Patent GB-1280717-A (GB)
Title: Portable power tool
IPC: B23B45/04
Filed: 1969-11-03
Abstract: 1280717 Portable power tools ROCKWELL MFG CO 3 Nov 1969 53860/69 Headings B3B and B3C A portable power tool comprises a housing 15, a rotatable spindle 95 including a hollow rearward end portion 97 with internal threads 99, means supporting said spindle 95 for axial movement relative to the housing, a tubular drive shaft 75 rotatably supported in said housing and including a forward end portion receiving said rearward end portion of said spindle, spline means 81 connecting said forward end portion of the drive shaft with the rearward end portion of said spindle, a motor 20 including a shaft 22, drive means connecting said shaft to said drive shaft 75 to rotate the spindle, a tubular feed shaft 85 rotatably supported within the drive shaft 75, expansible screw means 90 mounted on said feed shaft 85 for releasably engaging said internal threads 99, drive means connecting said motor shaft 22 to said feed shaft 85 for rotating it at a speed different from the speed of the drive shaft 75, a control rod 150 extending axially through said feed shaft 85 for actuating said screw means 90 to effect positive forward speed of said spindle in response to rotation of said feed shaft, and means for retracting said spindle. An end cap 135 contains control push-buttons and an air supply line 35 is provided for an air motor 20. In operation the portable power tool comprises a spindle 95 for attaching to e.g. a drill 245 for drilling a workpiece W, and a tubular member 16 surrounding the spindle and connected to the workpiece by means of a fixture 17. The motor 20 includes a governor control and valve for infinitely varying the speed of the motor. The tool includes (a) gear drive means for rotating the spindle, (b) gear drive means for positively feeding the spindle axially, (c) pneumatic means for rapid advance of the spindle, and (d) retraction means for the spindle. The rotary gear drive (a) of the spindle 95 operates through a planetary gearing 40, and spur gears 44, 78 to the drive shaft 75, and through the splines 81 to the spindle 95. The axial feed gear drive means (b) operates through an override clutch 46, 48 and spur gears 65, 185 to continuously rotate the feed shaft 85. When feed is required a button 175 is pushed to actuate control rods 150, 155, to expand the screw means 90 to engage the internal threads in the spindle portion 97. The gears 65, 185 may be interchanged to provide the required feed speed. To stop the feed a push-button (138) (Fig. 9, not shown), is pressed which releases the button 175. The rapid spindle advance (c) is provided by a pneumatic piston and rod actuating in a cylinder formed in the housing 15, (Fig. 8, not shown). A push-button (235) operates a valve to let air into the cylinder to move the rod. The rod carries a dog (210) which engages a collar and thrust bearing 114 mounted on the spindle 95 to move it forward. The spindle is retracted (d) by means of a spring 115 acting on the collar and bearing 114. The depth of feed is set by a collar 118 adjustable along the body 15. The position of the collar is adjusted by rotating a collar (137), (Fig. 9, not shown) surrounding a push-button (138) in the end cap 135. Rotation of the collar (137) rotates a shaft (126) and gear (145) which meshes with a gear ring 119 on the collar 118. When the bearing 114 abuts the collar 118 at the end of a working stroke a torque build up occurs which causes the override clutch 46, 48 to slip and cause a plate 58 to move and release the pushbutton 175 from a spring detent. The body 15 includes a window for observing the position of the collar 118.