US 2661780 A
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Description (OCR text may contain errors)
Dec. 8, 1953 J. P. MORGAN AUTOMATIC MAGNETIC BRAKE FOR BAND SAWS Filed Aug. 2, 1950 Joseph R Morgan BY Q4, WW
I N V EN TOR.
' Atlomrjs Patented Dec. 8, 1953 AUTOMATIC MAGNETIC BRAKE For: BAND sAws Joseph P. Morgan, Wampum,
Pa.,' assignor of forty-nine per cent to Harry CriscLNew Castle, Pa.
Application August 2, 1950, Serial N 0. 177,203
The present invention relates to new and useful improvements in safety means for band saws and more particularly to an improved automatically operated emergency safety mechanism to halt further travel of the band saw should the same become broken.
More specifically the invention comprises a normally de-energized electro magnet controlled by an electric switch which is actuated when the same saw breaks to energize the magnet and to which the broken blade of the saw is attracted for holding the saw from further movement until the power for operating the saw machine is cut off. An important object of the invention is to provide automatic switch means for the electro magnet which is held in open position by an unbroken band saw and providing spring means for closing the switch when the saw blade breaks.
A further object is to provide a device of this character of simple and practical construction, which is efiicient and reliable in operation, relatively inexpensive to manufacture and install in operative position on the saw machine and which is otherwise well adapted for the purposes for which the same is intended.
Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like parts throughout, and in which:
Figure 1 is a fragmentary side elevational view of a saw machine with parts broken away and shown in section to show the electro magnet and switch mounted in position thereon;
Figure 2 is an enlarged sectional view of the switch taken on a line 2--2 of Figure l; and
Figure 3 is an enlarged front elevational view of the magnet.
Referring now to the drawing in detail wherein for the purpose of illustration I have disclosed a preferred embodiment of the invention, the numeral 5 designates the guard or housing of a conventional type of band saw machine provided with the usual vertically travelling endless saw blade 6 which passes through the table I.
A switch housing 8 is secured to the underside of the table behind the front flight 9 of the saw blade, the housing enclosing a switch designated generally at I!) and which includes a pair of stationary contacts I I and I2 suitably insulated from the switch housing and a sliding switch arm I3 positioned between the stationary contacts with one end of the arm projecting outwardly of the housing and formed with a yoke I4 in which a roller I5 is journalled. A coil spring I6 is positioned in the switch housing at the rear end of switch arm l3 and engages a flange or cross pin I 1 fixed to the arm I3 to urge the latter outwardly.
A movable contact designated generally at I8 is suitably secured to the switch arm I3 and includes a pair of oppositely extending arms I9 and 20 positioned for engaging the contacts II and I2 upon an outward movement of the switch arm [3 by spring I6. The movable contact I8 is preferably adjustable on the switch arm it for adjusting the contact arms I9 and 20 relative to the contacts II and I2.
An electric circuit 2| connects the contacts II and i2 with a suitable source of current (not shown) and with an electromagnet 22 of a conventional type secured to the rear of the guard 5 in a position spaced from the rear flight 23 of the saw blade 6. In the operation of the device the spring I6 urges sliding switch arm l3 outwardly of the switch housing 8 to hold the roller I5 against the front flight 9 of the saw blade 6, the 25 spring being held under tension by the saw blade and the saw blade limiting outward movement of the switch arm I3 to hold the movable contact arms I9 and 20 spaced from the stationary contacts I I and I2, as shown in Figure 2 of the drawmgs.
The breakage of the saw blade usually occurs adjacent the table I and immediately upon such breakage spring I6 will slide switch arm I3 forwardly to close the circuit by bridging the stationary contacts I I and I2 by the contact arms I9 and 20 to thus energize the magnet 22 which thus attracts the rear flight 23 of the saw blade to hold the latter and halt its further. movement until the operator cuts off the machine and replaces the saw.
In view of the foregoing description taken in conjunction with the accompanying drawings it is believed that a clear understanding of the device will be quite apparent to those skilled in this art. A more detailed description is accordingly deemed unnecessary.
It is to be understood, however, that even though there is herein shown and described a preferred embodiment of the invention the same is susceptible to certain changes fully comprehended by the spirit of the invention as herein described and the scope of the appended claims.
Having described the invention, what claimed as new is:
1. In combination with a band saw, a switch including a slidable switch arm, spring means tending to close the switch, said arm being held in open position against and by the saw and against the urging of the spring and closed by the spring upon a break in the saw, and an electrically energized magnet connected to and controlled by the switch, said magnet being positioned adjacent the saw to attract and hold the latter stationary by the closing of the switch.
2. In combination with a band saw, a switch including a slidable switch arm, a roller at one end of the arm bearing against a travelling saw, spring means projecting the arm and holding the roller against the saw, a contact carried by the arm, a stationary contact in the path of movement of the first named contact and held spaced 4 therefrom by the saw, and an electro-magnet supported adjacent the saw and connected in a circuit with said contacts to energize the magnet and to attract and hold the saw stationary upon a break in the saw to release the switch arm and close the contacts.
JOSEPH P. MORGAN.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,927,203 De Groote Sept. 19, 1933 2,286,589 Tannewitz June 16, 1942 2,395,905 Oet'zel Mar. 5, 1946