ELECTRIC SHEARS

• US 3,787,742 A
• Filed: 03/07/1972
• Issued: 01/22/1974
• Est. Priority Date: 03/07/1972
• Status: Expired due to Term

• Current Assignee: Timothy C. Murphy
• Original Assignee: Timothy C. Murphy
• Inventors: Murphy, Timothy C.
• Primary Examiner(s): Shoop, Jr., William M.
• Application Number:
  US05/232,446
• Time in Patent Office: 686 Days
• Field of Search: 30/228 200/157 310/47,50,80 318/346,443,466
• US Class Current: 310/50
• CPC Class Codes: B26B 15/00 Hand-held shears with motor-driven blades
• CPC Class Codes: H01H 19/62 Contacts actuated by radial cams
• CPC Class Codes: H01H 9/06 Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner
• CPC Class Codes: H02K 7/145 Hand-held machine tool

Abstract

An electric shears in which there is provided a housing having swingably interconnected first and second cutting blades mounted therein and projecting outwardly therefrom. A gear train is mounted within the housing and is interconnected between a reversable electric motor and said second blade for moving said second blade with respect to said first blade. A manually manipulatable switch assembly is mounted on said housing and is coupled through a second switch assembly for actuating said motor to drive said gear train in a first direction to cause the cutting blades to open and close. A cam driven by the gear train is engageable with said second switch assembly for selectively opening and closing said assembly to control said motor to drive said gear train in a second direction for an interval sufficient to position the cutting blades in an open position and deactuate said motor.

Claims

1. In an electric shears, a housing, a reversable electric motor mounted in said housing, a plurality of first contacts adapted to be connected to a power source, a gear train mounted in said housing and connected to said motor, a fixed and a movable blade swingably interconnected to each other and projecting outwardly from said housing, a shaft carried within said housing, a gear mounted on said shaft and interconnected to said gear train and movable blade for rotating said shaft and moving said movable blade, a cam carried on said shaft for rotation therewith, a pair of switch arms swingably supported within said housing, a pair of second contacts operatively connected to said switch arms and said motor, a manually manipulatable switch mounted on said housing and engageable with said switch arms to move said arms to cause said second contacts to close against a pair of said plurality of first contacts to actuate said motor to drive said gear train in a first direction, and means on said can engageable with said switch arms when said switch is out of engagement therewith to move said arms to cause said second contacts to sequentially close against a second pair of said plurality of first contacts to actuate said motor to drive said gear train in a second direction and against a third pair of said plurality of first contacts to deactuate said motor.

2. An electric shears as set forth in claim 1 with the addition that said gear train is carried in a casing mounted in said housing, a pair of mounts projecting outwardly from said casing, and said shaft is rotatably supported in said mounts.

3. An electric shears as set forth in claim 1 with the addition that said gear train is carried in a casing mounted in said housing, first and second pairs of mounts project outwardly from said casing at one end thereof, and said shaft is rotatably supported on said first pair of mounts and said switch arms are swingably supported from said second pair of mounts.

4. An electric shears as set forth in claim 1 with the addition that said gear train is carried in a casing mounted in said housing, first and second pairs of vertically spaced mounts project outwardly from said casing at one end thereof, said shaft is rotatably supported on said first pair of mounts and said switch arms are swingably supported in laterally spaced relation from said second pair of mounts, and said cam is mounted on said shaft in alignment with said arms.

5. An electric shears as set forth in claim 4 with the addition that said cam has a pair of laterally spaced cam faces each disposed in alignment with one of said switch arms for moving said arms with respect to each other.

6. An electric shears as set forth in claim 1 in which said manually manipulatable switch comprises an L-shaped spring having a first leg connected to said housing and a second leg engageable with said switch arms, and a button carried on said first leg and received in an opening in said housing.

7. An electric shears as set forth in claim 6 in which said button is slidably mounted on said first leg, said button being movable into a position to engage said housing adjacent said opening to prevent said button from moving said spring.

8. An electric shears as set forth in claim 1 in which said manually manipulatable switch comprises an L-shaped spring having a first leg connected to said housing and a second leg engageable with said switch arms, a button slidably carried on said first leg and received in an opening in said housing, said button being movable into a position to engage said housing adjacent said opening to prevent said button from moving said spring, and means on said housing to prevent said button from sliding.

9. An electric shears as set forth in claim 8 in which said means on said housing compRises a rock rotatably mounted on said housing and having a radially projecting tongue movable into and out of the path of movement of said button.

10. In an electric shears, a housing, a fixed and a movable blade swingably interconnected and projecting outwardly from said housing;

a reversable electric motor mounted in said housing;

first, second, third and fourth electrical contacts adapted to be connected to a power source;

a gear train interconnected to said motor and movable blade for moving said movable blade;

first and second switch arms having fifth and sixth contacts operatively associated therewith and connected to said motor;

said fifth and sixth contacts being movable between a first position in which they are closed respectively against said first and second contacts for actuating said motor to drive said gear train in one direction and a second position in which they are closed respectively against said third and fourth contacts for actuating said motor to drive said gear train in an opposite direction and a third position in which they are closed respectively against said first and fourth contacts for deactuating said motor;

first means for moving said switch arms to cause said fifth and sixth contacts to move into said first position; and

second means for moving said switch arms to cause said fifth and sixth contacts to move successively into said second and third positions.

11. An electric shears as set forth in claim 10 in which said first and third contacts and said second and fourth contacts are wired in series.

12. An electric shears as set forth in claim 10 in which said first and third contacts and said second and fourth contacts are wired in series, a rectifier has one of its sides connected to said first and third contacts and its opposite side connected to said second and fourth contacts, and a transformer is connected to said rectifier.

13. An electric shears as set forth in claim 10 in which said fifth and sixth contacts are mounted on a pair of movable switch blades, and a spring is interconnected to each of said switch blades to one of said switch arms.

14. In an electric shears, a housing, a fixed and a movable blade swingably interconnected to each other and projecting outwardly from said housing, a reversable electric motor, a plurality of first contacts adapted to be connected to a power source, a gear train interconnected to said motor and movable blade for moving said blade, a pair of switch arms, a pair of second contacts operatively connected to said switch arms and connected to said motor, means engageable with said switch arms to move said switch arms to cause said second contacts to selectively open and close against said first contacts to selectively actuate said motor to drive said gear train in a first direction in a continuous manner and to drive said gear train through a predetermined interval in an opposite direction.

15. In an electric shears, a housing, a fixed and a movable blade swingably interconnected and projecting outwardly from said housing;

a reversable electric motor mounted in said housing;

gear means interconnected to said motor and movable blade for moving said blade upon actuation of said motor;

switch means connected to said motor and a power source and movable into a first position for actuating said motor to drive said gear means in a first direction, a second position for actuating said motor to drive said gear means in a second direction, and a third position for deactuating said motor; and

means for actuating said switch means to cause said switch means to move into said first, second and third positions.

16. An electric shears as set forth in claim 15 in which said means for actuating said switch means includes means for successively moving said switch means from said first through said third positions.

17. In an electric shears, a housing, a fixed and a movable blade swingably interconnected and projecting outwardly from said housing, an electric motor mounted in said housing, a geaR train carried in a casing mounted in said housing, said gear train being connected to said motor and having a driver gear, a shaft carried from said casing, a driven gear mounted on said shaft in mesh with said driver gear, an eccentrically mounted stud on said driven gear rotatably and slidably carried in a slot formed in said movable blade for moving said blade with respect to said fixed blade, a plurality of contacts interconnected between said motor and a power source, a leaf spring mounted in said housing, and a switch button mounted on said spring for moving said spring into a position to close said contacts for actuating said motor, said button being slidably mounted on said spring for movement to and from an inoperative position overlying said housing whereby said button is prevented from moving said spring.

18. An electric shears as set forth in claim 17 with the addition that a lock is mounted on said housing for engagement with said button to releasably lock said button in its inoperative position.

19. In an electric shears, a housing, a fixed and a movable blade swingably interconnected and projecting outwardly from said housing, a reversable electric motor mounted in said housing, a gear train carried in a casing mounted in said housing, said casing having pairs of vertically spaced mounts projecting therefrom, a shaft carried on one of said pairs of mounts, a cam mounted on said shaft for rotation therewith, a bevel gear mounted on said shaft, said gear drivingly interconnecting said gear train to said movable blade and shaft, an insulating board carried on the other of said pairs of mounts, a first set of contacts mounted on said board, a rectifier connected to a transformer and to said first set of contacts, a pair of electrically conductive hangers mounted on said board and connected to said motor, a pair of switch arms swingably mounted on said hangers and engageable with said cam, a pair of switch blades mounted on said hangers and having a second set of contacts closable against said first set of contacts, spring means interconnecting said switch blades and arms, and a manually manipulatable switch mounted on said housing engageable with said switch arms, said switch and cam being selectively engageable with said switch arms for moving said switch arms to cause said switch blades to move said second set of contacts to selectively close against said first set of contacts to successively actuate said motor to drive said gear train in a first direction, an opposite direction and to deactuate said motor.