US2437429A - Buffer spring device for drilling machines - Google Patents

Description

March 9, 1948.

` A. HOSSFELD l BUFFER SPRING DEVICE FOR DRILLING MACHINESI Filed Jan. 19, 1944 Y. UNITED Vsrrrrs Patented Mar. 9, 1 948 ,A

BUFFER SPRING DEVICE FOR .DRILLING MACHINES Albert nossfeia, Winona, Mining The Merchants National BankV of Winona, administratorlof said Albert Hossfeld, deceased Y Application January 19, 1944, Serial No. 519,071

7 Claims. (Cl. 267-1) My present invention relates to improvements in buffer spring devices for use vin drilling machines 'of the type disclosed and broadly claimed in 'my'United States Letters Patent No. 1,388,668, issued November 22, 1932. F

The drill 'in the type of drilling machine above referred to .is mounted fon a reciprocating lcarriage for endwise reciprocating movement that is independent ofthe reciprocating 'movement of the carriage. A pair of compression springs is provided for reciprocating the drill at a greater speed than that of the carriage. One of these springs :acts as a propelling spring for the drill to produce its operative :stroke and the other oi said springs acts Vas a buffer spring for starting the comparatively heavy drill on its upward stroke and accelerate its movement. The propelling spring is placed `under tension by the drill during its return stroke and drives said drill by its expanding movement a't high velocity during its operative stroke. The buffer spring is placed under tension during the rst part of the return stroke and its expanding movement Yduring the latter part of the stroke retracts the drill at high velocity. VDue to the high velocity at which the drill is operated, the life of ordinary propelling and buiier springs is relatively short.

The objection to the ordinary propelling spring was `overcome by substituting therefor a novel spring device disclosed and broadly claimed in my United States Letters Patent No. 1,930,098, issued October 10, 1933, and entitled 4Spring device for drilling machines.

It is well known that it is not the normal compression and expansionY of a compression spring that shortens its life, but the stretch thereof that takes place beyond the normal expansion of a spring expanding at high velocity.

The objects of this invention are: first, to provide positive means for preventing a buffer spring from stretching beyond its normal expanding limit; second, to provide a bu-ier spring assembly that will not loosen up or come apart under the terrific .strain placed thereon bythe high velocity of thedrill andv its reciprocatory travel; third, to provide a buier spring assembly that can be quickly and easily placed in .its operative position in a drilling machine while in the eld; and fourth, to `provide a .buier spring assembly in which the several parts .thereof can be put together without 'the use of tools.

To the above end, generally stated, the invention consists of the novel .devices and combination .of devices hereinafter described and `defined in the claims.

In the accompanying drawing which illustrates the invention, like characters' indicates like parts throughout the several views.

Referring to the drawing:

Fig. '1 ris a fragmentary perspective view of a drilling machine having the presentvinvention embodied therein;

Fig. 2 is an enlarged view ofthe buffer spring assembly in central Vlongitudinal section and also showing, fragmentari'ly, vassociatedparts :ofthe drilling machine;

Fig.. 3 is a view corresponding to Fig. 2, but showing only the lower vportion of the `buffer spring assembly and the lowercross-head of the drilling machine; f

Fig.. 2l is a bottom-'plan view of the buffer spring assembly, as shown in Fig. 3;

Fig. 5 is a View' in horizontal section taken on the line 55 of Fig. 3'; y l

Fig. Gis a view corresponding to'Fig. .5, with the exception'th'at the .collar quadrants are separated from the sleeve member;

vFig.. 7 is a View partly in elevation with the sleeve .member and the collar quadrants separated, as shown in Fig. '6; and

Fig. `8 is a view showing one of the rubber bands used in holding the collar quadrants applied to the sleeve.

Of the parts of the drilling :machine shown, it is important'tonote the vdrill 9, `the main frame it, the carriage H, the tilting frame I2, .the .connecting rods y:41% Vfor reciprocating the carriage H on Vthe frame le., the drill propelling spring device ifi, the buier spring assembly l5, which is the-subject matter of the vpresent invention, and

therfrictlon grip 1E; The drill A5l includes a bodyA il inthe form of `a long round steel rod and a cutter i8 on one end cisaid body. This drill e is :mounted on the vcarriage H for :compound reciprocating and rotary movements.

The tilting frameflZ'includes a pair yof laterally spaced guide posts island a pair of cross-tie plates 2Q rigidly rsecured thereto and held later ally spaced thereby, the one from the other. A striker plateZl for the grip t6 rests on the crosstie plates 2e and is secured thereto.

The carriage VIl includes ran .upper cross-head 22 slidably mounted on the posts t9, a lower cross-head ris that `affords a spring base and a pair of rods 24 which hold said lower cross-head suspended from the upper cross-head 22 between the cross-tie plates 20. axially through thel spring rdevice M and the buffer spring device l5. vSaid spring device lll, at its outer end, is Vattached'to -a Vrotatable `bear- The` drill 9 extends 3 ing 25 on the cross-head 22 and is oscillated during reciprocatory movement of the carriage II by connections 26 from said bearing to the tilting frame l2.

Obviously, the bearing 25 and hence the upper cross-head 22 afford a base of resistance for the spring device I4 and the spring of the buer spring device I5 rests on the lower cross-head 23 which aords a base of resistance therefor. The friction grip I6 is mounted on the drill body I1 between the spring device I4 and the buffer spring assembly I5. Normally the cutter I8 of the drill 9 rests on the material being drilled, the friction grip IB `iust contacting the striker plate 2| and the fully expanded buffer spring assembly I5 just contacting the friction grip I6.

Operation of the drilling machine -thus far described may be briefly described as follows, to wit:

As the carriage II starts on its upward travel, the buffer spring assembly I5 is compressed against the friction grip I6 and absorbs the shock of starting the comparatively heavy drill 9 on its upward stroke. As the carriage gradually slows down and comes to a stop at the upper end of its travel the compressed buffer spring assembly I5 expands thus retracting the drill 9 to a much higher speed than that attained by the carriage II at any point of its travel, During this upward travel of the drill 9, the grip I6 engages the propelling spring device I4', compresses the same under powerful tension and at which time the propelling spring device I4 absorbs the shock of the drill 9 and brings the same to a stop at the limit of the upward travel of the carriage I I. Downward movement of the carriage I I gives the drill 9 a powerful downward throw which is accelerated by the expansion of the compressed ypropelling spring device I4 and causes the drill 9 to attain a high velocity as it travels to its work. At or practically at the end of the downward stroke of the drill 8, the grip I6 is brought to a stop by its engagement with the striker plate 29 and as the drill 9 advances into the work, it drives itself through the grip I5 by the force of its momentum. The feeding of the drill 9 through the grip I6 takes place at a series of almost imperceptible steps of movement.

For the purpose .of this case, it is not thought necessary to describe in detail the rotary movement imparted to the drill 9 except to state that during the downward travel of the carriage II, and while the grip I6 is in engagement with the spring device I4, said spring device is given a turning movement about its longitudinal axis by the connections 26 which imparts a like movement to said drill by frictional engagement between the spring device I4 and the grip I6.

Referring now to the buffer spring assembly I5, in detail, the same includes a long sleeve 21 through which the drill 9 loosely extends. This sleeve 21 has on its upper end a spring seat 25 in the form of an annular shoulder that surrounds said sleeve. Encircling the sleeve 21 is a coiled spring 29. The lower end portion of the sleeve 21 has formed thereon a multiplicity of independent serrations 30. These serrations 30 lie in parallel planes and each thereof is endless. A serrated collar 3| is applied to the serrated end portion of the sleeve 21 and comprises separate quadrants. This collar 3| is internally serrated at 32 to match the serrations 30. An annular external channel 33 is formed in the collar 3l. The collar 3| is yieldingly held on the sleeve 21 with its serrations 32 interlocked with the serra- 4 tions 39 of said sleeve by a plurality of rubber bands 3, one of which is shown in Fig. 8. Each rubber band 3d is applied around the collar 3| in its channel 33 and stretched so that it is under strain to draw the collar quadrants onto the sleeve 21. It is important to note that the ends of the collar quadrants are spaced apart so as not to interfere with the clamping of said quadrants onto the sleeve 21.

rlhe sleeve 21 extends axially through a hole in the lower cross-head 23 with the spring 29 between the lower cross-head 23 and the spring seat 29 and the collar 3| is under the lower crosshead 23. In the under side of the cross-head 23 is a seat 35 for the collar 3|. This seat 35 and the upper end portion of the collar 3| have beveled or ball and socket engagement, the one with the-other. The adjustment of the collar 3| on the sleeve 21 is such that when pressure is removed from the buffer spring assembly I5, the spring 29 is held under slight compression. At

the time the buffer spring assembly I5 engages the grip I3, which is during the upward travel of the carriage ll, the spring 29 is compressed by the force of this engagement. The compression of the spring Z9 moves the sleeve 21 endwise downwardly through the cross-head 23 and the collar 3| out of the seat 35. When pressure is removed from the buffer spring assembly I5, the cornpressed spring 29 expands and returns the sleeve 21 and the collar 3| to their original positions. At the time the collar 3| enters the seat 35, the beveled or ball and socket surfaces thereof center the collar 3l in the seat 35 and the sleeve 21 in the hole in the cross-head 23.

From the foregoing, it is evident that the spring 29 is positively stopped from expanding beyond a predetermined point and this point is determined by the distance the spring seat 28 is positoned from the cross-head 23 and the nut 3|.

It has been found that by limiting the expanding movement of the spring 29 to prevent stretch thereof beyond its normal length, the life of said spring was materially increased.

The rubber bands Sil hold the collar 3| on the sleeve 21 so that there is no lateral movement of said collar relative to the sleeve and said collar will not work up or down on the sleeve 21 under the action of the jars produced on the buffer spring assembly i 5 by its engagement with the grip I6 and the alternate engagement of the collar 3| with the cross-head 23.

Toremove the collar 3| from the sleeve 21 it is only necessary to remove the rubber bands 34 from said collar and slightly compress the spring 29 to relieve the inward wedging action of the beveled or ball shaped seat 35 against the beveled or ball shaped end of said collar. In the absence of rubber bands, a piece of string or other slightly elastic material wrapped tightly around the collar 3| will serve as a tie and hold it securely to the sleeve 21.

It will be understood that the invention described is capable of various modications within the scope of the invention herein disclosed and claimed.

What I claim is:

1. In a device of the class described, a structure having a spring base, means for reciprocating the structure at high speed, a sleeve extending through the spring base for relative endwise movement, said sleeve having at one end a spring seat and at its other end portion a plurality of parallel serrations, a sectional serrated collar applied to the serrated end portion of the sleeve and having serrations matching the serrations on the sleeve, the sections of the serrated collar being separable by relative lateral movement, means holding the sectional collar contracted onto the sleeve, a spring compressed between the spring base and the spring seat and yieldingly holding the collar in engagement with the spring base, and a tool extending through the sleeve for relative reciprocation and which is thrown to its work by the reciprocating structure, said tool during movement to its work engaging the sleeve, compressing the spring and moving the collar away from the spring base, the expansion of the spring returning the tool from its work.

2. The structure dened in claim 1 in which the means holding the sectional serrated collar contracted onto the sleeve is a yielding means.

3. The structure dened in claim 1 in which the means holding the sectional serrated collar contracted onto the sleeve is a stretched rubber band applied around the collar.

4. The structure dened in claim 1 in which the serrated collar has therein an annular channel, and in which the means holding the sectional serrated collar contracted onto the sleeve is a stretched rubber band in the channel.

5. In a spring device, a spring base, a sleeve extending through the spring base for endwise movement, said sleeve having at one end a spring seat and at its other end portion parallel serrations, a sectional serrated collar applied to the serrated end portion of the sleeve and having serrations that match the serrations on the sleeve, the sections of the serrated collar being separable by relative lateral movement, means holding the collar with its serrations interlocked with the serrations on the sleeve, and a spring compressed between the spring base and the spring seat, said spring base having a seat for the collar, the contacting surfaces between the collar and its seat converging toward the longitudinal axis of the sleeve.

6. In a spring device, a spring base, a sleeve extending through the spring base for endwise movement, said sleeve having at one end a spring seat and at its other end portion parallel serrations, a sectional serrated collar applied to the serrated end portion of the sleeve and having serrations that match the serrations on the sleeve, the sections of the serrated collar being separable by relative lateral movement, means holding the collar with its serrations interlocked with the serrations on the sleeve, andk a spring compressed between the spring base and the spring seat, said spring base and collar having ball and socket engagement.

7. The structure defined in claim 1 in which the sleeve extends through a hole in the spring base with working clearance, said spring base having a seat for the collar, said seat and collar having contacting surfaces that center the sleeve in the hole in the spring base each time the sleeve is moved by the expanding spring.

ALBERT HOSSFELD.

Ymtrmmuciis CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 397,882 Westaway Feb. 12, 1889 576,119 Hess Feb. 2, 1897 576,543 Burr Feb. 9, 1897 1,464,524 Gilmour Aug. 14, 1923 1,595,317 Scholey Aug.'10, 1926 1,887,963 Stafford Nov. 15, 1932 1,930,098 Hossfeld Oct. 10, 1933 2,123,048 Hossfeld July 5, 1938 2,210,811V Kelpsch Aug. 6, 1940 2,226,914 Sharon Dec. 31, 1940

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