AU643720B2

AU643720B2 - Expansion tool for hollow working parts

Info

Publication number: AU643720B2
Application number: AU66855/90A
Authority: AU
Inventors: Karl-Heinz Velte
Original assignee: Rothenberger Werkzeugemaschinen GmbH
Current assignee: Rothenberger Werkzeugemaschinen GmbH
Priority date: 1990-05-30
Filing date: 1990-11-21
Publication date: 1993-11-25
Anticipated expiration: 2010-11-21
Also published as: AU6685590A; KR100197577B1; KR910019716A; DE4017404C1

Description

4 6437 COMMNWELTHOF AUSTRALIA Patents Act 1952 COMP L ET E SPE C I FI C ATIO N

(ORIGINAL)

Class Int. Class Application Number Lodged Complete Specification Lodged Accepted Published Priority May 1990.

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0S 0 S S 0@ Name of Applicant Address of Applicant Actual Inventor(zl Address for Service :ROTHENBERGER WERKZEUGE- MASCHINEN GmbH :GUTLEUTSTR. 167 D-6000 FRANKFURT AM MAIN 1 FEDERAL REPUBLIC OF GERMANY :KARL-HEINZ VELTE F.B. RICE CO., Patent Attorneys 28A Montague Street BAL'4AIN NEW 2041 Complete Specification for the invention entitled: "EXPANSION TOOL FOR HOLLOW WORKING PARTS 1 The following statement is a full description of this invention including the .best method of performing it known to us/,Me:- I *O s The invention concerns an expansion tool for hollow. in particular hollow cylindrical working parta with a basic tool body and a borehole, an expanding mandrel located in this borehole in an axially slidable position, protruding from the borehole, and having an exterior tapered end, with a swivelling control device also located in the basic tool body which acts on the expanding mandrel through a free rotating cylinder. Swivelling control device has an axis vertical to the borehole axis, and is connected to a hand lever which, when activated, causes the expanding mandrel to emerge from the basic body sliding at a preset stroke against a set of radially moving expanding wedges.

-3- These types of expanding tools are also called "Expanders". They are used like tongs, i.e. the swivel hand lever has a second hand lever of the same length, which is rigidly connected to the basic body. Expanders are mainly used to expand the ends of pipes to the extent necessary to allow the introduction of a second, non expanded pipe end into the expanded area, and to weld it to the first pipe end. It is used in construction sites and in workshops.

i.* The operating forces are determined by the transmission ratio in lto the operating system of the expanding mandrel, by the friction ratio between 'all the movable parts and not least by the flow of the material of the working part to be expanded. The following materials are suitable: plastic pipes, thin walled soft steel pipes, but mainly copper pipes, annealed as well as so called "hard" copper pipes. These tools are preponderantly used in the construction of pipes, particularly in the sanitary and installation fields.

In view of the ergonomic relations, it should be noted that the o angle of traverse of both hand levers in relation to each other, i taking into account the transmission ratio, is slightly over degrees. Since in this situation the actual power stroke occurs relatively early, the two hand levers are at a relatively unfavourable position to each other at the start of the power stroke. Since normally the basic tool body cannot be supported anywhere, the -4ef fective operating f orces can only run parallel to the axis of the expanding mandrel; all other reaction forces must be additionally absorbed by the person operating the device. For instance, it is not possible at the beginning of the power stroke Sto load the hand le-vers running radially in relation to the swivel axis of one of the hand levers, in a purely tangential direction (then the operator 'would pu~ll the basic tool body towards himself) instead purely paraxial. forces must be applied. Mechanically this is expressed in such form, that the effective length of the hand levers, which at this point form a 90 degree angle, is drastically ashortened. The ratios do improve as the hand levers approach each **other, whaich to a certain extent compensates for the increasing deformation forces during the expanding procedure, but depending on the chosen type of operation, can also cause the operating f forces to drop of f drast1-ically towards the end of the power stzoke, leaving the operator without any "feel" regarding which forces and reaction forces are released Inside the operating system.

**In the course of t-he development of this type of tong like to expanders, the following operating systems were created: In the expander according to GB-*S 866 994 (R.ast) an eccentrically positioned cam acts directly on the bevelled back of the expanding 0990*: mandrel. This causes the development of tangential power components a QS in relation to the cam curve, and radial components in relation to the expanding mandrel, which press the expanding mandrel against its bearing, thus also producing together with the increasing deformation forces of the working part, increased sl.uggishness. The expanding mandrel becomes in a way the brake shoe for the cam, so that the operating forces progressively increase during the expanding procedure. Anotheir disadvantage of this operating system consists in the fact that the expanding mandrel cannot be retracted. Since the return springs of the expanding wedges act as an automatic lock opposite the **expanding mandrel, also the expanding 'wedges with their control tOD surfaces, which can be seen as cone sectors, cannot produce the 0 retraction of the expanding mandrel. in the case of shrinking working parts; as is the case during the expanding of plastic pipes, this kind of expander cannot be easily dislodged from the pipe.

In a further development of this operating principle according to 601S1 485 098 (Rothenbevger) the power requirements for the axial sliding of the expanding mandrel were reduced by flattening :':the course of the curve of the cam, and the full stroke of the Do expanding mandrel was attained by operating the cam repeatedly and adjusting it after each stroke. For this purpose the cam axis is placed in two cranks with axially staggered recesses. However, the force economy due to the changed transmission ratio and the 09099:resulting lengthening of the operating path, was very limited the braking effect of the expanding mandrel on the cam surface remained practically unchanged. With this known system an enforced withdrawal of the expanding mandrel was absolutely impossible, since traction could neither be applied on the hand -t -6lever nor on the cam beo~ause of the connecting link guide. A compression spring placed between the expanding mandrel and the basic tool body was only able to produce a certain arresting effect on the connecting link guide, but not the enforced withdrawal of Sthe expanding mandrel., An expander is known according to RI-:Pj37 32 628, Awhich made the enforced withdrawal of the expanding mandrel, and with it a return NOON of the expanding wedges to the starting position, possible thanks 0 0 to a tension member between the expanding mandrel and the hand 9 q6* lever. However-, the high driving forces remained the same as in the expander according to~fdm P 866 994.

u.S-A In the operating system according toU-R 4 425 783 the friction LSforces between the cam and the expanding mandrel on one hand, and the expanding mandrel and its drive (borehole) on the other hand off are eliminated to a large extent, although without providing the 6 0: means for the enforced withdrawal of the expanding mandrel. This NO S is accomplished by placing a swivelling hammer shaped compression Q0 member between the expanding mandrel and the cam, and because the course of the curve of the cam, and of the surface of the compression member which rolls over it, is such that the axis of the expanding mandrel always intersects the common line of contact .0 0 of the can and the compression member. In order to start always the same initial position of the compression member, the latter has a return spring. However, when the power stroke is interrupted, then the compression member falls back under the effect of the return spring, and the prior existing correlation

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-7between cam and compression member no longer exists.

However, because of the complicated bearing of the cams and the hand levers, th is known system creates friction forces in another place, namely on the perimeter of two relatively large circular disks with which the hand levers and the cams are mounted in the basic tool body. In this case the basic tool boy acts, opposite the above mentioned circular disks, as a braking device under the influence of the axial operating forces.

An operating system is known according to patent S=6 0 252 868 in which low driving forces are paired with the enforced withdrawal of the expanding mandrel. This is accomplished by placing an elbow lever between the hand lever, which does not have a cam, and the expanding mandrel. This example has a disadvantage compared to the Expander according to prtent US-PS 4 425 783, namely that on one hand the slanted position of the elbow lever at the start of the working stroke creates transverse force components which act on the *o expanding mandrel, increasing the friction between the expanding mandrel and its bearing (borehole), on the other hand the elbow o: lever drive has the particularity that the output forces created Sby the same go towards infinity when the driven parts hit a stroke while all links of the elbow lever system are completely stretched.

If tolerances fall below normal values, particularly tolerances in Sthe accessory parts which usually include several sets of expanding 5D wedges of different diameters, an overstrain can occur which the operator would not notice because there is no corresponding increase in the operating force. Experience has shown that with the use of an elbow lever drive in an 8 expander, the force requirements at the end of the working stroke are practically zero, i.e. the hand levers can be put together, almost without requiring any force. Consequently the operator loses any "feel" for the expanding procedure. Usually elbow lever presses are equipped with overload clutches in order to prevent an overload when all three elbow lever links are stretched, and consequently avoid the destruction of the system. The installation of overload clutches is however not possible in the case of hand tools for space and weight reasons.

Lo An expansion tool of the type described at the beginning is known U OC?$ LOOOS03 through patent 88 07 784, in which the free rotating cylinder S. consists of a roller whose cylinder surface, the so called rolling surface for the control mechanism, is placed in a complementary S recess which runs transversally to the axis of the expanding mandrel. But this reduces the friction between the cam and the expanding mandrel only negligible, because the roller slides in its recess with the cylinder surface, i.e. with the same diameter on which also the cam surface rolls. This merely causes the shifting of the friction and braking forces to another place, or the cam S will slide on the stationary surface of the roller even in case of a slight slow down. Such a mechanical system is also called S "indifferent". It does not produce any changes in the friction and S in the transversal forces.

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9 It would be desirable to create an expansion tool of the type described above, i.e. one with a control mechanism in the operating system in which the friction forces are reduced to a minimum, the expanding mandrel withdraws, the operating forces remain constant to a large extent over the entire period of the working stroke, so that the operator has a "feel" for the proper development of the expanding procedure, and in which ann overload cannot occur, even in an unfavourable tolerance situation.

In one broad form the present invention provides expansion tool for hollow working parts, said tool comprising a basic tool body having a borehole with a central axis and a first hand lever fixed thereto, an expanding mandrel placed in an axially sliding position in said borehole, said mandrel having an exterior tapered end protruding from said borehole and an inner end with two parallel sidewalls defining a channel therebetween, a freely rotatable member having a cylindrical surface located in said channel and journalled on a cylinder pin placed in said sidewalls, said pin having an axis which is perpendicular to the central axis of the borehole, a control mechanism mounted for rotation about a swivel pin in said tool body an having a second hand lever fixed thereto, said mechanism acting on said cylindrical surface to move said mandrel through a preset stroke when said first and second hand leers are moved relative to 30 each other, a set of radially movable expanding wedges connected to the basic tool body and acted upon by said exterior ge tapered end of said mandrel when said mandrel moves through sai.d stroke, and 35 a withdrawal device which connects the mandrel to the 'eeI 9a second hand lever.

This type of roller is always operational, and in contrast to the expander according to US-A 4 425 783 it also does not lose its efficacy should the expansion stroke be interrupted. A roller also does not require a return spring.

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0 0 10 The friction forces are thus reduced to a minimum compared to patent W fB 4 424 783, because the link pins, and with it the mounting areas have a relatively small diameter, and further because the contact line between the cam surface and the cylinder surface of the roller is always located on, or at least in close proximity, of the axis of the expanding mandrel.

an-^ Uo cs oW Compared to4BgES 88 07 7844the friction forces are reduced because the roller axis has a shouldered and definitely smaller diameter 10 compared to the cylinder surface of the roller, so that equal compression forces acting axially on the expanding mandrel produce a distinctly lesser counter torque or braking couple. Consequently, no transverse forces or at least no noticeable transverse forces act on the expanding mandrel.

**0 Furthermore, the withdrawal device for the retraction of the expanding mandrel is easily integrated into the operating system.

In the first form of construction the withdrawal device consisted of a tension member in the form of a rigid tongue, which can be made of a relatively thin metal plate, and can he placed in a narrow slit of the control mechanism, since it is not exposed to pressure. The tension member also prevents in a very simple fashion the twisting of the expanding mandrel in relation to the cam, without requiring a special slaving guide for the expanding mandrel S in the basic tool body.

With the corresponding course of the control. curve in relation to the axis one can also easily achieve that the operating force raains constan~t to a large extent over almost the entire angle of traverse of the hand lever, but at least over the last portion of the field of traverse, thus giving the operator the fu-eling that the expanding procadure is being completed. Finally, t-ie overloac.

of the components of the entire expansion tool is rendered impossible, since the contact betwe~en movable parts and stationary 4:parts manifests itself immediately in an increase of the operating t f ce, thus informing the operator that the expanding procedure has been completed.

*ood So Because of the play of the tongue in longitudinal direction, it is possible to avoid exerting pressure on the tongue at any point during the expanding procedure. However, the tongue pin is placed in such a. fashion in a slot in the tonque., that the expanding mandrel retracts immediately when the hand lever is swung back~.

a. *Because the tongue embraces the roll in its outer perimeter, the roll axis cannot twist opposite the tongue and thea tension member.

Therefore, it is a particular advantage, if the recess of the control mechanism is located in the middle, and has side walls running parallel to th_- side walls of the contro'l mechanism located in the basic tool body, the other end of the tongue has a ~QS cylindrical borehole surrounding the roller in its axial middle, and~ when the tongue has an extension beyond the borehole placed 12 in the parallel slot of the expanding mandrel, and the mentioned slot opens out into the slit which houses the roller.

Finally, it is particularly advantageous if the swivel axis of the control mechanism and the roll axis intersect the borehole axis.

In this case practically only forces parallel to the axis are created within the system, so that friction forces and wear between the expanding mandrel and the borehole in the basic tool body are avoided.

c °N cc.^2r<«2.t^ Another 4 form of construction ct- of the invention has the same roller placement but is characterized by the fact that: the control mechanism has a curved slit running along its 1S swivel axis, whose ends are at different distances from the swivel axis in accordance with the stroke of the expanding mandrel, and whose internal width corresponds to the diameter of the roller, and in which the roller slides in both directions of the movement of the expanding mandrel, and the control mechanism is placed at least partially between both side sheeks of the expanding mandrel.

o S a AS In a sturdy construction, the curved surface of the slit (or the curved part of the control mechanism) nearest to the swivel axis of the control 'mechanism can embrace the roll from behind, allowing the expanding mandrel to guide in both axial directions, i.e. also into the enforced withdrawal position.

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13 The control mechanism, which can be a stamped metal part made of a steel plate or can be forged as a single part together with the hand lever, requiring only little finishing on the surface of the slit, serves at the same time as a guiding element for the expanding mandrel and prevents the latter from twisting. It is understood that the thickness of the control mechanism corresponds, at least in certain parts, to the internal distance of the side cheeks of the expanding mandrel.

LO It is specially advantageous, if the ends of the curve shaped slit form a stop gauge in order to limit the angle of traverse of the swivelling hand lever, i.e. the curve arch of the slit is limited in a defined manner. This accomplishes two things: Firstly one stop 0* gauge limits the approximation of the hand levers to a minimum 15S distance in order to prevent a crushing of the fingers, secondly the operating force of the hand lever at the end of the expanding procedure is also defined.

4 It is specially easy to make the course of the curved slit such, 0 in relation to the swivel axis of the control mechanism and to the S roller, that the operating force on the movable hand lever remains essentially constant over the last 20 degrees of the angle of traverse of the hand lever.

SOse S With regards to the assembly and manufacture, the size, the weight and the torsion rigidity of the movable hand lever in relation to the basic tool body, it is of particular advantage if the control mechanism forms one end of the swivelling hand lever, 14 and has an eyelet to pass the link pin through, which penetrates a slot in the basic body, and is located laterally in the same, outside the expanding mandrel, on the side opposite the hand levers on both sides of the slit in the basic body.

Material costs and weight can also be positively influenced if the control mechanism is built in the form of a plate shaped component, and is placed in a slit with parallel walls in the movable hand lever. This for instance allows a construction in which the basic *ie 1 O tool body and both hand levers are made of a light alloy, but the control mechanism is made of steel.

*0 to A particularly durable expansion tool which has a basic tool body with a thread, placed in a known manner concentrically to the I1 expanding mandrel, and to which the set of expanding wedges can be screwed by means of a threaded sleeve, can be manufactured if the thread is mounted on the outer surface of a connecting piece, which is connected to the basic tool body by means of a hollow cylindrical extension, and when the continuous borehole of the Co connecting piece and the extension form the axial guide way for the expanding mandrel.

0 pre..%rec The following figures 1 to 9 describe in more detail three forms of construction of the object of the invention: .e I t 15 They show: Figure 1 Figure 2 Figure 3 0C 01.t- 00 *L' 0 0 006 09 0 00 00 Figure 4 Figure 5 Figure 6 Figure 7 in a first form of construction, an axial section of the basic tool body with all essential operating parts; a top view from above the object in figure 1; an explosion view of the expansion tool according to figure 1; an enlarged partial detail of figure 1 in a sectional plane vertical to the drawing plane along the axis A-A; a diagram with a comparative representation of the operating forces according to the prior art, and according to the object of the invention; in a second form of construction, a lateral view of essential parts of the expanding apparatus at the end of the expanding procedure, i.e. with hand levers joined to a maximum, together with a representation in perspective of an unscrewed set of expanding wedges; a lateral view of the object in figure 6, but before the beginning of the expanding procedure, i.e. with hand levers at a maximum distance; I I I 16 Figure 8 the upper end of the expanding mandrel with roller, rotated by 90 degrees opposite figure 7, and on an enlarged scale, and Figure 9 a top view of essential parts of a third form of construction with a steel control mechanism mounted in a hand lever of light metal.

Figures 1 to 4 show an expansion tool 1 with a basic tool body 2, (O originally built as a swivel, to which a radially projecting first i. hand lever 3 is attached. The basic tool body 2 has an axis A-A and a borehole 4 'concentric to the axis, in which is mounted an expanding mandrel 5 which slides in axial direction, and whose one end 5a is conically tapered and protrudes from the basic tool body 2.

The end facing away from the end 5a of the expanding mandrel has a slit with parallel walls 6 in a place situated beyond the hand lever 3, into which opens the borehole 4. On both sides of the slit 0O 6 two cheeks 8 and 9 have come to a stop (Figure forming so to lot.. speak the bearing block for a control mechanism 10 in the form of a cam.

6 This control mechanism 10 has a borehole 10a which receives an axis S 7, placed in the slit 6, in which the axis center of the axis 7 runs perpendicular to the axis A-A, intersecting the same.

The control mechanism 10 has a cam 11 running eccentrically to the axis 7 and the borehole 10a, which acts on the expanding mandrel in a fashion which will be described in more detail below.

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17 The control mechanism 10 is connected to a second hand lever 12 forming one single piece, which protrudes laterally from the slit 6. Both hand levers 3 and 12 have handles on their ends, not shown here, so that both hand levers can be used like tongs in relation to the basic tool body 2. Figure 1 shows both hand levers 3 and 12 in its closest position. It can however be seen, that the second hand lever 12 can be swung counterclockwise in an angle of traverse of more than 90 degree, i.e. beyond the axis A-A, from its starting position shown in the drawing. The cam 11 has a geometric form in (10 relation to the axis 7, which allows the optimal flow of the working part and the optimal development of the operating forces as a function of the angle position of the hand lever 12, also allowing the operating force on the hand lever 12 to remain constant over the last 20 degrees of the angle of traverse. This LS type of course of forces is shown in figure 5 in the middle curve.

The basic tool body 2 has on the end facing the end 5a of the expanding mandrel 5, a thread 13 and a ring shoulder 14 for the mounting of a set 15 of single expanding wedges 16, which are ~go distributed on the circumference of the expanding mandrel 5. The expanding wedges 16 can be slid in radial direction by means of a !rivet 17, and are guided and supported in the inside facing flange of a screw cap 18, which is screwed to the thread 13 against the ring shoulder 14. Figure 1 shows that the set of expanding wedges S15 can be pushed to the tside radially, IS 15 can be pushed to the outside radially, I

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18 by inserting the conically shaped end Sa into the expanding wedges 16. The retraction is accomplished with an annular spring 16a which, however, due to the existing automatic locking cannot displace the expanding mandrel The expanding mandrel has in its inner end two side cheeks 5b and which enclose a slit 5d with parallel walls, located in the middle. In this slit a cylinder 19 has been placed by means of a cylinder axis 19a in a free rotating position; the cylinder axis o1 19b of the cylinder 19 runs parallel to the axis 7. The cylinder surface 19b of. the cylinder 19 protrudes through the slit 5d only towards the top, and sideways in the direction of the hand lever 12, as shown in figures 1 and 4. This way the cylinder can roll

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SS." off the cam 11 of the control mechanism 10 (Figure However, S1 the cylinder surface 19b does not touch parts of the surface of the expanding mandrel 5: The cylinder 19 in the expanding mandrel is only supported by the cylinder axis 19a.

A withdrawal device 20 is mounted between the expanding mandrel So and the hand lever 12 for the enforced withdrawal of the expanding mandrel from the expanding wedges; the expanding mandrel 5 is connected to the control mechanism 10, and also with the hand lever 12 by means of a rigid tcngue 21. The rigid tongu- consists of a stamped tin plated with parallel faces, with a cylindrical borehole .;25 z21a on one end, and a slot 21b on the other end. The tongue 21 is connected to the control mechanism 10 through the slot 21b with a tongue pin 22. The tongue 21 19 surrounds the cylinder 19 in its axial middle by means of the cylindrical borehole 21a. The tongue 21 has an extension 21c beyond and underneath the borehole 21a, which engages into the slit with parallel walls of the expanding mandrel 5. This occurs with the least possible play, in order to prevent the twisting of the expanding mandrel 5 with the cylinder 19 in relation to the tongue 21. The slit 5e opens into the middle of the slit 5d in which the cylinder 19 is mounted (Figure 1, in connection with figure 4 in particular). The extension 21c can realize swivelling and S. (0 longitudinal movements inside slit 5e. The control mechanism 10 has a borehole 10a, in which the axis 7 is placed, when the device is assembled. Both ends of axis 7 are placed in two aligned boreholes

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in both side cheeks 8 and 9. Figure 3 shows only one of the s*oe boreholes 8a.

The control mechanism 10 also has a borehole 10b, which runs eccentrically to the borehole 10a, and in which the tongue pin 22 is placed, when the device is assembled. More specifically, the *g borehole 10b is interrupted in the middle by a slit shaped recess 5'o 10c, into which the upper end of the tongue 21 is mounted in a manner that protects against torsion. The side walls of the recess 10bc run parallel to each other, and parallel to the side walls of the control mechanism 10, guided in the basic tool body 2 by means of the side cheeks 8 and 9. The width of the recess 10c is only S slightlv larger than the thickness of the tongue 21.

ease 06 0 20 Figure 1 in particular shows that the slit shaped recess 10c has such a circumference in relation to axis 7, that the base lod of the recess 10c cannot touch the tongue 21 in any possible position of the hand lever 12.

Figure 5 shows a diagram in which the difference in diameter D, and the double expansion path is shown in millimerers on the abscissa, and on the ordinate the operating force between the two hand levers 3 and 12 is shown in dimensionless units. The reason for using dimensionle,-.,s units on the ordinate is because the operating force naturally depends on the diameter to be expanded, the wall thickness, and the deformation characteristics of the working part. The first millimeter path in the diameter expansion =0 the expanding wedges occurs in the so called idle stroke. In IS this case only reduced friction forces have to be overcome in the system. The working part is then deformed elastically up to a point P, followed by a plastic deformation of the working part until the part has reached the final diameter (dotted line) The slight spring-back after releasing the working part should be disregarded.

.)0 The upper curve C1 shows the force distribution in an expansion tool, in which the cam 11 glides on the inner blunt end of the expanding mandrel. it can be clearly seen, that the force requirement increases progressively to a very high final value. 0:0&0: Go

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21 The lower curve C2 shows the force distribution in a elbow lever expander, and it is clearly visible that the force requirement after exceeding a maximum value, drops drastically to a very low value. This decrease of the operating force, however, does not 5 imply a decrease of the forces in the system. Quite the contrary @6 is the case: since the stretched position of the liN-ks of the elbow lever are reached in the area of the dotted line, the forces necessarily increase to the infinite value, provided there is a corresponding counteracting force, which for instance could also t' 10 occur unintentionally due to a too low tolerance.

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The middle curve C3 describes the force distribution in the operating system of the invention, and it is clearly visible that the operating forces remain essentially constant, at least in the last portion of the expansion path of the part. If during this process any parts touch each other inside the operating system, a sudden force increase occurs in the direction of the curve section C4, i.e. the operator immediately receives a signal informing him that that part cannot be expanded any further.

*o 6 *0 6 S 60 It is of course possible to impart the control mechanism or the cam 11 a course that will cause the operating forces to decrease drastically towards the end of the procedure. This for instance would be the case if the cam 11 would run almost tangent to a DS radius running through axis 7, in the section that is processed last. But on the other hand it is impossible to decrease the force requirements in an operating system according 22 to curve Cl or to increase the force requirements correspondingly in an elbow lever system acording to curve C2. An elbow lever system has the unavoidable characteristic that the output forces go towards infinity when all link axles are stretched, while the operating forces simultaneously practically drop to zero. The fact that the operating forces can be influenced is also the main reason why the known cam drive of the expanding mandrel has maintained its position on the market for decades.

Figures 6 and 7 show expansion tool 101, which has a basic tool body of steel 102 with a first, rigidly mounted hand lever 103 also made of steel, a borehole 104, and an expanding mandrel 105 with a tapered exterior end 105a which protrudes from the borehole, and is placed in the borehole in an axially sliding position. In the IS opposite end of the expanding mandrel 105, which also protrudes from the basic tool body 102, a free rotating cylinder 107 is placed by means of a cylindrical roller axis 106, whose pivot is perpendicular to the axis of the mandrel.

The basic tool body 102 has an adapter 102a in which the expanding *o S mandrel is placed, and which has the approximate shape of a square with rounded corners and edges. The expanding mandrel 105 protrudes with the cylinder 107 in a upward direction from the adapter 102a. Between the adapter 102a, and the rigid hand lever DS 103 made of one piece, which has a T-shaped cross section

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23 with a flange 103a placed below, is a transition piece 102b with the corresponding bevelled wall surfaces to prevent gradations and kinks (the design corresponds approximately to that according to figure The adapter 102a and the trani~~- piece 102b have a 5 slit shaped recess 102c which opens towards the top, and is represented with the dash-dot line, into which the control mechanism 109, described in more detail below, can be introduced (Figure 6).

10 The swivelling control mechanism 109 which acts on the cylinder 107, is also placed in the basic tool body 102 by means of a swivel axis 108; the control mechanism is connected, forming one piece, to a second swivelling hand lever 110, which also has a T-shaped cross section, in this case with the flange 110b located on the IS( top.

*.0 The control mechanism 109 and the crosspiece ll0c have the same thickness. Through the control mechanism 109, the expanding mandrel 105 can be moved,clockwise by activating the hand levers, into the Do position according to figure 6, emerging from the basic tool body at a preset stroke, and moving against a set of radially movable expanding wedges 112, which can be connected to the basic tool body, and which are placed in a threaded sleeve. The threaded sleeve 112 together with the expanding wedges 111 can be screwed aS to a counterthread 112a, which is placed concentrically to the expanding mandrel 105 on the underside of the adapter 102a, The parts 111 and 112 also called expanding head and its operxin are prior art, therefore a more detailed explanation is not required.

24 The description "above" and "below" refer to the position shown in the figures.

The cylinder axis 106 has a noticeably smaller diameter than the cylinder 107 and its rolling surface 107a, which during the work procedure rolls off the first cam 113 of the control mechanism. By means of the cylinder axis 106, the cylinder 107 is placed in the same fashion as shown in figures 1 and 4 in and between the two side cheeks 105b and 105c, limited inside by two parallel walls, 10 of the expanding mandrel, i.e. in a slit.

The control mechanism 109 has a slit 114 which spans from one side to the other, running in a curve around the swivel axis 104, and which is limited on one side by the first cam 113, and on the ~5 opposite side by the second cam 115. The inner width of the slit 114 corresponds at each Ioint to the diameter of the cylinder 107 (plus a small play), so that the cylinder 107 is enclosed the slit 1l', and is mechanically guided in the two directions of the expanding mandral, with the cam 113 causing the expanding ~0 procedure, and the eam 115 which encloses the cylinder 107 from behind, bringing about the enforced withdrawal. The withdrawal device 126 is formed by a part of the control mechanism 109 which supports the cam 115.

SIn the area of the cams 113 and 115, the control mechanism 109 fits into the slit between the side cheeks 105b and 105c of the expanding mandrel with little play, so that a twisting of the mandrel between the two side cheeks is prevented.

25 Both half cyl indri cal -concave shaped ends 116 and 117 of the curved slit 114 are connected to each other by the cams 113 and 115, and their center of curvature which in both possible end positions coincide altrnatively with the axis of the cylinder 107, are at Sdifferent distaaces from the swivel axis 108, in accordance with the stroke of the expandingi mandrel The course of the curve is a. monotonous, i.e. no position of the expanding mandrel is passed S twice during the swinging o. the control mechanism in one '.direr.tion.

The ends 116 and 117 form stops limiting the angle of travo~rse of the swivellin4 hand lever 110, in which one stop (end 116) limits the approximation of the hand levers tg a minimum distance in order to avoid a crushing of the fingers (Figure The other stop (end 15117) limits the opening movement of the hand lever in accordance with figure 7.

The curved slit 114 has such a course in relation to the swivel axis 108 of the control mechanism 109 and to the cylinder 107, that ?othe operating force used on the movable hand lever 110 remains essentially constant over the last 20 degrees of the angle of traverse of the hand lever.

The control mechanism 109 for s one end of the swivelling hand lever 110 made of forged steel, and has an eyelet for the placing of the swivel axis 108. The latter penetrates a slit 119 in the basic tool body 102, and is placed in the same laterally, outside of the expanding mandrel 105 on the side opposite the hand levers 103 and 110, on both sides oA2 the slit 119.

26 In order to prevent any hindrance between the eyelet 118 and the expanding mandrel 105, the latter has a milled slot 120 on one side in an extension of the slit between the side cheeks 105b and 105c.

One can also see that the swivel axis 108 is clearly closer to the counterthread 112a than the axis 7 in the construction form according to figures 1 to 4.

0g Because of the slit 114, the part of the control mechanism 109 facing the swivel axis 109 forms a bend, which could also be called a crank which support the cam 115. In order to maintain to a large extent the full cross section of the expanding mandrel, the control mechanism 109 -has a recess 121 on the side of the eyelet 118 (Figure so that the lower edge of the control mechanism 108 practically wraps itself around the expanding mandrel in the above 15 mentioned slit during the final position, as seen in Figure 6.

e* It is quite baffling that although the swivel axis 108 is traversed in relation to the axis of the expanding mandrel 105, no disturbing transverse forces act on tbc expanding mandrel, which could caus ,n the expanding mandrel to slow down.

Figure 9 shows another form of construction 201. In this case the control mechanism 209 consists of a plate shaped piece also made of steel and rigidly mounted in a parallel walled slit 222 of the movable hand lever 210a. This hand lever has the shape of a housing 223 located in the expanding mandrel 205, which in -27 Figure 9 covers the basic tool body, and also in a lateral view which is not shown encloses the expanding mandrel 205 and the cylinder, thus also covering them; The basic tool body and both hand levers (of which only 210 is visible) in this case consist of a light alloy, which results in a considerable weight reduction.

The counter thread 112a is placed in this case on the outer *~*su~rface of a coupling piece 224, which is connected to the basic tool body with a hollow cylindrical extension. For clarification IC) we refer to Figure 7 in which this extension 125 is shown in a dash line in order -to c *,aracterize its geometry and its position. The coupling p'Lece 22 and the extensidon 125 which form one single O piece and are made of steel, have a borehole that passes through, 0 41 and which forms the axial guide 1..the expanding mandrel 105 and [o I 205. It is understood that, in case of a basic tool body made of' steel, the use of parts 224 and 125 is not necessary.

Also the position of the swivel, axis 108 in a plane underneath of a plane placed across the cylinder axis 106 (both planes o perpendicular to the mandrel axis A-A) i.e. between any possible position of the cylinder axis 106 and the tapered end 105a of the expanding mandrel 105 is of special importance in view of the compact construction of the object of the invention. This makes a prolongation of the basic tool body 102 in the direction of the Saxis A-A upwards and beyond the end of the expanding mandrel unnecessary.

Claims

1. Expansion tool for hollow working parts, said tool comprising a basic tool body having a borehole with a central axis and a first hand lever fixed thereto, an expanding mandrel placed in an axially sliding position in said borehole, said mandrel having an exterior tapered end protruding from said borehole and an inner end with two parallel sidewalls defining a channel therebetween, a freely rotatable member having a cylindrical surface located in said channel and journaled on a cylinder pin placed in said sidewalls, said pin having an axis which is perpendicular to the central axis of the borehole, a control mechanism mounted for rotation about a swivel pin in said tool body and having a second hand lever fixed thereto, said mechanism acting on said cylindrical surface to move said mandrel through preset stroke when said first and second hand levers are ioved relative to each other, a set of radially movable expanding wedges connected to the basic tool body and acted upon by said exterior tapered end of said mandrel when said mandrel moves through said stroke, and a withdrawal device which co>. Jts the mandrel to the second hand lever.

2. Expansion tool according to claim 1 wherein the control mechanism comprises a cam surface formed as one 30 wall of a slot, and the withdrawal device comprises a cam surface formed as the opposite wall of said slot.

3. Expansion tool according to claim 2 wherein said slot is curved about the swivel pin and has opposite ends at S different distances from the swivel pin in accordance with 35 the stroke of the expanding mandrel, the width of the slot CCCf? 29 corresponding to the diameter of the freely rotating member and guiding the movement of the expanding mandrel in both directions, the control mechanism being at least in part guided between the two side walls of the expanding mandrel.

4. Expansion toc¢l according to claim 3 wherein the ends of the slot form stops which limit the angle of traverse of the hand levers. Expansion tool according to claim 3 wherein the slot has such a course with respect to the swivel pin of the control mechanism and the cylinder, that the operating force on the second hand lever is essentially constant over at least the last 20 degrees of the angle of traverse of the hand lever.

6. Expansion tool according to claim 3 wherein the inner end of the expanding mandrel protrudes from the basic tool body.

7. Expansion tool according to claim 3 wherein the control mechanism forms one end of tho second hand lever, and has an eyelet through which said swivel pin passes, which pin penetrates a channel in the basic tool body, and is placed in same laterally, outside of the expanding mandrel opposite the hand levers on both sides of the channel in the basic tool body. 3. Expansion tool according to claim 3 wherein the swivel pin is set on a first plane located between a second plane, in which the cylinder pin runs in any possible position, and the tapered end of the expanding mandrel, where both planes run perpendicularly to the 30 central axis.

9. Expansion tool according to claim 3 wherein the seo control mechanism is in the form of a plate and is fixed in a parallel walled slot of the movable hand lever.

10. Expansion tool according to claim 3 wherein the basic 35 tool body and both hand levers are made of light alloy, S PAZ \NKA17 30 and the control mechanism is made of steel.

11. Expansion tool as in claim 10 wherein the basic tool body comprises a coupling piece having a hollow cylindrical extension which is coaxially received in the borehole of the basic tool body, said coupling piece having an external thread concentric to the expanding mandrel, said set of expanding wedges comprising a threaded sleeve screwed onto the external thread of said coupling piece.

12. Expansion tool as hereinbefore (escribed with reference to the accompanying drawings. DATED this 27th day of May 1993 ROTHENBERGER WERKZEUGE-MASCHINEN GmbH Pat,-at Attorneys for the Applicant: F.B. RICE CO. q..4 0 so 0 e: *04 00000 0 0000 ^9^