US3780242A

US3780242A - Safety device for industrial machines with improved mechanical sensor and associated circuit breaker assembly

Info

Publication number: US3780242A
Application number: US00224767A
Authority: US
Inventors: J Bendror
Original assignee: Robbins and Bendror Associates Inc
Current assignee: Robbins and Bendror Associates Inc
Priority date: 1972-02-09
Filing date: 1972-02-09
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A safety device for industrial machines, having a plurality of individually movable mechanical sensor elements, sensing means for sensing relative movement between mechanical sensor elements, and circuit making and breaking means controlled by the sensing means, whereby the circuit making and breaking means is actuated to stop the machine on which the safety device is installed, when one of the mechanical sensor elements encounters an obstruction, such as an operator''s hand, and relative movement between mechanical sensor elements results.

Description

United States Patent 11 1 Bendror Dec. 18, 1973 SAFETY DEVICE FOR INDUSTRIAL 3,663,770 5/1972 Groskopfs 200/18 X MACHINES WITH IMPROVED 3,293,381 12/1966 Eitel 200/18 X 3,071,659 1/1963 Kimball zoo/1s x MECHANICAL SENSOR AND ASSOCIATED 3,303,304 2 1967 Campbell, Jr. et al. ZOO/61.42 x CIRCUIT RE R ASSEMBLY 3,272,929 9/1966 Hacker 200/16 B x [75] Inventor: Jack Bendror, Sands Point, NY.

Primary Examiner-J. R. Scott [73] Asslgnee' fi z g s z w gfiyf g z z Attorney-Samuel J. Stoll et a1.

[22] Filed: Feb. 9, 1972 [57] ABSTRACT [21] App! 224767 A safety device for industrial machines, having a plurality of individually movable mechanical sensor ele- 52 US. Cl zoo/61.41, ZOO/61.42, 200/81 R, ments, Sensing means for sensing relative movement Z O/ 3 R, 317/53 317/59 between mechanical sensor elements, and circuit mak- 51 Int. Cl. H01h3/16, H02h 1/00 ing and breaking means controlled y the sensing [58] Field 61 Search 200/16 B, 11 TW, means, whereby the circuit making a breaking 200/17 R, 61.63, 61.71, 61.79, 153 L, 18, means is actuated to stop the machine on which the 1 44,144 31 R 3 317 53 59 safety device is. installed, when one of the mechanical 7 sensor elements encounters an obstruction, such as an [5 R f r n Ci operators hand, and relative movement between me- UNITED STATES PATENTS chanical sensor elements results.

3,283,088 l/l966 Scow et al 200/17 R X 12 Claims, 22 Drawing Figures 7 I0 20 D 20. i 7 i I a a 50 i I 40 1 PATENTEI] DEE] 81973 SHEU 1 OF 4 SAFETY DEVICE FOR INDUSTRIAL MACHINES WITH IMPROVED MECHANICAL SENSOR AND ASSOCIATED CIRCUIT BREAKER ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to safety devices for industrial machines such as stamping, forging and hydraulic presses.

2. Description of the Prior Art The following patents constitute the closest prior art known to applicant:

No. 2,7l4,732 Traettino No. 3,081,725 Treer No. 3,l42,957 Cornell, Jr. No. 3,206,960 Moxley No. 3,352,230 Hunnicutt No. 3,393,635 Richardson No. 3,575,077 'Herdeg Various kinds of safety devices for industrial machines are shown in these prior art references. Some are controlled by photoelectric cells, e.g., Herdeg and Moxley; others are mechanically controlled, e g., Cornell and Iraettino. Although Traettino is not strictly a safety device, its use is analogous in the sense that it insures alignment of the work, namely, a book, in a book press. Traettino utilizes an alignment bar for controlling the operation of the press. This bar engages a pair of limit switches, one at each end. When the bar is properly aligned, both limit switches will be engaged and the operating circuit will be closed. Should the bar be misaligned so that only one of the switches is engaged, the operating circuit will not close.

Cornell uses a gravity-urged feeler to control the operation of a press. When-the feeler encounters an obstruction, its descent islimited, and the press remains inoperative.

Traettino and Cornell and the other prior art references suffer from the same inherent deficiency, namely,

inability to cope with employees who would choose to with the other. A plurality of. mechanical sensor elements or feelers cannot be neutralized with one hand while the other hand operates the machine. None of the other prior art references known to applicant provide safety means which will protect the operator against his own desire to forego such protection.

SUMMARY OF THE INVENTION The present invention comprises a safety device of the character described, having a plurality at least two but preferably three or more of mechanical sensor elements or feelers which are individually movable relative to each other, sensing means for sensing any relative movement between them, and circuit making and breaking means, controlled by the sensing means, for stopping the machine when any one of the mechanical sensor elements encounters an obstruction such as the finger or hand of an operator. When all of the mechanical sensor elements move in unison, there is no relative movement between them for the sensing means to detect, and hence the circuit making and breaking means is not actuated.

In the preferred form of thisinvention two spaced oppositely disposed groups of mechanical sensor elements or feelers are provided. While it might be possible for a machine operator to neutralize one group of mechanical sensor elements, it would not be feasible to neutralize both groups. In short, the machine operator would be protected even against his own effort to bypass protection. Y

The sensing means of the present invention may be sensitive and responsive to mechanical sensor element misalignment of relatively small proportions, e g., one thirty-second or one sixty-fourth of an inch. This would insure a stop motion action triggered by an operators little finger.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view showing the present invention applied to a book press and showing the relationship of its mechanical sensor elements in the absense of an unintended obstacle between the platens of the press.

FIG. 2 is a similar view showing the fingers of an operator engaging one of the mechanical sensor elements and causing it to be misaligned with respect to the other mechanical sensor elements in the same bank.

FIG 3 is a top view of a safety mechanism made in accordance with one preferred form of the invention.

FIG. 4 is a sectional view on the line 4-4 of FIG. 3.

FIG. 5 is a top view of one of the assemblies of the safety device shown in FIG. 3, this view showing misalignment among the three mechanical sensor elements of that section. v

FIG. 6 is a view similar to that of FIG. 5, also showing misalignment of the mechanical sensor elements but in a different manner.

FIG. 7 is a section on the line 77 of FIG. 6.

FIG. 8 is a section on the line 88 of FIG. 6.

FIG. 9 is a circuit diagram relating to the embodiment shown in FIG. 3.

FIG. 10 is a top view of a modified form of the first embodiment of the invention.

FIG. 11 is a section on the line llll of FIG. 10.

FIG. 12 is a top view of a second embodiment of the invention.

FIG. 13 is a section on the line I313 of FIG. 12.

FIG. 14 is a section onthe line l4--14 of FIG. 12.

FIG. 15 is a circuit diagram relating to the second embodiment of the invention.

FIG. 16 is a top view of a third form of the invention.

FIG. 17 is a schematic view of the magnetic switch mechanism of said third form of the invention.

FIG. 18 is a circuit diagram relating to the third form of the invention.

FIG. 19 is a top view of a safety mechanism made in accordance with a fourth embodiment of the invention.

FIG. 20 is an enlarged schematic view of an air bellows switch which may be used in connection with the fourth form of the invention.

FIG. 21 is an enlarged schematic view of an air vane switch which may be used inconnection with the fourth form of the invention.

FIG. 22 is a circuit diagram relating to the fourth form of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring to one preferred form of the invention as shown in FIGS. l9 of the drawing, it will be seen that safety device 10 is installed in a conventional book press 12, this installation being purely illustrative of the invention. Book press 12 has a stationary platen 14 and a movable platen 16 and the safety device has corresponding

sections

10a and 10b, respectively. These sections may be identical and a description of either is a description of both. Moreover, either may be installed and used separately or they may both be installed and used jointly.

Each

section

10a, 10b of the safety device comprises a supporting plate or frame20, a plurality of

slidable bars

22, 24 and 26, mechanical sensor elements or

feelers

28, 30 and 32 on said bars, cross-bars 34 and 36 secured to said supporting plate and providing guide means for

bars

22, 24 and 26, springs 38 interconnecting bar 34 with

bars

22, 24 and 26,

limit switches

40 and 42 on bar 24, switch-actuating

arms

44 and 46, including rollers (cam followers) 48 on said

limit switches

40 and 42, and

cam elements

50 and 52 on

bars

22 and 26 engaging'said switch arm rollers 48.

More specifically, cross-bars 34 and 36 are milled transversely to form channels 54 which receive and guide

bars

22, 24 and 26. Other guides or bearings may be used for the purpose, e.g., roller bearings 56. This is illustrated in FIG. 10.

Springs 38 are attached at one end to cross-bar 34 and at their opposite end to lugs 58 and 60 of

bars

22 and 26, and lugs 62 and 64 of bar 24. The springs are biased to urge

bars

22, 24 and 26 of section 10a toward the corresponding

bars

22, 24 and 26 of opposing section 10b. Since mechanical sensor elements or

feelers

28, 30 and 32 are provided on said

bars

22, 24 and 26, the spring action is to urge the mechanical sensor elements of each said section toward the mechanical sensor elements of the opposing section.

Adjustably attached to lugs 62 and 64 of bar 24 are

limit switches

40 and 42 with their

switch arms

44 and 46 and cam follower rollers 48.It will be observed that said cam followers 48 are engageable with

cams

50 and 52 on

bars

22 and 26. When all of the

bars

22, 24, 26 move in unison and there is no relative movement among them, there is no relative movement between the cam followers 48 and the

cams

50, 52. But when any one of the

bars

22, 24, 26 does move relative to any other bar, there will be relative movement between at least one of the cams and associated cam followers, and this will result in actuation of the related limit switch.

When a book 70 is placed between press platens l4 and 16 and between

mechanical sensor elements

28, 30 and 32 of section 10a and the corresponding

mechanical sensor elements

28, 30 and 32 of section 10b, all of said mechanical sensor elements will be engaged by the book and there will be no relative movement as between any of the mechanical sensor elements of each said section. But if the machine operator should place his hand or finger between the book and any of the mechanical sensor elements of either section, the result will be misalignment of the mechanical sensor elements, and hence misalignment of their supporting bars, resulting in actuation of at least one of the limit switches. The effect of this action is interruption of operation of the book press to prevent injury to the operators hand.

A simple electrical circuit, as depicted in the drawing, will illustrate this stop-motion" action of the safety device under discussion. As appears in FIG. 9, the

several switches

40 and 42 of both

sections

10a and 10b ofthe safety device are connected in series with each other and with a relay 72. Also included in the circuit is a starting or master switch 74 and a power source. In the illustrated form of the invention, the limit switches are normally open and they are held in closed condition by engagement of their respective cam followers 48 with

cams

50 and 52. When relative movement occurs as between mechanical sensor elements, at least one cam follower 48 will move relative to one of the cams 50, S2, and the corresponding limit switch will open. This will interrupt the circuit to relay 72 to stop or reverse the operation of the machine, for example, by means of a clutch-actuated braking mechanism or a hydraulic directional control valve. Alternatively, the limit switches may be normally closed and held in open condition by the cams and cam followers. In such case, relative movement between the mechanical sensor elements will cause one of the limit switches to close, thereby energizing the relay and actuating the stopmotion" control mechanism.

Referring now to the second embodiment of this invention as illustrated in FIGS. 12l5 of the drawing, it will be observed that safety device has substantially the same mechanical parts and features as safety device 10. It differs mainly in its sensing means for sensing relative movement between the

mechanical sensor elements

28, 30, 32.

More specifically, safety device 100 is provided with a photoelectric cell 102 and a light source 104 with a focusing optical system 106 for each bank or group of mechanical sensor elements and supporting bars. A light beam from the light source impinges upon the photoelectric cell through aligned light passages 108 in supporting

bars

22, 24, 26 when the mechanical sensor elements and their supporting bars are in alignment. Relative movement between said mechanical sensor elements and supporting bars will cause misalignment of light passages 108, thereby interrupting the light beam and preventing its impingement upon the photoelectric cell.

The circuit diagram depicted in FIG. 15 will show how the photoelectric sensing system functions as a stop-motion device for the machine on which it is installed. The photoelectric cells of both banks of mechanical sensor elements are connected in series with master or starting switch 110 and relay 112 which controls the machine circuit. I

Turning now to the third'forrn of this invention as illustrated in FIGS. 16-18 of the drawing, it will be seen that safety device corresponds to safety devices 10 and 100, except as to the sensing means for sensing relative movement between the

mechanical sensor elements

28, 30, 32.

Each bank or group of mechanical sensor elements and their respective supporting bars is provided with magnetically responsive switches 122 and switch controlling magnets 124. These switches are connected in series with each other and with master or starting switch 126 and relay I28. Relay 128 controls the circuit which controls the operation of the machine on which the safety device is installed. When any one of the mechanical sensor elements of either bank is moved relative to the'others, one of the magnetic switches is actuated, resulting in actuation of the relay.

The fourth illustrative form of the invention is depicted in FIGS. 19-22, where safety device 140 corresponds substantially to above described

safety devices

10, 100 and 120 except for the sensing means. In safety device 140 mechanical sensing means are used, said sensing means comprising a pressure sensitive fluidic switch 142, a series of conduits 144, and a tube 146 connecting one of said conduits to a conventional.

source of air pressure (notshown). In the illustrated form of this sensing system, the pressure sensitive switch is mounted on one of the supporting bars 22, the conduits are mounted on the. other supporting

bars

24, 26, and the source of pressurized air is situated at any convenient location. I

Fluidic switch 142 is of the bellows type. It comprises a bellows 148, a limit switch 150 in engagement with said bellows, and a tube 152 which communicates with said bellows. When conduits 144 are in alignment with tube 152, air pressure maintains the bellows in expanded condition, exerting pressure against the limit switch. When the mechanical-

sensor elements

28, 30, 32 are out of alignment, by reason of movement of any one of them relative to the others, at least one of the conduits 144 will be out of alignment with the other conduits and tube 152 andthe pressurized air will be deflected from the bellows. This will cause the bellows to collapse and its pressure upon the limit switch will be relieved, resulting in actuation of the limit switch.

The fluidic switch may take another form, as illustrated by switch 160. This device comprises a limit switch 162 which is controlled by a vane 164. When pressurized air flows through tube 152, it impinges upon the vane and deflects it from its position shown in FIG. 21 of the drawing. When the pressurized air flow is interrupted (upon misalignment of one of the conduits 144) the vane will be relieved of the air pressure and it will revert to its position shown in the drawing. This movement of the vane will actuate the limit switch.

The circuit diagram shownin FIG. 22 applies to this fourth form of the invention. It consists of a pair of limit switches 150 (or 162), one for each bank of

mechanical sensor elements

28, 30, 32, a starting or master switch 166 and a relay 168, all connected in series. This circuit controls the operation of the machine on which the safety device under discussion is installed.

The foregoing is illustrative of preferred forms of the invention, and it will be understood that these forms may be modified and otherflforms may be provided within the broad scope of the appended claims. For example, two opposed banks or groups of mechanical sensor elements are used in the preferred forms of this invention. However, there are applications in which only a single bank or group of mechanical sensor elements will suffice. Additionally, the particular sensing means for sensing relative movement between the mechanical sensor elements, as shown in the drawing, are to be taken only as illustrative of the principles of the invention, and this is equally true of the circuit making and breaking means which are shown in the drawing. 6

Moreover, it is immaterial whether the sensing means and the circuit making and breaking means are separate means working conjointly or whether they are the same means performing both functions. What is significant is the principle of using a plurality of mechanical sensor elements and providing them with means for sensing relative movement or misalignment between them and means actuated by or included within the sensing means for stopping the motion or operation of the machine in which the device herein claimed is installed.

I claim:

1. A safety device for industrial machines having relative movable machine parts capable of crushing or otherwise injuring a workers hand or other part of his body between them, said safety device comprising:

a. a plurality of mechanical sensor elements mounted adjacent each other in the vicinity of said machine parts and positioned to intercept a workers hand or other bodily part before it is injured by said machine parts,

b. said mechanical sensor elements being individually movable relative to each other, and being also jointly movable as a group without relative movement between them,

0. stabilizing means normally maintaining said mechanical sensor elements in such intercepting position, and

d. sensing means disposed on at least one of said mechanical sensor elements, and operable upon movement of any of said mechanical sensor'elements relative to any other of said mechanical sensor elements,

e. said sensing means being insensitive to joint movement of said mechanical sensor elements as a group without relative movement between them.

2. A safety device in accordance with claim 1,

wherein:

a. the mechanical sensor elements are arranged in side-by-side relationship along a generally common line,

b. said mechanical sensor elements being movable in substantially parallel paths which are generally perpendicular to said line.

3. A safety device in accordance with claim 1,

wherein: Y

a. there are two spaced, oppositely disposed groups of mechanical sensor elements, all occupying a substantially common plane, I

b. each group consisting of a plurality of mechanical sensor elements arranged in side-by-side relationship along a generally common line and movable in substantially parallel paths which are generally perpendicular to said line,

c. said lines of side-by-side mechanical sensor elements being substantially parallel to each other,

(I. whereby the mechanical sensor elements of each group are individually movable both relative to each other and to the mechanical sensor elements of the other group.

4. A safety device in accordance with claim 1,

wherein: I

a. the sensing means includes electric switch circuit making and breaking means,

b. said circuit making and breaking means being actuated when relative movement between the mechanical sensor elements is sensed.

5. A safety device in accordance with claim 1,

wherein the sensing means consists of:

a. an electric switch and actuating means therefor operative between adjacent mechanical sensor elements,

b. the switch being connected to one of said adjacent mechanical sensor elements, and

c. the switch actuating means being connected to the other of said adjacent mechanical sensor elements,

d. whereby movement of either of said adjacent mechanical sensor elements relative to the other causes the switch actuating means to actuate the switch.

6. A safety device in accordance with claim 5, wherein the circuit making and breaking means consists of a relay in circuit with the electric switch.

7. A safety device in accordance with claim 1, wherein the sensing means consists of:

a. a light source,

b. a photoelectric cell, and

c. light passages connected with said mechanical sensor elements,

d. said light passages being normally in alignment with each other and with said light source and photoelectric cell. I

8. A safety device in accordance with claim 7, wherein the circuit making and breaking means consists of a relay in circuit with the photoelectric cell.

9. A safety device in accordance with claim 1, wherein the sensing means consists of:

a. a magnetically responsive switch and a magnet operative between adjacent mechanical sensor elements,

b. the magnetically responsive switch being connected to one of said adjacent'mechanica] sensor elements, and

c. the magnet being connected to the other of said adjacent mechanical sensor elements,

d. whereby movement of either of said adjacent mechanical sensor elements relative to the other causes the magnet to actuate the magnetically responsive switch.

10. A safety device in accordance with claim 9, wherein the circuit making and breaking means consists of a relay in circuit with the magnetically responsive switch.

11. A safety device in accordance with claim 1, wherein the sensing means consists of:

a. a fluidic switch which is actuated by pressurized air,

b. a pressurized air source, and

c. a plurality of conduits aligned on the mechanical sensor elements to provide communication between said fluidic switch and said pressurized air source,

d. whereby movement of said mechanical sensor elements relative to each other causes disalignment of said conduits and interrupts communication between said fluidic switch and said pressurized air source.

12. A safety device in accordance with claim 11,

wherein the circuit making and breaking means consists of a relay in circuit with the fluidic switch.

Claims

1. A safety device for industrial machines having relative movable machine parts capable of crushing or otherwise injuring a worker''s hand or other part of his body between them, said safety device comprising: a. a plurality of mechanical sensor elements mounted adjacent each other in the vicinity of said machine parts and positioned to intercept a worker''s hand or other bodily part before it is injured by said machine parts, b. said mechanical sensor elements being individually movable relative to each other, and being also jointly movable as a group without relative movement between them, c. stabilizing means normally maintaining said mechanical sensor elements in such intercepting position, and d. sensing means disposed on at least one of said mechanical sensor elements, and operable upon movement of any of said mechanical sensor elements relative to any other of said mechanical sensor elements, e. said sensing means being insensitive to joint movement of said mechanical sensor elements as a group without relative movement between them.

2. A safety device in accordance with claim 1, wherein: a. the mechanical sensor elements are arranged in side-by-side relationship along a generally common line, b. said mechanical sensor elements being movable in substantially parallel paths which are generally perpendicular to said line.

3. A safety device in accordance with claim 1, wherein: a. there are two spaced, oppositely disposed groups of mechanical sensor elements, all occupying a substantially common plane, b. each group consisting of a plurality of mechanical sensor elements Arranged in side-by-side relationship along a generally common line and movable in substantially parallel paths which are generally perpendicular to said line, c. said lines of side-by-side mechanical sensor elements being substantially parallel to each other, d. whereby the mechanical sensor elements of each group are individually movable both relative to each other and to the mechanical sensor elements of the other group.

4. A safety device in accordance with claim 1, wherein: a. the sensing means includes electric switch circuit making and breaking means, b. said circuit making and breaking means being actuated when relative movement between the mechanical sensor elements is sensed.

5. A safety device in accordance with claim 1, wherein the sensing means consists of: a. an electric switch and actuating means therefor operative between adjacent mechanical sensor elements, b. the switch being connected to one of said adjacent mechanical sensor elements, and c. the switch actuating means being connected to the other of said adjacent mechanical sensor elements, d. whereby movement of either of said adjacent mechanical sensor elements relative to the other causes the switch actuating means to actuate the switch.

7. A safety device in accordance with claim 1, wherein the sensing means consists of: a. a light source, b. a photoelectric cell, and c. light passages connected with said mechanical sensor elements, d. said light passages being normally in alignment with each other and with said light source and photoelectric cell.

9. A safety device in accordance with claim 1, wherein the sensing means consists of: a. a magnetically responsive switch and a magnet operative between adjacent mechanical sensor elements, b. the magnetically responsive switch being connected to one of said adjacent mechanical sensor elements, and c. the magnet being connected to the other of said adjacent mechanical sensor elements, d. whereby movement of either of said adjacent mechanical sensor elements relative to the other causes the magnet to actuate the magnetically responsive switch.

11. A safety device in accordance with claim 1, wherein the sensing means consists of: a. a fluidic switch which is actuated by pressurized air, b. a pressurized air source, and c. a plurality of conduits aligned on the mechanical sensor elements to provide communication between said fluidic switch and said pressurized air source, d. whereby movement of said mechanical sensor elements relative to each other causes disalignment of said conduits and interrupts communication between said fluidic switch and said pressurized air source.

12. A safety device in accordance with claim 11, wherein the circuit making and breaking means consists of a relay in circuit with the fluidic switch.