GB2202025A

GB2202025A - Oscillating right angle drive system

Info

Publication number: GB2202025A
Application number: GB08729203A
Authority: GB
Inventors: Phil Snider
Original assignee: Cooper Industries LLC
Current assignee: Cooper Industries LLC
Priority date: 1987-03-12
Filing date: 1987-12-15
Publication date: 1988-09-14
Also published as: GB8729203D0; DE3800923A1

Description

- 1 RIGHT DRIVE SYSTEM 2 0 2 0 2 ' -j The present invention pertains to

oscillating power tools, more particularly the present invention pertains to oscillating power tools wherein the driven tool is mounted at a right angle with respect to its driver.

Exemplary of oscillating power tools having a linear mounting with respect to the motor-driver is the saw used to saw a cast off a patient after a broken bone has healed. Such oscillating saws having a linear. orientation have not been commonly used in industrial settings because of the difficulty and inconvenience caused by the motor-driver getting in the way of the sawing operation. Conventional portable oscillating saws with the output spindle essentially aligned with the axis of the motor, are limited in their capability of transmitting power to the saw blade because of the tendency of the blade to stall while the housing oscillates in the operators hand. Even during lighter cutting, the axial arrangement causes considerable vibration.

There is therefore a need in the art to provide an oscillating power tool such that the motor-driver will not get in the way of the operation of the tool and thus inconvenience or limit the operator in the types of work that may be done.

2 SUMMARY OF THE INVENTION

An output drive for a pneumatic tool which is used to drive an oscillating tool such as a saw blade and will not cause difficulty for or inconvenience the operator includes a rotating driver having an offset finger cam. The rotating driver is attached to the output shaft of a motor-driver such as an air motor or an air motor and clutch assembly. The offset finger cam on the rotating motor-driver engages a U- shaped slot in a cam follower. It is the engagement between the offset finger cam and the U-shaped slot in the cam follower which transforms the rotary motion of the offset finger cam into oscillating motion of the cam f6llower. The oscillating motion of the cam follower is about an axis which is substantially perpendicular to the axis of the rotary motion of the motor-driver.

Mechanically attached to the cam follower is an output drive shaft. This mechanical attachment of the output drive shaft to the cam follower is accomplished by means of a key and keyway. At the distal end of the cam follower is a tool mounting assembly such as located a series of threads, an inner flange and an outer flange. A tool such as an oscillating saw blade is sandwiched between the inner flange and the outer flange when mounted on the distal end of the drive shaft.

The right angle drive of the present invention is contained within a housing. The horizontal portion of the housing is mounted to the drive end of the power tool and contains the offset finger cam while the vertical portion of the housing contains the cam follower and output shaft.

A better understanding of the right angle system of the present invention may be had by reference to the figures wherein:

Figure 1 is a front elevation, in partial section of a pneumatic tool connected to the right angle drive system of the present invention; Figure 2 is a detailed view of the cam and cam follower which transforms rotary motion into dcillating motion; Figure 3 is a front elevational view, in partial section, of the right angle drive system; Figure 4 is a top plan view, in partial section, of the right angle drive system; and Figure 5 is an exploded perspective view thereof.

A better understanding of the right angle drive system 20 of the present invention may be had by reference to Figures 1-4 wherein it may be seen that tool 10 consists of an air motor 12 with a lever actuator 14 on its side, a clutch portion 16, an adaptor housing 18 and a right angle drive system 20. It is the right angle - 4 drive system 20 which incorporates the present invention. For purposes of illustration a saw will be shown as the driven tool; however it will be understood that other type tools may be used without departing from the scope of the invention.

Attaching right angle drive system 20 to air motor 12 and clutch housing 16 is adaptor housing 18 which threadably mounts the horizontal portion 21 of right angle drive system 20. At the output or distal end 19 of vertical portion 64 of right angle drive 20 is located saw blade 22 which receives the oscillating motion of right angle system drive 20.

A better understanding of right angle drive system 20 may be had by reference to Figure 3. geginning at motor output drive shaft 24, it may be seen that drive shaft 24 includes external threads 26 which are threadably engaged with internal threads 28.

Internal threads 28 are contained within rotating driver 30. Rotating driver 30 includes offset shaft 34 which is mounted within recess 35. Rotatably mounting shaft 34 within recess 35 are a pair of bearings 32 which are positioned by spacer 38. Surrounding the end of shaft 34 which protrudes from driver 30 is roller bearing 36, which along with offset shaft 34, makes up finger cam assembly 80. Finger cam assembly 80 engages U-shaped follower opening 42.

U-shaped follower opening 42 is formed in cam follower 40. When finger cam assembly 80 rotates, its slight off center location as shown in Figure 2 causes cam follower 40 to move back and forth in an oscillatory motion. This back and forth movement is transmitted via output shaft 48 to saw blade 22 thus causing saw blade 22 to move back and forth in a vibratory motion.

Locating output shaft 48 within housing 60 are upper bearing 52 and lower bearing 521. Transmitting motion from cam follower 40 to output shaft 48 is key 44 which is located in key way 46 formed in the side of output shaft 48. Flange 50 of output shaft Ii 48 rides on ring 52. Holding the parts within housing 60 is retainer ring 58 which is threadably engaged 68 to the bottom of housing 60. Positioning saw 22 on the bottom of output shaft 48 is outer flange 74. Saw blade 22 is sandwiched between outer flange 74 and inner flange 72, both of which are threadably engaged 70 on the end of output shaft 48. This right angle Mounting of saw blade 22 allows the operator to use a tool such as a saw blade without being hampered by the drive motor housing.

OPERATION Saw blade 22 is mounted on the end of output shaft 48 by unscrewing outer flange 74 from its mounting threads and placing saw blade 22 on inner flange 72. Outer flange 74 is then replaced and saw blade 22 is sandwiched between inner flange 72 and outer flange 74.

When air motor 12 is caused to rotate, the rotary motion from air motor 12 is transmitted by motor output drive shaft 24 to rotating driver 30. As finger cam assembly 80 is located slightly - 6 offset from the center line of rotation of output shaft 24, finger cam assembly 80 travels in a small circle. This circular rotation of finger cam assembly 80 acts upon U-shaped opening 42 of cam follower 40. As may be best seen by reference to Figures 2 and 4, this small circular motion is translated into an oscillatory or vibratory motion of cam follower 40. As cam follower 40 is keyed to output shaft 48 this oscillatory or vibratory motion is transmitted to the end of the output shaft 48 on which saw blade 22 is mounted. Accordingly, saw blade 22 is moved in a back and forth motion and may be used to cut wood, plastic or any other material typically sbaped by a saw blade.

The utility of a pneumatic tool employing the right angle drive system 20 of the present invetion may be enhanced by forming saw blade 22 in a pie shape or a shape having two parallel straight edges. This particular blade configuration, as opposed to the circular configuration shown, may be used to cut straight side holes in a work piece. The ability to cut straight sides holes in a work piece has been severly limited by oscillating saws with linear drive systems.

For purposes of illustrating the preferred embodiment the 20drive system 20 of the present invention has been shown used with an air motor. Other drive motors such as electric or fluid motors may be used without departing from the scope of the invention.

There is thereby provided by the device of the present invention an oscillating saw which enables the user to translate the 25vibratory motion of the saw to a work piece such that the driver for 9 7 the saw is out of the way of the sawing operation such that the saw may be more conveniently used. Because of the fact that in the right angle arrangement, the mass of the tool and the handle portion are offset-from the output spindle, it has been found that the resulting leverage greatly reduces vibration of the tool and reduces the tendency to stall the blade.

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Claims

1. An output drive for a pneumatic tool comprising:

a rotating driver having an offset finger cam; a cam follower constructed and arranged to engage said offset finger cam, said cam follower transforming the rotary motion of said offset finger cam to oscillatory motion along an axis substantially orthogonal to said rotating driver; an output drive shaft; means for mechanically transmitting the oscillatory motion of said cam follower to said output drive shaft; means for attaching an oscillating tool such as a saw blade or the like to said output drive shaft; a housing constructed and arranged for mounting of said output drive shaft, said cam follower and said rotating driver.

2. The output drive as defined in Claim 1 wherein said means for attaching an oscillating tool such as a saw blade or the like to said output drive shaft includes inner and outer flanges which are threadably attached to the end of said output drive shaft.

3. The output drive as defined in Claim 2 wherein said means for mechanically transmitting the oscillatory motion of said cam follower to said output drive shaft is a key and key way.

4. The output drive as defined in Claim 1 wherein said 2. offset finger cam includes a rotary bearing for engagement with said cam follower.

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5. The output drive as defined in Claim 4 wherein said cam follower includes a U-shaped slot for engagement with said offset finger cam.

6. The output drive as defined in Claim I wherein said offset finger cam is mounted in at least one rotatable bearing.

7. The output drive as defined in Claim 1 wherein said housing includes ball bearings for rotatably mounting said output drive shaft.

8. A pneumatic tool comprising:

an air motor; a clutch section; means for threadably mounting a tool accessory to said clutch section; a rotating driver mechanically connected to said clutch section, said rotating driver having an offset finger cam; a cam follower constructed and arranged to engage said offset finger cam, said cam follower transforming the rotary motion of said offset finger cam to oscillating motion along an axis substantially orthogonal to said rotating driver; an output drive shaft; means for mechanically transmitting the oscillating motion of said cam follower to said output drive shaft; means for attaching an oscillating tool such as a saw blade or the like to said output drive shaft; a housing constructed and arranged for mounting of said output drive shaft, said cam follower and said rotating drive shaft.

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9. A method for transforming the rotary motion of a pneumatic tool to an oscillating 'motion, said method comprising the steps of:

- attaching a rotating driver having an offset finger cam to the output of the pneumatic tool; engaging said offset finger cam with a cam follower; placing said cam follower in a housing such that a rotating motion of said cam follower is transformed into oscillating motion along an axis substantially orthogonal to the axis of said rotating motion; mechanically affixing an output drive shaft to said cam follower; drive shaft.

mounting a saw blade or the like to the end of said output 9 4