This invention relates to grinding apparatus particularly, but not necessarily, for grinding flat the ends of cylindrical articles, for example coil or helical compression springs, the ground ends being perpendicular to the central axis of the article.

The process of grinding coil springs can often be the operation in the manufacturing process involving the longest time duration and therefore means to reduce the time period required would be beneficial from a manufacturing cost consideration.

Heretofore, manufacturers who manufacture large numbers of identical springs use special purpose dedicated grinding machines which grind boths ends of a coil spring simultaneously in large batches. However these machines are expensive to purchase, operate and maintain and are not flexible in the quantities they can economically produce and are therefore unsuitable for batches of springs from, for example 1 to about 1 ,000 springs, ie. quantities which may be required by a small engineering or business enterprise. There is a large market for supplying springs of differing sizes and lengths in small batches. This market is presently being serviced by conventional surface grinding machines which are general purpose machines which are not designed

around the problems peculiar to grinding, for example springs.

Accordingly, the present invention is a grinding apparatus comprising an article holder, a grinding device, and means to transfer an article from the holder, clamp same in a determined fashion and present an end of the article to the grinding device, the ground article thereafter being ejected into a collection facility. Preferably, the apparatus is mounted on a structure having an elongate top on or along one elongate side of which the holder and the grinding device are mounted in spaced relation with the transfer means comprising a carriage tracking a first set of rails lengthwise of the top, the carriage being movable along the rails between the holder and a grinding position. The movement of the carriage is desirably controlled by a first ram and cylinder arrangement. The carriage desirably mounts a second set of rails at right angles to the first set, the rails being tracked by a sub-carriage on which clamping means are carried. The movement of the sub-carriage is beneficially controlled by a second ram and cylinder arrangement. The top is preferably a table top having an upstanding rim therearound.

Preferably also, the grinding device is an endless

belt arrangement with the outer surface of the belt having an abrasive coating. The arrangement is desirably positioned uprightly with the forward flight direction downwardly. The belt is desirably entrained between two vertically spaced rollers with a tensioning device provided to maintain the tension in the belt, such tensioning device may be a jockey roller acting against the rearward flight.

Preferably further, the clamping means comprises a horizontally-oriented elongate housing having an open bottom of width to allow passage of an article, the housing having internally thereof two or more gripping members. The gripping members are desirably of similar length to the housing and are of arcuate cross-section or substantially so. Two members are provided and preferably lie in a horizontal plane with one member fixed and the other member movable towards and away from the one member. The movement of the other member may be controlled by a third ram and cylinder arrangement. The clamping means beneficially has an oscillating mechanism to oscillate an article against the belt while its end is being ground. The oscillating mechanism may comprise a shaft co-axial with the housing and extending therefrom, the shaft having an arm projecting radially therefrom to be linked to a fourth ram and cylinder arrangement for providing reciprocating movement to oscillate the housing and therefore any

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article held therein.

The holder preferably has a chuck for gripping an article extending therefrom. Alternatively, the holder is a horizontally-oriented endless chain belt arrangement on which a plurality of grippers to which articles are removably attached is provided in a determined spaced relationship along upper and lower flights of the chain belt arrangement, movement of the chain belt arrangement being indexed to bring each gripper and article in turn into a selected transfer position.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying illustrative drawing, in which:- Fig. 1 shows a perspective view of a grinding apparatus with parts cut away for clarity;

Fig. 2 is a perspective view of an alternative holder; and

Fig. 3 is a perspective view of a clamping means. Referring to the drawing, a grinding apparatus for grinding one end of cylindrical articles, ie. coil or helical springs in this embodiment, comprises a spring holder 10, a grinding device 12 , and means to transfer a spring 14 from the holder 10 , clamp same in a determined fashion and present an end of the spring 14 to the grinding device 12. The ground spring is

thereafter ejected into a collection facility, ie. a tray and extension guides 16.

The apparatus is mounted on a structure 17 having an elongate table top 18 having an upstanding rim 20 therearound. On or along one elongate side of the top

18, the holder 10 and the grinding device 12 are mounted in spaced relation as shown with the transfer means comprising a carriage 22 tracking a first set of rails 24 lengthwise of the top 18. The carriage 20 is movable along the rails 24 between the holder 10 and a grinding position. The movement of the carriage 22 is controlled by a first ram and cylinder arrangement 26. The carriage 22 mounts a second set of rails 28 at right angles to the first set 24, the rails 28 being tracked by a sub- carriage 30 on which clamping means are carried. The movement of the sub-carriage 30 is controlled by a second ram and cylinder arrangement 32.

The grinding device 12 is an endless belt arrangement with the outer surface of the belt 34 having an abrasive coating. The arrangement is positioned uprightly as shown with the forward flight direction downwardly. The belt 34 is entrained between two vertically spaced rollers 36 (only one being shown) with a tensioning device such as, as shown, a jockey roller 38 acting against the rearward flight of the belt 34 to maintain tension in the belt 34 under control of a piston and cylinder arrangement 38A. A plate 34A is

provided behind the belt 34 at that area, ie. grinding position, against which a spring 14 is presented for grinding. The grinding device 12 is housed in a casing 40. A manifold 56 to receive coolant is provided on the front of the casing 40 above the grinding area with a series of downwardly directed spray outlets to lubricate and carry away grindings from the spring being ground and a collector 58 is provided below the grinding area to collect the grindings-entrained coolant to carry away to waste or filtering and recycling.

The clamping means comprises a horizontally- oriented elongate housing 42 having an open bottom of width to allow passage of a spring 14. The housing 42 has internally thereof two or more gripping members 44A, 44B (only two being used in this embodiment). The gripping members 44A, 44B are of similar length to the housing 42 and are of arcuate cross-section or substantially so. The members 44A, 4B are opposed to each other and lie in a horizontal plane with one member 44A fixed and the other member 44B movable towards and away from the one member 44A. The movement of the other member 44B is controlled by a third ram and cylinder arrangement 46. The clamping means has an oscillating mechanism to oscillate a spring 14 against the belt 34 while its end is being ground. The oscillating mechanism comprises a shaft 48 co-axial with the housing 42 and

extending therefrom. The shaft 48 has an arm 50 projecting circumferentially therefrom to be linked to fourth ram and cylinder arrangement 52 for providing reciprocating vertical movement to oscillate the housin 42 and therefore a spring 14 held therein. The arrangement 52 is carried on the sub-carriage 30. The holder 10 has a chuck 54 for gripping a spring 14 extending horizontally therefrom. In a modification, the holder 10A is a horizontally-oriented endless chain belt arrangement on which a plurality of grippers 60 to which springs 14 ar removably attached is provided in a determined spaced relationship along upper and lower flights of the chain belt arrangement. Movement of the chain belt arrangemen is indexed to bring each gripper 60 and spring 14 in turn into a selected transfer position.

The sequence of steps of the ram and cylinder arrangements 26, 52, 46, 32 and 52 are arranged in casade fashion. For use, the apparatus is switched on from a powe source, ie. mains or generated electric power, and with the belt 34 rotating and arrangement 38A of the tensioning device extended, the sub-carriage 30 extends along rails 28 away from the belt 34 under control of the arrangement 32, and then the carriage 22 extends along the rails 24 towards the holder 10 under control of arrangement 26. The ram of the ram and cylinder

arrangement 32 is extended for the housing 42, at the end of the extension of the ram of arrangement 26, to overlie the spring 14 in the holder 10, 10A. The ram of arrangement 46 originally in a retracted position is extended to clamp the spring 14 between members 44A,

44B. The clamping position is such that the members 44A, 44B grip the spring as close to the end to be ground as is practicable. The carriage 22 then is returned towards the grinding position and sub-carriage 30 is moved towards the grinding position at which stage the arrangement 52 starts to reciprocate causing oscillation of the housing 42 and spring 14 therein. In this position, the end to be ground has been presented to the belt 34 and the oscillation movement assists in the grinding process. The grinding process is complete when the carriage 22 reaches a fixed stop position provided on the top 18. The sub-carriage 30 then is moved away from the belt 34, the oscillation is stopped and the ram of arrangement 46 retracted allowing the spring 14 to drop onto the tray and guides 16 for subsequent collection. During this sequence of steps, the holder 10 is recharged with another spring or the holder 10A is indexed forwardly to present another spring. The sequence of steps is repeated as often as is required. After being ground on one end, the springs can be represented for grinding on the other end, if required.

Coolant can be used in manifold 56, if required, during the grinding process.

In a modification, the tensioning device comprise only the piston and cylinder arrangement 38A acting on the top roller 36 to move the top roller away from the bottom roller thereby tensioning the belt.

Variations and modifications can be made without departing from the scope of the invention described.