Field of Search:
74/612,615,616 160/29R,29F,DIG.9 242/100.1 192/129R,129A,134
Claims:
Having described the invention, the exclusive rights therein are defined by the following claims
1. A guard comprising a length of flexible fabric for providing a fence-like extension relative to portions of a machine to which accidental access is to be prohibited; spring-loaded reel means on which the fabric may be rolled for storage, first attachment means permanently attaching one end of the fabric to the reel means and second attachment means at the other end of the fabric for supporting the fabric when in an extended position, the guard including a short length of chain operably attached to the other end of the fabric, the chain including means for rendering inoperative a mechanism to be guarded unless the means is connected to the mechanism upon extension of the fabric to a "guard" position.
2. The guard according to claim 1 wherein the chain has attached thereto an electrical plug adapted for insertion into a receptacle and the closing of a circuit attached thereto.
3. In combination, a machine having moving parts providing "pinch points" during operation thereof and reel means carrying a length of flexible fabric adapted and positioned for enclosing the "pinch points" during operation of the machine to guard against accidental access thereto, the fabric being rolled onto the reel means when the machine is inoperative to permit access to the so enclosed portions of the machine.
4. The combination according to claim 3 wherein the machine has a plurality of access areas to the "pinch points" around its sides, the fabric is of a length such that it may be extended to enclose the access areas and there is included a plurality of support means for supporting the fabric at various points along its length and at various points around the machine.
Description:
BACKGROUND
This invention relates to improvements in machine guards or safety devices to be used on machines in which there are exposed moving parts which provide "pinch points" hazardous to operators and standers-by. "Pinch points" are defined herein as any part of a machine which may cause injury by smashing parts of the body or gripping loose clothing or the like and dragging parts of the body into the machine.
Many types of guards and safety devices have been provided heretofore. However, they have ordinarily constituted relatively expensive, unwieldly structures or structures difficult and time consuming to remove and replace when maintenance or changes in the set-up of the guarded machine are required.
SUMMARY
It is an object of this invention to provide a guard which is relatively inexpensive, one which is readily positioned around various shaped machines and one which is self-retracting when not in use. A spring loaded clutch release type reel on the guard allows positioning and unrolling with one hand and also permits tension adjustment when the guard is positioned.
The invention takes the form of a length of flexible metal mesh or fabric, one end of which is attached to a reel on which the metal fabric may be stored by rotating a reel mechanism and winding or wrapping the mesh about the reel in the same manner in which a window blind is rolled up. A length of metal fabric may be unwound from the reel to be extended and positioned in front of or about portions of a machine which are to be guarded during machine operation. There is thus provided a fence-like structure which prevents access to the "pinch point" or "points" in any machine. Preferably the reel will be spring biased as described hereinbelow so as to be self-retracting. It will also preferably include an electrical interlock arrangement such as that described hereinbelow and will also include a spring loaded clutch release mechanism on the reel.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary showing of a machine on which a guard according to this invention has been mounted. The guard is shown in the extended or "guard" position. The metal fabric is shown in fragment.
FIG. 2 is a plan view showing the operating and/or reel mechanism of the machine guard reel.
FIG. 3 is an enlarged sectional view of the guard reel and mechanism showing the parts when the reel is in the freely rotating position.
FIG. 4 is an exploded perspective view of the parts of the clutch or reel locking mechanism.
FIG. 5 is a schematic showing of an extended machine guard positioned around three sides of an irregular shaped machine.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring specifically to FIG. 1, a machine 10 is shown having two upright members 12 and 14 which support a machine guard generally indicated at 16, according to this invention. Guard 16 is shown in the extended or "guard" position in which it may be manually placed when machine 10 is in operation. In this position, access to the working parts of the machine is ordinarily prohibited.
Guard 16 includes a fence-like length of metal mesh or fabric 18, one end of which is attached to reel 20. The terms "mesh" and "fabric" are intended to collectively describe various screen or fence type materials useful for preventing accidental passage to machine "pinch points." The material need not be metal if other material is desired so long as it is strong enough for the purposes intended herein, although metal is preferred. Various mesh sizes may also be used, it being only necessary one can see through the material to observe the machine. Wire belt material such as that sold under the trademark FLAT-FLEX by the Wire Belt Company of America, Winchester, Mass. has been found to be suitable. Such a belt is indicated in FIG. 1.
The other end of the fabric 18 is permanently attached to an elongated support member, such as bracket 22, which includes two or more engagement hooks or the like 24. Hooks 24 are placed in cooperating hook receiving members 26, carried by machine member 14, when it is desired to place the guard in the extended "guard" position. A short length of chain 28 is shown attached to member 22. Chain 28 carries a male electrical plug 30 at one end, shown inserted into a receptacle 32. Receptacle 32 is positioned in proximity to the end of the extended mesh 18 such that plug 30 must be removed from receptacle 32 if the engagement hooks 24 are removed from the receiving members 26 by more than a slight distance.
Receptacle 32 is connected into the electrical operating control circuit (not shown) of machine 10 such that the machine is inoperable unless plug 30 is inserted into receptacle 32. The length of chain 28 is selected so as to make it necessary for all practical purposes to place the hooks 24 into the receiving members 26 in order for plug 30 to reach receptacle 32. A plug and receptacle of the type made available by the Hubbel Company and marketed under the trademark HUBBELLOCK, catalog numbers 20415 and 20403 have been found to be satisfactory for the purposes of this invention. Details of the electrical connection of the receptacle 32 into the machine operating circuit need not be described here as various suitable arrangements will be readily apparent to those skilled in the electrical arts. It is merely necessary to understand that the circuit is "open" until plug 30 is inserted into the receptacle to complete it. Until that time, the machine is inoperable even if the "on" button for the control circuit in box 34 is actuated. Plug 30 may be readily modified by jumping its terminals so that it will be capable of completing the circuit when placed in the receptacle. 2-wire and 4-wire plugs may be so modified for this purpose depending on the type of machine control circuit involved and other plugs may also be readily adapted for use.
In accordance with the invention it is preferred that reel 20 be spring loaded like a window blind. It is further preferred that it include a reel member as shown at 36 which is of the spring loaded clutch release and rotated type. It is spring loaded so that a biasing spring is wound up as the metal fabric is extended thereby spring loading the reel to cause it to retract and wind up the fabric when it is released. Such a mechanism is provided, for example, in U. S. Pat. No. 2,989,267 which issued on June 20, 1961. That patent discloses a reel mechanism normally intended for use with clothes lines but readily adapted to the use of this invention. It includes additional features useful herein such as clutch and ratchet arrangements. The disclosure of the patent is hereby incorporated by reference into this disclosure and only so much as is necessary to understand this invention described hereinbelow. None of the reel mechanism per se constitutes this invention.
Referring now to FIGS. 2, 3 and 4, arranged at one end of the unit shown in FIG. 3 is an end plate 40 having an axial opening which receives a tubular shaft 42. The other end of shaft 42 is received in an axial opening in a mounting bracket 44 and held in position there by pin 54. A second mounting bracket 46 is suitably affixed to the other end of the mechanism as shown.
A reel in the form of a hollow cylindrical shell 20 has centrally apertured hub plates 48 and 50 at respective opposite ends of the shell through which shaft 42 extends axially to provide a bearing support for the reel. Each hub plate 48 and 50 includes an inwardly axially offset central portion so as to provide an annular shoulder fitted within the periphery of shell 20. Hub plate 48 is rigidly fastened to shell 20 by a screw 52 while hub plate 50 is fixed to the shell and shaft by pin 54.
Flexible material 18 has its inner end fixed to reel 20 as previously described so as to be wound thereon and unwound therefrom by rotation of the reel. Reel 20 is resiliently urged in a direction of rotation to wind the fabric 18 thereon by coil spring 60 having one end fastened as at 62 to hub plate 40 with the other end fastened as at 64 to shaft 42. As fabric 18 is withdrawn or unwound from reel 20 power is stored in spring 60 to effect rotation of the reel in the direction on which it is turned to receive the fabric thereon. Such an arrangement is known as being "spring loaded."
When member 22 at the free end of fabric 18 is drawn away from the reel mechanism to extend the fabric, it is necessary to lock reel 20 against further rotation to prevent playout of additional fabric when pressure is applied against the extended fabric as for instance when someone pushes or leans against the guard, moving it toward the machine. The locking action is also arranged in U.S. Pat. No. 2,989,267 to tension the fabric so as to maintain a taut condition therein. To accomplish this the reel mechanism utilizes a cam plate 66 which is mounted on shaft 42 for relative axial sliding movement between end plate 40 and hub plate 48. A coil spring 68 surrounding the shaft acts between hub plate 48 and cam plate 66 to normally position the latter in axially spaced relationship to hub plate 48 and in engagement with end plate 40. Handle 70 is supported on the end of shaft 42 for rotation coaxially with reel 20. A pair of arcuate slots 72 spaced uniformly circumferentially apart in end plate 40 provide clearance for integral pins 74 on the head 76. The pins extend between end plate 40 and cam plate 66. Cam plate 66 is fastened to the inner ends of pins 74 whereby cam plate 66 is rotated about shaft 42 in unison with rotation of crankarm 70 according to the range of travel of the pins between opposite ends of the slots 72. When pins 74 are located in their most clockwise rotated position relative to slots 72 a pair of cams 78 on plate 66 arranged at 180° spaced apart positions circumferentially of a circle concentric with the axis of reel 20 having engagement with face portions of end plate 40 opposite thereto under pressure of spring 68 acting between plate 66 and hub plate 48 to maintain reel 20 in free rotation relative to shaft 42. When the crankarm 70 is rotated toward an advanced rotated position in a counter-clockwise direction cams 78 in response to corresponding rotation of cam plate 66 under control of pins 74 will be moved into engagement with arcuately arranged cam faces 80 on end plate 40. Such interengagement of cams 78 with cam faces 80 causes cam plate 66 to be moved axially along shaft 42 toward hub plate 48. By thus axially shifting cam plate 66, locking lugs 82 engage with corresponding lugs 84 on hub plate 48 whereby reel 20 is rotated counterclockwise in accordance with such rotation of crankarm 70, which is the direction of rotation of reel 20 to wind the fabric thereon and tighten the same after it has been connected as shown in FIG. 1 at its free end to the hook receiving member 26. A retractable latch pin 86 mounted on crank handle 70 is normally urged into an extended position as shown in FIG. 3 by spring 88. A ratchet bar or segment 90 having teeth with which pin 86 is selectively engageable when in the extended position, is operative to prevent rotation of crank handle 70 in a direction to unwind fabric from reel 20. These teeth cooperate with pin 86 to allow the latter to slide thereover as handle 70 is rotated in a counterclockwise direction to wind fabric onto the reel. Thus, while latch pin 86 engages one of the teeth in a selected position of crank handle 70, if it is desired to further rotate the latter in a direction to unwind the fabric from reel 20, it is necessary to move the latch pin into a retracted position out of engagement with the tooth. Such retraction of pin 86 is accomplished by release lever 92 which pivots at 94 relative to handle 70.
Referring lastly to FIG. 5, there is indicated a guard arrangement in which fabric 18 extends around several sides of a machine 10 showing the adaptability of this guard to irregular shapes and access from different sides of the machine. In such a case, supports, such as vertical support bars 100, may be attached to the machine to space the fabric away from the machine and support it as it changes direction in extending about the machine. A wide variety of shapes and uses of this guard will be obvious from the above.