US2115461A - Polishing machine - Google Patents

Description

April 26, 1938. E. HARTMANN POLISHING MACHINE Filed Dec. 1, 1956 W. I I,

3 w m. 2 E V////. .9 m n 7 $v individual workpiece.

Patented Apr. 26, 1938 UNITED STATES,

PATENT [OFFICE rousnme MACHINE Edmund Hartmann, Dessau, Germany, assig-nor to Junkers Flugzeug-und-Motorenwerke- Aktiengesellschaft, Dessau, Germany Application December 1, 1936, Serial No. 113,561

In Germany December I, 1935 8 Claims.

My invention relates to the treatment of metal and other bodies for the purpose of producing on such bodies absolutely true surfaces. It has particular reference to means for producing smooth and accurately truecylindncal surfaces on workpieces and quite particularly inner surfaces of hollow cylinders. It is an object of my invention to provide a machine capable of doing this kind of work in a better and more eficient manner than similar devices hitherto in use.

Hitherto smooth and accurately true cylin-' drical surfaces and more especially inner surfaces of hollow cylinders have been produced with the aid of polishing or honing methods, wherein a polishing tool made of metal, stone or the like,

to which grinding or polishing agents and lubricatingor rinsing liquids were supplied, was carried in alternating directions in contact with the surface to be polished. To this end-the tool was fixed on the spindle which was permanently r0- 7 tated and simultaneously reciprocated' by means of suitable gearing. In devices of this kind the number of rotations and the stroke of the tool. were adapted to the workpiece to be machined and remained unaltered throughout the machining operation. In a device of this kind it is scarcely possible to adapt the tool motion to the particular character of the surface and to for instance treat particularly vigorously local eccentricities or rough parts of the surface under treatment.

The accurate-polishing machine according to the present invention is designed with a view to allowing a ready adjustment of the intensity .of.

treatmentandan automatic" adapting of this treatment to the condition of the surface of the spindle carrying the polishing tool is rotatably arranged on a reciprocable part, such as a slide or the like, and means are provided for imparting to the spindle a non-positive rotation which varies from one sense in one direction to the opposite sense when travelling in the opposite direction. 'I further provide resistances influencing the angle ,of the rotary reciprocation brought about by' this drive, the resistances effective during the tool movement in one direction differing from those arising during the movement of the' tool in the opposite direction, whereby the angular movements imparted to the spindle in one and the other direction are different also. I may further provide means whereby the different resistances influencing the angular movements of the spindle may. be increased and reduced, re-

spectively, in the same proportion,

In the new machine the instance adopt the form of brakes which may be made to act on the sleeve or on the spindle itself. In the drawing afiixed to this specification and forming part thereof a polishing machine embodying my invention is illustrated diagrammatically by way of example.

In the drawing v Fig. 1' is a vertical axial section of the machine,

' while Fig. 2 is a cross-section on the line'lIII in Fig. 1.

Fig; 3 is an axial section of a modified form of the internally threaded sleeve and the parts cooperating with it.

Referring to the drawing and first to Figs. 1 and 2, I is the standard carrying the operative parts of the machine and 2 is a guide, on which a slide 3 is mountedfor vertical reciprocation.

I influencing the rotation of the spindle may fordis a shaft driving an adjustable crank 5 with the crank pin 6, connecting rod 1 and pin 8 mounted on the, slide 3, whereby the slide is reciprocated. 0n the projecting arm 9 of the slide 3 is supported forready rotation a spindle in two parts L0 and I2, which is secured against axial movement relative to the arm 9. The axial forces acting on the spindle are taken up by ball bearings 21, 22. The top end of the spindle I0 is formed with a steep multiple screw thread II, the bottom part l2 of the spindle is vconnected with the toppart "I, being longitudinally adjust able, but secured against angular movement relative. to it. To this end the part- I 2 is surrounded by a nut i3 arranged to be screwed on a screw thread l4 formed on the part It], being securable in its position by a counter-nut IS. The bottom end of spindle I2 is guided in a bearing IS fixed to the standard I and supports the tool carrier l1 carrying the polishing tool I 8.

The work piece 20, for instance a hollow cylinder, the inner surface of which is to be polished,

is fixed on the bottom part of the standard by means of a screw cap 23 of by other suitable tive to the standard I without suffering any- 'screw thread of a sleeve 25 which is rotatably mounted in a hub 3| formed in the top end of the standard I. The sleeve is secured relative to the standard inaxial direction by bearings formed of flanges 26, 21 of the sleeve whichcooperate' with the end faces of the hub body 3|. The smooth metal surface of the bottom flange 25 is in direct contact with the bottom surface of the hub body 3|,while between the top flange 21 and the top surface of the hub body a washer 30 is inserted which is made of. a material, such as a compressed asbestos composition possessing a higher friction coeificient than a smooth metal surface. In a cavity 32 formed in the hub body 3| supporting the sleeve 25 is seated a brake block 33 which is forced against the sleeve by a powerful spring 31 acted upon by a screw bolt 36, which can be flxed in position by a counter-nut 35. In a cavity of the arm 9 supporting the spindle I0 is seated a brake block 4| which can be pressed against the spindle l0 by means of a screw bolt 40.

The operation of this device is as follows: When the driving shaft 4 rotates, the slide-3 is reciprocated in the vertical direction together with the spindle l0, l2 and tool l8 by meansof the crank gear 5, 6, 1, the spindle brake 4| being assumed to be cut out, of action. 'If the threaded sleeve 25 is assumed to be prevented from turning, the,

spindle III will execute a reciprocatory rising and dropping movement in the screw thread of. the sleeve, its angular movements being the same and ending at-the same levels throughout the operation of the device. On the other hand, assuming the sleeve 25 to be free' to rotate relaresi'stance, then spindle l0, l2 and the tool l8 will only ascend and descend, however owing to the friction arising between the tool l8 and workpiece 20 the parts will not turn, but the sleeve 25 will execute the angular reciprocatory movement resulting from the stroke of .the spindle III and the pitch of the screw thread. The actual movement of the spindle l0, l2 during the operation of the machine occurs between these two limits. During the ascending stroke the smooth metallic surface of the flange 26 of sleeve 25 abuts against the smooth surface of the hub body 3|. There is little friction between these two parts and the sleeve is therefore free to rotate through a comparatively large angle, while the spindle l0, I2

will rotate only'through a smallangle. During the descending stroke the metal surface of the flange 21 of sleeve 25 applies itself onto the surface of the friction disk or washer 30, whereby the resistance offered to an angular movement of the sleeve 25 is increased. In consequence of this resistance the sleeve will turn through a smaller, the spindle through a larger angle. During the successive ascending and descending strokes of the spindle this latter will thus be rotated alter nately through smaller angles in one sense and through larger angles in the opposite sense the starting positions of the individual angular reciprocations varying permanently. Owing to this composite movement imparted to the tool an absolutely accurate and true cylindrical surface is formed in the work piece 20.

The resistanceopposed by the sleeve 25 may be varied by adjusting the brake block 33 and the angular deflections of the spindle l0 and I2 will be varied correspondingly, becoming the larger, the more vigorously the brake is made to act on the sleeve 25. The angular deflection is further regulated automatically to a certain extent by the frictional resistance offered to the tool by the upon more vigorously than smooth parts, so that the machine automatically adapts the degree of machining to the condition of surface in different places of the workpiece.

It is also possibleto influence at will the friction between the tool and the workpiece, for instance by varying the force, which'is exerted as a rule by springs, which presses the parts together, or by varying the lubrication, the grinding agent or the like, thereby also varying the magnitude of the angular oscillations of. the spindle.

By. forcing the brake block 4| against the spindle III the resistance offered to the spindle against rotation is increased and their angular oscillations are correspondingly reduced. If the spindle is stopped altogether by the brake, the tool will execute only a. vertical reciprocating movement. Y

It will frequently be advantageous to machine a workpiece in such 'manner that at'the beginning the tool ,is turned through large angles. (by

braking the sleeve 25) in orderto quickly equalize the eccentric portions and the like which may be presentfwhereupon the brake acting on the sleeve is thrown out and the magnitude of the angular oscillations is merely determined by the {automatic adjustment by the machine, depending upon the extent of polishing attained at any paroscillations are gradually reduced, by braking are executed with the spindle fixed in position by the brake, i. e. without any oscillation of the tool. 1

After the polishing procedure has come to an end, the part H of the spindle can be lifted by means of thescrew l3 and the tool withdrawn from the1workpiece'20. Another workpiece may now be mounted in place in the machine and the part |-2 of the spindle lowered into the correct position for work by turning the nut l3. The adjustable crank 5 enables the stroke of the slide 3 and spindle l0, l2 to be adapted to the equal length of the workpiece 2|! to be machined.

In the modification illustrated in Fig. 3 the sleeve 25 is held against axial displacement in the hub 3 l-of the standard I by an anti-friction bearing'l2 at one end and by a sliding bearing, formed by the smooth coacting surfaces of the flange 21 and hub 3|, at the other end. Here again one of the bearings, in the present case the anti-friction bearing 42, offersless resistance to the rotation of the sleeve than the other (sliding) bearing.

I wish-it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a 'person skilled in the art.

1. Polishing or honing machine comprising in combination, a standard, a sleeve rotatably supported in and secured against axial displacement relative to said standard and formed witha coarse internal threading, a tool carrier spindle formed with a corresponding external threading in gear with the threading in said sleeve and arranged for ticular moment, and that flnally the angular 2,115,401 axialreciprocation and for rotation and means' arranged to oppose to said sleeve more resistance against rotation, when said spindle moves axially in one direction, than when said spindle moves axially in the opposite direction.

2. Polishlngor honing machine comprising in combination, a standard. a sleeve rotatably supported in and secured against axial displacement relative. to. said standard and formedwitha coarse internal threading, a tool carrier spindle formed with a corresponding-external threading in gear with the threading in said sleeve and arranged i'or axial reciprocation and for rotation and checks associated with said sleeve which secure-it against axial displacement and'which are arranged to oppose to said sleeve more resistance against rotation, when said spindle moves axially in one direction, than when said spindle moves axially in the opposite direction.

3. The machine of claim 2, in which the checks form thrust bearings, one of which is formed with a-smcoth metallic sliding surface, and means between said sleeve and the other cheek having a higher iriction coeiilcient than metal. 4..1he machine of claim 2, in which the checks form thrust bearings, one or which is formed with a smooth metallic sliding surface. and an antii'riotion bearing between said sleeve and the other 5. Polishing or honing machine comprising in combination, a standard, a sleeve rotatably supported in and secured against axial displacement relative to said standard and formed with a coarseinternalthreading,atoolcarrierspindle 35 formed with a corresponding external in gear with the threading in said sleeve and arranged ior axial reciprocation and for rotation and means for braking the rotati movement of said sleeve. r

6. Polishing or honing machine comprising in rotation of said carrier in one sense duringone axial stroke and in the opposite sense during the v succeeding axial stroke, and automatically active means arranged to change the extent of angular movement of said carrier during alternating axial strokes...

8. Polishing or honing machine comprising in combination, a'tool carrier arranged for axial reciprocation and for rotation, means for causing rotation of said carrier in one sense during one axial stroke and in the opposite sense during the succeeding axial stroke, automatically active means arranged to change the extent of angular movements oi said carrier during alternating axial strokes and adiustable means for changing said alternating angular movements to an equal extent,

| EDMUND HAR'IMANN. I

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