US1569108A

US1569108A - Tap

Info

Publication number: US1569108A
Application number: US716884A
Authority: US
Inventors: Charles E Williams
Original assignee: Bay State Tap & Die Co
Current assignee: Bay State Tap & Die Co
Priority date: 1924-05-31
Filing date: 1924-05-31
Publication date: 1926-01-12
Anticipated expiration: 1943-01-12

Description

. c- E. WI MS Patented Jan. 12, 1926.

UNITED STATES PATENT'OFFICE- CHARLES E. WILLIAMS, OF MANSFIELD, MASSACHUSETTS. ASSIGNOR .TO BAY STATE TAP & DIE COMPANY, OF MANSFIELD.

MASSACHUSETTS.

MASSACHUSETTS, A CORPORATION OF TAP.

Application filed May 31, 1924. Serial No. 716,884.

tapping out the hole. With some kinds of metal this produces satisfactory results but with other kinds as, for instance, stringy metal, forgmgs, steel stampings, cast steel,

- etc., the tap so made tears the thread.

I have found by experiment that if one of the walls of each thread is lowered far enough to give it clearance so that it will not cut and the other wall does all the cutting the friction is greatly reduced, the tearing of the threads is obviated and a much clearer, smoother thread is formed in the work. 'I have found further that the bestv results are obtained by lowering the walls of the threads on alternately opposite sides so that not only does each thread have only one cutting wall but the cutting walls of two proximate threads Will come in immediate succession followed by two successive non cutting walls, one on each of two proximate threads; also that the walls which serve as cutters shall be so disposed with re lation to each other that the apex of the converging cutting walls shall be atthe bottom of the thread instead of at the top. v The advantages of this invention are especially great in taps with tapered threads, but it is not limited to use in such taps.

The invention will be fully understood from the following description when taken in connection with the accompanying drawings and the novel features thereof will be pointed out and clearly defined in the clalms at the close of this specification.

In the drawings:

Fig. 1 is a view in elevation of a tap em? bodymg the invention.

Fig. 2 is a section on line 22, Fig. 1.

Fi 3 is a development showing the staggere relation of the cutting edges of the threads of one land to the threads of another land. Fig. 4 is a view in profile of the threads of the several lands showing the relation of the cutting edges and the lowered portions, the dotted lines showing the edges after the wall has been lowered to give the clearance.

Fig. 5 is a sectional view showing the effect of the threads of one of the lands of the tap on the work. v

Fig. 6 is a view similar to Fig. 5 showing the effect of the threads of the next succeeding land which are in staggered relation to those shown in Fig. 5.

Referring now to the drawings:

There is shown at 1 the shank of a tap with tapered threads having five flutes 2 dividing the tap into five lands in which are formed the spiral threads. For convenience of reference the five lands are designated 25 t, t, f, and t also for con-- venience of reference the face or wall of back face or wall.

The cutting sides are designated a and the non-cutting sides I). For further convenience in distinguishing the non-cutting sides from the cutting sides, the non-cutting sides are lined or shaded in Figs. 1 and If the threads are formed with uniform distance between their apices and with the same angle of face as shown by the-full the same thread will be referred to as the lines in Fig. 4, both walls of each thread will act as cutters when the tool is in operative position. In order to render certain of the sides inoperative, that is to be' noncutting, the walls of said sides are cut back or lowered to give clearance,. as shown by the dotted lines in Fig. 4., a suitable distance so that they will be entirely free from engagement with the work, as shown in Figs. 5 and 6, while the other sides are operative to do the cutting. Furthermore, instead of having the cutting and non-cutting walls in regular alternation, that is, all of the front walls formed as cutters and all of the rear walls as non-cutters, or vice versa, the

threads are so formed that'the cutting walls or sides of two proximate successive threads Wlll come in immediate succession, and then two non-cutting .walls; that is, ifthe front face of one thread is'non-cutting, the rear face of that same thread and the front face of the next following thread will both be cutters and the rear face of said .second thread and the front face of the third thread will be non-cuttcrs and so on as clearly shown in Fig. 3.

Another feature of the invention consists in staggering the cutting walls or sides of the thread of each land with relation to the cutting walls of the adjacent lands both preceding and following, as clearly shown I in one land will be in helical alignment with a pair of adjacent non-cutting walls of the proximate preceding and following lands.

In order to provide a continuous staggered relation it is necessary there be an odd number of flutes thereby producing an odd numberof lands. In the form shown in the drawings the tap is shown with five flutes and five lands.

As shown in the drawings the groove between the non-cutting sides of the walls is cut to a greater depth than the groove between the cutting walls. This is convenient in reducing the non-cutting wall during the formation of the tap although not essential to the invention.

What I claim is:

1. A tap having the threads so formed and arranged that one wall of each thread will have cutting engagement with the work, the opposite wall of each thread being so relieved that it will not have cutting engagement with the work, the cutting walls being on alternately opposite faces of the successive threads so arranged that there will be two proximate cutting walls followed by two proximate non-cutting Walls and so on in the same manner.

2. A fluted tap having the threads so formed and arranged that one wall of each thread will have cutting engagement with the work, the opposite wall of each thread being so relieved that it will not have cutting engagement with the work, the cutting walls being on alternately opposite faces of the successive threads so arranged that there will be two proximate cutting walls f0llowed by two proximate non-cutting walls and so on in the same manner, each air of proximate cutting walls of each lan being in helical alignment with a pair of adjacent non-cutting walls of the proximate preceding and following lands.

3. A fluted tap having. the threads so formed and arranged that one wall of each thread will have cutting engagement with the work, the opposite wall of each thread being so relieved that it will not have cutting engagement with the work, the cutting Walls being on alternately opposite faces of the successive threads so arranged that there will be two proximate cutting walls followed by two proximate non-cutting walls and so on in the same manner, the cutting and non-cutting walls of each land being in staggered relation with respect to the cutting and non-cutting walls of the proximate lands.

4. A tap having the threads so formed and arranged that one wall of each thread will have cutting engagement with the work, the op osite wall of each thread being so relieved that it will not have cutting engagement with the work, the cutting walls being on alternately opposite faces of the successive threads of each land and being so arranged that there will be two proximate cutting walls followed by two proximate non-cutting walls and so on in the same manner, the cutting and non-cutting walls of each land being in staggered relation with respect to the cutting and non-cutting walls of the proximate lands, the non-cutting walls being so formed relative to the cutting walls as to afford clearance to prevent contact with the work.

In testimony whereof I aflix my signature CHARLES E. WILLIAMS.