US7499A - Improvement in machines for cutting screws - Google Patents

Description

3 Sheets-8heet 1.

PaEt eIjte d JuLy 9, 1850. A

v T. J. SLOAN.

Making Wood Screws.

3 Sheets-Sheet 2.

T. J. SLOAN.

Making Wood Screws.

Patented July 9, 1850. I

3 Sheets-Sheet 3;

Patented July 9, 1850.

T. J. SLOAN.

' Making Wood Screws.-

m v m -w H- /f w M m h m W, M h N M W N WU UNITED STATES PATENT ()EEICEe THOMAS J. sLOANpOF NEW YORK, N. Y.

IMPROVEMENT IN MACHINES FOR CUTTING SCREWS.

Specification forming part of Letters Patent No. 7,499, dated July 9, 1850.

To all whom. it may concern.-

Be it known that I, THOMAS J. SLOAN, of the city, county and State of New York, have invented a new and useful Improvementin the Machine for Threading Wood-Screws; and I do hereby declare that the following is a full, clear, and exact description thereof, of the principle or character which distinguishes it from all other things before known, and of the method of making, constructing, and using the same, reference being had to the accompanying drawings, making part of this specification,in which- Figure 1 is aplan of my improved machine, Fig. 2 an elvation of the rear end, and Figs. 3, 4, and 5 vertical sections taken at the lines A a, B b, and O c of Fig. 1.

The same letters indicate like parts in all the figures.

In my improved machine, the pitch of the thread is determined by a screw, termed the leader, placed on a rotating shaft, the threads of which leader engage the teeth of a comb on a sliding bar connected with a chaserhead or tool-holder. The shaft of the leader has its bearings in the arms of a rock-shaft provided with an arm that bears against a cam which, at the end of the threading motion, lifts the leader out of the teeth of the comb to permit the chaser or tool to be carried back for a repetition of the threading operation, and which, at the end of the return motion, permits the leader to re-engage the teeth of the comb; and on the shaft of the cam which operates the leader to engage and liberate the comb there is what I denominate the relief and return cam, which, at the end of the threading motion, acts on the comb-bar to push it forward to relieve the threads of the leader, that they maybe lifted out of the combteeth without friction, and when the comb is liberated permits the gradual return of the chaser or tool and comb.

The principle or character which (listinguishes my invention from all other things before known consists in determining the pitch of the threads by means of a leader, which turns in the arms of the rocking shaft operated by a cam so formed as at the end of each threading motion to disengage the threads of the leader from the teeth of a comb on a bar which operates or carries the tool-holder, and to re-engage them at the end of each return motion, when this is combined with a relief cam, which at the end of each threading motion acts upon the comb-bar and pushes it forward with greater velocity to relieve the leader preparatory to its being disengaged from the comb, and then to ease the said barin its back or return motion.

In the accompanyingdrawings, (It represents the frame of the machine, and b a mandrel for carrying and rotating the screw-blanks to be threaded. The jaws usually employed for gripping the blanks and the appendages for operating them are not represented, as these make no part in my invention, and may be made in any desirable and appropriate manner. Nor have I represented the means necessary to operate the chaser or tool 0 to cause it to approach the blank and recede therefrom at each successive cut, as these make no part of my present invention and may be made in any known effective way.

The arbor cl of the tool-holder e is cylindrical and tits in two boxes 0" c, and one end bears so that it can turn and slide therein to admit of giving the tool the required motions. There is a sliding bar f, which I denominate the comb-bar, adapted to slide longitudt nally and accurately in a standard, and one of the boxes 0, in which the arbor d of the tool-holder e slides, the two abutting against each other, so that by means of a spring h, which bears on the end of the arbor d of the tool-holder, the two are at all times forced backward to give the back or return motion to the tool whenever permitted by the mechanism which determines the pitch of the thread of the screws to be threaded. The said barf carries or is formed with a series of comb-teeth i, which are inclined on theirfront faces and square on their back faces-that is to say, at right angles to the line of motion of of the barand these teeth are engaged by the threads of a leader or screw j on a shaft lo, which has its bearings in two arms I Zof a rock-sl1aft m. The teeth of this leader are made to [it accurately the comb-teeth, and are therefore the reverse of them, so that in giving the threading motion the threads 'of the leader act on the teeth by the faces, which are at right angles to the line of motion, to prevent any inaccuracies such as would arise from the use of beveled threads. provided with another arm n, the outer end of which is borne up against a cam 0 by the tension of a spring 19, and the form of this The rock-shaft mis' cam is such relatively to its rotary motion that at the end of the threading motion it forces out the arm to lift the threads of the leader out of the comb-teeth, to permit the tool to be carried back by the tension of the spring h preparatory to another threading motion, and at the end of the return motion permlts the arm to approach its axis, that the leader may .re-engage the comb-teeth for a a repetition of the threading operation. The required rotary motion is given to the leader by a cog-wheel g on its shaft, which engages the cog of another wheel r of the same diameter on a shaft .9, that passes through the rock-shaft m, made hollow for that purpose,

that the two cog-wheels may continue in gear during the rocking motion of the arms that carry the shaft of the leader. The outer end of the shaft 8 carries a large cog-wheel t, which engages a pinion u on the rear end of the mandrel a, the relative proportions ofthe pinion u and cog-wheel t, together With the pitch of the thread of the leader, determining the pitch of the thread to be cut, so that by simply changing the relative proportions of the pin.- 10n and cog-wheel the pitch of the threads to I be cut will be varied.

- On the shaft 3, just within the cog-wheel if,

there is a small cog-wheel t, which engages I another cog-wheel w on the shafta: of the cam 0 ,'before described, and the relative proportions of these two cog-wheels will determine the length of the thread to be cut, so that by simply changing their relative proport o the maclune can be adapted to the cutting of screws of different lengths.

On the shaft a: of the cam 0 there is an other 0am y, called the relief-cam, so formed (as shown in the drawings) that at the end of the threading motion, and just before the cam 0 lifts the leader out of the teeth of the comb, It acts on the rear end of the comb-bar ftopush it forward faster than the motion der1ved from the leader, and which therefore ves the threads of the leade f0le h leader is lifted out of the co teefll, d thus avoid the friction and we r of the threads and comb-teeth, and so soon as the cam 0 has disengaged the leader the a y ecedes to permit the comb-bar and 001 to be carried back with an easy motion by the spring h. In this way the threading and return motions are given and repeated as oftenas may be determined .by other parts of the mechanism not herein specified,

as they make no part of my present invention.

The advantage of determining the pitch of a thread by a threaded or screw leader has long been known, for it is composed of a number of threads which engage the comb, preventing in a great measure inaccuracies, for the reason'that any defectin any part of the thread. or comb will be compensated by the other portions; but as heretofore applied the use of a leader has been attended with serious practical difficulties-such, for instance, as the wear of the edges of the thread of the leader and the comb when the two are engaged and disengaged Without being previously relieved, and the serious injury which the machinery sustains when the return motion is not properly eased off, and finally the difficulty of varying the pitch of the threads of the screws to be out. All these difficulties are avoided by my improved method of applying a leader.

Having thus specified the principle of my invention and the mode of constructing and using the same which I have essayed, I do not wish to be understood as limiting myself to the precise mode of constructing and arranging the parts, as these may be varied within the range of the principle of my invention.

What I claim, therefore, as my invention, and desire to secure by Letters Patent, is

The method, substantially as herein described, of determining the pitch of the thread of wood-screws by means of a leader, the threads of which are alternately engaged and disengaged from the teeth of a comb on a sliding bar when this is combined with a releaf and return cam, which, at the end of each threading motion, pushes the comb forward to relieve the leader before it is disengaged from the teeth of the comb, and then eases off the return motion of the comb-bar, substantially as described.

THOS. J. SLOAN.

Witnesses:

ALEX. PORTER BROWNE, CHAS. M. KELLER.

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