US2767819A - Safety device - Google Patents

Description

1956 J. F. CULLERTON, JR, ET AL 2,767,819

SAFETY DEVICE Filed Feb. 26, 1954 2 Sheets-Sheet 1 Za a fm/wey Oct. 23, 1956 J. F. CULLERTON, JR., E AL 2,767,819

SAFETY DEVICE Filed Feb. 26, 1954 2 Sheets-Sheet 2 United States Patent C SAFETY DEVICE James F. Cullerton, Jr., and Arthur C. Haapoja, Chicago, Ill., assignors to Mandex Mfg. Co., Inc., Chicago, 111., a corporation of Illinois Application February 26, 1954, Serial No. 412,784

3 Claims. (Cl. 192-134) This invention relates to safety devices and more particularly is concerned with a safety device for use with a punch press or the like equipment.

Although not specifically limited thereto, the invention is especially applicable to and intended for use in connection with arbor presses used for riveting, punching and performing other mechanical operations on small pieces. The accident rate of workers using this type of press, that is, small presses which operate on small work pieces,

. is quite high. The reason for this is that these small pieces must be handled with the fingers of the worker and come close to not only the work piece but as well, the mandrel and the movable punch or member which comes down upon the work piece. Because of this, insurance rates in shops where such types of equipment are in use, are high. The accident rates are obviously also high and workers are reluctant to use this type of machine.

Certain labor groups and other organizations such as insurance underwriters have insisted that tweezers be used to handle small work pieces in machines of this kind, but the obvious result is that considerable time is spent in grasping the piece, placing it upon the mandrel and removing it, such that production is thereby considerably decreased.

The principal object of the invention therefore, is to provide a safety device which will alleviate all of the difficulties referred to hereinabove.

In addition to the difiiculties which have been set forth hereinabove, even in the use of equipment wherein safety is not as great a factor as in the use of smaller machines, the invention has great uses and advantages. For example, in the use of automatic machines, where parts are intended to be seated in cavities or recesses, or where proper alignment of a part in a die is required, the invention may be used to prevent the male member of the die from being brought into contact with the female member thereof where there is displacement or improper alignment.

It is therefore still a further object of the invention to provide the advantages inherent in eliminating the difficulties immediately above described.

A further object of the invention is to provide a safety device which is extremely simple and which comprises a feeler or guide which is so formed as to very closely approach the work piece such that, if the work piece is not in proper position either because of'not fitting into the die or seat, or if the hands or fingers of the operator are in the path which will be taken by the movable staking member or punch, the feeler will not be permitted to approach the work piece to a predetermined extent and the punch press or other press will not be permitted to operate.

Still a further object of the invention is to provide a safety device associated with an arbor press in. which means for actuating movement of the arbor press are normally rendered inoperative, and the said means can only be rendered operative through the proper positioning of the safety device with respect to the work piece and the movable parts of the press.

Still a further object of the invention is to provide a novel and improved safety device in which there is associated with an arbor press a movable feeler normally located in a position removed from the work piece so as not to interfere with the placement of the work piece upon the seat or mandrel or die, and thereby enabling the Worker to properly position the work piece and see the same prior to causing the operation of the press, the said safety device acting to prevent injury to the worker or damage to the press, unless it is permitted to move to a position predetermined with respect to the work piece and the mandrel upon which the same is seated.

In connection with the immediately above referred to object there is an additional object of the invention to provide a press having the safety device associated therewith and in which the press is operated by a treadle adapted to be depressed by the worker, and in which the operation of a treadle causes the feeler to move to a proper position to permit the press to operate, the movement of the feeler serving to activate means for causing the press to be driven, whereby the staking or punch tool will engage the work piece.

A further object of the invention is to provide a safety device of the character described for use in connection with an arbor press, said safety device including a feeler required to move into predetermined association relative to a work piece in order to render the press operative, there being two switches, one controlling a solenoid for providing the power stroke of the press, and the other comprising a treadle switch in series with the first mentioned switch for activating a second solenoid for causing movement of the feeler, whereby, unless both switches are closed the press will not operate.

A further object of the invention is to provide a safety device of the character described suitable for operation in connection with punch presses the power stroke of which is initiated through operation of some fluid drive-n device.

Still a further object of the invention is to provide a safety device not easily rendered inactive by the workman, whereby it is difiicult to operate the punch press unless the safety device is in position and properly operating.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangement and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out .in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of this invention, there is illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, this invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawings:

Fig. 1 is a perspective view of the conventional type of. arbor press for use with small work, mounted upon a bench and having the invention associated therewith, portions being shown broken away and diagrammatically in order to explain the invention.

Fig. 2 is a fragmentary side elevational view of the apparatus of Fig. 1 showing the feeler and its associated apparatus.

Fig. 3 is a diagrammatic view showing the circuit of the apparatus for use in connection with an electrically operated arbor press.

Fig. 4 is a diagrammatic view similar to that of Fig. 3 except that the invention is here applied to a hydraulically or air-operated press.

Generally, the invention is associated with an arbor press which is operated upon its power stroke by means of a fly-wheel which is constantly rotating. The movement of a lever clutches the fly-wheel to the punch moving mechanism for one stroke. The invention contemplates the use of a conventional treadle for actuating movement of the punch. Instead of being connected to move the lever which clutches the fiy-wheel to the punch, the treadle is arranged to energize the solenoid which moves a feeler into position relative to the work piece or to the die or mounting upon which the work piece is adapted to be seated. Such mechanical movement of the feeler must be completed in order for the feeler to close a power circuit which in turn is connected to a solenoid which pulls the lever for clutching the fly-Wheel to the remainder of the linkage. It is preferred that the treadle operated switch and the switch arranged to close the power circuit to the solenoid for pulling the fiy-wheel clutching lever be connected in series.

Referring now to the figures, in Fig. 1, there is illustrated generally an arbor press 10, the base 11 of which is mounted upon a work bench 12. It will be seen that the arbor press has a conventional punch driving mechanism 13 adapted to move a punch or stake 14 into engagement with the work piece arranged to be placed upon the mandrel or bed 15. There is a fly-wheel 17 which is driven through a belt 18 by a motor 19 mounted upon any suitable bracket 20 secured to the base 11. The mechanical connection between the fly-wheel 17 and the punch driving mechanism 13 is well known and conventional, and hence there is no need to describe or explain the same, except that it is intended for each power stroke that the flywheel 17 be clutched or connected to a suitable mechanical coupling by the movement of a lever 22 in a downward direction. This lever extends through the work bench 12 and in most installations is connected with a treadle so that each time the operator desires that there be a power stroke, he depresses the treadle, clutching the fiy-wheel into the mechanism 13 for a single stroke. Most presses are so arranged that keeping the treadle depressed will result in continuous power strokes from the punch 14, although it is preferred that the press be arranged to make only a single stroke when the lever 22 is moved down, further strokes requiring further reciprocation of said lever.

It will be seen in Fig. 1 that there is provided a bracket 26 of any suitable construction secured to the bottom of the work bench 12, as for example, by a Z-shaped member 27 braced by a member 28.

On the front end of the bracket 26 and located between the bottom platform 30 and a plate 32, there is located a solenoid 34, the movable core of which is linked to the link 22 as indicated at 37. Obviously, energizing the solenoid 34 will result in its core 35 being pulled downward at which time the lever 22 will also be pulled downward causing clutching of the fly-wheel to the mechanism 13 and operation of the punch press through movement of the staking member 14.

Referring now to Fig. 2, especially, it will be seen that the punch or stake 14 reciprocates in a vertical base formed on the arbor 41. The bed or mandrel 15 supports some manner or die or tool 43 upon which the work piece 44 is adapted to be disposed. Just as an example, there may be a grommet, or eyelet, or another member intended to be riveted or otherwise secured to the work piece 44. Such a member is indicated at 46. It will be obvious that the workers fingers must come in very close proximity to the staking tool 14 during the operation of securing the member 46 to the work piece 44. In many instances the work piece 44 is considerably smaller than that illustrated so that the worker has considerable difficulty in grasping the work piece without approaching very closely the path of the punch or staking tool 14.

To the bottom or side of the arbor 41 there is secured a support member or frame 50 by means of a strap or projection 51, preferably integrally formed with the said frame 50. The frame mounts a downwardly extending shelf or seat 53 upon which there is disposed an electric switch 55, the actuating button 57 of which projects upward for a purpose to be described. It will be noted that the switch has its two terminals connected to electrical leads 58 and 59 which extend to the circuit being controlled by the said switch 55.

The frame 50 also mounts hearings or journals, one of which is shown at 61, and pivotally rotatable within the said journals is a pintle or stub shaft 63 attached to a rocker arm 64. The forward portion of the rocker arm 64 is provided with a socket or slot 66, and the said socket or slot has an undercut portion 68 spaced rearwardly thereof. The undercut portion or recess 68 is so arranged that when the feeler which is presently to be described is not inserted into the socket 66, movement of the rocker arm 64 about the pivot 63 will have no effect upon the switch 55 since the push-button 57 of the said switch will clear and engage into the said recess 63. The socket 66 is split, much like a simple C-clamp, only a side view being illustrated in Fig. 2, and is provided with ears 70 which are held together by any fastening means such as bolts or rivets 72, so that when the feeler member is inserted into the socket, it may be clamped tight. A tension spring 74 extends from an ear 76 formed of the frame 50 to a perforation 78 in the car 70. The arrangement of the spring 74 is such as to bias the rocker arm 64 to move its limit in a clockwise direction. The rear end of the rocker arm 64 is pivotally linked at 79 to the armature 80 of the solenoid 81. The solenoid 81 is set into the usual electromagnetic core 82 which is mounted in the frame 50. Leads from the solenoid 81 are designated 84 and 85 and the said leads are connected to the treadle switch in a manner presently to be described.

The feeler is designated generally by the reference character and same is formed of a bent wire member having an elongate shank 91 provided with several bends 92, 93 and 94. The number and arrangement of the bends is a matter of design, and from project to project the exact configuration of the shank 91 may change.

The secured end of the feeler 90 is provided with a straight portion 96 which is inserted into the socket 66 and extends past the recess portion 68 so that there is an exposed part 97. In the rocking or rotating movement of the rocker arm 64, it is this portion 97 which comes into contact with and engages switch button 57, and unless this feeler 90 is in position, rocking movement of the rocker arm 64 will not close electrical contact of the switch 55. At its free end, the t'eeler 90 is provided with a loop 99, the general configuration of which is perhaps best seen in Fig. 1. The loop 99 is intended to rather closely conform with the shape of the stake or punch 14 so that it is practically impossible for a worker to insert his finger or hand between the portion of the feeler forming the loop and the stake or punch 14.

In its quiescent position, that is, with the machine not operating, the feeler is arranged as shown in the solid lines of Fig. 2. The spring 74 pulls the rocker arm 64 in a clockwise direction to its limit as determined by any suitable stop member (not illustrated) or as determined by stop members on the armature 80 of the solenoid 81. In any event the rest position of the feeler 90 is with the looped portion 99 out of the way of the work piece 44 and the mandrel 43. As shown in Fig. 2 the loop is disposed even above the uppermost extent of movement of the stake or punch 14 so that it encompasses the same. When the solenoid 81 is energized the armature 80 will be pulled upwardly and the rocker arm 64 will be pivoted about the pivot 63 bringing the feeler down upon the work piece against the bias of the spring 74 to the position indicated by the broken lines in Fig. 2. This will cause the portion 97 of the straight part 96 to engage and depress the switch button 57 to energize the circuit connected to the electrical leads 58 and 59.

It is desired to point out that the particular structures which are shown are not necessarily limitations upon the invention. Although shown as a wire member formed of opposite halves, that is, of an integrally formed bent wire, the feeler 90 could just as easily be a cast member, or a sheet metal arm of any suitable construction. It is perhaps desirable in a case of small shops, or in establishments where a press is desired to be considerably flexible, and the size, shape and arrangement of the work piece, the dies and the mandrels vary from time to time, that the feeler 90 be replaceable with other feelers whose loops or end portions 99 conform to the different jobs at hand. Likewise it is best that the feelers in such case be readily installed or removed from the sockets 66.

Referring now to Fig. 3, there is illustrated in the said figure a circuit diagram of a system which is substantially that used in connection with the structures hereinabove described. in this case however, instead of having an additional switch such as indicated at 55, the feeler itself serves as a switch. Thus, there is a power line such as the ordinary 110 volt A. C. line connected to the termirials d and 161. This could be for example, an ordinary male plug as illustrated in Fig. 1 at 102 intended to be inserted into the ordinary female outlet. One lead 103 extends to a switch 104 which is preferably operated by a treadle 105 as shown in Fig. 1, but which may be operated manually or by the operators knee, etc. The second line 106 extends to one side of the solenoid 81 connecting with the same at the terminal 85. From the switch 104 there is an electrical lead 107 which connects with the opposite terminal of the solenoid at 84. Closing the switch 104 by stepping on the treadle 105 will result in the solenoid being energized, causing the arma ture 3% to be pulled into the solenoid in the usual manner. The armature as may be directly connected to the combined rocker arm 64 and feeler 90 as shown in Fig. 2 or, as indicated diagrammatically in Fig. 3 there may be a simple link 110 pivotally connected between the arm 90 and the armature 80. As shown in Fig. 3 the feeler 90 is pivotally secured at 111 and biased to rotate in a clockwise direction by the spring 74. The feeler 90 is connected electrically by means of a lead 112 to the solenoid 3d, the opposite side of the solenoid being connected by an electrical lead 113 to the electrical lead 107. It will be seen that when the feeler 90 is pulled down it will engage the contact 115 which is in turn connected by the electrical lead 116 with the electrical lead 106, thereby completing the energizing circuit to solenoid 34 and pulling the armature 35 into the solenoid to cause the power stroke of the punch press 10.

As explained above, this is a slight modification over the structure which is illustrated in Figs. 1 and 2 in which there is an additional switch 55 used, instead of just using the feeler 90 for the purpose of conducting the current between the two leads 112 and 116. The electrical arrangement using both the feeler 90 and the switch 55 is diagrammatically illustrated in the modified form of Fig. 4. In the said Fig. 4 it will be noted that feeler 90 is not electrically in the circuit. Again, it is held in an upward position by the spring 74, it is drawn downwardly when desired through the medium of solenoid 81 which is connected by the leads or terminals 84 and 85 to the conductors 107 and 106 respectively. Again, the switch which is treadle operated and indicated at 104, and the leads 1% and 103 connect respectively to the terminals 101 and 100. When the feeler 90 is pulled downwardly, it will engage the button 57 of the switch 55 which is connected by the leads 58 and 59 in series with the sole noid 34. The connection from the lead 107 to the solenoid is designated 113 while the connection from the lead 59- to the solenoid is designated 112.

The switch 55 may be any commercial structure which will provide single pole make-break contact. The actual structure of the invention as embodied in a commercial example utilized a switch manufactured under the trade name Microswitch.

The system which is illustrated in Fig. 4 is intended for use in connection with hydraulically controlled punch presses or air-controlled punch presses. Presuming that the system is specifically for air, the reference character 120 designates a valve for example, of the type illustrated in U. S. Letters Patent #2,415,417, the plunger of which is intended to be reciprocated by the movement of the armature of the solenoid 34. Obviously there are commercially available solenoid-operated air valves which are sold as complete units suitable for the same purpose. Inlet and outlet lines are connected at 121 and 122, and suitable air lines 123 and 124 lead to the opposite ends of a conventional air cylinder 125. The connecting rod 126 is intended to be connected with the reciprocal vertical link 22 in order to clutch the fiy-wheel 17 into a power stroke. When the treadle 105 is depressed according to the switch 104, the solenoid 81 is energized pulling down the feeler 90 and thereby closing the switch 55. This energizes the solenoid 34 which is connected with the valve 120 to pull the connecting rod 126 down. Simple return mechanisms such as internal springs in the valve 120 will move the connecting rod 126 back to its lower position Where the punch press is rendered inoperative.

There are several important features with respect to the operation of the device which render the apparatus highly advantageous over prior safety devices. In the first place it will be noted that in both of the systems. illustrated in Figs. 3 and 4 in order for the solenoid 34 to be energized it is necessary that two switches be closed. In the case of Fig. 3 the feeler must be in engagement with contact 115 and in addition, switch 104 must be closed. In the case of Fig. 4 the switch 55 must be closed, and in addition the switch 104 must be closed. Thus, it is impossible for an operator or someone who is tidying up in the vicinity of the punch press 10 to depress the feeler manually and cause operation 01. the punch press unless simultaneously he steps on the treadle 105. In the instances referred to above where it may be necessary to change the feeler 9% to one of the different configurations, it is impossible for the workman to cause operation of the punch press.

in connection with the removability of the feeler 90, another safety factor is added in that unless there is a feeler inserted into the socket or receiver 66 of the rocker arm 64, the movement of the rocker arm will have no effect upon the press. For example, if the machine is not intended to be used, and the feeler has been removed, depressing the treadle to close the switch 104 cannot result in any operation of the press since there will be nothing to engage the button 57 and close the switch 55. Obviously, in the type of construction which is diagrammatically illustrated in Fig. 3, the removal of the feeler 00 will provide the same safety arrangement, since there will now be no contact member available to engage contact 115.

It will be seen that there has been provided a novel and improved safety device whereby many advantages have been achieved. In the first place, through the use of such safety device as hereinabove described, the insurance rates of any shop will be lowered because of the decrease in accidents. Furthermore, it is not necessary that tweezers or other holding tools be used on small work where used on presses equipped with the apparatus of the invention. It is furthermore possible through the use of the invention to decrease tool breakage in maintenance and also to decrease rejects which would occur because of failure properly to seat the work piece on the die or mandrel of the punch press. It should further be obvious that the above has been accomplished through the use in the structure of easily obtainable parts of a simple nature.

Many other advantages will become apparent to those skilled in the art, and it is intended that those recited above shall be merely illustrative of that which is achieved through the use of the invention. Obviously variations in the formation, size and details of the parts of the invention are possible without in any way departing from the spirit or scope of the invention as defined in the appended claims.

What it is desired to claim in Letters Patent of the United States is:

1. In a device of the character described which includes a punch press having a movable punch, a mandrel for supporting a work piece, and a driving mechanism for driving the punch, said mechanism including a reciprocable lever the reciprocation of which will actuate the power stroke of the press, an elongate rocking arm normally positioned with its free end spaced from the mandrel but capable of being rocked to a second position immediately adjacent the mandrel, electrical circuit connecting means adapted to close a circuit by movement of said rocking member, but only when the rocking member is positioned immediately adjacent the mandrel, means biasing the rocking member to its normal position, and means actuated by the punch press operator for moving the rocking member to its second position, electro-magnetic means for reciprocating said lever, a source of electrical power, and said circuit closing means serving to connect the source of power to said electro-magnetic means, a rocker arm mounted on the press and telescopically connected with said rocking member, said electrical circuit closing means including a movable energizing projection and said rocking member having a portion thereof exposed adjacent its connection with the rocking member positioned to engage said projection only when said second position is achieved and the rocking member is so connected.

2. In a device of the character described which includes a punch press having a movable punch, a mandrel for supporting a work piece, and a driving mechanism for driving the punch, said mechanism including a reciprocable lever the reciprocation of which will actuate the power stroke of the press, an elongate rocking arm normally positioned with its free end spaced from the mandrel but capable of being rocked to a second position immediately adjacent the mandrel, electrical circuit connecting means adapted to close a circuit by movement of said rocking member, but only when the rocking memher is positioned immediately adjacent the mandrel, means biasing the rocking member to its normal position, and means actuated by the punch press operator for moving the rocking member to its second position, electro-magnetic means for reciprocating said lever, a source of electrical power, and said circuit closing means serving to connect the source of power to said electro-magnetic means, a rocker arm mounted on the press and removably connected to said rocking member, said electrical circuit closing means including a movable energizing projection, said rocker arm having a socket receiving said rocking member therein and said arm having a recess aligned with said projection but blocked by said rocking member when same is in the socket, whereby rocking of the arm will depress the projection, but only with the rocking member in place.

3. In a device of the character described which includes a punch press having a movable punch, a mandrel for supporting a work piece, and a driving mechanism for driving the punch, said mechanism including a reciprocable lever the reciprocation of which will actuate the power stroke of the press, an elongate rocking arm normally positioned with its free end spaced from the mandrel but capable of being rocked to a second position immediately adjacent the mandrel, electrical circuit connecting means adapted to close a circuit by movement of said rocking member, but only when the rocking member is positioned immediately adjacent the mandrel, means biasing the rocking member to its normal position, and means actuated by the punch press operator for moving the rocking member to its second position, electro-magnetic means for reciprocating said lever, a source of electrical power, and said circuit closing means serving to connect the source of power to said electro-magnetic means, a rocker arm mounted on the press and removably connected to said rocking member, said rocker arm having a socket therein, said rocking member comprising a wire member bent at one end thereof to provide two parallel legs the free ends of which are removably secured in the socket and the bent end has a loop formation the dimension of which is sufficient to accommodate the punch therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,370,369 Scofield Mar. 1, 1921 2,210,886 Dewey Aug. 13, 1940 2,236,730 MacBlane Apr. 1, 1941 2,337,143 Yanchenko Dec. 21, 1943 FOREIGN PATENTS 288,219 Switzerland May 1, 1953

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