US 3861016 A
A guard is movably mounted in a machine adjacent to shiftable operating mechanism potentially capable of injuring an attendant as by clamping his hand when it is inadvertently interposed between the operating mechanism and some other portion of the machine. A safety circuit associated with the guard includes a switch means responsive to guard contact with an obstruction, and/or to manual displacement of the guard in any of several directions whereby the operating mechanism is at once deactivated and injury avoided. One advantageous embodiment of the invention, for instance, is in an automatic component inserting machine wherein the head and/or the work support is programmed for relative traverse.
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Description (Le texte OCR peut contenir des erreurs.)
United States Patent Johnson et al.
ELECTRIC SAFETY CONTROL MECHANISM Inventors: Herbert Johnson; Frederick S.
Sillars, both of Beverly, Mass.
Assignee: USM Corporation, Boston, Mass.
Filed: Nov. 19, 1973 Appl. No.: 417,417
US. Cl. 29/203 B, 83/544 Int. Cl. HOSk 13/04, B26d 5/08 Field of Search 29/203 8, 203 R; 83/544,
References Cited UNITED STATES PATENTS 9/1972 Pickles 83/544 X 3/1974 Connors et al. 83/546 X Primary Examiner-Thomas H. Eager Attorney, Agent, or FirmCarl E. Johnson; Vincent A. White; Richard B. Megley  ABSTRACT A guard is movably mounted in a machine adjacent to shiftable operating mechanism potentially capable of injuring an attendant as by clamping his hand when it is inadvertently interposed between the operating mechanism and some other portion of the machine. A safety circuit associated with the guard includes a switch means responsive to guard contact with an 0bstruction, and/or to manual displacement of the guard in any of several directions whereby the operating mechanism is at once deactivated and injury avoided. One advantageous embodiment of the invention, for instance, is in an automatic component inserting ma chine wherein the head and/or the work support is programmed for relative traverse.
10 Claims, 8 Drawing Figures ELECTRIC SAFETY CONTROL MECHANISM BACKGROUND OF THE INVENTION This invention relates to safety mechanism and more especially to a combination guard device and responsive circuitry for deenergizing operating portions of a machine.
Various devices have hitherto been provided for insuring that, in the course of the relative movement of approach of machine parts accidental interpositioning of an obstruction or of a limb will not result in damage or injury. One well-known expedient is the resort to socalled dead man controls. Another approach, for example, is disclosed in US. Pat. No. 3,690,206 issued Sept. 12, 1972. There a cutting press has its vertical head movement toward work to be cut terminated by an arm leading the head contacting an obstruction, and a switch for controlling drive of the head is consequently actuated adequately in advance of a position wherein damage would otherwise be incurred.
Where several portions of a machine are simultaneously relatively movable and their movements of approach can occur at different localities and perhaps with different speeds, there is likely to be an increased risk of personal injury encountered. Thus, for instance, where a workpiece is programmed for horizontal X-Y coordinate movements and an operating head has parts reciprocating vertically thereabove with possibly additional cooperating mechanism in motion below the level of the workpiece, there is a potential danger that a finger, hand, or even an arm may be caught between convergent power driven machine elements. Consequently a need exists for insuringthe safety of an operator (and in some situations the safety of the equipment also) against his unintended interference with automatic machine functions. Even the experienced operator who may become overly familiar with the machinery should welcome the protection afforded by an untiring auxiliary surveilance mechanism watchful of operations from more than one point of view.
SUMMARY OF THE INVENTION The present invention resides in a novel combination, in an apparatus having elements with relative movement of approach, of a displaceable guard member and associated safety control circuitry connected to means driving the elements, the circuitry including a switch responsive to movement of the member in any one of several directions for immediately deenergizing the drive means and terminating motion of the elements. As herein shown the guard member is mounted as a fence about operating instrumentalities or about a single, otherwise exposed tool and has freedom to yield laterally, heightwise, fore and aft and pivotally about an axis. In any one or more of these guard displacements from a normal operating position, as may be occasioned for instance by the presence of an unwanted obstruction or the limb of an operator, a switch is responsively actuated to deenergize the drive of the apparatus. The guard member may be at least partly transparent so that ones view of the operation is not impaired. Advantageously, the member may be automatically returned to its neutral position as by spring means whereby machine operation is restored as soon as the interferring item is cleared from. the operating zone.
It may be noted that where equipment has more than one potential danger zone a second or additional fencelike guard of the type herein disclosed may be utilized and have operative connection with a common safety control circuit.
BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention will now be more particularly described in connection with an illustrative embodiment and with reference to the accompanying drawings thereof, in which:
FIG. 1 is a perspective view of a portion of a machine provided with our electric safety control mechanism, the machine in this instance-being designed to install electronic components in printed wiring boards;
FIG. 2 is a view in front elevation of a portion of the control mechanism shown in FIG. 1 including a guard and an associated switch mechanism;
FIG. 3'is a plan view of the mechanism shown in FIG.
FIG. 4 is an enlarged plan view of the switch shown in FIGS. 2 and 3;
FIG. 5 is a view similar to that of FIG. 4 but with a switch actuating arm shown tilted by displacement of the guard;
FIG. 6 is an end view of the mechanism shown in FIG. 5;
FIG. 7 is a perspective view showing the guard and switch mounting, and
FIG. 8 is a diagram of a safety control circuit responsive to displacement of the guard.
DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1 an electronic component inserting apparatus 10 comprises an insertion head generally designated 12, work supporting means such as a pallet 14 movable in X-Y coordinates for carrying a printed circuit board (not shown) in its own horizontal plane, and lead clinching mechanism 16 operable beneath the printed circuit board for clinching the protruding ends of the leads which may have been cut, formed and then thrust endwise by the head 12 through preformed holes of the board held on the pallet by spaced clips 18,18 (only one shown). By means not herein shown, the pallet 14 may be manually shifted horizontally as required or automatically programmed by means not herein shown; alternatively the head 12 may be programmed for X-Y movement relatively to the board, or both the pallet and the head may be respectively shifted in horizontal planes. In FIG. 8, a motor driving means associated with the head and/or the pallet is schematically shown at M.
In using the apparatus 10, an attendant customarily may, for instance, place successive circuit boards on the pallet 14 to be releasably held thereon by the spaced clips 18. The head 12 comprises vertical guides 20,20 between which operating mechanism collectively and generally designated 22 (including perhaps such instrumentalities as cyclically operable lead cutters, guides, formers and driver bars) move reciprocably toward and from the board (and sometimes horizontally as well) to mount the successive components thereon in cooperation with the vertically reciprocable mechanism 16, the board intermittently being shifted horizontally with the pallet by appropriate drive means (not shown) to receive the component leads. Of the mechanism 22, only the lead guides 23 for a so-called DIP Component are shown in FIG. 1. The lead clinching mechanism 16 (FIG. 1) is shown in its lower or retracted position to be clear of the pallet 16 but is cyclically movable upwardly nearly to the receiving locality of the board to clinch protruding ends of the inserted leads. It will accordingly be appreciated that, as is typical with many different types of machinery, operating conditions are such that without a safety mechanism herein generally designated 24 and about to be disclosed, an operators arm A or hand H can be injured if caught in the convergent paths of any two relatively moving parts or between a moving element and a stationary one.
To avoid risks and injury of the sort indicated, the safety mechanism 24 comprises a fence or guard 26 (FIGS. l-3 and 7) mounted on the head 12 as will be described and associated circuitry controlled by the guard as will later be explained. The guard 26 is in this instance serving as a fence for the head 12 and hence extends in front of the head and about the zone of operation of the operating instrumentalities 22. Although in another application of the invention the shape of the guard 26 may appropriately be different, it is here rectangular and box-like, preferably having its front side provided with a transparent material 28 affording a window on the operating elements.
The guard 26 is pivotally supported for relative lateral movement on coaxial horizontal trunion pins 30 (FIGS. 2 and 7) and 32 (FIGS. 1 and 2) by means of upwardly extending angular arms 34,36 respectively projecting from rearward side extensions 35,35 (FIGS. 1, 3) of the guard 26. For this purpose, the pin 32 is carried by the lower end of a bracket 38 fixedly secured to the right side of the head 12 as shown in FIGS. 1-3, and the pin 30 projects from the left side of the head to have its outboard end received in the lower end of a bracket 40 affixed to the head. The guard 26 is yieldably urged against gravity into horizontal position by a spring plunger 42 (FIGS. 3 and 7) adjustably carried by a block 44 affixed to the guard side 35, the free end of the plunger abutting the lower end of the head 12. For urging the guard 26 to yieldably assume a neutral lateral position with respect to the head 12, the upper end of the arm 34 is slidably and pivotally received by the pin 30 between a pair of oppositely acting springs 46,46 (FIGS. 2 and 7) mounted on the pin, one spring having ends confined between the head and arm 34, and the other spring having its ends confined by the arm 34 and the lower end of the bracket 40.
From the foregoing, it will be understood that the guard 26 is movable with the head 12 in any direction and also relatively displaceable laterally of the head in opposite directions as well as heightwise and fore and aft thereof from a horizontal or neutral position. As will next be described this freedom of relative movement of the guard upon displacement is advantageously used to effect immediate deenergization of drive means M upon signal from a control or computer C (not herein shown except schematically) connected to the head 12, the mechanism 16, and/or the pallet 14 through a safety control circuit shown in FIG. 8, the drive means beingactuated and deactivated through operation of a switch assembly generally designated 50 (FIGS. 1-7) of the safety circuit and responsive to the positioning of the guard with respect to the head and its operating instrumentalities. The switch assembly 50 is adjustably secured on the bracket 40 by screws 52,52 (FIGS. 4 and 5) extending through transverse slots 54,54 respectively formed in the switch. The assembly 50 comprises a left hand normally closed, held open switch 56 having a contact 58, an actuating arm 60, and a roller 62 carried by an end of the arm 60, and a right hand normally open switch 64 similarly having a contact 66, an actuating arm 68 and a roller 70 carried by an end of the arm 58. For operating the switches 56,64 (which are electrically connected in parallel as shown in FIG. 8) by means of displacement of the safety guard 26 from its normal neutral" position, an L-shaped actuator 72 (FIGS. 4-7) is fixedly secured at one end to the arm 34 as by a bolt 74 and a nut 76. The free end of the actuator 72 is generally flat except for a recessed arcuate portion 78 adapted, when in a central neutral position, to nest the roller 70 as shown in FIGS. 4 and 7 when the machine 10 is at rest.
The safety circuit shown in FIG. 8 as corresponding to normal operating condition of the apparatus 10 thus is adapted to deenergize drive means M of the apparatus 10 when either one of the switches 56 or 64 is effectively closed by a relative displacement of the guard 26, or when a push button 80 (FIG. 8) is manually closed. Deenergization of the drive M is at once effective, for example, through signal from the computer C. The assembly' 50 as indicated in FIG. 4 accordingly has its switches 56 and 64 in positions of normal apparatus drive since neither of the rollers 62 or 70 has then been depressed by the actuator 72 to close either of the contacts 58 or 66. When, however, relative guard displacement laterally of the head 12 is effected in either direction as by hand contact with the guard, lateral yielding displacement of the actuator 72 to one of the two dash line positions shown in FIG. 4 will allow the contact of switch 64 to close stopping motor drive at once. Similarly, as the attendant or an obstacle inadvertently causes pivotal movement upwardly of the guard about the axis of the trunion pins 30,32 during operation of the apparatus, thereby shifting the actuator 72 to its relative position shown in FIGS. 5 and 6, the normally closed, held open switch 56 is allowed to close to stop apparatus operation by reason of the relative rearward movement of the recess portion 78 from the roller 70. Alternatively, should the guard 26 be pivotally depressed about the trunion axis for any reason during operation of the machine, the normally open switch 56 remains open while the switch 64 is closed. thereby again insuring immediate cessation of machine drive and avoidance of damage or injury.
Having thus described our invention what we claim as new and desire to secure by Letters Patent of the United States is as follows:
1. In a machine having elements relatively movable along convergent paths, and power means for driving at least one of the elements, a safety means comprising a guard mounted for movement with said one of the elements and displaceable in two or more directions relative to said one element, and a circuit for controlling actuation of the drive means, the circuit including a switch means responsive to displacement of the guard in any one of said directions for immediately deenergiz ing the power drive means.
2. A machine as in claim 1 wherein the guard is mounted for yielding displacement on said one element from a neutral or inoperative position on the guard, and spring means is adapted to urge return of the guard to said neutral position to restore operation of the machine.
3. A machine as in claim 1 wherein the guard is formed as a box-like fence adjacent to operating instrumentalities and is at least partly transparent to permit visual operation of the instrumentalities of the machine.
4. A machine as in claim 1 wherein the safety guard is mounted for pivotal movement about an axis, and is yieldable in either of opposite directions parallel to said axis.
5. A machine as in claim 1 wherein the switch means is mounted on said one element and includes a pair of independently operable, spaced switches, and switch actuating means associated with the guard and adapted to partake of its relative displacement is operable to actuate either of the switches to deenergize the machine drive means.
6. Safety mechanism for a machine having elements movable with relative approach to each other in a manner such that there is risk of an operator or article being caught or being endangered therebetween, the safety mechanism comprising a guard pivotally mounted on one of the movable elements for movement about a horizontal axis, means permitting the guard lateral yieldable movement in either of two directions along the axis from a neutral inoperative position, power means for driving said one or more of the elements, a safety control circuit connected to the power means and including switch means actuatable for deenergizing said power means, and mechanism responsive to deflection of the guard about said axis or along that axis for causing the switch means to deenergize said circuit and thereby render the power means inoperative.
7. Safety mechanism as in claim 6 wherein spring means is yieldingly operable to urge the deenergizing mechanism to resume an angular position wherein the control circuit remains energized.
8. Safety mechanism as in claim 6 wherein the switch means includes a pair of switches connected in parallel, and the mechanism for causing the switch means to deenergize the control circuit comprises a switch actuator connected to the guard and having a cam portion formed to cooperate with the pair of switches.
9. Safety mechanism as in claim 8 wherein said switch actuator is an extension of the guard having a recessed portion for accommodating the actuating arm of one of the pair of switches when the machine is in normal operating condition.
10. The combination with an electronic component mounting machine comprising a frame, means movably mounted on the frame for supporting a wiring board which is to receive leads of the components in different predetermined positions, a component processing head movably mounted on one side of the board supporting means, lead clinching mechanism operable on the other side of the board supporting means, and power means for driving at least two of said head, clinching mechanism, and board supporting means with relative movement of approach toward one another, of a safety mechanism including a guard yieldingly associated with at least one of the head, clinching mechanism and board supporting means, and a control circuit responsive to displacement of the guard from an inoperative position to stop said relative movement of approach by deenergizing the power means, the control circuit including switch means actuatable by relative heightwise, lateral, or pivotal movement of the guard with respect to the head, clinching mechanism, or board supporting mechanism with which the guard is associated.
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