible to obtain the stitches with the help of any existing standard machine. From patent search, we find another method of manufacturing cricket ball. Reference may be made to patent no. GB 2097320 dated 03.11.1982 which comprises of placing two cover forming pieces in a spherical cavity of a mould. A suitable core forming material such as polyurethane is injected into the space between the said pieces so as to form, after setting a core for the ball which also connects the two pieces together. Each of said pieces may be provided around its periphery with one or more rows of stitching which project outwardly so as together to form a seam for the completed ball. This method does not describe the decorative stitching and it is useful only for joining two hemispherical cups. Decorative stitching specially on cricket ball surface is guided by standard. In order to maintain the specified standard, it is essential to have a two needle sewing system. The existing two needle system cannot be used to provide the specified'decorative stitching on cricket balls for the following reasons: a) Distance between needles of existing two needle system is much more than what is required for decorative stitching. b) Two needles cannot be held closely apart with the existing two needle holding system. c) Proper needle looper interaction is not possible within the extremely narrow space of the order of less than 1 mm between the two needles with the existing two needle system. From the above noted prior art details, we find that to the best of our knowledge there is no machine existing anywhere in the world for providing a finished cricket ball in general and for providing decorative stitching in particular. The main object of the present invention is to provide a novel machine for decorative stitching useful in the manufacture of cricket balls which obviates the drawbacks associated with the manual process. Another object of the present invention is to provide low cost automation for a small scale industry so that productivity increases and production cost of cricket balls is reduced. Yet another object of the present invention is to provide uniform quality of stitching of cricket balls and reduce the rejections, thereby increasing productivity. In the drawings accompanying this specification, figs 2A, 2B and 2C show the schematic drawing of the novel dual needle looper assembly consisting of needles (5a, 5b), needle holder (5), loopers (4a, 4b) and looper holders(4<:> In the drawings accompanying this specification, figs 3, 4 and 5 show the schematic views of an embodiment of the novel machine of the present invention for decorative stitching which comprises the following : Stitching head retrofitted with a hemispherical mandrel comprising of hemispherical mandrel (1), hemispherical leather segment (2), ball bearing (3), Looper holder (4), needles (5). Indexer assembly comprising of Ball holder (13), Encoder (14), Pinion handle (15), Locking handle (16), Stepper motor (17), Stepper motor housing (18), Worm shaft (19), Worm wheel (20), Top cover (21), Indexer housing (22), Encoder housing (23), Front end cover (24) . Power transmission comprising of clutch motor (9), V-belt pulleys (10), V-belt (11), Gear box (6), Timer pulleys (7), Timer belt (8) . Fig 2 shows the novel dual needle looper arrangement for decorative stitching on the spherical surface of hemispherical leather cups. The needles (5a,5b) are closely spaced in a parallel distance of 3 mm but offset circumferentially to enable the loopers (4a,4b) fixed to looper holders (4c,4d) make coordinated oscillating movements with respect to the reciprocating movements of the needles of diameter 2 mm. Two bobbins (5d and 5e) fixed ,on the stitching head supply thread (5c) required for the stitching operation. Fig 3 shows the stitching head which has been used for chain stitching using two needles and two loopers as detailed in fig 2. A hemispherical mandrel (1) is attached to the machine in such a way that it holds the hemispherical leather segment (2) firmly against the hemispherical cup fixed to the indexer shaft. The hemispherical mandrel (1) is freely mounted on a ball bearing support (3) which helps the indexing movements of the leather segment. The loopers (4a,4b) and needles (5a,5b) are suitably mounted to ensure proper interaction between them during stitching. The gear box (6) is suitably designed along with a pair of timer pulleys (7) to provide suitable speed to the needles. The clutch motor (9) drives the gear box through V belt (11) (Fig. 4). The indexer assembly (Fig 5) consisting of a worm (19) and worm wheel (20) is used to hold and provide indexing motions to the hemispherical leather segment (2) with respect to the reciprocating needle movements. A stepper motor (17) has been used to drive the indexer shaft. Locking mechanism (16) has been used as locking device for the indexer assembly (12) while stitching. An electronic control unit has been used to maintain a fixed number of stitches over the full circumference. An encoder (14) mounted on the rear end of the indexer shaft is sued to obtain accurate indexing and thereby uniformity in the spacing of the chain stitches. An optical sensor fixed on the upper part of the body of the stitching machine is used to sense the position of the needle with respect to the leather segment. As some as the needle moves out of the leather segment, stepper motor (17) starts indexing movement and the controller starts counting of the pulses form the encoder (14). As soon as the required couSnt of stitches on the periphery is reached, stepper motor (17) stops automatically. The accuracy of indexing depends on the accuracy of the encoder (14). Accordingly the present invention provides a novel machine for decorative stitching useful in the manufacture of cricket balls which comprises, characterized in that a dual needle looper assembly essentially consisting of needles (5a) and (5b) placed parallel to each other in an offset manner having corresponding loopers (4a) and (4b) fixed in looper holders below the needles, the said needles being fixed onto needle holder (5), the said needle holder being fixed to the shaft of a conventional reciprocating stitching head provided with an optical sensor fixed onto the body of the stitching head in such a manner so as to sense the needle position with respect to the leather cup, the said loopers (4a, 4b) in looper holders (4c, 4d) being encased within a hemispherical hollow mandrel assembly (1) having an opening for the reciprocating movement of the needles, the said hemispherical mandrel assembly being fixed on to the body of the said stitching head in such a manner so as to be capable of holding a hemispherical leather cup, on which decorative stitching is to be done, onto a ball holder (13) in such a manner that the needles are perpendicular to the surface of the said hemispherical leather cup, the said ball holder being attached to an indexer assembly, (12) provided with a known encoder and electronic control capable of providing accurate preset circular indexing movements in coordination with reciprocating movements of the needles. In an embodiment of the present invention the needles are placed at a parallel distance at the order of 3 mm from watch other in an offset manner at a diagonal distance of the order of 4.6 mm. In another embodiment of the present invention, the conventional stitching head may be provided with an optical sensor fixed onto the body of the stitching head in such a manner so as to sense the needle position with respect to the leather cup. In still another embodiment of the present invention the indexer assembly being provided with a known encoder and electronic control capable of providing accurate preset circular indexing movements in coordination with reciprocating movements of the needles. The sequence operations of the novel machine is as follows: Initially the machine should be set such that the following conditions are ensured: (1) The loopers are in proper orientation with the needles. (2) The threads have proper tensions. (3) The clutch motor is in disengaged condition. One hemispherical leather segment (2) is placed over the hemispherical mandrel (I) attached to the stitching machine such that the axis of the hemispherical mandrel (1) and hemispherical leather segment (2) is properly aligned. The indexer assembly (12) is moved towards the hemispherical mandrel (1) by manually operating the pinion handle (15). Some amount of pressure is applied to the hemispherical leather segment (2) by means of pinion handle (15). The indexer assembly (12) is locked in this position by means of locking handle (16). Additional clamping pressure if required can be applied by special holding arrangement. The clutch motor (9) is initially in disengaged condition and the initial position of the needles (5) - 2 nos. is above the leather segment (2). As the machine is switched on the clutch motor (9) will be on and the clutch will move into engagement with the motor. The rotation of the motor produces reciprocating movement of the needles (5) through V belts (11), gear box (6), Timer belts (8) and linkage mechanism built into the machine. Simultaneously the motion is also transferred to the Looper shaft which produces oscillating movements of the loopers (4). Proper interaction between needles (5) and loopers (4) is necessary for proper stitching. The position of the needle above the leather segment (2) is sensed by an optical sensor fixed on the machine and sends signal to the stepper motor (17) for indexing. The stitching will be completed after 65 stitches are made on the circumference of the leather segment (2). As soon as the required counts of the stitches on the periphery is reached, stepper motor (17) stops automatically. The indexer assembly (12) is released from the lock and pushed away so that the stitched leather segment (2) can be removed from the machine. The machine of the present invention is new as there is no such machine existing which is useful for providing decorative stitching on hemispherical leather cup of a cricket ball. Therefore, the machine of the present invention is itself novel. Specifically the novelty resides in the specific manner in which it is constructed to provide the desired output of decorative stitching which is an essential part during the process of manufacture of cricket balls. More specifically, there is a clear non-obvious inventive step of providing an unique dual needle looper assembly wherein the needles are placed parallel to other but in an offset manner. The following example is given by way of illustration of the present invention.oW, Example The machine of the present invention with two needles and loopers was used to produce two parallel decorative stitches at the same time on a hemispherical leather segment using wax coated cotton thread of 20 kg breaking strength. These leather segments were supplied by one of the industries and are actually used for producing the cricket balls as per international/national standards. The specifications of the decorative stitches produced by the machine of the present invention were as follows: Total number of stitches in a single row over the circumference : 65 Distance between two rows of decorative stitches : 3 mm Diameter of the needle : 2 mm Diameter of the thread : 1 mm Thickness of the leather : 3.5 mm - 4 mm Diameter of the hemispherical leather segment : 72 mm The function of the machine was satisfactory. The main advantages of the novel machine of the present inventions are : 1. It takes about one hour to complete decorative stitching (two rows) on one hemispherical leather segment by the manual process whereas it takes about 5 minutes for the same operation by the machine of the present invention. 2. The quality of stitching is in conformity with standards laid down. 3. The quality of stitching does not depend on the skill of the operator. 4. The cost of machine stitching is much lower than that of the manual stitching. 5. There is an increase in productivity. We Claim: 1. A novel machine for decorative stitching useful in the manufacture of cricket balls which comprises, characterized in that a dual needle looper assembly essentially consisting of needles (5a) and (5b) placed parallel to each other in an offset manner having corresponding loopers (4a) and (4b) fixed in looper holders below the needles, the said needles being fixed onto needle holder (5), the said needle holder being fixed to the shaft of a conventional reciprocating stitching head provided with an optical sensor fixed onto the body of the stitching head in such a manner so as to sense the needle position with respect to the leather cup, the said loopers (4a, 4b) in looper holders (4c, 4d) being encased within a hemispherical hollow mandrel assembly (1) having an opening for the reciprocating movement of the needles, the said hemispherical mandrel assembly being fixed on to the body of the said stitching head in such a manner so as to be capable of holding a hemispherical leather cup, on which decorative stitching is to be done, onto a ball holder (13) in such a manner that the needles are perpendicular to the surface of the said hemispherical leather cup, the said ball holder being attached to an indexer assembly, (12) provided with a known encoder and electronic control capable of providing accurate preset circular indexing movements in coordination with reciprocating movements of the needles. 2. A novel machine as claimed in claims 1 wherein the needles are placed at a parallel distance of the order of 3 mm from each other in an offset manner at a distance of the order of 4. 6 mm. 3. A novel machine for decorative stitching useful in the manufacture of cricket balls substantially as herein described with reference to the example and figures of the drawings accompanying this specification.

Documents:

903-del-2000-abstract.pdf

903-del-2000-claims.pdf

903-del-2000-correspondence-others.pdf

903-del-2000-correspondence-po.pdf

903-del-2000-description (complete).pdf

903-del-2000-drawings.pdf

903-del-2000-form-1.pdf

903-del-2000-form-19.pdf

903-del-2000-form-2.pdf

903-del-2000-form-3.pdf

903-del-2000-petition-138.pdf