US2082345A - Expansible mandrel - Google Patents

Description

June 1, 1937. E. LssER EXPANSIBLE MANDREL 2 Sheets-Sheet 1 Filed NOV. 2l, 1955 .772 venfor [ml Lasser Atarngs June l, 1937. E LSSER I 2,082,345

EXPANSIBLE MANDREL Filed Nov. 2l, 1935 2 Sheets-Sheet 2 BMgM/Hiorne 5 Patented June l, 1937 UNITED STATES PATENT OFFICE EXPANSIBLE MANDREL Emil Lsser, Zurich, Switzerland, assignor to Maag-Zahnrder und-Maschinen A.G., Zu-

rich, Switzerland 9 Claims.

My invention relates to a tool such as a mandrel or gauge which is so constructed as to be capable of undergoing a deformation changing a dimension, for instance a diameter, of the element.

It is common practice to use a mandrel for the attachment of work pieces thereon having an end provided with two or more diametrical slots whereby separate fingers are formed which may be spread apart by cooperation with a conical core to vary the outer diameter. Such a variation, however, 'involves necessarily a departure of the outer surface of the fingers fro-m their truly cylindrical form. It is an object of my invention to avoid this disadvantage and to provide a mandrel or gauge capable of undergoing a deformation which, while changing a dimension of the element, Will not objectionably distort its geometrical contour. I attain this object by providing the mandrel or other member with a plurality of Yuniform separate recesses which extend from a surface of the member obliquely thereto to a certain depth and are vso spaced with regard to the elasticity of the material that the projections formed between the recesses are capable of bending transversely to the surface. Such bending will vary a dimension of the member measured from the surface as a base. In event of a cylindrical member, for instance, the slots may extend axially thereto at an angle to kthe diameter of the member toa certain depth and may be so circumferentially distributed and spaced that the arms or projections formed between them may be bent, Whereby the diameter of the cylindrical surface of the member will be varied. Suitable means may be provided for bending the projections or arms the desired extent.

Further objects of my invention will appear from the description of various embodiments following hereinafter and the features of novelty will be pointed out in the claims.

In the drawings Fig. 1 illustrates a prismatical member of variable width,

Fig. 2 a cylindrical mandrel of variable diameter having axially extending slots and a work piece fixed thereon, the Work piece being shown in section,

Fig. 3 the section taken along line 3-3 of Fig. 2,

` Fig. 4 a modified form of a cylindrical mandrel having helical slots,

Fig. 5 an end view of the mandrel shown in Fig. 4 and a work piece attached thereon, the

normal position of the projecting arms of the mandrel being shown in dotted lines, v

Fig. 6 an axial section through an adjustable cylindrical gauge constructed in accordance with my invention, the section being taken along line 6-6 of Fig. 7,

Fig. '7 an end view of Fig. 6,'one of the adjusting nuts being removed,

Fig. 8 a perspective view of the gauge shown in Figs. 6 and 7, the adjusting nuts being removed,

Fig. 9 a cylindrical broaching needle constructed in accordance with my invention,

Fig. .110 a cross-section of Fig. 9 taken along line Ill-l0 of Fig. 9,

Fig. 11 a section of a modified form of a cylindrical mandrel taken along line II-II of Fig. 12,

Fig. 12 an end view of the mandrel shown in Fig. 11,'

Fig. 13 an end View of a bushing having a vari u able inner diameter constructed in accordance with my invention,

Fig. 14 an axial section through a modied form of a bushing .having a variable inner diameter,

Fig. 15 a cross-section through a further modliication of a cylindrical mandrel or gauge, and

Fig. 16 a cross-section through a modication of a lcylindrical hollow tool or machine element having a variable inner diameter.

In Fig. 1 I have shown a prismatical member of substantially square cross-section which is so constructed in accordance with my invention `that its width a may be varied while its height b and its length c is invariable. For this purpose, each of the two side faces of the member is provided with a plurality of uniform separate recesses or slots llll which extend from the side face of the member at the acute angle: a of approximately forty-.five degrees thereto to a certain depth d which in the instant case amounts approximately to one quarter of the width of the member. The recesses I0 are so spaced that the projections Il formed between them are capable of bending transversely to the side face. Such a bending will res-ult in a variation of the angle a and thus of the width a of the member. Viewed from another aspect, the machine element shown in Fig. 1 may be described as comprising a body portion I2 which has a plurality of adjacent projections ll terminating in a common surface which is the side face of the member. The length of the projections Il is so dimensioned withy regard to their thickness and to their elasticity that the projections may be bent an extent sucient to varyr the width a of the member the required amount. If desired, suitable means may be provided for bending the projections I I, as will be described later.

Figs. 2 and 3 illustrate the application of my invention to an expansible mandrel. 'I'he cylindrical body I2 of the mandrel is provided with six circumferentially distributed ,longitudinal slots I3 which extend to such a limited depth-as to form between them projecting farms I4 which extend over substantially the entire length of the mandrel and have such a limited thickness indicated at e as to be capable of bending under a pressure applied to the arms I4 in radial direction. Preferably, the slots extend tangentially to an imaginary coaxial cylinder' I6 shown in Fig. 3 in dotted lines. The outer face of the arms is preferably offset inwardly from the cylindrical contour over the width f asshown at I5. Therefore, the outer end face I 'I of each arm only coincides normally with a true cylinder of the diameter g. When a work piece such as shown at 'i having a slightly smaller interior diameter than g is slipped ony the mandrel, the arms I4 may yield resiliently and the end faces I'I of the arms I 4-will snugly bear .against the boring of the work piece 'I and the arms I4 will hold the work piece in truly coaxial position with great power and with great accuracy owing to the concentrical disposition of the end, faces I1. f

While the slots I3 and the arms I4 formed thereby extend in axial direction in the embodiment of Fig. 2, they may also extend helically as illustrated in Figs. 4 and 5.. In Fig. 5 the arrangement of the slots is the same as in Fig. 3

and, therefore, need not be described in detail. However, in Fig. 5 I have shown the arms I4 in inwardly bent condition in full lines and in normal condition in dotted lines. The pitch of the helix may be varied in accordancewith the particular requirements provided the windings of the helix or helices are so spaced with regard to the elasticity of the material of the member that the arms are suicientlycapable of ben-ding.

In Figs; 6, 7 and 8 I have shown an adjustable gauge constructed in accordance with my invention. The gauge comprises ia spindle 20 formed with a collar 2l and provided with screwthreads 22 on both sides of the collar. The edges of the collar are preferably tapered as indicated at 23. The collar is provided with six circumferentially distributed. longitudinal slots 24 extending to a certain depth tangentially to the periphery of the spindle 20, whereby six longitudinally extending arms 25 are formed. The outer face of these arms is inwardly offset from the periphery of the collar, as indicated at k26, except for a marginal zone 2-1. Moreover, the end faces of each of the arms are out out, as shown in Fig. 8, so as to reduce the length of the inner portions of the arms, whereas the outer portion of each arm extends between the conical end faces 23.

These conical end faces are engaged by nuts 28 screwed on the threads 22-and provided with suitable inwardly tapered end faces 29. It is evident that when the nuts 28 are tightened, they will force the arms 25 inwardly and thereby decrease the distance of the diametrically opposed faces 2l, that is to say,.the diameter of the gauge. The flexibility of the arms is enhanced by the reduction of the length of their inner portions. As any arm 25 will move bodily towards or away from theV central axis' of the spindle 2i! without skewing, no matter whether the pressures applied to its end faces are equal or not, the gauge will always preserve its truly cylindrical form with any adjustment of its diameter. While in this particular embodiment the adjustable means 28 for bending the .arms 25 are so arranged as to bend them inwardly, it is obvious that these means could be so arranged as to act in the opposite direction.

In Figs. 9 and 10 I have illustrated a broaching needle constructed in accordance with my invention. The needle comprises a cylindrical member 30 provided with seven circumferentially distributed longitudinal arms 3| which are formed by slots 32 extending to a certain depth substantially as shown in Figs. 2 and 5. Each arm 3| is provided with a cutting edge 8 at its free end, the rake face 33 of the cutting edge being formed by grinding a recess into the outer face of the arm 3|. As the arms extend at an angle to the diameter of the broaching needle, they will vary this diameter by bending. Owing to the elasticity of the arms 3| provided with the cutting edges 8 the breaching needle is Very efcient and .accurate in operation.

Figs. ll and 12 illustrate a machine element differing from those shown in Figs. 2, 3, 4 and 5 by the transverse disposition of the slots. The rod or spindle 35 is provided with a plurality of conical collars 36 formed by the circumferential slots 31 which extend from the cylindrical outer surface to a certain depth at an acute angle to the axis of the element. To enhance the exibility each collar 36 is provided with six radial slots 38, compare Fig. 12, splitting up each collar into six sector-shaped projections. These projections are so dimensioned with regard to the elasticity of the material as to ensure the required flexibility. The element illustrated in Figs. 11 and 12 may be used as a mandrel, for instance as that shown in Fig. 1.

In Fig. 13 I have illustrated a bushing 4G having a variable inner diameter. The bushing is provided with twelve equally spaced longitudinal borings and with slots 4I extending from the borings inwardly and opening into the hollow inner space of the bushing. As these slots extend at an angle to the diameter of the bushing,

interior resilient arms o r projections 42 are formed. VIf desired, means similar to those illustrated in Fig. 6 may be provided for bending the arms 42, whereby the inner diameter of the bushing may be varied.

In Fig. 14 a bushing 43 is shown provided with a plurality of interior conical collars 44 which are equally spaced by gaps or recesses 46 and provided with suitable longitudinal slots 45. Each section of a collar is flexible whereby the inner diameter of the collars 44 may be varied. f

In the embodiment illustrated' in Fig. 15, the projections or arms 44 are not integral with the member 45 but are produced separately therefrom and then suitably united therewith. For this purpose, the cylindrical member 45 is provided with twelve circumferentially distributed recesses in which the plates I4 are inserted so as to freely project a distance which is sufficiently long with regard to the thickness of the arms 44 to permit them to bend, whereby the distance of the outer ends of two opposed arms 44 may be varied. It will be noted that all of the arms terminate in a cylindrical surface just as do the arms I4 in Fig. 3.

The embodiment of Fig. 16 is similar to that of Fig. 13.1 The lprojections El, however, are formed by plates which are 4non-integral with the bushing 50 and are rigidly secured thereto; For this purpose, the interior of the bushing is provided with six circumferentially distributed recessesin which the outer ends of the plates 5I are inserted and fixed in place by soldering or welding or the like. It will be noted that the plates extend at an angle to the diameter of the bushing tangentially to an imaginary cylinder. Their ends may be formed with shallow recesses 52 conforming to this cylinder, the diameter of which may be varied by bending the plates so as to change their angular disposition relative to the diameter. Hence, the function is the same as that of the element shown in Fig. 13.

While I have described my invention in its application to expansible mandrels or broaching tools, it is to be understood that my invention is applicable to any tool or machine element, where the variation of a dimension is desired.

No specific reference has been made to the material of which the tool or machine element consists, except for the statement that such material should be elastic. The material will be selected to meet the requirements of each particular case. In many instances ordinary steel may be used.

While I have described various specific embodiments of my invention, I wish it to be understood that numerous changes may be made without departing from the spirit of my invention.

What I claim is:

l. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having a plurality of contact surfaces and separate uniform recesses intermediate said surfaces and extending therefrom and obliquely thereto to a certain depth, and thereby forming a plurality of projections; each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, said relcesses being so spaced with regard to the elasticity of said material that the projections between said recesses are capable of bending transversely to said surfaces whereby the diameter of said mandrel is variable.

2. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having a plurality of contact surfaces and axially extending grooves of uniform width intermediate said surfaces extending therefrom and at an acute angle thereto to a certain uniform depth, and thereby forming a plurality of projections; each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, said grooves being so spaced with regard to the elasticity of said material that the projections between said grooves are capable of bending transversely to said surfaces whereby the diameter of said mandrel is variable.

3. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having a plurality of contact surfaces and helical grooves intermediate said surfaces and extending therefrom and at an acute angle thereto to a certain depth and thereby forming a plurality of projections; each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, said grooves being so spaced with regard to the elasticity of said material that the projections between said grooves are capable of bending transversely to said surfaces whereby the diameter of said mandrel is Variable.

4. A work-holding mandrel adapted to engage a workpiece comprising' altubularf'memb'er of elastic material having a plurality of interior contact surfaces and grooves-of uniform width intermediate said K'surfaces yandoextending therefrom and obliquelythereto to a certain uniform depth, and thereby forming a plurality of projections; each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, said grooves being so spaced with regard to the elasticity of said material that the projections between said grooves are capable of bending transversely to said surfaces whereby the inner diameter of said mandrel is variable.

5. A work-holding mandrel adapted to engage a work piece comprising a tubular member and a plurality of separate uniform fingers of elastic material each secured at one end thereof to said member and projecting from the inner wall of said member at an acute angle thereto, each of said fingers having an arcuate contact surface at its free end adapted to have blunt stationary Contact with said work piece and extending a distance, relative to the width of said fingers and their elasticity, suicient to render said fingers capable of bending transversely to said inner wall whereby the inner diameter of said mandrel is variable.

6. A work-holding mandrel adapted to engage a work piece comprising a member, a plurality of adjacent projections of elastic material secured at one end thereof to said member, each of said projections having an arcuate contact surface at its free end adapted to have blunt stationary contact with said work piece and extending at an acute angle to said surface, the length of said projections being so dimensioned with regard to their width and their elasticity that they are capable of bending in a direction changing said angle whereby the diameter of said mandrel is variable.

7. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having a plurality of contact surfaces and separate uniform recesses intermediate said surfaces and extending therefrom and obliquely thereto to a certain depth, and thereby forming a plurality of projections, each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, and adjustable means for bending said projections transversely to said surfaces whereby the diameter of said mandrel is variable.

8. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having conical end faces, a plurality of contact surfaces, and circumferentially distributed axially disposed grooves of uniform width intermediate said surfaces and extending therefrom and at an acute angle thereto to a certain depth, and thereby forming a plurality of projections, each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, and annular members engaging said conical end faces and mounted for axially y adjustable movement relative to said member, whereby said projections are bent in a direction to change said acute angle and the diameter of said member is varied.

,9. A work-holding mandrel adapted to engage a work piece comprising a member of elastic material having conical end faces, a plurality of contact surfaces, and circumferentially distributed axially disposed grooves of uniform width inter- CIL mediate said surfaces and extending therefrom and at an acute angle thereto to a certain depth, and thereby forming a plurality of projections, each of said contact surfaces forming an arc adapted to have blunt stationary contact with said work piece, and annular members engaging said conical -end faces and mounted for axially adjustable vmovement relative to said member, whereby said projections are bent in a direction to change said acute angle and the diameter of said member is varied. v

Y ENEL LASSER.

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