US375284A - Taper-tap - Google Patents

Description

( OMO Z1 1 I v GRIBBBNI TAPER TAP.

No. 375,284. Patented Dec. 20, 1887.

xxx-m UNITED STATES PATENT OFFICE.

JOHN GRIBBEN, OF PITTSBURG, ASSIGNOR OF ONE-HALF TO FRANK H. CLARK, OF ALLEGHENY COUNTY, PENNSYLVANIA.

TAPER-TAP.

SPECIFICATION forming part of Letters Patent No. 375,284, dated December 20, 1887.

Application filed July 7, 1887. Serial No. 243,699. (No model.)

To aZZ whom it may concern:

Be it known that I, JOHN GRIBBEN, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Taps for Forming Taporing Screw-Threads in Sockets; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification. I

My-invention relates to an improvement in taps for forming taperingv screw-threads, the object being to provide a tap with two independent sets of cutting-blades, the first and stationary set to enter in advance, in order to perform the heavy portion of the work, leaving the second or moving set only that portion of the work as is required to finish the thread already formed to the required taper; and with this cndin view myinvention consists in certain details of construction and combination of parts, as will be fully described hereinafter.

In the accompanying drawings, Figure 1 is a sectional view taken through the center of the tap on the line :0 00. Fig. 2 is a rear end view of the same. Fig. 3 is a cross-section of my improved tap, taken on the lineyy. Fig. 4 is an outside elevation showing the relative position of the two sets of cutting-blades.

To put my invention into practice, I provide a cutter-head, a, of suitable size and form of construction,having a central circular opening extending through its entire length, in which is neatly fitted a fixed rod or shaft, 1), provided near one end with a double tapering portion, (1, corresponding to the desired taper of the socket. A portion, 0, of the rear of this cutter-head (t is in the form of a square, the object of which is to afford a means for applying power to the same. At the forward end of this cutterehead a, I arrange in radial lines a suitable number of cutting-blades, f, which are capable of a slight movement in the direction of their length, and limited to that movement by small set-screws 9, project ing into grooves h, formed in the rear of each blade f. These cutter-blades f are placed in radial slots formed in the head a, and held in that position by neatly-fitting projections t", formed on a cap, j, which is securely bolted to the forward end of the cutter-head a. Between these cutter-bladesf, Iarrange another set, It, projecting some distance in advance of those first mentioned. This set of blades is are permanently secured in slots in the cutterhead a, and held rigidly in that position by the cap j.

It will be seen by reference to Fig. 3 on the drawings that the cutting-edge of each blade, both stationary and movable, is in radial line with the cutter-head a. The object of this arrangement is to have the edge doing the cutting slightly in advance of the heel or rear of the blades.

In operation the central shaft, 1), is fixed stationary and the cutter-head (4 moved back until the movable blades f, by means of the tapering portion (1 of the shaft Z1, are out to their full extent. Suitable power is applied to the cutter-head to slowly revolve the same. The stationaryblades k first entering the socket perform the heavy cutting at the start, leaving the movable blades f to form the taper, by reason of the same moving along the tapering.portion d'of the fixed shaft b.

Any required taper may be given the thread in the socket by substituting shafts b, having different tapers.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, 1s-

1. In a tap for the purpose set forth, the cutter-head to, having a series of radially-arranged cutting-blades, f, capable of a limited movement in the direction of their length, and an intervening set of fixed or stationary blades, 76, operating in advance of those first men tioned, as and for the purpose described.

2. In a tap for forming tapering screwthreads in sockets, the moving cutting-blades f, secured in the cutter-head a by set-screws g, which allow the same a short movement in the direction of their length, the fixed or stationary blades k, the central shaft, I), having a tapering portion, (2, formed thereon, and tense in advance of the moving blades, as and the capj, for holding the cutting-bladesf k in for the purpose set forth.

position. 7 T 3. In a tap for the purpose described, the JOHN GRIBBDI" 5 fixed and moving cutting-blades arranged in "Witnesses:

the head a in radial lines and alternately with M. E. HARRISON, each other, the fixed blades is being some dis- H. T. MORRIS.

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