US2097944A - Grinding machine - Google Patents

Description

NOV. 2, 1937. 3- CASEY 2,097,944

GRINDING MACHINE Filed Feb. 1, 1937 y l Vl IIIIIIHII-v IIN/Hl INVENTOR, LEDGEWORTH G CASEY MMMQMW ATTORNEY.

Patented Nov. 2, 1937 PATENT oFFlcE GRINDING MACHINE Ledgeworth G. Casey, Cincinnati, Ohio, assigner to The Cincinnati Electrical Tool Company,' Cincinnati, Ohio, a corporation of Ohio Application Februaryl, 1937, Serial No. 123,328

8 Claims.

My invention pertains to grinding machines and more particularly to the driving mechanism for the grinding element or grinding wheel of such machines.

'I-Ieretofore, it has been Vdifficult to provide a smooth drive to a grinding wheel which was subjected to intermittent cutting operations on a work piece such as is encountered in hand grinding and snagging operations. In such operations f, there is a tendency for the grinding wheel to momentarily drive the driving motor at the instant the wheel is removed from the work piece because of its usually greater mass and momentum which causes it to be less susceptible to 3 changes in speed than the armature of its driv- .Y nonconformity of motion objectionable in grinding machines wherein the transmission connecting the driving motor to the grinding wheel has slack or backlash, such for example as is found in the usual reduction gearing between the motor and the grinding wheel in portable electric hand grinding tools, because of the chatter and vibration set up which tends to destroy the transmission and the accuracy of the grinding operations.

An object of my invention is to provide in a grinding machine, between the driving motor and the grinding wheel, a transmission mechanism wherein the motor may drive the grinding wheel but the grinding wheel may not drive the motor.

Another object is to provide in a grinding machine, a motor and a grinding Wheel and a transmission mechanism incorporating an over-running clutch connecting said motor to said grinding wheel whereby the momentum of the grinding wheel can not cause said wheel to driveV the motor.

And a further object is to provide in a hand grinder, a motor and grinding wheel and a gear reduction transmission mechanism incorporating an over-running clutch connecting said motor to said grinding wheel.

Other objects of this invention will be understood from the following detailed description of the drawing, in which:

Figure I is a plan View partly in section on line I-I of Figure II showing an exemplary embodiment of my invention in a portable electric hand grinder.

Figure II is a transverse section through the transmission mechanism on line II-II of Figure I.

As an exemplary embodiment I show my invention applied to a portable electric hand grinder comprising the usual electric motor housing lI and switch handle 2 to which is attached the electric supply cord 3. Connected to the motor housing I by suitable screws 4 is the bear- 5 ing plate 5 and the grinding wheel spindle housing 5. The grinding wheel spindle 1 is journaled in bearing 8, in housing 5 and in bearing I0 in the plate 5. A grinding wheel I I is appropriately mounted on the wheel spindle 'I by the usual l0 mounting means I2.

The armature shaft I3 of the armature I4 of the motor I5 in the housing I is journaled in the bearing l5 in the plate 5 and has a pinion I'I fixed thereon which engages the ring gear I8. Journaled on the bearing portion I9 of the spindle l isthe cup member which has a hub portion ZI which is journaled in the bearing 22 mounted in the housing 6, thereby providing free rotation of cup on the spindle 'I while at the 20 same time providing an adequate intermediate support for said spindle. The ring gear I8 is xed on the `outside portion of the cup 25 and held in positive driving relation by means of the key 23.

Fixed in driving relation on the spindle l is the star wheel 24 by means of key 24a which has the rollers- 25 associated therewith in the usual manner for an over-running clutch. A suitable disc 25 also xed on the spindle 'I ad- 30 jacent the bearing I serves to maintain the rollers 25 in proper axial relation to the star wheel 24 and cup 25.

The over-running clutch comprising the cup 2li, the star wheel 24 and associated rollers 25 are 35 so arranged that driving power may be delivered from armature I4 through the pinion I'I and ring gear I8 to drive the spindle l, but the spindle can not drive the ring gear I8. The result of providing such an arrangement. is to cause the ring gear I8 to at all times be driven by the pinion and to prevent the spindle 1 from causing the gear I8 to drive or tend to accelerate the speed of rotation of the motor pinion and armature I4 thus preventing any backlash movement be- 45 tween the pinion I'I and the gear I8 and its inherent chatter and vibration.

Having described my invention, what I claim as new and desire to secure by United States Letters Patent is:

l. In a grinding machine, a frame, a grinding wheel spindle rotatably mounted in said frame, a grinding wheel mounted on said spindle, a motor incorporated in said frame having an armature mounted on an armature shaft rotatably mounted 55 in said frame, a driving pinion on said armature shaft, an over-running clutch mounted on said wheel spindle, and a gear associated with said over-running clutch and engaged by said pinion whereby said motor may drive said grinding Wheel and said grinding wheel may not drive said motor.

2. In a grinding machine, a frame, a grinding Wheel spindle journaled in said frame, a grinding Wheel mounted on said spindle, a motor incorporated in said frame having an armature mounted on an armature shaft rotatably mounted in said frame, a driving pinion Xed on said armature shaft, an over-running clutch mounted on said Spindle comprising a star W'heel x'ed to said spindle, a cup journaled on said spindle, and associated rollers, and a ring gear fixed to said cup and adapted to be driven by said pinion whereby said grinding wheel may be driven by said motor and said grinding Wheel may not drive said motor.

3. In a grinding machine, a frame, a grinding wheel spindle journaled in said frame, a grinding Wheel mounted on said spindle, a motor incorporated in said frame having an armature mounted on an armature shaft rotatably mounted in said frame, a driving pinion fixed on said armature shaft, an over-running clutch associated With said spindle comprising a star wheel Xed to said spindle, a cup rotatably mounted on said spindle and in said frame, and associate rollers, and a gear xed to said cup and adapted to be driven by said pinion 'whereby said motor may drive said grinding wheel and said grinding wheel may not drive said motor.

4. In a portable electric hand grinder having wheel spindle, motor, and switch handle portions, a grinding Wheel spindle rotatably mounted in said wheel spindle portion, a grinding wheel mounted on said spindle, an armature mounted on an armature shaft rotatably journaled in said motor portion, a pinion Xed on said armature shaft, an over-running clutch associated with said wheel spindle, comprising a star wheel Xed on said spindle, a cup journaled on said spindle, and associated rollers, and a gear xed on said cup adapted to be driven by said pinion whereby said motor may drive said grinding Wheel and said grinding wheel may not drive said motor.

5. In a portable electric hand grinder, a frame, a wheel spindle rotatably mounted in said frame, a grinding wheel mounted on said wheel spindle, an electric motor incorporated in said frame, an over-running clutch mounted on said wheel spindle, and means inter-connecting said motor with said clutch whereby said Wheel spindle may be rotated by said motor and said motor may not be rotated by said Wheel spindle.

6. In a grinder, a frame, a wheel spindle rotatably mounted in said frame, a grinding wheel mounted on said wheel spindle, an electric motor incorporated in said frame, an over-running clutch mounted on said Wheel spindle, and means inter-connecting said motor with said clutch whereby said wheel spindle may be rotated by said motor and said motor may not be rotated by said wheel spindle.

7. In a grinder, a frame, a wheel spindle rotatably mounted in said frame, a grinding wheel mounted in said frame, a grinding wheel mounted on said wheel spindle, an electric motor incorporated in said frame, an over-running clutch mounted on said wheel spindle, and lgear-reduction means inter-connecting said motor with said clutch whereby said Wheel spindle may be rotated by said motor and said motor may not be rotated by said wheel spindle.

8. In a grinder, a frame, a wheel spindle rotatably mounted in said frame, a grinding wheel mounted on said Wheel spindle, an electric motor incorporated in said frame, inter-connecting means including an over-running clutch between said motor and said wheel spindle whereby said wheel spindle may be rotated by said motor and said motor may not be rotated by said Wheel spindle.

LEDGEWORTI-I G. CASEY.

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