US 3365963 A
Description (OCR text may contain errors)
Jan. 30, 1968 R. HAPPE BATTERY POWERED SCISSORS Filed July 19, 1965 INVENTOR.
' Reyna/d Happe BY I W TORNEY WITNESS Mafia a JL Unit d States Patent 3,365,963 BATTERY POWERED SCISSORS Reynold Happe, Whippany, N.J., assignor to The Singer 0mpany, -New York, N.Y., a corporation of New ersey Filed July 19, 1965, Ser. No. 472,873
' 6 Claims. (Cl. 7447) ABSTRACT OF THE DISCLOSURE This invention relates to a driving mechanism adapted for use in rotary powered cutting tools, which mechanism is particularly adapted to convert rotary motion into oscillating motion. a
More specifically the driving mechanism of the present invention is especially adaptable for use in lightweight portable tools wherein a drive shaft is rotatably driven by an electric motor supplied by a battery contained in the tool.
In recent years the portable appliance field has exhibited marked growth. The lightweight and simple construction of these appliances has contributed to their popularity. A common type of these appliances (e.g. Scissors, saws, etc.) requires that the rotary motion of the motor powered drive shaft be converted to oscillatory motion at the output end thereof. The output end is connected to and imparts oscillatory motion to a tool member, such as a blade.
While magnetic vibratory motors, such as A.C. solenoids, have been used to obtain a reciprocatory motion directly, these have in general been unsatisfactory because of an inherent tendency for the amplitude of vibration to decrease as the load increases for such devices. The cutting efiiciency of tools so powered is greatly reduced because of less work output per stroke as the amplitude decreases.
The importance of a constant amplitude motion for the cutting tool is thus established and this invention is directed towards simple low-cost and effective means for obtaining such motion.
An object of the present invention, therefore, is to provide a power driving mechanism which also converts rotary motioninto oscillating motion.
' A further object of this invention is to provide a driving mechanism for use in a portable appliance which also converts rotary motion into oscillating or reciprocatory motion, which mechanism is lightweight and of simple low-cost construction and produces an oscillating motion of constant amplitude regardless of the applied load. Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and .arrangements of parts as illustrated in the presently preferred embodiment of the invention which ishereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings. in which:
FIG. -1 is a plan view, partly in section, of a battery powered scissor illustrating an embodiment of this invention,
FIG. 2 is a perspective view of the disassembled mechanism for converting rotary motion to linear oscillating or reciprocating motion,
FIG. 3 is a longitudinal sectional view, partly in elevation, taken substantially on line 3-3 of FIG. 1,
FIG. 4 is a detailed plan view, partly in section, of a modified form of this invention. 1
One embodiment of this invention comprises a housing 12 formed of two hollow sections 14 and 16. Section 14 may be split longitudinally as shown for ease of assembly. Bolts 18 and 20 extend through the upper section 16 and are screwed into openings 22 and 24 in fingers 26 and 28 of lower section 14 thereby to hold the two sections together.
A battery 30 having contacts 32 and 34 snugly fits within section 16. A conventional motor 36 having a drive shaft 38 is contained in part of section 14, as shown. Contacts 40 and 42 on the opposite end of the motor 36 are in pressure contact with battery contacts 32 and 34. A switch (not illustrated) when actuated, electrically connects the motor 36 in circuit with the battery 30, causing the drive shaft 38 to be rotated.
A crank or hub 44 having preferably a hemispherical recess 46 eccentrically located on the face thereof is secured by means of a set screw 48 to the drive shaft 38 for rotation therewith.
A flexible beam 50 of resilient spring material comprises a flexing portion 52 and a non-flexing portion 54 (see FIG. 1). A spherical ball 56 is integral with one end of the beam 50 and is journaled within the hemispherical recess 46. The flexible beam 50 has stub shafts or pins 58 extending from both sides thereof which are pivotally received in posts 60 and 62 of section 14. The stub shafts 58 are provided with collars 64 and 66 which are preferably rotatably journaled thereon and fit between the beam 50 and the posts 60 and 62. Screws 68 and 69 hold the split halves of section 14 together and tighten the posts 60, 62 against the collars 64 and 66 which in turn abut against the beam 50 so as to prevent lateral movement thereof. The restraint exerted by the collars against the beam is such that the beam 50 will not be laterally displaced at the pivotal axis 58 regardless of the position of the ball 56 in the recess 46. Therefore the drive shaft 38 may rotate the crank 44 so that the ball 56 is laterally displaced between two opposed positions without any lateral displacement being transmitted to the non-flexing portion 54 of beam 56. The ball 56 will follow the path of the crank face recess 46 because the beam 50 is laterally flexible to permit component motion in one direction and is pivoted to permit component motionin a direction normal thereto. When the drive shaft 38 rotates the crank 44 so that the ball is vertically displaced between two opposed positions, the beam 50, being relatively stiff in this direction, will vertically pivot about pins 58 producing oscillatory or reciprocatory motion at the output end of the beam opposite the ball 56. The dotted line representation in FIG. 2 shows successive beam positions for a degree crank revolution. When the ball is in its highest position, the end of the beam opposite thereto will be in its lowest position as indicated by L. Similarly when the ball is in its lowered position the end of the beam opposite thereto will be at its highest position (not illustrated). 1
It is clear from the above that the beam 50 need'be laterally flexible only over the flexing portion 52 where it is needed to permit the lateral components of the circular input motion, the vertical components being permitted by the pivotal mounting afforded by the pins 58. Thus the non-flexing portion 54 could be of any desirable section (for example circular), and stiff enough to transmit the desired forces. For convenience in manufacture, the beam 50 is shown here as being formed from a single 3 piece of flat spring stock and so has a similar cross section throughout its length.
A flat, round tab 70 is located on the end of the beam 50 opposite the ball portion 56 and reciprocates and oscillates with said member. A scissor blade 72 having a cutting edge 74 is pivotally connected to pin 76. The rear of the scissor blade 72 has a sleeve 78 thereon which slidably receives the tab 70 of flexible beam 50. The sleeve 78 extends outwardly from the blade 72 on the opposite side of pivot 76 at an angle so that downward movement imparted to the sleeve 78 will cause upward movement of the blade 72. Similarly upward movement imparted to the sleeve 78 will cause downward movement of the blade 72. Therefore, when the tab 70 is moved downwardly by the beam 50 the sleeve 78 will be lowered and the scissor blade 72 will be raised. Similarly when the tab is moved upwardly by the beam 50 the sleeve 78 will be raised and the scissor blade will be lowered. Although a scissor blade has been illustrated in this embodiment it is within the scope of this invention to drive other tools requiring reciprocatory motion by this mechanism.
A stationary scissor blade 80 having a cutting edge 82 is fixedly secured to the inner surface of section 14 by two screws 84 and 86. The pivot pin 76 extends through the lower portion of the scissor blade 80 so that the scissor blade 72 is operatively associated therewith. The article to be cut is placed between blades 72 and 74 and the motor is actuated to drive scissor blade 72 downwardly so that the article is cut by the shearing action of the descending scissor blade 72 and the stationary scissor blade 80.
FIG. 4 represents a modification of the connection between the drive shaft and the flexible beam. In this figure a drive shaft 38' is connected to a crank 44' by a set screw 48. The crank face has a cylindrical recess 46' therein whose centerline CL2 is offset from the centerline CLl of shaft 38 and in which a spherical or selfaligning sleeve bearing member 47 is seated. A coupling member 49 connects the drive shaft 38' to the flexible beam 50'. The coupling member 49' comprises a conical section 51' to which is secured one end of the flexible beam 50'. A rod 52' formed on the conical section 51' is journaled in the bearing member 47 thereby joining the beam 50' and the crank 44' for motion transmission. Since the centerline CL2 of the recess 46' is offset from the centerline CLI of the drive shaft 38', rotation of the drive shaft 38' will cause the input end of beam 50' to be driven in a circular path around the centerline CLl of the drive axis. Thus the same circular motion will be imparted to the end of beam 50 as is imparted to the end of beam 50 in the embodiment of FIGS. 1 through 3. The crank 44 is provided with annular fins 53 which radiate the heat generated by friction losses between the bearing 47 and crankface recess 46'. The modification in FIG. 4 is suitable for use with the general structure set forth in FIGS. 1 through 3.
General operation The general operation of this battery-powered scissor will be explained with reference to that embodiment of the present invention illustrated in FIGS. 1 to 3. A switch or other actuating means (not illustrated) closes an electric circuit between battery 30 and motor 36 whereby drive shaft 38 will be caused to rotate. Drive shaft 38 will rotate the crank 44 mounted thereon and the ball member 56 which is journaled in the crank and is driven thereby will tend to rotate the attached end of flexible beam 50 in a circular path.
Lateral movement of the beam 50 is confined to and absorbed by the laterally flexing portion 52 by the lateral restraint provided by the pins 58 and collars 64 and 66 confined between the posts 60 and 62. Vertical movement of the input end of the beam 50 will be converted directly to similar vertical output movement by the pivotal action of pins 58. The flexible beam 50 will thus pivot vertically upon crank rotation, and will cause a scissor blade 72 operatively connected thereto to reciprocate into cutting relationship with the scissor blade 80 fixedly mounted on the section 14 so that an article placed between the scissor blades will be cut. Although the motion conversion system has been illustrated in use with a battery powered scissor it may be used in various other mechanisms requiring simple, low-cost structure. The oscillatory motion of the scissor blade is of constant amplitude and is directly proportional to the length of the lever arm, degree of eccentricity and position of pivot point.
From the above it will be perceived that there is provided by this invention a simple, low-cost and effective driving mechanism for converting rotary input motion to linear reciprocatory output motion which mechanism uses a laterally flexible beam with a laterally restrained pivot for absorbing lateral components of input circular motion While permitting components of motion normal to said lateral components to pass through said pivot to produce output reciprocatory motion in a single plane and of constant amplitude.
Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.
Having thus described the nature of the invention, what I claim herein is:
1. In a tool having a cutter powered by a rotary electric motor having an output shaft, power transmitting means for converting the rotary motion of said shaft into reciprocatory motion of said cutter comprising a hub mounted on said output shaft for rotation therewith, a recess formed in the face of said hub and located eccentrically of said shaft, a beam having an input end and an output end, means secured to the input end of the beam and journaled in said recess for imparting circular motion to said input end, pivotal means located intermediate the ends of the beam to restrain the motion thereof to pivotal motion in a single plane, said beam being laterally flexible at least in the portion between the intermediate pivotal means and the input end to provide easy bending movement thereof in directions normal to said single plane, and means connecting the output end of the beam to the cutter.
2. Apparatus according to claim 1 wherein the means secured to the input end of the beam is a spherical ball and the recess formed in the hub is of hemispherical configuration for universally journaling the ball.
3. Apparatus according to claim 1 wherein the means secured to the input end of the beam is a rod journaled in a spherical sleeve bearing member and the recess formed in the hub is of cylindrical configuration for journaling the bearing member.
4. Power transmitting means for converting rotary motion to reciprocatory motion comprising a beam having input and output ends, means at the input end for imparting circular rotary motionthereto, pivotal restraint means located intermediate the ends of the beam for restraining the beam to pivotal motion in a single plane, said beam being laterally flexible at its input end to permit easy bending movement in directions normal to said single plane.
5. A mechanical drive for converting rotary motion to oscillatory motion comprising a beam having an input end and an output end, means imparting circular motion to the input end of said beam, means located intermediate the ends of the beam for restraining the motion of the beam to pivotal motion in a single plane about a single axis, said beam being laterally flexible at the input end to permit easy deflection thereof in directions nor mal to said single plane whereby oscillatory motion in 5 said single plane is imparted to the output end of the beam.
6. Power transmitting mechanism for converting ro-,
tary circular motion to reciprocatory motion comprising a beam having an input end and an output end, means at the input end for imparting thereto rotary motion in a circular path, pivotal means located intermediate the ends of the beam constraining the beam to pivotal movement in a single plane, said beam being laterally flexible at its input end to permit easy transverse deflection thereof in directions normal to said single plane whereby only the components of the input circular motion in said single plane are passed through the pivotal means to produce reciprocatory motion of constant amplitude at the output end of the beam.
References Cited UNITED STATES PATENTS 1,480,586 1/ 1924 Willett 74-47 2,379,049 6/ 1945 Tompkins 1522 2,617,133 11/1952 Cocchiola 7447 2,635,335 4/1953 James 30--247 2,875,458 3/1959 Tsuda 1522 3,029,651 4/1962 Flatt 1522 3,149,494 9/1964 Hulse 74-47 3,160,902 12/1964 Aymar 74-47 3,278,963 10/1966 Bond 1522 FRED C. MATTERN, 1a., Primary Examiner.
W. S. RATLIFF, Assistant Examiner.