US1881147A - Work rest for material reducing machines - Google Patents

Description

Oct. 4, 1932.

F. THOMA Filed Feb. 11, 1951 2 Sheets-Sheet 2 Oct. 4, 1932.

WORK REST FOR MATERIAL REDUCING MACHINES Patent d Oct. 4, 1932 I PATENT OFFICE FRANZ THOMA, 015' KAAN-MARIENBORN, GERMANY WORK BEST FOR MATERIAL REDUCING MACHINES A lication filed February 11, 1931, Serial No. 515,087, and in Germany January 18, 1930.

The invention relates to'work rests used 7 for supporting heavy pieces of work such as rolls in material reducing machines. Such rests are'used for accurate work in lathes,

5 grinder and like machines adapted to reduce the diameter of the piece of Work.

I The usual method of setting up the work is to support it'between centers;ffor particularly accurate results dead centers are used,

i. e. such as do not participate in the rotationof the work. The centers are then re- 7 lieved as far as possible of the weight of the w'orkby placing supports of some kind under the work contacting with. it by bearing saddles or rollers. Y

It has hitherto been usual to adjust the pressure exerted by such supports or Work rests simply by feeling and then to clamp the adjustment fast so that the distance of the rest from the machine centerv was invariable. It occurs in some cases that the part of the work engaged by'the rest is not accurately round and so th'e'pressure taken up by the rest varies during the rotation of the work.

Thus the thrust on the center is continually varying in the'course of onerotation and center holes are worked into the piece of work with axes displaced from the original axis; in other words the centers run out of line.

The object of the present invention is to overcome this drawback. According to the invention the work is supported in combination with the centering devices by one or against the work with a predetermined pres sure. Preferably thepressure means is such as to give nearly constant pressure throughout the useful range, of movement. This may be accomplished by weights, springs or other suitable means. Usually the pressure means is adjustableto suit different pieces of work; in general the pressure is adjusted to the value it would have if no support at all were'afi'orded the centers. In the case of a symmetrical arrangement with two supports the value would thus be half the weight of the work oneach of them.

i If a saddle bearing with sliding contact is used it should preferably be movable in all directions'or by being placed on a spherical work at every position.

more intermediate yieldable-supports urged seating, so that it may contact well with the I prefer, however, to use as supporting structure two rollers placed respectively in front of and behind the vertical plane through the centers, in the 5 simplest case equidistant from this plane, and to press the rollers against the work with forces which are in equilibrium with the proportion of the weight acting at the point of support. These rollers are preferably jour nailed in levers having their fulcrums in the body of the rest. While the levers associated with the front and back rollers may be independently pivoted and loaded I prefer to PlVOll both levers in the vertical plane passing through the centers and to connect the outer ends of the levers by an adjustable spring thus providing a scissors movement. 7

Further features of the invention will be described in conjunction with the accompanying drawings, in which 2- Figure 1 is a diagrammatic elevation of a grinder will a mill roll in place supported by weight loaded work rests according to the invention, but omitting the grinding and driving mechanisms for sake of clarity.

Figure 2 is a cross'section through 11-11 of Figure 1 but on a larger scale.

Figure 3 is a view similar to Figure 2 of a modification showing a spring loaded rest with rollers, and

Figure 4 is a plan, partly the rest of Figure 3.

Referring to Figure 1 the bed of a grinder is shown at 1 on which the heads 2 carrying the dead centers .3 are mounted in the usual manner. A mill roll 4 is shown mounted on in section, of

the centers and is adapted to be rotated by a fixed arm 9 projects forwards and upwards and the base plate also carries a pm or shaft 10 slightly in front of the vertical center plane of the machine forming a fulcrum for the lever 11. The shorter or rear arm of this lever has on its upper face a spher cal seat ng 12 accommodating thes'pherical face'13 of af bearing saddle 14L shaped to lit the'journalb.

It will be noted that the arc'of contact'of the bearing saddle lt is a compartivelysmall part of the circumference of the ournal 5,

so that the greater part-of the latter is'available for the access of the grinder and for the necessary cooling, which latter isyof very great importance in accurate work The longer or front arm. ofthe lever 11 is connected' at its end 33 by a link 15 touaf lever 34at a point 35 between its fulcrum "36 on the arm 9 and its outer end, Atthe outer end '37 of the lever134-a rod38 is suspended for the reception of disc weights '16. Any desired number of. weights '16 may be put into placelso as tocounterbalance through the I "lever system the proportion of the eight of the troll to be borne by the saddle -1 As stated above this is usually half the welght of the roll,.two[similarrests being provided" 7 atthe positions 6 and? of Figure ,1. 30-

An alternative construction is shown in Figures and 4. 'The'base plate 8 of the restis supported as before and carriesin the center. plane ofthe machine a'bearing pin-or shaft .parallelto the machine axis. Two levers 18" are pivoted on the shaft 17 and-arc connected together at their. shorter rear ends by a shaft 19 and at'their longer front ends by rotatable distancepiece 20. The shaft 19 carries by'means of roller bearings 21 a roller. 22. Discs 23 fast on the sha'fto 19 are shaped to form with the sides of 'the'roller 22 a labyrinthpackinggfor the inside of the roller, so that one'lubrication ofthe rollerlasts a very long time. Betweenthe levers 18land also on the shaft'17 there are pivoted two other levers 24 connected at their outer ends by a rotatable distance piece 25 and by'a shaft'26 at a distance from the pivot 17 equal to the distance of theshaft 19 therefrom but inthe opposite direction; The shaft 26 carries a roller 27 precisely similar to the roller 22. T The front or outer ends ofthe levers; 18 are bent obliquely upwards, and those of the lever 24 obliquely downwards; also the ratio of leverage is the same in both, so that-the I distancepiece is a certain distance verticallyabove 25. V v r Throughholes in the distance pieces a rod 28 is passed. VA spiral spring 29 threaded on the rod. 28 bears atthe one end against the distance piece and at the other against the nut30 screwed onto the, rod. The upper end of th-e rod is provided with a long screw thread 39 on which the hand wheel 40 with tapped bore forrns' a nut. This hand wheel Without strain; The other work rest is simi-' larly set. Then the handwheels 40 of both are -turned,still furtherftensioning the spring 29 until the rollers 22 and 27 press upward-s with 'the' d'esiredforce-against the roll journals 5 and thus relievethe centers 30f all weight.

If the, center line of the work retains its intended, and one or both. journals are .not true, it will beseen that the rollers 22 and 27 move up anddown as the radius from thecen ter line to thepointof contactoftheroller on;

the journal varies I This '1 movementis transmitted inincreasedvalueto the distance piece,

. position Lunchangedbetween thecenters, as is so that the spring29 is subjected at each ro- 7 tation' of the work tora' slightly varying'strain I so long as the journals runout' of line; As

.such' pieces of work are; only set on precision 7 machines after accurate preliminary work, 9

theIlackof accuracy ofthe journals is of course veryslight, and the properties ofthe spring 295 are so selected that the'force wit-hf which the rollers'are pressed on to the work 7 remains practicallyconstant-in spiteof the va nation in sprlngtenslom When in the course -of the line. grinding the journals have become quite true,fthe oscillations of the spring 29 inthe construction of Figures 3 andf t and of the :rod38 in the construction 'of Figure 2 f'cease, so that a reliable signal is provided in: f

dicating the progress of the work.

Clearly the mechanism serving to press the, saddle, rollers," or other-supporting members againstthe work must not b'ese'lf locking, i. e. such as to be capableof movement in one direction only, but it must on thecontrary be reversible. in that the supporting members can rise and fall exerting substantially the same'pressure in both cases. Further there r must be nofstop for the innermost working position, that is the position nearest, the center l i'ne of the work; on the other handithe rest 'ln'this position, which it reaches when the Journal is down to correct. size, 'rnuststill 1 exert the predetermined pressure onthe work. 1

I claim: a V y Means for supporting heavy pieces of work in material reducing machines comprising in combination with centering devicestwo work supporting rollers located one-on either side ofv the vertical planethrough the axis of rotationof thework 'andrmountedon pairs of levers fulcrumed substantially'in the said plane, the longerarmsof the levers project ingtowards the same side of the machine, one pair obliquely upwards and'the other pai'r obliquely downwards, and a tension rod with a nut bearin on a distance piece connecting the ends of t e arms of one lever pair and a nut bearing in the opposite direction through a spring on a distance piece connecting the ends of the arms of the other lever pair, giving a scissors movement of the levers.

In testimony whereof I atfix my signature.

FRANZ THOMA.

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