Safety System And Method

Abstract

A safety system and method for operating a machine by an operator. The operator must initially interrupt a light beam with both hands to activate a first switch. This initiates a first time delay interval. Within this first time interval the operator must strike two palm button switches before the machine will operate.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to the field of methods and apparatus for providing safety to an operator of machinery.

2. Prior Art

Safety devices to prevent injury during operation of a machine are known in the art. In some prior devices, the operator activates a swich remote from the machine working area to operate the machine. However, with only one switch the operator only needs one hand to operate the machine. Therefore, the operator may carelessly stick the other hand or another part of his body in the machine working area during operation, possibly causing serious injury. Operators have been known to jam the single switch in an activated operating mode. This causes continuous action of the machine resulting in an increased possibility of injury.

In other prior devices, the operator activates a pair of switches in order to operate the apparatus. However, the operator may use one hand to consecutively activate each switch, allowing one hand to remain free. The free hand then may be injured in the machine working area.

Other devices using two switches mounted remote from the working area are time delay connected. Each switch must be activated within a predetermined time of the other in order to operate the machine. If the time delay is short enough, the operator theoretically must use both hands to operate the machine. However, in their desire to increase machine productivity, operators can make a device which when held in one hand is capable of striking both switches simultaneously. This leaves one hand free wich may be caught in the working area of the machine during operation.

In other prior devices, the working area of a machine may be protected by a guard during the machine operating cycle. However, such guards are often removed by the operators because it is sometimes a cumbersome task to insert the working piece around the guard. When a guard is placed in combination with two machine activating switches, both switches may still be activated by a device held in one hand of the operator, thus leaving one hand of the operator free which may result in injury.

SUMMARY OF THE INVENTION

A method of safely actuating a power operated machine through movement of an operator's hand by maintaining the operator's hands external to a working area of the machine. A first switching mechanism displaced from the working area is actuated by the operator's hands for initiating a first time interval. A pair of switching mechanisms displaced from the working area and positioned adjacent to the first switching mechanism is then actuated by the operator's hands within the first time interval for operating the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective drawing of a section of an apparatus showing the safety system mounted thereon;

FIG. 2 is a perspective blow-up view of an operator's hand passing through a light operated switch prior to the striking of a palm button; and,

FIG. 3 is an electrical schematic diagram of the safety system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2, there is shown a press or other power operated machine 10 which may only be operated by use of palm buttons 12, 14 in combination with photooptic devices 16, 18 within a predetermined time interval. The purpose of safety device 22, shown schematically in FIG. 3, is to prevent an operator from inserting his hands 11 or other parts of the body within work area 20 when machine 10 is operational. Additionally, sonic or laser mechanisms 21 prevent operation of system 10 when other portions of the operator's body come dangerously close to work area 20.

In general, the operator to actuate system 10 must pass his hands through light paths between 16, 16' and 18, 18.varies.. The breaking of at least one light path initiates a time interval during which machine 10 may be operated. However, operation can only be established by also striking or otherwise closing palm buttons 12, 14 during the light path initiated time interval.

As will later be described in detail, four points of contact must be made before machine 10 will cycle. The points of contact are controlled by time delay relays on each point which may be set from a time of zero to a maximum time interval determined by the particular relay circuit being used. If anyone of the four points is activated without the other cooperative points, safety device 22 will automatically lock machine 10 and not permit operation. The operator must then remove his hands and begin the activation process again.

Both appendages which includes hands or limbs of the operator must consecutively interrupt light path 56 and within a predetermined time interval palm buttons 16, 18. Fiber-optic devices 16, 18 have a first time delay interval associated with them that allow operation of machine 10 only when palm buttons 16, 18 are pressed. Each of buttons 16, 18 has a respective second and third time interval delay within which time one switch 16 or 18 must be actuated with respect to the other. This is conditionally based on the fact that both of switches 16 and 18 must be actuated within the first time interval delay defined from the interruption of light path 56.

The time delay for each switch mechanism may be adjusted over a range dependent on the particular time delay relay being used. As an example, assume that fiber optics device relay is set for half a second and devices 16, 18 are set for a quarter of a second. Then the operator has a total time of one half a second to pass his hands 11 through light paths 56 and depress both palm buttons 12, 14. Additionally, each of palm buttons 12, 14 must be depressed within one quarter of a second of each other in order to operate machine 10.

FIG. 3 is an electrical schematic diagram of safety device 22 in line with power operated machine 10. In operation, motor disconnect switch 24 is engaged in a normally closed position as is shown. This closes motor switch 26 which is in line with motor starter relay 28. This in turn closes normally open motor start switch 23.

However, the apparatus system motor may not be activated until instantaneous start switch 30 is closed. This activates relay 32 which is connected to nodal line points 34, 36, 38, and 40. Relay 32 closes relay switch 25, thereby providing a closed electrical path from node 27 through stop switch 29, normally closed sonic or laser switch 31, motor start switch 23 and relay switch 25. Start switch 30 then returns to its normally open state, however, relay 32 remains actuated through the now closed path from node 27 to relay 32. It should be noted that when the operator's body intersects the path between mechanisms 21, shown in FIG. 1, switch 31 is opened. This breaks the electrical path to relay 32 and apparatus 10 will not operate irrespective of the fact that the operator intersects light beams 54, 56 and presses palm buttons 12, 14 in the prescribed time intervals. Additionally, actuation of relay 32 closes normally open motor switch 42 as well as switch 44. Further photo-optic power input switch 48 is closed providing power to photo-optic unit 50. With motor switches 26 and 42 closed, the motor of machine system 10 is activated. In order to show that the motor has been activated, light 46 being electrically connected to relay 32 at node 34 is turned on. Actuation of light 46 provides a visual manifestation that motor starter 28 has been actuated and that operation of safety device 22 will ensure cycling of apparatus system 10.

As has been described, the basic object of safety device 22 is to permit cycling of machine 10 only when the operator's body is out of work area 20. In order to accomplish this, the operator must activate both sets of switches 16, 18 and 12, 14 within a predetermined time interval. When the two sets of switches are activated in the prescribed time interval, machine 10 is energized and may pass through a cycle of operation. Energization essentially consists of closing switches 62, 64, 66, 68, 70 and 72 at one point in time such that a continuous current passes from node 52 to 38. The following state table provides a time-line base showing the condition of each switch at each point in the system operating process. ##SPC1##

The safety device state table is explained in relation to schematic FIG. 3 and electrical time-line flow in the following paragraphs. Initially, the operator passes his hands through displaced light paths 54, 56 of photo-optic unit 50. This closes switch 58 which activates time delay relay 60. Time delay relay 60 is connected to optic switches 62 and 64. At an initial time, switch 64 is closed and switch 62 is open. Once beams 54 and 56 have been interrupted, switch 62 is moved to a closed position. thus completing a portion of the circuit between nodal points 52 and 38. Time delay relay 60 maintains switch 64 in a closed position for a predetermined time interval between time lines B and D on the state diagram. The operator must now close switches 70 and 66 during this time interval or switch 64, responsive to time delay relay 60, will open driving safety device 22 to a de-energized state and breaking the circuit between nodes 52 and 38 analagous to a condition shown in time-line E of the state table.

The operator must now close switches 70 and 66 within the time interval defined by time delay relay 60. Assume the operator strikes palm button 14 first (time-line C of the state table). This actuates timer relay 74 which is connected to switches 70, 72. Immediately, switch 70 is closed completing another portion of the circuit between nodal points 52 and 38. Switch 72 is thus maintained in a closed position throughout a time interval defined by time delay relay 74. At the conclusion of this time interval, switch 72 will open as is shown in time-line F of the state table. Once switch 72 is open, irrespective of the condition of any other switch conditions, apparatus system is deenergized.

Finally, the operator strikes palm button 12 which is connected to time delay relay 76. This has the effect of instantaneously closing switch 66 and maintaining switch 68 in a close state for a predetermined time interval. Once switch 66 has been closed, a continuous electrical path is now achieved between nodes 52, 38 and the current flow actuates machine 10 through an operating cycle. In this state, power operated machine 10 is energized, where all switches 62, 64, 66, 68, 70 and 72 are closed (shown in time-line E of the state table).

When machine 10 has reached a predetermined point in its cycle, timers 60, 74 and 76 are reset to an initial condition. Further, switches 62, 64, 66, 68, 70 and 72 are reset to the initial condition shown as time-line A of the state table. The resetting of the relay and switch elements may be accomplished by a cam reset or like technique well known in the art. In this way only one cycle of system 10 can be achieved by the operator without the necessity of having to begin the time-line operations detailed in the state table.

Although machine 10 is dependent on safety device 22 for a cycling operation, the machine may be moved through only a portion of a cycle by using jog switches 78. In this mode of operation, disconnect switch 24 may be positioned to a manual setting whicn in turn closes jog manual switch 80. This opens motor switch 26 and closes manual switch 82, In this way open relay switch 42 is bypassed and motor starter 28 is actuated. Further normally closed operation switch 84 is opened and manual switch 86 is closed. As is seen when jog switches 78 are closed, current flows in continuous fashion to node 38 providing actuation of machine 10.

Photo-optic device 50 and sonic or laser mechanism 21 mounted on machine 10 are well known in the art. One type of optic device 50 which has been used successfully is Model 32 - 37.intg.15 manufactured by Bausch & Lomb, Inc. One type of sonic device 21 is manufactured by Asco Fluidic Controls MOdel 6090165.

Claims

1. A method of safely actuating an apparatus through movement of appendages of an operator's body by maintaining said appendages external to a working area of said apparatus, including the steps of:

a. actuating a first switching means displaced from said working area with said operator appendages for initiating a first time interval; and

b. actuating a pair of switching means displaced from said working area and positioned adjacent said first switching means with the same operator appendages used to actuate said first switching within said first time

2. The method of safely actuating an apparatus as recited in claim 1 wherein said operator appendages must be continuously moved from said first switching means to said pair of switching means in a nonintersecting

3. The method of safely actuating an apparatus as recited in claim 1 wherein the actuating steps include the steps of contacting each of said

4. The method of safely actuating an apparatus as recited in claim 1 wherein movement of said apparatus in said working area is prevented when one of said pair of switching means is actuated after said first operable

5. The method of safely actuating an apparatus as recited in claim 1 wherein movement of said apparatus in said working area is prevented when at least one of said pair of switching means is actuated before said first

6. A system for safely operating an apparatus by an operator, comprising:

a. first switching means operably connected to said apparatus for initiating a first time interval upon actuation of said first switching means by an appendage of the body of said operator; and

b. a pair of second switching means operatively connected to, and positionally located with respect to said first switching means in a manner such that the same operator body appendage must actuate said first switching means prior to said second switching means for operation of said apparatus, and means whereby said apparatus is operable only when both of said second switching means are actuated during said first time interval.

7. The system for safely operating an apparatus by an operator as recited in claim 6 wherein said first switching means includes light means to detect movement of said appendage of said body of said operator for

8. A method of providing safety in activating a system by an operator including the steps of:

a. manually actuating first switching means for initiating a first time delay interval;

b. manually actuating second switching means within said first time interval for initiating a second time delay interval; and

c. manually actuating a third switching means for operating said system only when said third switching means is activated within said first and

9. The method of providing safety in activating a system by an operator as recited in claim 8 wherein the actuating steps include the steps of activating each of said switching means remote from a working area of said

10. The method of providing safety in activating a system by an operator as recited in claim 8 wherein the actuating steps include the steps of actuating each of said switching means consecutively, responsive to the movement of an operator's limbs.