US3912061A

US3912061A - Safety fence

Info

Publication number: US3912061A
Application number: US408793A
Authority: US
Inventors: Jr Joseph E Foster
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-10-23
Filing date: 1973-10-23
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An electrically operated safety fence which is designed to protect workers from the moving parts of an electrically powered machine and consists of a series of base plate sections which are fastened to the floor about the hazard. The base plate sections have sockets which are vertically oriented to removably receive fence sections thereon and to vertically support the fence sections. The base plate sections act as raceways for electrical circuitry wiring and the sockets contain switches which are wired into the electrical circuit. The switches are functioned by the installation or removal of the fence sections. The electrical circuitry of the base plate section switches is wired in series with the electrical power circuit of the machine which functions the moving parts so that when a section of the fence is removed, its associated switch will be activated to automatically interrupt current to the machine.

Description

' United States Patent [191 Foster, Jr.

[4 1 Oct.-14, 1975 1 SAFETY FENCE Joseph E. Foster, Jr., PO. Box 262, Exton, Pa. 19341 [76] Inventor:

[52] US. Cl. 192/133; ZOO/61.58 R [51] Int. Cl F16? 31/00 [58] Field of Search 256/1, 24, 59, 21, 22;

74/608, 612; 340/280, 272, 273, 276, 274; 200/61.58 R, 52 R, 85 R, 294, 296, 329, 340;

[56] References Cited UNITED STATES PATENTS 1,229,473 6/1917 Keenan 200/61.58 R X 1,781,061 11/1930 l-loneycutt 192/133 FOREIGN PATENTS OR APPLICATIONS 289,180 12/1915 Germany 192/133 Primary ExaminerDennis L. Taylor Attorney, Agent, or FirmWeiser, Stapler & Spivak ABSTRACT An electrically operated safety fence which is designed to protect workers from the moving parts of an electrically powered machine and consists of a series of base plate sections which are fastened to the floor about the hazard. The base plate sections have, sockets which are vertically "oriented 'to removably receive fence sections thereon and to vertically support the fence sections. The base plate sections act as raceways for electrical circuitry wiring and the sockets contain switches which are wired into the electrical circuit. The switches are functioned by the installation or removal of the fence sections. The electrical circuitry of the base plate section switches is wired in series with the electrical power circuit of the machine which functions the moving parts so that when a section of the fence is removed, its associated switch will be activated to automatically interrupt current to the machine.

11 Claims, 4 Drawing Figures U.S. Patent Oct. 14, 1975 SAFETY FENCE BACKGROUND OF THE INVENTION The invention relates generally to the field of safety devices, and more particularly is directed to an electrically actuated safety fence suitable for installation above the moving parts of industrial machines.

Industrial accidents frequently occur in conjunction with moving mechanical apparatus such as power transmission belts, shafts, pulleys, fly wheels, crank shafts and similar normally moving pieces of machine equipment. In order to prevent injury to workers, safety measures of various complexities have been employed in the past. Various types of belt guards, fences, shields and other more or less permanent and sophisticated types of equipment have been designed and installed in an effort to reduce the number of accidents. Generally satisfactory results have been achieved during the routine function of the machinery and. the day to day activities within the plant. However, experience has shown that when a piece of machinery malfunctions for any reason and it is necessary for a worker to approach the machine in close proximity for the purpose of adjustment or repair, then such workers are unusually susceptible to injury by the faulty equipment. It has been found that in order to make the required repairs or adjustments, a worker generally has to remove the existing safety device or guard. Usually, the equipment switch is moved to the of position so that no injury from moving machine parts can result. However, it'has been found that sometimes, through inadvertence, either the switch is not moved to the off position or else the switch is unintentionally reactivated, thereby giving rise to the possibility of accidents.

SUMMARY OF THE INVENTION The present invention relates generally to the field of electrical interlocks, and more particularly, is directed to a safety fence construction which is wired into the machine operating circuit in a manner to automatically stop the machine operation upon removal of any portion of the fence material.

The safety fence of the present invention incorporates a series of base plate sections which are fastened to the floor to form a physical barrier about the machine to be protected. The base plate sections include wire ways through which conventional branch circuit wires can be run in a protected manner to conform to usual electrical construction safety standards, such as the requirements of the National Electrical Code, NFPA No. 70.

The base plate sections are equipped with sockets on predetermined centers and each section is equipped with at least one pressure switch which is wired in series with the machine control circuit of the machinery or hazard to be protected. Cooperating fence sections fit into the sockets and serve the dual purpose of acting as a barrier about the machine and of functioning the pressure switches to a closed position to maintain circuit continuity. Should a fence section be removed, the associated pressure switches will open to automatically and rapidly shut off the machine operating circuit to thereby prevent possible injury to an operator. If desired, an alarm circuit can be conventionally wired into the safety fence circuit to sound an alarm, operate an annunciator or function any other similar type of control or alarm equipment.

The safety'fence of the present invention has been designed to comply with the regulations of the Department of Labor promulgated under the Occupational Health and Safety Act as specified in Occupational Safety and Health Standards, Sub-part O entitled Machinery and Machine Guarding" and particularly with reference to Section 1910.219.

It is therefore an object of the present invention to provide an improved safety fence of the type set forth.

It is another object of the invention to provide a novel safety fence to protect workers from the moving parts of electrically operated machines and which includes switch contacts wired in series with the machine operating circuit for machine control purposes.

It is another object of the present invention to provide a novel safety fence to protect workers from moving parts of a machine and which incorporates a series of base plate sections capable of being fastened to the floor about the machine for accommodating branch circuit wiring and control switches which are wired into the machine operating circuit.

It is another object of the present invention to provide a novel safety fence for protecting the working parts of a machine which includes a plurality of base plate sections which are fastened to the floor about the machine, the base plate sections being provided with sockets to receive fence sections in removable arrangement and which further include switches functioned by the base plate sections to control the operation of the machine main electrical circuit.

It is another object of the present invention to provide a novel safety fence incorporating a plurality of base plate sections, each section being equipped with an upstanding socket to receive a fence section thereon, each base plate section being equipped with a pressure activated switch which is positioned to be controlled by the application or removal of a fence section relative to the socket.

It is another object of the present invention to provide a novel safety fence including a plurality of base plate sections, each section incorporating an end positioned socket and a switch in vertical alignment below the socket, the socket receiving a fence section therein for switch control purposes, the said switches being wired in series with a machine circuit to electrically deactivate the machine when a fence section is removed from its association with a socket.

It is another object of the present invention to provide a novel safety fence that is inexpensive in manufacture, simple in installation and trouble free when in use.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims'of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a safety fence constructed in accordance with the present invention and installed about a machine to be protected.

FIG. 2 is an enlarged, partial, elevational view looking from line 2-2 of FIG. 1, and partially broken away to expose details of interior construction.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2, looking in the direction of the arrows, and

partially broken away to expose details of interior construction.

FIG. 4 is an electrical schematic diagram of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of my invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.

Referring now to the drawings,.l show in FIG. 1, a safety fence l constructed in accordance with the invention and installed in a manner to protect a worker (not shown) from the moving parts of mechanical equipment 12 which may include potentially dangerous components such as, for example, exposed gears, belts, pulleys, shafts, or the like. A plurality of base plate sections 16 position directly upon the surface of the floor 14 and preferably are secured in place in well known manner by suitable fasteners, such as by employing expansion bolts (not illustrated). The base plate sections 16 support vertical fence sections 18 which serve the dual purposes of functioning base plate enclosed switches in the manner hereinafter more fully set forth and also in preventing workers from gaining access to the machinery 12 while the machinery is operating.

Referring now to FIGS. 2 and 3, I show each base plate section 16 terminating endwardly in a support member 20 which is bolted or otherwise securely affixed to the top surface 22 of the base plate section 16. Each support member 20 comprises a base 24 upon which are supported a pair of vertical sockets 26 which open upwardly to receive the fence sections 18 in the manner hereinafter more fully set forth.

The top surface 22 of the base plate section 16 and the base 24 of the support member 20 are drilled or otherwise machined to receive the operators 28 of a pressure activated switch 30 therethrough. The pressure activated switches 30 are of the normally open type which function to prevent the flow of current therethrough unless the switch operators 28 are depressed. All of the the switches are wired in series with the motor 32 of the machine 12 which is being protected so that the opening of any switch 30 will function to stop the flow of current to the machine motor. See FIG. 4. The vertical socket 26 preferably is fabricated of steel round tubing of 1% inch outside diameter and 1 /2 inch inside diameter. The sockets 26 may be welded or otherwise securely affixed to the base 24 in well known manner to provide a secure and rugged assembly. As illustrated in FIG. 1, sufficient base plate sections 16 are employed in end to end relationship to prevent unauthorized access to the machinery 12 when equipped with the fence sections 18.

The switches 30'are securely mounted to the top surface 22 of the base plate section 16 in conventional manner such as by employing suitable lock nuts 34 to provide a sturdy installation and to assure that the switch operators 28 always project upwardly above the top surface of the support member bases 24 at the sockets thereof. Preferably, the operators 28 are oriented in concentric relationship within each vertical socket 26.

Each fence section 18 is fabricated to a generally U- shaped configuration having an upper web section 36 and a pair of

legs

38, 40 integrally depending therefrom. The fence section framing is preferably fabricated of carbon steel round tubing of 1 /2 inch outside diameter and inch wall thickness to provide adequate strength and to snugly fit within a vertical socket 26. The space defined within the web and the depending legs is conventionally closed by wire screening of suitable strength to prevent trespass. Each

leg

38, 40 terminates downwardly in a bottom plug 42 which is welded or otherwise secured to the bottom terminus 44, 46 of each respective depending

leg

38, 40. Each plug 42 comprises a flat steel plate that is approximately ls inch in thickness and 1% inches in diameter to completely close the bottom opening of each leg. The

legs

38, 40 are sized to be a sliding fit within the vertical sockets 26.

As best seen in FIGS. 2 and 3, when a fence section 18 is applied to a base plate section 16 by sliding the respective depending

legs

38, 40 into base plate associated vertical sockets 26, the weight of the fence section 18 acts downwardly to seat each fence section securely at the bottom of each respective vertical socket 26 so that the bottom plugs 42 contact the switch operators 28. The switches 30 are of the pressure activated type with normally open contacts. The action of the bottom plugs 42 upon the switch operators 28 acts to respectively close each switch 30 by pressing downwardly on each switch operator 28 until its associated switch closes. Removal of a fence section 18 from its association with a base plate section 16, such as might occur when it is desired to enter the machinery enclosure area 48 for maintenance or service of the machinery 12, will automatically open the corresponding switch 30 by removal of the bottom plugs 42 from its association with the switch operator 28. Removal of the pressure applied by the bottom plugs 42 will cause the pressure activated switches 30 to return to their normally open position, thereby interrupting the flow of electrical current to the machinery motor 32.

In order to use the safety fence of the present invention, the base plate sections 16 are first securely affixed about the machinery 12 to be protected. A series circuit 50 (FIG. 4) is then established about the machinery 12 to control the machinery motor 32. Circuit wires 52 are wired in series with the machinery motor 32 and the various pressure activated switches 30 in well known manner. The wires 52 are run within the sections 16 which serve as wire raceways for mechanical protection of the circuit wires. A conventional motor control switch 54 is also wired in series in the series circuit 50 to conventionally control the operation of the machinery 12. Thus, in order for the machinery 12 to be operative, the motor control switch 54 and all of the pressure activated switches 30 must be closed. Accordingly, the removal of any fence section 18 from its association within a socket 26 will release the associated switch operator 28 which projects upwardly within the socket 26 to thereby open its pressure activated switch 30 to automatically open the machinery circuit 50. The interruption of the flow of current in the circuit 50 inactivates the machine motor 32, thereby preventing the possibility of injury.

To gain access to the machinery 12 without the necessity of actually removing a fence section 18, it may be desirable to provide a gate section 56 which could conventionally be of a horizontal swinging type. In this instance, a gate interlock 58 could conventionally be provided and wired into the series circuit 50 (FIG. 4) in a manner to open the series circuit 50 as soon as the gate section 56 is pivoted from its closed position. Thus, should anyone attempt to enter the machinery enclosure area 48 either by removing a fence section 18 or by opening a gate section 56, the

switches

30, 58 will function to open the machinery circuit 50 and to automatically and positively deenergize the machinery motor 32, thereby preventing industrial accidents which may result when a workman contacts a moving piece of the machinery 12.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and in the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

I claim:

1. In a safety fence for protecting a worker from contacting machinery which is functioned by an electrical motor, the combination of A. a plurality of base plate sections affixed about the machinery,

1. said base plate sections having an elongated configuration and terminating transversely in a first end and a second end and upwardly in a top surface,

2. said base plate sections being arranged in end to end juxta position about the machinery;

B. support members associated with the base plate sections,

1. each support member including a hollow socket and means to hold the socket in a generally vertical orientation to receive a portion of a fence section therein,

a. each hollow socket terminating upwardly in an open end and downwardly in a bottom end;

C. a plurality of switches secured to the base plate sections in vertical alignment with the support members,

1. each switch including a switch operator and switch contacts,

2. each switch operator projecting upwardly into a hollow socket at the bottom end thereof;

D. a control circuit including circuit wires, the electrical motor and the switches,

1. each said switch being wired into the circuit to control the operation of the electrical motor in response to function of its associated switch operator,

Efand a plurality of fence sections removably attachable to the support members at the sockets thereof,

1. each fence section carrying means to function a switch operator.

2. The invention of claim 1 wherein the switch contacts are normally open and are wired in series with the electrical motor.

3. The invention of claim 2 wherein each base plate section is fabricated to an inverted, generally U-shaped configuration to define an interior space, the said interior space enclosing a portion of the circuit wires and the switches therein.

4. The invention of claim 3 wherein the means to hold the socket includes a flat base upon which the socket is affixed, said base being secured to the top surface of the base plate section.

5. The invention of claim 4 wherein each base and its associated top surface of the base plate section are provided with openings, said openings being in vertical alignment.

6. The invention of claim 5 wherein each switch operator projects upwardly into the hollow socket through the aligned openings.

7. The invention of claim 6 wherein each fence section is fabricated with a bent frame member which is bent to an inverted U-shaped configuration, said frame member including an upper web and a pair of legs depending therefrom, said legs terminating downwardly respectively in a bottom terminus.

8. The invention of claim 7 wherein each bottom terminus inserts downwardly into a hollow socket through the said open end thereof.

9. The invention of claim 8 wherein each bottom terminus is pushed downwardly within a socket a sufficient distance to contact a switch operator.

10. The invention of claim 9 wherein the means to function a switch operator are affixed to a said bottom terminus.

11. The invention of claim 10 wherein the means to function a switch operator comprises a bottom plug, said bottom plug being positioned to contact a switch operator when a bottom terminus is inserted into a hollow socket.

Claims

1. In a safety fence for protecting a worker from contacting machinery which is functioned by an electrical motor, the combination of A. a plurality of base plate sections affixed about the machinery, 1. said base plate sections having an elongated configuration and terminating transversely in a first end and a second end and upwardly in a top surface, 2. said base plate sections being arranged in end to end juxta position about the machinery; B. support members associated with the base plate sections, 1. each support member including a hollow socket and means to hold the socket in a generally vertical orientation to receive a portion of a fence section therein, a. each hollow socket terminating upwardly in an open end and downwardly in a bottom end; C. a plurality of switches secured to the base plate sections in vertical alignment with the support members, 1. each switch including a switch operator and switch contacts, 2. each switch operator projecting upwardly into a hollow socket at the bottom end thereof; D. a control circuit including circuit wires, the electrical motor and the switches, 1. each said switch being wired into the circuit to control the operation of the electrical motor in response to function of its associated switch operator, E. and a plurality of fence sections removably attachable to the support members at the sockets thereof, 1. each fence section carrying means to function a switch operator.

2. said base plate sections being arranged in end to end juxta position about the machinery; B. support members associated with the base plate sections,

2. each switch operator projecting upwardly into a hollow socket at the bottom end thereof; D. a control circuit including circuit wires, the electrical motor and the switches,