US 3848502 A
A safety device for protecting an operator's hands from the cutting edge of the blade of a band saw characterized by a shield disposed in a protective relationship with the blade and supported for rectilinear reciprocation along a path paralleling the plane of the blade, a double-acting pneumatic cylinder for imparting rectilinear motion to the shield, and a feeler disposed in juxtaposition with the shield and connected therewith for initiating operation of the cylinder in response to an engagement therewith of a selected workpiece as the workpiece is advanced toward the blade.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 91 1111 3,848,502 ONeill 1451 Nov. 19, 1974  SAFETY DEVICE FOR PROTECTING AN 3,648,552 3/1972 Bradley 83/544 X OPERATOR 'S HANDS Edwin R. ONeill, 2393 Barstow Ave., Fresno, Calif. 93705 Filed: Nov. 5, 1973 Appl. No.: 413,356
U.S. Cl 83/814, 83/544, 83/440.2, 83/860 Int. Cl B26d 4/22, 326d 7/22 Field of Search 83/814, 860, 544, 446, 83/422, 440.2
References Cited UNITED STATES PATENTS 3/1921 McDonnell 83/814 10/1955 Dremel 9/1963 Bretthauer 83/814 Primary Examiner-Willie G. Abercrombie Attorney, Agent, or Firm-Huebner & Worrel  ABSTRACT A safety device for protecting an operators hands from the cutting edge of the blade of a band saw characterized by a shield disposed in a protective relationship with the blade and supported for rectilinear reciprocation along a path paralleling the plane of the blade, a double-acting pneumatic cylinder for imparting rectilinear motion to the shield, and a feeler disposed in juxtaposition with the shield and connected therewith for initiating operation of the cylinder in response to an engagement therewith of a selected workpiece as the workpiece is advanced toward the blade.
7 Claims, 7 Drawing Figures SAFETY DEVICE FOR PROTECTING AN OPERATOR'S HANDS BACKGROUND OF THE INVENTION The invention relates to safety devices for protecting an operators hands from the cutting edge of blades disposed in a vertically oriented plane and more particularly to a safety device for protecting the hands of a meat cutter as he employs a band saw in the performance of meat cutting operations.
As can readily be appreciated by those familiar with the art of cutting meat, large and heavy cuts of meat often are sent through a band saw for purposes of reducing their bulk and weight prior to being supplied to an ultimate consumer. Such cuts, of course, frequently lack uniformity, are chilled, and are quite heavy and are difficult to handle. Moreover, the cuts frequently are coated with layers of fatty tissues. This, coupled with the additional fact that meat cutting procedures normally must be performed by highly paid personnel, tends to increase production costs. As a natural consequence, personnel involved in meat cutting operations attempt to feed band saws employed in cutting meats at rapid rates. This, in turn, tends to lead to injuries being suffered by such personnel.
To date, band saws employed in meat cutting operations simply have not been provided with suitable safety devices capable of protecting an operators hands. It is therefore the general purpose of the instant invention to overcome the aforementioned difficulties by providing a safety device, including a shield for the blade of the band saw and a feeler responsive to an engagement therewith of a selected cut of meat, for initiating a raising and lowering of the shield through a throw equal to the vertical thickness of the cut of meat.
OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the instant invention to provide an improved safety device for band saws.
It is another object to provide a safety device for protecting an operators hands as he employs a band saw in performing meat cutting operations.
It is another object to provide a safety device for use with band saws including a shield disposed in a protective relationship with the blade of a band saw and a feeler supported in juxtaposition with the shield for detecting a workpiece as the workpiece is advanced toward the blade and an actuator responsive to a detection of the workpiece for elevating the shield through a throw equal to the vertical thickness of the workpiece.
These and other objects and advantages are achieved through the use of an elongated shield circumscribing a vertical segment of a run for a band saw blade and supported for rectilinear motion along a path paralleling the segment, a cyclically operable fluid-driven actuator having a linear output shaft for imparting rectilinear motion to the shield, a flow control valve and a feeler connected therewith and supported in juxtaposition with the shield for initiating operation of the actuator in response to an engagement therewith of a cut of meat as the cut is advanced toward the blade, as will hereinafter become more readily apparent by reference to the following description and claims in light of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of a band saw equipped with a safety device embodying the principles of the instant invention. 1
FIG. 2 is an end view of the band saw shown in FIG.
FIG. 3 is a sectional view taken generally along line 3-3 of FIG. 2.
FIG. 4 is a fragmentary view on an enlarged scale illustrating an operative relationship of the safety device with the blade of the band saw shown in FIG. 2.
FIG. 5 is a fragmented view of a selector valve employed in controlling the safety device of the instant invention.
FIG. 6 is a cross-sectional view, taken generally along line 6-6 of FIG. 5.
FIG. 7 is a schematic view of a control system employed for controlling the operation of the safety device of the instant invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now with more specificity to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a band saw, generally designated 10, embodying the principles of the instant invention.
It should here be noted that the band saw 10 is a commercially available design and is of a type frequently found in butcher shops, meat packing plants and the like. Since such saws are well known, a detailed description of the saw 10 is omitted in the interest of brevity. However, it is to be understood that the band saw 10, as illustrated, includes a blade 12 and has particular utility in cutting large cuts of meat 14 preparatory to their being supplied to consumers, retailers and the like. The blade 12 is supported by a pair of vertically spaced, coplanar drums driven along a unidirectional path including a pair of mutually spaced, vertically oriented runs extending between the drums. A table 16 is provided for supporting the cuts of meat 14 as they are fed to the blade 12 by an operator, such as a meat cutter.
As illustrated in the drawings, the band saw 10 is provided with a safety device, generally designated 20, which embodies the principles of the instant invention. The safety device 20 includes a vertically oriented shield 22, formed of a right-angle extrusion, which partially encases the blade 12 in a protective disposition relative to the blades cutting edge or teeth.
While not shown, it is to be understood that the shield 22 is supported at its uppermost end by suitable bearing structures, which accommodate vertical reciprocation. At its lowermost end, the shield 22 is supported by a lifting plate 24 connected therewith in any suitable manner. The plate 24, in turn, is united with a vertically oriented guide rod 26, also in any suitable manner, as by welding and the like. The guide rod 20.
nated 30. The cylinder 30 includes a barrel suspended to the housing of the band saw blade 10, in an inverted disposition, by a suitable clevis coupling 31. The cylinder 30 also includes a downwardly extended piston shaft 32, which serves as an output shaft supported for rectilinear reciprocation. Reciprocation is imparted to the shaft 32 as the end portions of the barrel are reversely pressurized, in a manner and for a purpose well understood by those familiar with double-acting, pneumatic cylinders.
At the distal end of the output shaft 32, there is a clevis 34. The clevis 34 is pinned to a bracket 36 by a suitable pin 38, which, in turn, is affixed to the guide rod 26 at its lowermost end. Thus the shaft 32 is connected with the shield 22 through the plate 24 and the bracket 36.
Therefore, it should be apparent that as the output shaft 32 is retracted, relative to the barrel of the double-acting pneumatic cylinder 30, the guide rod 26 and the shield 22 simultaneously are elevated through a distance dictated by the length of the stroke or throw of the output shaft. Similarly, the shield 22, along with the guide rod 26, are lowered through a distance dictated by the throw of the shaft 32, as the shaft is extended relative to the barrel of the cylinder 30.
It is to be clearly understood that the shield 22 normally is disposed in protective relation with the blade 12. However, upon a retraction of the output shaft 32, relative to the barrel of the cylinder 30, the shield 22 is elevated out of such relation with the blade 12. Thus a feeding of a cut of meat 14 to the blade 12 is facilitated. Once lowered, the shield 22 serves to protect the hands of the operator from the effects of the blade.
Pressurization of the barrel of the cylinder 30, for advancing the shaft 32 in extension and retraction strokes, is dictated by a selector valve 40. This valve communicates with the end portions of the barrel of the cylinder 30 through a pair of pressure lines 42 and 44, coupled with suitable ports provided within the opposite end portions of the barrel of the cylinder 30. The selector valve 40 also is connected, through a pressure line 45, with a pump or other suitable source of pressurized fluid, designated 46, FIG. 7.
While a liquid hydraulic fluid could be employed equally as well for purposes of pressurizing the cylinder 30, pneumatic fluid is preferred in order to achieve a more rapid response. Of course, therate of the response achieved must be consistent with the intended mode of operation for the device 20. Consequently, in order to control the rate at which the shield 22 is elevated and lowered, a flow restrictor 48 is connected in each of the pressure lines 42 and 44, immediately adjacent the barrel of the cylinder. Thus by varying the rate of flow of fluid through the restrictors 48, the rate at which the shaft 32 is advanced is precisely controlled for thereby accurately controlling the rate at which the shield 22 is raised and lowered.
As shown, the valve 40 is a three-position valve and includes a housing 50 and a spool 52 supported for rotation within the housing. Additionally the housing is provided with a first pressure port 54, a second pressure port 56 and an exhaust port 58. Within the spool 52 there is formed an axial bore 60. This bore is connected with the source of fluid 46 through a suitable port, not designated, and the pressure line 45. The spool 52 also includes, in communication with the bore 60, a first radial bore 62 and a second radial bore 64 axially spaced from and angularly related to the first radial bore 62. These radial bores are alternatively aligned with the pressure ports 54 and 56, when the spool 52 is advanced to positions at the extremities of its throw.
About the spool 52 there is provided an arcuate groove 66 of an angular length such that one pressure port 54 or 56 can be caused to communicate with the exhaust port 58, via the arcuate groove, while the other pressure port is in communication with the axial bore 60, via one of the radial bores 62 or 64. Hence, it is to be understood that when either of the ports 54 or 56 is in communication with the axial bore 60, via one of the radial bores 62 or 64, the exhaust port 58 is in direct communication with the double-acting pneumatic cylinder 30. Moreover, the groove 66 and the radial bores 62 and 64 are so interrelated that the spool 52 can be rotated to a centered position wherein neither of the pressure lines 42 or 44 is in communication with either the axial bore 60 or the exhaust port 58. Thus, it is possible to arrest pressurization of the cylinder 30 and hence the motion of the output shaft 32.
The spool 52 further includes an axially extended stub shaft 67. This shaft is extended from the housing 50 and receives an actuator arm 68. The arm 68 is secured to the stub shaft 67 through any suitable means including a pin 70. Preferably, the arm 68 includes a base segment 72, FIG. 5, radially extended from the stub shaft 57 and an angularly related distal segment 74. This segment, in practice, is arranged in substantial parallelism with the axis of rotation for the spool 52. Consequently, oscillatory motion is imparted to the spool 52 as the distal segment 74 of the arm 68 is caused to oscillate about the valve 40. Thus, the valve 40 is manipulated.
The arm 68 is spring-biased in a first direction by a suitable compression spring 76, FIG. 4, suitably seated on the valves housing, in an abutting engagement with the arm 68. Displacement of the arm 78 in a second direction, opposite to the first direction, is achieved through a use of an actuator arm 78 rigidly affixed to and extended from a skid, generally designated 80 which functions as a feeler for sensing the pressure of a cut of meat.
The skid 80 is coupled with the bracket 36 through ajournal 82 and includes a base 84 to which the journal 82 is connected. The arm 78 also is affixed, as by welding and the like, to the base 84. Extended forwardly from the base 84, at opposite sides of the blade 12, is a bifurcated framework 86 having an upturned distal portion 88 which imparts an inclined configuration to the skid 80. An arcuate connecting member 90 extends between the opposite sides of the bifurcated framework 86. The skid 80 is caused to pivot about the journal 82, as the forward end thereof is lifted, whereupon the distal end of the extended arm78 is caused to engage the arm 68. Continued pivotal motion of the skid serves to impart additional angular displacement to the arm 78, whereupon the'arm 68 is caused to impart angular displacement to the spool 52 within the housing 50 of the valve 40.
As a practical matter, the connection between the distal end of the arms 68 and 78 is accommodated through a pad 92 affixed to the distal segment 74 of the arm 68 and a protuberance 94 adjustably secured to the distal end of the actuator arm 78. The protuberance 94, as shown, is an elongated screw-threaded member received within a screw-threaded opening, not designated, provided in the distal end of the actuator arm 78. By advancing or retracting the protuberance 94, relative to the planes of the arm, the effective angular relation of the skid 80 to the spool 52 can be varied. Thus the spool 52 is caused to rotate through a predetermined angle, relative to the ports 54, 56, and 58, as the skid 80 is pivotally displaced through a predetermined angle relative to a horizontal plane. It will therefore be appreciated that the shield 22 is elevated through a throw dictated by the angular displacement of the skid 80 as a cut of meat is caused to engage the distal end 88 and rotate the skid about the journal 82. Of course, the shield is subsequently lowered in response to a disengagement of the cut of meat with the skid.
Moreover, since the cylinder 30 is a double-acting pneumatic cylinder, controlled by the position assumed by spool 52, the bracket 36 is elevated, as the spool is advanced to a first position, through a distance sufficient only for accommodating a passage of a cut of meat beneath the skid, due to the fact that as the skid 80 is caused to achieve the horizontal disposition a responsive centering of the spool 52 occurs. Once the skid 80 is permitted to rotate, in an opposite direction, the spool 52 also is caused to be rotated in an opposite direction to a second position under the influence of the spring 78 for thereby oppositely pressurizing the cylinder 30. Such pressurization of the cylinder 30 causes the bracket 36, and hence the shield 22, to be lowered until such time as the skid 80 engages the surface of the table 16 for thus causing the spool 52 to center. Thus motion of the shield is arrested.
OPERATION It is believed that in view of the foregoing description, the operation of the device will readily be understood and it will be briefly reviewed at this point.
With the safety device 20 mounted on the band saw 10, in the manner hereinbefore described, the device is prepared for use in performing meat cutting operations.
An operator grasps a cut of meat 14 and forces it beneath the distal end portion 88 of the skid 80 whereupon the skid 80 is caused to pivot at its journal 82 for initiating a cycle of operation. Pivotal motion of the skid 80 causes the distal end of the threaded protuberance 94 to engage the pad 92, located at the distal end of the arm 68. As the cut of meat is advanced beneath the skid 80, the skid is caused to continue to rotate. Such continued rotation of the skid causes angular displacement to be imparted to the spool 52, within the housing 50 of the selector valve 40. Sufficient rotation of the spool 52 causes the spool to be advanced to its first position wherein the radial bore 64 is brought into alignment with the pressure port 56. At this instant, the source of pneumatic pressure 46 is caused to communicate with the cylinder 30, via the bores 60 and 64, within the spool 52, the pressure port 56 and the pressure line 42. Hence, the output shaft 32 is retracted relative to the barrel of the cylinder as pressure is introduced into the lowermost end of the cylinder 30. Retraction of the shaft is accommodated as the uppermost end of the cylinder 30 is permitted to communicate with the exhaust port 58, via the pressure line 44, the pressure port 54 and the arcuate groove 66. However, due to the effects of the flow restrictors 48, within the pressure lines 42 and 44, the rate at which retraction of the output shaft 32 is retarded.
As the shaft 32 is retracted, the lifting plate 24 is elevated for thereby lifting the shield 22 for accommodating the passage of the cut of meat through blade 12. Of course, once the lifting plate 24, as well as the bracket 36, has been lifted a distance sufficient for accommodating a passage of the cut of meat 14, beneath the skid 80, the skid assumes a zero angular relation with respect to the horizontal, whereupon the spool 52 is rotated to its centered position, under the influence of the spring 76. Centering of the spool 52 within the housing 50 of the selector valve 40 interrupts communication through the valve whereupon all motion of the output shaft 32 is arrested.
As the cut of meat 14 is passed beneath the skid 80, the distal end 88 is permitted to pivot downwardly, for permitting the arm 68 to be further displaced, under the influence of the spring 76, whereupon communication between the axial bore 60 and the pressure port 54 is established through the radial bore 62. Simultaneously therewith, the arcuate groove 66 permits the pressure port 56 to communicate with the exhaust port 58. In this configuration, the selector valve 40 causes the lower end of the double-acting pneumatic cylinder 30 to communicate with ambient atmosphere while the upper end of the cylinder is caused to communicate with the source of pressure 46 for forcing the output shaft 32 in an extension stroke.
Extension of the shaft 32 causes the bracket 36, and consequently the lifting plate 24, to be lowered sufficiently for permitting the skid to rest upon the top surface of the table 16. As the skid 80 comes to rest it is rotated in an opposite direction for again centering the spool 52 within the housing 50 whereupon downward motion of the output shaft 32 and the shield 22 is arrested. Thus, a cycle of operation for the safety device 20 is completed.
In view of the foregoing, it should readily be apparent that the device of the instant invention provides a practical solution to the perplexing problem of protecting the hands of meat cutters when employing band saws for cutting large and unwieldy cuts of meat.
Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.
Having described my invention what I claim as new and desire to secure by Letters Patent is:
1. A safety device for protecting an operators hands from the cutting edge of a blade disposed in a vertically oriented plate, comprising:
A. a shield disposed in protective relation with a vertically disposed blade supported for linear motion along a vertical path paralleling the plane of the blade; and
B. actuating means responsive to an engagement of a workpiece therewith for elevating the shield out of protective relation with the blade and further responsive to a disengagement of the workpiece for lowering said shield into protective relation with the blade, including,
1. a fluid driven actuator having an output shaft supported for cyclic rectilinear motion connected with the shield for imparting thereto rectilinear reciprocation,
2. means including a cylically operable fluid selector valve responsive to manipulation for imparting cyclic rectilinear motion to the shaft, and
3. feeler means mounted in juxtaposition with said shield for manipulating said valve in response to sequential engagement and disengagement with said workpiece.
2. The device of claim 1 wherein said actuating means includes means for limiting vertical motion imparted to said shield, as the shield is elevated, to a throw equal to the vertical thickness of said workpiece.
3. The device of claim 1 wherein said feeler means includes:
A. a pivotal skid extended in a substantially horizontal direction forwardly of said blade; and B. means including an arm rigidly fixed to said skid for manipulating the selector valve.
4. The device of claim 3 wherein said fluid-driven actuator comprises a double-acting pneumatic cylinder including means defining a pressure port located at each of its opposite ends, and a flow reduction valve connected with each of the pressure ports for reducing the rate of rectilinear motion imparted to the shaft.
5. The device of claim 4 wherein said fluid selector valve comprises a three-position valve including a third position wherein said valve interrupts the flow of pneumatic fluid to either port of said double-acting pneumatic cylinder; a second position wherein pneumatic fluid is directed to a first port; and a first position wherein said fluid is directed to the other port.
6. A safety device for protecting an operators hands in combination with an endless blade of a band saw having a vertical run and driven in unidirectional displacement, said device comprising:
A. an elongated shield partially circumscribing a segment of the run for said blade and supported for rectilinear motion along a path paralleling said segment;
B. A cyclically operable, fluid-driven actuator having a linear output shaft for imparting rectilinear motion to said shield; and
C. means including a feeler disposed in juxaposition with said shield and connected therewith for initiating operation of said actuator in response to an engagement therewith of a selected workpiece as the workpiece is moved relative to the blade.
7. In a safety device for protecting an operators hands from the cutting surface of a device adapted to cut hand-fed workpieces, the improvement comprising:
A. a shield adapted to be arranged in juxtaposition with a cutting surface of a selected device supported for rectilinear motion along a substantially linear path extending between a first position wherein the shield is disposed in a protective relation with said cutting surface and a second position, spaced from said first position, wherein said shield is disposed in non-protective relation with said cutting surface; and
B. actuating means including a fluid-pressurizable actuator connected to said shield adapted to respond to pressurization for moving said shield from said first position to said second position, means for selectively pressuring said actuator including a selectively operable fluid control valve connected to a source of fluid maintained under pressure, and feeler means connected to said fluid control valve adapted to respond to an engagement with a workpiece for operating the fluid control valve and so disposed as to be engaged by a workpiece as the workpiece is hand-fed to said device.
UNITED STATES' PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 848 SQZ Dated N y fi 12 Inventor(s) Edwin R. O'Neill I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column '7', line 3, delete "cylically" and :i. nsert ---cyc1i .ca11y---.
Signed and sealed this 14th day of January 1975.
(SEAL) Attest: I
OY M. GIBSON JR. c; MARSHALL mm figuring Officer Commissioner of Patents USCOMMDC 60376-P69 US. GOVERNMENT PRINTING OFI'ICE 869- 930 F ORM PO-IOSO (10-69)