Field of the Invention:-

The present invention is in the field of conventional lathe and it relates to operator safety aspects while working on lathe.

Objective of the Invention:-

The main objective of the invention is to provide safest working condition in turning center by using fool proof method.
The second objective is to avoid mishandling of chuck key while lathe is in running condition.

Background of the Invention:-

In the field of manufacturing lathe plays a major role in performing various operations like turning, facing, grooving, threading, etc... During time of working in lathe, there is a chance for accidents to occur due to switching ON a lathe without removing of chuck key from lathe chuck due to operators carelessness/ignorance. This makes thrown up of chuck key in the direction of operators position and leads to severe accidents. So, there is a necessity to avoid such a kind of accidents occurring due to operators carelessness/ignorance. In order to avoid such accidents simple mechanism used foolproof device is designed to hold and lock the chuck key safely away from lathe chuck with the help of circular clamp and rotary cam operated electrical switch.

Description of the Prior Art:-

The present invention is unique and better than prior inventions. Like the prior art of DE4313003 (Al) describes the machine can only start when the chuck key is put away in the chuck-key holder. For that inductive proximity switches are used to sense damping surfaces (coating) of the chuck key in such a way that the electric circuit of the machine is closed.
The another art of US3761654 (A) describes to start the machine the chuck key is to be put in the notch and rotate it to activate the micro switch by using leaf spring which slides over the chuck key when it is rotated. Whereas the present invention uses rotary cam operated electrical switch to control the ON/OFF of power source and said mechanical circular clamp is used to lock and hold the chuck key safely when the lathe is running.

Summary of the Invention:-

The present invention relates to the safety aspects of operator while using of chuck key to tighten and loosen the chuck to hold the work piece. The present device is safer than existing device mechanisms like leaf spring activated micro switch, etc... The present device consists of a simply designed circular clamp to lock the projection given in the chuck key and rotary cam operated electrical switch to close and open the electrical circuit based on the locked and unlocked position of projection in chuck key. By setting this device made essential to remove chuck key from chuck and insert it into the circular clamp. After inserting the chuck key into the circular clamp, it needs to be rotated clockwise about 90° which in turn rotates the rotary cam operated electrical switch to close the electrical circuit. At the time of rotating chuck key in clockwise direction about 90°, the projection given in the chuck key automatically gets locked into the L-shaped slots given in the circular clamp. So it adds additional safety of preventing removal of chuck key from present device during lathe is operating. Suppose one wants to remove chuck key from present device, it should be turned in counterclockwise direction about 90°, which causes electrical circuit to open as a result lathe spindle gets stopped.

Detailed Description of the Invention:-

The present device consists of circular clamp; rotary cam operated electrical switch and lathe chuck key with projection perpendicular to the central axis of wrench. The circular clamps used here have L-shaped slots on opposite sides of the circular wall. When the chuck key is inserted into the circular clamp, the projections given in chuck key will get slide through vertical portion of the L-shaped slots and get mating on small groove given in the outer circular ring which is coupled with the circular clamp. The circular ring, which is coupled with circular clamp, has two sets of holes in opposite sides of the circular wall in order to fix the electrically insulating connector which is connected to the shaft of rotary cam switch. The circular ring and shaft of rotary cam switch are connected with electrically insulating connector with the help of bolts and nuts. Therefore the use of electrically insulating connector prevents from electrical contact happening between metal surfaces of the circular ring and shaft of rotary cam switch. When the chuck key is inserted and rotated about 90° in clockwise direction, this motion will be transmitted to shaft of rotary cam switch through circular ring and electrically insulating connector. Due to this 90° rotation of rotary cam switch shaft, the electrical circuit gets closed and lathe motor gets switched ON. At this time the projections given in the chuck key get locked into the L-shaped slots. This prevents removal of chuck key from present device when lathe spindle is in rotating state that adds additional safety to the operator.

Suppose one wants to remove chuck key from the circular clamp, chuck key should be rotated about 90° in counterclockwise direction so that the rotary cam switch shaft also rotates counterclockwise direction about 90°. Therefore the electrical circuit gets opened and lathe motor is switched OFF. At the same time the projection in chuck key gets unlocked and it can be taken off from the circular clamp/present in the device.

Brief Description of the Drawing:-

Fig 1 shows the front view of conventional lathe with present device.

Fig 2 shows the side view of complete assembly of the present device.

Fig 3 shows the front view of chuck key with projection on its wrench.

Fig 4 shows the front view of assembly of circular clamp with circular ring and electrically insulating connector.

Fig 5 shows the block diagram of electrical connections. Detailed Description of the Drawings:-

Fig 1 shows the front view of conventional lathe that consists of present device (2) and the lathe chuck key (1). And this illustrates the position of present device (2) in the lathe and explains how to move chuck key (1) from lathe chuck socket (3) of present device (2). Fig 2 shows the side view of present device (2) with chuck key (1), circular clamp (12), circular ring (10), electrically insulating connector (8) and rotary cam operated electrical switch (6). The circular clamp (12) is inserted into the circular ring (10) with sliding contact between them. Then it is coupled with electrically insulating connector (8) and shaft (7) of the rotary cam switch (6) with the help of bolts and nuts. In this assembly, the circular clamp (12) and rotary cam switch (6) are attached with base frame (5) for supporting with the help of small links (4). When the chuck key (1) is inserted into the circular clamp (12), the projection (11) given in chuck key (1) along radial direction will slide through the L-shaped slots (13) which are given in opposite directions of the circular clamp (12). At the bottom of L-shaped slots (13) the projections (11) on the chuck key (1) mate with small groove (14) provided on the circular ring (10) which is in sliding contact with circular clamp (12). If the chuck key (1) is rotated clockwise direction about 90° the same 90° clockwise rotation is transmitted to circular ring (10) through projection (11) given in chuck key (1) and groove (14) in circular ring (10). In turn, this 90° clockwise rotation is given to shaft (7) of rotary cam switch (6), through electrically insulating connector (8), which 1 is attached with circular ring (10) by using bolts and nuts. Due to this 90° clockwise rotation of rotary cam switch (6), electrical circuit gets closed; correspondingly lathe motor gets switched ON. The locking of chuck key (1) projection (11) in L-shaped slots (13) prevents removal of chuck key (1) when lathe is in running state and also it holds chuck key safely. Suppose one wants to remove chuck key (1) from the present device (2), it should be turned through 90° in counterclockwise direction and pulled upward. This makes relieving of projection (11) in chuck key (1) from groove (14) of the circular ring (10). Similarly, the rotary cam switch shaft (7) rotates in counterclockwise direction about 90° which makes the electrical circuit to open, and switch OFF the lathe motor. Fig 3 shows the front view of chuck key (1) in which the small square shaped projection (11) is placed perpendicular to its center axis. The projections (11) are placed nearer to the chuck key end (19). These projections (11) help to lock the chuck key (1) safely in the circular clamp (12) during switching ON of lathe motor.

Fig 4 shows the front view of assembly of circular clamp (12), circular ring (10) and electrically insulating connector (8). Here the circular clamp (12) is inserted into the circular ring (10) so that the external step in circular clamp (12) properly mates with internal step provided on circular ring (10), in order to hold the circular clamp (12) in position and to provide a sliding contact. One side of electrically insulated connector (8) which is used to couple circular ring (10) and rotary cam switch shaft (7) is fixed on circular ring (10) with bolts and nuts. And another side of connector (8) is coupled with shaft (7) of rotary cam switch (6) with the help of bolts and nuts. The additional projecting hollow circular surface (9) given in the electrically insulated connector (8) is used to provide necessary support to the circular clamp (12) and hold in proper position. Finally, it all results transmitting of 90° rotation whether in clockwise or counterclockwise direction from chuck key (1) to shaft (7) of rotary cam switch (6) and at the same time it helps to lock the chuck key (1) when lathe motor is in ON condition. Fig 5 shows the block diagram of electrical connections. It shows when the chuck key (1) is in unlocked condition the electrical circuit gets open and lathe motor is switched OFF and the chuck key in locked condition closes the electrical circuit and supply electrical power to the lathe motor.

Claims:-

The embodiment of this design in which an exclusive privilege is claimed are defined as follows

1) The present device (2) consists of a circular clamp (12), circular ring (10), rotary cam switch (6), electrically insulating connector (8) and chuck key (1) with projection (11).

2) As per claim 1, where in chuck key (1) has square shaped projection (11) perpendicular to its center axis and it is placed nearer to the chuck key end (19). These projections (11) in chuck key (1) are provided to lock the chuck key (1) in circular clamp (12) when lathe is in running condition.

3) As per claim 2, where in circular clamp (12) have L-shaped slots (13) with groove (14) on circular ring (10). This groove (14) in circular ring (10) helps to transmit 90° rotation whether in clockwise/counterclockwise direction from chuck key (1) to shaft (7) of rotary cam switch (6) through electrically insulated connector (8).

4) As per claim 3, where in electrically insulated connector (8) is coupled between circular ring (10) and shaft (7) of rotary cam switch (6) for providing mechanical contact between them.

5) As per claim 4, where in rotary cam operated electrical switch (6) have cam and electrical connectors. When cam is turned 90° clockwise direction electrical connector gets contact with power source and switch on the lathe motor and vice versa.